Effects of Different Varieties of Maca (Lepidium meyenii) on Bone Structure in Ovariectomized Rats

合集下载

蜜环菌Am-07-22发酵对玉米赤霉烯酮降解效果影响及机理初探

王泽贤，赵宇楠，贾丹丹，等. 蜜环菌Am-07-22发酵对玉米赤霉烯酮降解效果影响及机理初探[J]. 食品工业科技，2024，45（1）：162−169. doi: 10.13386/j.issn1002-0306.2023030070WANG Zexian, ZHAO Yunan, JIA Dandan, et al. Effect and Mechanism of Armillaria mellea 07-22 Fermentation on the Degradation of Zearalenone[J]. Science and Technology of Food Industry, 2024, 45(1): 162−169. (in Chinese with English abstract). doi:10.13386/j.issn1002-0306.2023030070· 生物工程 ·蜜环菌Am-07-22发酵对玉米赤霉烯酮降解效果影响及机理初探王泽贤，赵宇楠，贾丹丹，纪晚唐，许　丁，向杨玲，蔡　丹*，刘景圣*（吉林农业大学食品科学与工程学院，小麦和玉米深加工国家工程研究中心，吉林长春 130118）摘　要：本研究以蜜环菌Am-07-22为试验菌株，采用真菌生物发酵的方式降解玉米赤霉烯酮（ZEN ），对蜜环菌降解ZEN 的降解效果进行研究，包括菌株对不同浓度ZEN 的降解效果以及不同培养时间、培养温度、初始pH 和接种量对菌株降解ZEN 的影响。

然后对降解机理进行初探，分析了菌丝体、发酵上清液、细胞内容物对ZEN 的降解作用，并研究了不同发酵时间、pH 、金属离子对发酵上清液降解ZEN 的影响，以及降解效果与菌株产漆酶活力的相关性分析。

结果表明：蜜环菌Am-07-22对ZEN 的降解效果良好，当ZEN 浓度为5 μg/mL 时，最适降解条件为培养时间8 d ，培养温度27 ℃，初始pH7.0，接种量10%，此时对ZEN 的降解率为78.72%。

麦芽及其酿造性能（EBC）

When buying malt, the brewery is looking for a product, which will yield the most economic extract (wort) and will operate satisfactorily under brewhouse conditions and throughout the brewing process. Malt, which is difﬁcult to handle can cause quality and process problemsinvolving additional costs. T o ensure that an appropriate malt is supplied the brewer will set and agree a suitablespeciﬁcation with his supplier. B rewhouse performance of the malt isaffected by the interactions between malt quality and:• The type of brewing process.• The type of brewhouse equipment.• Other materials that are used with the malt e.g. adjuncts.The brewer has certain objectives when purchasing malt:• T o recover a high yield of sugar (extract) from the malt.• That the malt will operate satisfactorily in the plant without additional processing or treatments.• The malt will pass through the plant within the required cycle time (run off time).• The wort produced from the malt provides all the necessary nutrients to ensure a satisfactory fermentation.• The malt delivers the ﬂavour and process requirements of the brewer and his customers.All of these beneﬁts are supplied on consistent and reliable basis.Malt speciﬁcationsBarley, and the malt produced, is derived from natural living material, and hence subject to all the variations which can occur as a result of genetic and environmental conditions. It follows that no two batches of malt are alike.Malt is analysed in accordance with standard industry tests such as the IoB, EBC and ASBC methods of analysis. However, standard malt speciﬁcations are not always a reliable indicator of how well the malt will perform in the brewery. Brewers and maltsters are continually looking for better predictions of brewing performance of a malt.Barley varietyThere is a list of approved barley varieties for malting. Each barley variety has its own characteristics through its genetic make-upwhich will determine certain properties ofimportant to brewing. Some varieties producebetter malt than others.Barley variety will inﬂuence malt quality interms of variables such as:• % nitrogen or protein in grain (see later)• % beta-glucan after malting• Size and homogeneity of grain – plumpergrains yield better extracts and are easier tomalt and mill. Most brewers specify that allgrains should be ≥2.2 mm• Not all barley varieties have similar abilities toproduce enzymes, this can be importantparticularly when using high levels ofadjunct.The environment also inﬂuences thesefactors, e.g. weather, soil type and the use offertiliser.The barley variety used to make the malt isconsidered important not only because of itsbrewing properties, but because of specialcharacters it gives to the ﬁnished beer. T odaymany traditional ale brewers still specify MarisOtter as they believe it makes better qualitybeer, even though this variety is no longerrecommended because of its poor yield andagronomic performance.Extract YieldExtract is a measure of the amount of sugarrecovered from the malt after mashing. Theextract value is based on a laboratory mash.There are two basic laboratory proceduresused for measuring extract.• The IoB method, which involves mashing10% malt with, distilled water and letting themash stands for 60 minutes at 65°C. Theextract is measured as the speciﬁc gravity ofthe ﬁltered solution at 20°C. The results areexpressed as litre degrees per kilogram.• In the EBC (European Brewery Convention)method two mash stand temperatures of45°C and 70°C are used. The Extract isexpressed % sugar (sucrose) over totalweight of maltExtract value for typical malt made fromstandard 2-row barley.Malt extract “dry” IoBl°/kg EBC°PlatoStandard ale malt 305 – 315 81 – 82Standard Lager malt 300 – 310 80 – 81Both methods give a prediction of brewhouseperformance. However under laboratoryconditions mashing are not optimised whichexplains how extract recoveries of greaterthan 100% can be achieved with moremodern mashing and wort separationtechniques such as the modern mash ﬁlter.The factors which favour high extractrecovery include:1. Varietial effects – different barley varietiesgive different yields2. The total nitrogen content – the higher thenitrogen the lower the extract.3. Corn size – large even corns size give bettermalting and milling performance.4. Modiﬁcation – the malt should beadequately but not over-modiﬁed – seelater.5. Enzyme capacity – the malt should havesufﬁcient enzymes to degrade the starchand convert it to simple sugars.6. Low in gums – extract recovery can bereduced by the presence of gums –particularly beta-glucans in the malt. Thisproblem is often resolved by the addition ofexogenous beta glucanase.Malt Nitrogen (usually expressed as %nitrogen)The higher the level of nitrogen the lower the% extract. Therefore brewers specify the %nitrogen or protein in malt.T ypical % nitrogen is in the range of :Ale Malt 1.4 – 1.6%Lager Malt 1.6 – 1.8%(Nitrogen is sometimes expressed as% protein which is % nitrogen x 6.25)However nitrogen plays an essential role inthe quality of the beer:• Nitrogen, in the form of amino acids, isrequired for yeast growth with typical valuesof 160 to 240 mg/l depending on yeaststrain and wort gravity.• Hydrophobic nitrogen from the malt providethe beer foam and head retention in beer.• Some long chain polypeptides causecolloidal instability (chill and permanenthaze) in beer and have to be reduced in thebrewing process.• Proteins and polypeptides contribute to thetexture and mouthfeel of the beer. Excessiveremoval leads to a thin tasting beer withpoor foam.It is important to ensure a avoid excessnitrogen in the barley, but ensure sufﬁcient ofthe nitrogen available is broken down tosoluble nitrogen. The ratio of total to solublenitrogen is an important indicator or brewingperformance. Most of the nitrogen breakdownoccurs during malting.Technical Summary 10By Tim O’RourkeContinuing this series oftechnical summaries forthe Institute & Guild’sAME candidates.Malt speciﬁcations & brewing performanceMoisture (usually expressed as % moisture) The lower the % moisture, the higher the extract in the malt. Malt speciﬁcations express the extract as “extract dry” or “extract as is”–which includes the moisture content.The darker the malt colour, the higher or longer the kilning time. This results in lower % moisture. Because of their darker colour ale malts tend to have a lower % moisture than lager malt.Kilning uses a large amount of energy. The next process stage after kilning is mashing when the malt is re-hydrated, There is no beneﬁt in excessive moisture reduction and the trend is to move to higher lager malt moistures to reduce energy costs. For safe storage and good milling performance malt moisture should not exceed 6%.The higher the moisture, the lower the extract yield per tonne of delivered malt. This has to be adjusted in the price since the brewer wants to pay for malt not water.T ypical % moisture values for standard malts: Standard ale malt = 2 – 3% moisture Standard lager malt= 4 – 6% moistureColourDuring kilning chemical reactions take place between the malt components to produce colour compounds. There are a number of colour and ﬂavour reactions. The principal reaction is between amino acids and sugars called the “Maillard reaction” which produces both colour and ﬂavour active compounds.The higher the kilning temperature, the greater the amount of colour compounds produced. As well as producing colour, these compounds also contribute to ﬂavour.The colour of the malt is based on the colour obtained from the IoB or EBC mash using a 10% solution. This colour value provides an approximate indicator of ﬁnal beer because it is based on a dilute laboratory mash with an original gravity of 1030°(8°Plato). Further colour develops during wort boiling.ModiﬁcationBefore the brewer can break down the starch in malt to sugars during mashing, the maltster has to break down the cell structure in the endosperm to make the starch granules accessible. This process is called modiﬁcation and is the most important measurement when predicting brewing performance and extract yield from malt.Modiﬁcation gives a measurement of how evenly the cell structure in the endosperm has been broken down during the malting process. Enzyme activity starts from the embryo and the aleurone layer surrounding the endosperm to break down the protein and beta-glucan cell walls surrounding the starch granules (see Figure 1).The process of modiﬁcation has the effect of stripping away the cell wall structure and is shown in the two electron micrographs (Figures 2 and 3).The degree of modiﬁcation can be measured in a number of ways:Direct observationThe electron micrographs clearly show thedegradation of the cell walls. This is acomplicated and expensive technique forroutine analysis.However, the presence of cell wall materialcan be detected using a calcoﬂuor stain. Thecalcoﬂuor dye binds with beta-glucans (cellwall material) and ﬂuoresces under UV light.Thus if sectioned grains are exposed to thisdye those parts of the corn rich in beta-glucanwill ﬂuoresce. This technique can be used todetermine both the proportion of corns thathave modiﬁed as well as the extent ofmodiﬁcation within individual corns.By taking a series of transverse sectionsthrough the gain it is possible to make directobservation of the endosperm and evaluatethe degree of modiﬁcation. It is found thatthese observations correlate well with brewingperformance.Indirect measurementsAnother way of measuring modiﬁcation isassessing factors inﬂuenced by thebreakdown of the endosperm structure in thegrain:1.During malting the protein matrix, whichsurrounds the starch granules inside eachstorage cell is broken down. The greater thevalue of soluble nitrogen, the higher themodiﬁcation. The IoB analysis it is usuallyexpressed as the “Soluble Nitrogen Ratio”(SNR), which is the soluble nitrogen/totalnitrogen expressed as a %. The EBC methoduses a similar ratio based the EBC mashwhere it is called the Kolbach Index.2. Unless the malt is fully modiﬁed a number ofcells within the endosperm will not bedegraded and will remain intact with coarsermilling. When the malt is mashed theenzymes will not be able to penetrate thecells and gain access to the starch. Thesecells are ruptured with ﬁne milling and theextract can be recovered. Anothermeasurement of modiﬁcation is thecourse/ﬁne difference, which measures thedifference in extract yield between ﬁnelyand coarsely ground malt. The smaller thedifference the better the modiﬁcation.3. During malting the cell walls in theendosperm are dissolved away making thegrain softer and easier to mill. It is possibleto use this property to measure the degreeof modiﬁcation, by measuring the amount ofenergy required to grind the malt (Friability).The method takes 50 grams of malt which ismilled with a constant pressure over a meshscreen. The well modiﬁed grain will fallthrough the screen leaving the chunks ofunder-modiﬁed malt. The weight of groundmalt indicates the degree of modiﬁcation. Italso measures the homogeneity orevenness of modiﬁcation.4. Cold water extract measures the amount ofsugars broken down and released duringthe malting process. – higher cold waterextracts indicate higher modiﬁcation (seeTable 1).It is important to use malt that has beencorrectly modiﬁed:In under-modiﬁed malt all the cell walls have Figure 1 – Process of modiﬁcation of a barleycorn.Figure 2. Before – showing the beta glucan cellwalls surrounding the starch granules in theendosperm before in barley before malting.Figure 3. After – showing how the cell structurehas been stripped away exposing the starchgranules,which can now be degraded byenzymes during mashing.Thanks to Professor G. Palmer,Heriot Watt University,forpermission to use the electron-micrographs.Index of modiﬁcation Pale Ale Malt Lager Malt Kolbach % (Sol N/Total N) 38 – 39 40 – 43Course/Fine difference (l°/kg) 3– 6 2 – 3 Friability % ≥95 ≥95Homogeneity % ≥88 ≥82Cold water extract % 1.8 – 2.0 2.0 – 2.2 Table 1: Typical speciﬁcation for modiﬁcation in pale ale and wellmodiﬁed lager malt.not been broken down, it usually has a lower soluble protein content (SNR is lower) and there may still be small starch granules present which can give starch conversion and haze problems. Under-modiﬁed malt will give brewhouse problems and give poor extract recovery.In over-modiﬁed malts the cell structure is fully broken down, the soluble protein is higher (high SNR), and most of the small starch granules have be broken down. It is much easier to recover but extract from overmodiﬁed malt, but some extract may have been used up during the malting process. Excessive nitrogen breakdown may lead to loss of foam positive proteins and poorer beer foam performance.Enzyme Activity.The principal activity of malting is to encourage the barley to produce its own enzymes. Some of the enzymes are required during malting to modify the corn structure. The other enzymes, principally the Diastase enzymes (which break down starch) are required to work during mash conversion in the brewhouse.There are two principle diastatic enzymes:• Alpha amylase which randomly hydrolysesthe starch to produce shorter chains andreduces the viscosity. The activity of theenzyme is measured by the length of timerequired to break down a standard starchsolution to a speciﬁc colour standard usingan iodine indicator. The activity is expressedas dextrinizing units (DU).• The other enzyme, beta amylase attacks thenon reducing end of the starch chain toproduce maltose sugar. The enzymic poweris measures as DP (Diastatic Power in°Lintner) in the IoB methods of analysis.The DP is around 35 – 40 for standard AleMalts, but can be as high as 100 to 125 forlager malts and over 160 for some high proteinsix row North American malts. The latter maltshave far more enzymic power than theyrequire just to convert the starch from the maltitself and enable the brewer to use high levelsof unmalted starch adjuncts (see a laterseries.)In EBC analysis the diastatic power ismeasured as °WK (Windisch-Kolbach units).The value of °WK can be converted to °Lintnerby the formula:DP °Lintner = (°WK + 16) / 3.5The contribution of malt to ﬂavourMalt is the principal ingredient in beersupplying sugar to the yeast which producesalcohol. In addition to sugar, yeast requires avariety of essential nutrients which arenecessary for satisfactory yeast growth andnutrition. The typical components requiredinclude:• Simple sugars (glucose, maltose andmaltotriose) for fermentation• Amino acids (free amino nitrogen > 150 mg/l)for yeast growth• Mineral ions for enzymes – typically zinc,copper etc• Vitamins for healthy growth• Some lipid material for cell wall production –although yeast manufactures most of thesecompounds using available oxygen in thewort.During fermentation yeast will produce anumber of ﬂavour compounds as a directconsequence of metabolising brewing wort.Changes in wort composition will inﬂuencethis metabolism and hence the ﬂavour of thebeer produced.Malt also contributes directly to the appear-ance ﬁnal character and taste of the beer:Murphy Halfpage adImportant JIB news for membersPlease note that as an added service to members, the Journal of the Institute of Brewing(JIB) is now available online on the IGB website and may be downloaded fromw Printed copies of the JIB will continue to be available to members whospeciﬁcally request a copy.If you wish to continue receiving your copy by post please contact Nicky Baker at the IGB.Tel:+44(0)74998144email:*******************.ukThe Institute & Guild of Brewing。

备战新高考英语模拟卷带答案

【赢在高考·黄金8卷】备战2024年高考英语模拟卷（北京专用）黄金卷01（考试时间：120分钟试卷满分：150分）注意事项：1．答卷前，考生务必将自己的姓名、准考证号填写在答题卡上。

2．回答选择题时，选出每小题答案后，用2B铅笔把答题卡上对应题目的答案标号涂黑。

如需改动，用橡皮擦干净后，再选涂其他答案标号。

回答非选择题时，将答案写在答题卡上。

写在本试卷上无效。

3．考试结束后，将本试卷和答题卡一并交回。

第一部分知识运用（共两节,满分30分）第一节完形填空（共10小题;每小题1.5分,共15分）阅读下面短文, 掌握其大意, 从每题所给的A、B、C、D四个选项中, 选出最佳选项, 并在答题卡上将该项涂黑。

（2023秋·北京海淀·高三统考期中）On a sunny afternoon, Anthony Perry stepped off the train at Chicago’s 69th Street station. The 20-year-old, who worked nights in a grocery store, was on his way to see his 1 .On the platform, something unthinkable happened: a man fell over the edge and onto the electrified train tracks! As Perry and other horrified passengers watched, he shook uncontrollably as the 2 moved through his body.“Help him!” someone cried. “Please, someone!”Perry couldn’t just stand there and 3 . He sat at the edge of the platform and eased himself down.4 all rails between the man and him were electrified, he quickly leaped towards the victim, using a high-knee technique from his high school football days.Perry soon reached down and grasped the victim’s wrist. 5 , he felt a powerful electric shock shoot through his body. Perry jumped back. He reached down a second time, and was shocked again. But the third time he seized the man’s wrist and forearm, and managed to move the guy’s body away from the 6 .“Give him chest compressions!” yelled an old lady on the platform.Perry was no expert, but for a few moments h e worked on the man’s heart until the victim regained 7 . Then, first-aiders arrived. Perry let the professionals 8 . Heart still racing from the electric shocks, he climbed back up onto the platform, grabbed his things and continued on to hi s grandfather’s.The evening news reported the incident, 9 an unnamed hero with saving the victim’s life. To many,Perry’s 10 deeds demonstrated the power of choosing compassion over personal safety. 1．A．manager B．client C．grandfather D．aunt2．A．current B．oxygen C．wave D．blood3．A．imagine B．watch C．shout D．record4．A．Hoping B．Assuming C．Complaining D．Recalling5．A．Instantly B．Slightly C．Normally D．Surprisingly6．A．train B．crowds C．platform D．rails7．A．strength B．balance C．consciousness D．control8．A．look ahead B．take over C．get around D．keep away9．A．providing B．engaging C．assisting D．crediting10．A．generous B．grateful C．courageous D．faithful【答案】1．C 2．A 3．B 4．B 5．A 6．D 7．C 8．B 9．D 10．C【导语】本文是一篇记叙文。

2014全国高考英语试题分类汇编阅读之科普知识类

2014全国高考汇编阅读之科普知识类一（2014安徽卷）BRecordings of angry bees are enough to send big, tough African elephants running away, a new study says. Beehives (蜂窝)-either recorded or real-may even prevent elephants from damaging farmer's crops.In 2002, scientist Lucy King and her team found that elephants avoid certain trees with bees living in them. Today, Lucy wants to see if African honeybees might discourage elephants from eating crops. But before she asked farmer to go to the trouble of setting up beehives on their farms, she needed to find out if the bees would scare elephants away.Lucy found a wild beehive inside a tree in northern Kenya and set up a recorder. Then she threw a stone into the beehive, which burst into life. Lucy and her assistant hid in their car until the angry bees had calmed down. Next，Lucy searched out elephant families in Samburu National Reserve in northern Kenya and put a speaker in a close to each family.From a distance, Lucy switched on the pre-recorded sound of angry bees while at the same time recording the elephants with a video camera. Half the elephant groups left the area within ten seconds. Out of a total of 17 groups, only one group ignored the sound of the angry bees. Lucy reported that all the young elephants immediately ran to their mothers to hide under them. When Lucy Played the sound of a waterfall (瀑布) instead of the angry bees to many of the same elephant families, the animals were undisturbed. Even after four minutes, most of the groups stayed in one place.Lucy is now studying whether the elephants will continue to avoid the sound of angry bees after hearing it several times. She hasn't tested enough groups yet to know, but her initial (最初的) results were promising enough to begin trials with farmers. She has now begun placing speakers in the fields to see if elephants are frightened away.60. We know from the passage that elephants may he frightened of .A. loud noisesB. some cropsC. video camerasD. angry bees61. As mentioned in the passage, LucyA. works by herself in AfricaB. needs to test more elephant groupsC. has stopped elephants eating cropsD. has got farmers to set up beehives on their farms62. Why did Lucy throw a stone into a wild beehive?A. To record the sound of bees.B. To make a video of elephants.C. To see if elephants would run away.D. To find out more about the behavior of bees.63. Which of the following is true according to the passage?A. Young elephants ignore African honeybees.B. Waterfalls can make elephants stay in one place.C. Elephants do not go near trees with bees living in them.D. Farmers do not allow Lucy to conduct tests in their fields.60. 【答案】D 61. 【答案】B 62. 【答案】A 63. 【答案】C二（2014北京卷）DMultitaskingWhat is the first thing you notice when you walk into a shop? The products displayed (展示) at the entrance? Or the soft background music?But have you ever notice the smell? Unless it is bad, the answer is likely to be no. But while a shop’s scent may not be outstanding compared with sightsand sounds, it is certainly the re. And it is providing to be an increasing powerful tool in encouraging people to purchase.A brand store has become famous for its distinctive scent which floats through the fairly dark hall and out to the entrance, via scent machines. A smell may be attractive but it may not just be used for freshening air. One sports goods company once reported that when it first introduced scent into its stores, customers’ intension to purchase increased by 80 percent.When it comes to the best shopping streets in Pair s, scent is just as important to a brand’s success as the quality of its window displays and goods on slaes. That is mainly because shopping is avery different experience to what it used to be.Some years ago,the focus for brand name shopping was on a few people with sales assistants’ disproving attitude and don’t-touch-what-you-can’t-afford displays. Now the rise of electronic commerce (e-commerce) has opened up famous brands to a wider audience. But while e-shops can use sights and sounds, only bricks-and-mortar stores (实体店) can offer a full experience from the minute customers step through the door to the moment they leave. Another brand store seeks to be much more than a shop, but rather a destination. And scent is just one way to achieve this.Now a famous store uses complex man-made smell to make sure that the soft scent of baby powder floats through the kid department, and coconut (椰子) scent in the swimsuit section. A department store has even opened a new lab, inviting customers on a journey into the store’s windows to smell books, pots and drawers, in search of their perfect scent.67. According to the passage, what is an increasingly powerful tool in the success of some brand store?A. Friendly assistant.B. Unique scents.C. Soft background musicD. attractive window display.68. E-shops are mentioned in the passage to _______ .A. show the advantages of brick-and-mortar storesB. urge shop assistants to change their attitudeC. push stores to use sights and soundsD. introduce the rise of e-commerce69. The underlined word ―destination‖ in Paragraph 5 means _______ .A. a platform that exhibts goodsB. a spot where travelers like to stayC.a place where customers love to goD. a target that a store expects to meet70. The main purpose of the passage is to ______ .A. compare and evaluateB. examine and assessC. argue and discussrm and explain67. 【答案】B 68. 【答案】A 69. 【答案】C 70. 【答案】D三（2014广东卷）DScientists today are making greater effort to study ocean currents (洋流) . Most do it using satellites and other high-tech equipment. However, ocean expert Curtis Ebbesmeyer does it in a special way --- by studying movements of random floating garbage. A scientist with many years’ experience, he started this type of research in the early 1990s when he heard about hundreds of athletic shoes washing up on the shores of the northwest coast of the United States. There were so many shoes that people were setting up swap meets to try and match left and right shoes to sell or wear.Ebbesmeyer found out in his researches that the shoes — about 60,000 in total — fell into the ocean in a shipping accident. He phoned the shoe company and asked if they wanted the shoes back. As expected, the company told him that they didn't. Ebbesmeyer realized this could be a great experiment. If he learned when and where the shoes went into the water and tracked where they landed, he could learn a lot about the patterns of ocean currents.The Pacific Northwest is one of the world's best areas for beachcombing(海滩搜寻) because winds and currents join here, and as a result, there is a group of serious beachcombers in the area. Ebbesmeyer got to know a lot of them and asked for their help in collecting information about where the shoes landed. In a year he collected reliable information on 1, 600 shoes. With this data, he and a colleague were able to test and improve a computer program designed to model ocean currents, and publish the findings of their study.As the result of his work, Ebbesmeyer has become known as the scientist to call with questions about any unusual objects found floating in the ocean. He has even started an association of beachcombers and ocean experts, with 500 subscribers from West Africa to New Zealand. They have recorded all lost objects ranging from potatoes to golf gloves.41. The underlined phrase swap meets in Paragraph 1 is closest in meaning to ______________.A. fitting roomsB. trading fairsC. business talksD. group meetings42. Ebbesmeyer phoned the shoe company to find out _____________.A. what caused the shipping accidentB. when and where the shoes went missingC. whether it was all right to use their shoesD. how much they lost in the shipping accident43. How did Ebbesmeyer prove his assumption?A. By collecting information from beachcombers.B. By studying the shoes found by beachcomber.C. By searching the web for ocean currents models.D. By researching ocean currents data in the library.44. Ebbesmeyer is most famous for ___________________.A. traveling widely the coastal cities of the worldB. making records for any lost objects on the seaC. running a global currents research associationD. phoning about any doubtful objects on the sea45. What is the purpose of the author in writing this passage?A. To call people's attention to ocean pollution.B. To warn people of shipping safety in the ocean.C. To explain a unique way of studying ocean currents.D. To give tips on how to search for lost objects on the beach.41.【答案】B 42. 【答案】C 43. 【答案】A 44. 【答案】D 45. 【答案】C四（2014湖北卷）CWorking with a group of baboons (狒狒) in the Namibian desert, Dr. Alecia Carter of the Department of Zoology, Cambridge University set baboons learning tasks involving a novel food and a familiar food hidden in a box. Some baboons were given the chance to watch another baboon who already knew how to solve the task, while others had to learn for themselves. To work out how brave or anxious the baboons were, Dr. Carter presented them either with a novel food or a threat in the form of a model of a poisonous snake.She found that personality had a major impact on learning. The braver baboons learnt, but the shy ones did not learn the task although they watched the baboon perform the task of finding thenovel food just as long as the brave ones did. In effect, despite being made aware of what to do, they were still too shy to do what the experienced baboon did.The same held true for anxious baboons compared with calm ones. The anxious individuals learnt the task by observing others while those who were relaxed did not, even though they spent more time watching.This mismatch between collecting social information and using it shows that personality plays a key role in social learning in animals, something that has previously been ignored in studies on how animals learn to do things. The findings are significant because they suggest that animals may perform poorly in cognitive (认知的) tasks not because they aren’t clever enough to solve them, but because they are too shy or nervous to use the social information.The findings may impact how we understand the formation of culture in societies through social learning. If some individuals are unable to get information from others because they don’t associate with the knowledgeable individuals, or they are too shy to use the information once they have it, information may not travel between all group members, preventing the formation of a culture based on social learning.59. What is the first paragraph mainly about?A. The design of Dr. Carter’s res earch.B. The results of Dr. Carter’s research.C. The purpose of Dr. Carter’s research.D. The significance of Dr. Carter’s research.60. According to the research, which baboons are more likely to complete a new learning task?A. Those that have more experience.B. Those that can avoid potential risks.C. Those that like to work independently.D. Those that feel anxious about learning.61. Which best illustrates the ―mismatch‖ mentioned in Paragraph 4?A. Some baboons are intelligent but slow in learning.B. Some baboons are shy but active in social activities.C. Some baboons observe others but don’t follow them.D. Some baboons perform new tasks but don’t concentrate.62. Dr. Carter’s findings indicate that our culture might be formed through ______.A. storing informationB. learning from each otherC. understanding different peopleD. travelling between social groups59. 【答案】A 60. 【答案】D 61. 【答案】C 62. 【答案】B五（2014湖南卷）CThe behaviour of a building’s users may be at least as important as its desig n when it comes to energy use, according to new research from the UK Energy Research Centre (UKERC). The UK promises to reduce its carbon emissions (排放）by 80 percent by 2050, part of which will be achieved by all new homes being zero-carbon by 2016.But this report shows that sustainable building design on its own — though extremely important- is not enough to achieve such reductions: the behaviour of the people using the building has to change too.The study suggests that the ways that people use and live in their homes have been la r gely ignored by existing efforts to improve energy efficiency (效率)，which instead focus on architectural and technological developments.‘Technology is going to assist but it is not going to do everything,’explains Katy Janda, a UKERC senior researcher，‘consumption patterns of building users can defeat the most careful design.’In other words，old habits die hard, even in the best-designed eco-home.Another part of the problem is information. Households and bill-payers don’t have the knowledge they need to change their energy-use habits. Without specific information，it’s hard to estimate the costs and benefits of making different choices. Feedback (反馈）facilities, like smart meters and energy monitors，could help bridge this information gap by helping people see how changing their behaviour directly affects their energy use; some studies have shown that households can achieve up to 15 percent energy savings using smart meters.Social science research has added a further dimension (方面），suggesting that individuals’behaviour in the home can be personal and cannot be predicted 一whether people throw open their windows rather than turn down the thermostat (恒温器) , for example.Janda argues that education is the key. She calls for a focused programme to teach people about buildings and theirown behaviour in them.66. As to energy use, the new research from UKERC stresses the importance of________.A. zero-carbon homesB. the behaviour of building usersC. sustainable building designD. the reduction of carbon emissions67. The underlined word ―which‖ in Paragr aph 2 refers to‖________.‖A. the waysB. their homesC. developmentsD. existing efforts68. What are Katy Janda’s words mainly about?A. The importance of changing building users, habits.B. The necessity of making a careful building design.C. The variety of consumption patterns of building users.D. The role of technology in improving energy efficiency.69. The information gap in energy use_______.A. can be bridged by feedback facilitiesB. affects the study on energy monitorsC. brings about problems for smart metersD. will be caused by building users’old habits70. What does the dimension added by social science research suggest?A. The social science research is to be furthered.B. The education programme is under discussion.C. The behaviour of building users is unpredictable.D. The behaviour preference of building users is similar.66. 【答案】B 67. 【答案】D 68. 【答案】A 69. 【答案】A 70. 【答案】C六（2014江苏卷）CMost damagingly, anger weakens a person's ability to think clearly and keep control over his behaviour. The angry person loses objectivity in evaluating the emotional significance of the person or situation that arouses his anger.Not everyone experiences anger in the same way; what angers one person may amuse another.The specific expression of anger also differs from person to person based on biological and cultaralforces. In contemporary culture, physical expressions of anger are generally considered too socially harmful to be tolerated. We no longer regard duels(决斗) as an appropriate expression of anger resulting from one person's awareness of insulting behaviour on the part of another.Anger can be identified in the brain, where the electrical activity changes. Under most conditions EEG (脑电图) measures of electrical activity show balanced activity between the right and left prefrontal (额叶前部) areas. Behaviourally this corresponds to the general even-handed disposition （意向）that most of us possess most of the time. But when we are angry the EEG of the right and left prefrontal areas aren't balanced and. as a result of this, we're likely to react. And our behavioural response to anger is different from our response to other emotions, whether positive or negative.Most positive emotions are associated with approach behaviour: we move closer to people we like. Most negative emotions, in contrast, are associated with avoidance behaviour: we move away from people and things that we dislike or that make us anxious. But anger is an exception to this pattern. The angrier we are. the more likely we are to move towards the object of our anger. This corresponds to what psychologists refer to as offensive anger: the angry person moves closer in order to influence and control the person or situation causing his anger. This approach-and-confront behaviour is accompanied by a leftward prefrontal asymmetry (不对称) of EEG activity. Interestingly, this asymmetry lessens if the angry person can experience empathy (同感) towards the individual who is bringing forth the angry response. In defensive anger, in contrast, the EEG asymmetry is directed to the right and the angry person feels helpless in the face of the anger-inspiring sitaation.61. The "duels" example in Paragraph 2 proves that the expression of anger _ .A. usually has a biological basisB. varies among peopleC. is socially and culturally shapedD. influences one's thinking and evaluation62. What changes can be found in an angry brain?A. Balanced electrical activity can be spotted.B. U nbalanced patterns are found in prefrontal areas.C. E lectrical activity corresponds to one's behaviour.D. Electrical activity agrees with one's disposition.63. Which of the following is typical of offensive anger?A. Approaching the source of anger.B. Trying to control what is disliked.C. Moving away from what is disliked.D. Feeling helpless in the face of anger.64. What is the key message of the last paragraph?A. How anger differs from other emotions.B. How anger relates to other emotions.C. Behavioural responses to anger.D. Behavioural patterns of anger.61. 【答案】C 62. 【答案】B 63. 【答案】A 64. 【答案】D七（2014辽宁卷）AA new study shows students who write notes by hand during lectures perform better on exams than those who use laptops（笔记本电脑）.Students are increasingly using laptops for note-taking because of speed and legibility（清晰度）. But the research has found laptop users are less able to remember and apply the concepts they have been taught.Researchers performed experiments that aimed to find out whether using a laptop increased the tendency to make notes ―mindlessly‖ by taking down word for word what the professors said.In the first experiment, students were given either a laptop or pen and paper. They listened to the same lectures and were told to use their usual note-taking skills. Thirty minutes after the talk, they were examined on their ability to remember facts and on how well they understood concepts.The researchers found that laptop users took twice as many notes as those who wrote by hand. However, the typists performed worse at remembering and applying the concepts. Both groups scored similarly when it came to memorizing facts.The researchers’ report said, ―While more notes arc beneficial, if the notes are taken mindlessly, as is more like ly the case on a laptop, the benefit disappears.‖In another experiment aimed at testing long-term memory, students took notes as before but were tested a week after the lecture. This time, the students who wrote notes by hand performed significantly better on the exam.These two experiments suggest that handwritten notes arc not only better for immediate learning and understanding, but that they also lead to superior revision in the future.21. More and more students favor laptops for note-taking because they can.A. write more notesB. digest concepts betterC. get higher scoresD. understand lectures better22. While taking notes, laptop users tend to be .A. skillfulB. mindlessC. thoughtfulD. tireless23. The author of the passage aims to ___ .A. examine the importance of long-term memoryB. stress the benefit of taking notes by handC. explain the process of taking notesD. promote the use of laptops24. The passage is likely to appear in ___ .A. a newspaper advertisementB. a computer textbookC. a science magazineD. a finance report21.【答案】A 22. 【答案】B 23. 【答案】B 24. 【答案】C八（2014辽宁卷）CWould it surprise you to learn that, like animals, trees communicate with each other and pass on their wealth to the next generation?UBC Professor Simard explains how trees are much more complex than most of us ever imagined. Although Charles Darwin thought that trees arc competing for survival of the fittest, Simard shows just how wrong he was. In fact, the opposite is true: trees survive through their co-operation and supp ort, passing around necessary nutrition ―depending on who needs it‖.Nitrogen（氮）and carbon are shared through miles of underground fungi（真菌）networks, making sure that all trees in the forest ecological system give and receive just the right amount to keep them all healthy. This hidden system works in a very similar way to the networks of neurons （神经元）in our brains, and when one tree is destroyed, it affects all.Simard talks about ―mother trees‖, usually the largest and oldest plants on which all other trees depend. She explains how dying trees pass on the wealth to the next generation, transporting important minerals to young trees so they may continue to grow. When humans cut down ―mother trees‖ with no awareness of these highly complex ―tree societies‖ or the networks on which they feed, we are reducing the chances of survival for the entire forest.―We didn’t take any notice of it.‖ Simard says sadly. ―Dying trees move nutrition into the young trees before dying, but we never give them chance.‖ If we could put across the message to the forestry industry, we could make a huge difference towards our environmental protection efforts for the future.29. The underlined sentence ―the opposite is true‖ in Paragraph 2 probably means that trees.A. compete for survivalB. protect their own wealthC. depend on each otherD. provide support for dying trees30. ―Mother trees‖ are extremely important beca use they .A. l ook the largest in size in the forestB. pass on nutrition to young treesC. seem more likely to be cut down by humansD. know more about the complex ―tree societies‖31. The underlined word ―it‖ in the last paragraph refers to .A. h ow ―tree societies‖ workB. h ow trees grow oldC. h ow forestry industry developsD. h ow young trees survive32. What would be the best title for the passage?A. Old Trees Communicate Like HumansB. Young Trees Are In Need Of ProtectionC. Trees Are More Awesome Thart You ThinkD. Trees Contribute To Our Society29. 【答案】C 30. 【答案】B 31. 【答案】A32. 【答案】C九（2014山东卷）DHow fit are your teeth? Are you lazy about brushing them? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush, and it lets you track your performance on your phone.The Kolibree toothbrush was exhibited at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection.The toothbrush will be able to teach you to brush right (don’t f orget the insides of the teeth!) and make sure you’re brushing long enough. ―It’s kind of like having a dentist actually watch your brushing on a day-to-day basis,‖ says Thomas Serval, the French inventor.The toothbrush will also be able to talk to other applications on your phone, so developers could, for instance, create a game controlled by your toothbrush. You could score points for beating monsters among your teeth. ―We try to make it smart but also fun,‖ Several says.Serval says he was inspired by his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They said ―yes,‖ but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed.The company says the Kolibree will go on sale this summer, for $99 to $199, developing on features. The U.S. is the first target market.Serval says that one day, it’ll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.56. Which is one of the feature of the Kolibree toothbrush?A. It can sense how users brush their teeth.B. It can track users’ school performance.C. It can detect users’ fear of seeing a dentist.D. It can help users find their phones.57. What can we learn from Serval’s words in Paragraph 3?A. You will find it enjoyable to see a dentist.B. You should see your dentist on a day-to –day basis.C. You can brush with the Kolibree as if guided by a dentist.D. You’d like a dentist to watch you brush your teeth every day.58. Which of the following might make the Kolibree toothbrush fun?A. It can be used to update mobile phones.B. It can be used to play mobile phone gamesC. It can send messages to other usersD. It can talk to its developers.59. What is Paragraph 5 mainly about?A. How Serval found out his kids lied to him.B. Why Serval thought brushing teeth was necessary.C. How Serval taught his kids to brush their teeth.D. What inspired Serval to invent the toothbrush60. What can we infer about Serval’s children?A. They were unwilling to brush their teethB. They often failed to clean their toothbrushes.C. They preferred to use a toothbrush with a dry head.D. They liked brushing their teeth after Serval came home.61. What can we learn about the future development of the Kolibree?A. The brush handle will be removed.B. A mobile phone will be built into it.C. It will be used to fill holes in teethD. It will be able to check users’ teeth56. 【答案】A 57. 【答案】C 58【答案】.B 59. 【答案】D 60. 【答案】A 61. 【答案】D 十（2014四川卷）DWith around 100 students scheduled to be in that 9 am Monday morning lecture, it is no surprise that almost 20 people actually make it to the class and only 10 of them arc still awake after the first IS minutes; it is not even a surprise that most of them are still in their pyjamas (睡衣). Obviously, students are terrible at adjusting their sleep cycles to their daily schedule.All human beings possess a body clock. Along with other alerting (警报) systems, this governs the sleep/wake cycle and is therefore one of the main processes which govern sleep behaviour. Typically, the preferred sleep/wake cycle is delayed in adolescents, which leads to many students not feeling sleepy until much later in the evenings. This typical sleep pattern is usually referred to as the "night owl" schedule ofThis is opposed to the "early bird" schedule, and is a kind of disorder where the individual tends to stay up much past midnight. Such a person has great difficulty in waking up in the mornings. Research suggests that night owls feel most alert and function best in the evenings and at night.Research findings have shown that about 20 percent of people can be classified as "night owls" and only 10 percent can be classified as "early birds" - the other 70 percent are in the middle. Although this is clearly not true for all students, for the ones who are true night owls this gives them an excellent excuse for missing their lectures which unfortunately fall before midday.43. What docs the author stress in Paragraph I?A. Many students are absent from class.B. Students are very tired on Monday mornings.C. Students do not adjust their sleep patterns well.D. Students are not well prepared for class on Mondays.44. Which of the following is true according to Paragraph 2?A. Most students prefer to get up late in the morning.B. Students don't sleep well because of alerting systems.C. One's body clock governs the sleep/wake cycle independently.D. Adolescents' delayed sleep/wake cycle isn't the preferred pattern.45. Which of the following is closest in meaning to the underlined word "classified"?A. Criticised.B. Grouped.C. Organised.D. Named.46. What docs the text mainly talk about?A. Functions of the body clock.B. The "night owl" phenomenon.C. Human beings' sleep behaviour.D. The school schedule of "early birds".43. 【答案】C 44. 【答案】D45. 【答案】B46. 【答案】B十一（2014四川卷）EWomen are friendly. But men are more competitive. Why? Researchers have found it's all down to the hormone oxytocin (荷尔蒙催生素). Although known as the love hormone, it affects the sexes differently."Women tend to be social in their behavior. They often share with others. But men lend to be competitive. They are trying to improve their social status," said Professor Ryan.Generally, people believe that the hormone oxytocin is let out in our body in various social。

不同采收成熟度对蜜奈夏橙果实营养品质的影响

李慧敏，郑洁新，曾凯芳，等. 不同采收成熟度对蜜奈夏橙果实营养品质的影响[J]. 食品工业科技，2023，44（19）：390−400. doi:10.13386/j.issn1002-0306.2023020014LI Huimin, ZHENG Jiexin, ZENG Kaifang, et al. Effect of Different Harvest Maturity on the Nutritional Quality of Midknight Valencia Orange Fruit[J]. Science and Technology of Food Industry, 2023, 44(19): 390−400. (in Chinese with English abstract). doi:10.13386/j.issn1002-0306.2023020014· 贮运保鲜 ·不同采收成熟度对蜜奈夏橙果实营养品质的影响李慧敏1，郑洁新1，曾凯芳1,2，邓丽莉1,2, *（1.西南大学食品科学学院，重庆 400715；2.西南大学食品贮藏与物流研究中心，重庆 400715）摘　要：蜜奈夏橙（Midknight Valencia Orange ）是重要的晚熟柑橘品种之一。

为研究不同采收成熟度对该品种夏橙果实营养品质的影响，以确定其最适采收期，测定了采收期Ⅰ~Ⅴ蜜奈夏橙果皮色差值、硬度，果实类胡萝卜素、可溶性糖、有机酸、游离氨基酸、矿质元素、黄酮、总酚等品质指标，并进行相关性分析。

结果表明：不同采收成熟度对蜜奈夏橙果实的品质影响显著，随着采收时间的推迟，果皮颜色由果顶至果蒂逐渐变黄，且在花后360 d 时果实呈鲜艳的亮黄色；果实总类胡萝卜素、抗坏血酸、总酚和黄酮含量呈上升趋势；可溶性固形物含量先增加后降低，可滴定酸含量显著降低。

蜜奈夏橙果实中主要的可溶性糖是葡萄糖、蔗糖、果糖、塔罗糖、肌醇，其中葡萄糖、蔗糖含量在采收期间呈上升趋势；主要的有机酸是柠檬酸、苹果酸、奎宁酸，其中柠檬酸含量在采收期间呈下降趋势；主要的游离氨基酸是脯氨酸、精氨酸、丝氨酸，且在采收期间总体呈上升趋势。

玛咖格瓦斯饮料的研制

万方数据
万方数据
万方数据
万方数据
玛咖格瓦斯饮料的研制
作者：公伟广，王晓丹，杨雪，邱树毅， GONG Weiguang， WANG Xiaodan， YANG Xue， QIU Shuyi
作者单位：公伟广,杨雪,邱树毅,GONG Weiguang,YANG Xue,QIU Shuyi(贵州省发酵工程与生物制药重点实验室,贵州贵阳550025;贵州大学酿酒与食品工程学院,贵州贵阳550025)，王晓丹,WANG Xiaodan(贵州省发酵工程
与生物制药重点实验室,贵州贵阳550025;贵州大学酿酒与食品工程学院,贵州贵阳550025;贵州大学生命
科学学院,贵州贵阳550025)
刊名：
中国酿造
英文刊名：China Brewing
年，卷(期)：2014,33(12)
引用本文格式：公伟广.王晓丹.杨雪.邱树毅.GONG Weiguang.WANG Xiaodan.YANG Xue.QIU Shuyi玛咖格瓦斯饮料的研制[期刊论文] -中国酿造 2014(12)。

竞争理论

第6章竞争理论张大勇姜新华6.1 竞争的定义与分类从达尔文时起，竞争就一直是生态学和进化研究的焦点；竞争理论几乎就是生态学理论的代名词。

竞争可以从许多角度来定义，但最简单也是最具有概括性的一个定义是：在同一因子(资源、资源组合或捕食者等)控制下所产生的有机体(同种的或异种的)之间的相互妨碍（王刚、张大勇 1996）。

竞争作用亦可从多个角度去进行分类。

首先，从生物类群的角度分类。

竞争是生物有机体之间相互的负作用；那么，当这些有机体属于同种时，就称之为种内竞争；当这些有机体属于不同种时，就称之为种间竞争。

种间竞争是竞争理论的主体。

在谈及竞争时，如没有特别指出，就应认为是种间竞争。

以往对于种内竞争的研究主要是在整个种群水平上进行的；竞争的效应用出生率、死亡率或净增长率等“平均个体”的特征来表示。

这种简化忽略了种群内个体之间的差异和种群内的各种结构。

如果我们是相对于种间竞争而论及种内竞争，那么这种忽略有其一定程度的合理性和必要性；但如果我们是专门研究种内竞争，那么种内的个体差异和种群结构将是不容忽略的。

而且，如我们将在6.7.3节看到的那样，正确认识物种间竞争与共存同样需要考虑种群内部结构。

种群的结构特征有多方面，如性比、年龄结构、遗传结构、个体大小等级等。

在考虑到这些结构的基础上研究竞争条件下的种群行为是近年来种内竞争研究的新趋向（王刚、张大勇 1996），但本章限于篇幅不再涉及。

关于竞争的第二种分类是将竞争分为利用性竞争和干扰性竞争。

利用性竞争为利用共同有限资源的生物个体之间的妨害作用，是通过资源这个中介而实现的。

参与竞争的所有个体都在降低资源的可利用程度，而资源可利用度的下降影响所有个体，降低它们的适合度。

这里没有个体间直接的行为上的对抗，其主要特征表现为参与竞争的个体对资源水平的反应。

干扰性竞争为一个个体以行为上的直接对抗影响另一个个体。

这种个体间干扰行为的实质还是为了资源的利用，因而干扰性竞争是一种潜在的资源竞争。

高三英语英语学习大数据分析单选题40题

高三英语英语学习大数据分析单选题40题1.In the era of big data, we need to analyze large amounts of information _____.A.thoroughlyB.approximatelyC.randomlyD.occasionally答案：A。

thoroughly 意为“彻底地、完全地”；approximately 意为“大约、近似地”；randomly 意为“随机地、任意地”；occasionally 意为“偶尔、间或”。

在大数据时代，我们需要彻底地分析大量信息，所以选A。

2.Big data can provide _____ insights into customer behavior.A.preciousB.valuableC.worthlessD.trivial答案：B。

precious 意为“珍贵的、宝贵的”，通常用于形容物品或情感；valuable 意为“有价值的”，可用于形容信息、建议等；worthless 意为“无价值的”；trivial 意为“琐碎的、不重要的”。

大数据能提供有价值的关于客户行为的见解，所以选B。

3.The analysis of big data requires powerful _____ tools.putationalB.manualC.primitiveD.ineffective答案：A。

computational 意为“计算的”；manual 意为“手工的”；primitive 意为“原始的”；ineffective 意为“无效的”。

大数据分析需要强大的计算工具，所以选A。

4.Big data analytics can help businesses make more _____ decisions.rmedB.uninformedC.randomD.hasty答案：A。

informed 意为“有根据的、明智的”；uninformed 意为“无知的、未被通知的”；random 意为“随机的”；hasty 意为“匆忙的”。

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

Downloaded by: Zhejiang University 61.153.148.200 - 7/27/2014 9:57:20 AM
Introduction Osteoporosis, described as a reduction of bone mass and an alteration in bone micro-structure, is a result of decreased serum estrogen levels during and after menopause. In postmenopausal women, loss of estrogen is associated with an elaboration of cytokines that not only increase the formation of precursors of osteoclasts and their differentiation into osteoclasts but also decrease the development and function of osteoblasts [1]. This results in an increase of bone fragility and fractures [1]. In fact, the high incidence of fractures by postmenopausal osteoporosis is an important public health problem, resulting in increased financial charges for health services. It is well known that antioxidants have a beneficial effect on this altered cytokine balance [2]. Hormone replacement therapy (HRT) has been used to treat post-menopausal bone loss. However, HRT has several secondary effects including breast cancer, heart and brain vascular failures and blood clots [3]. For these reasons, alternative treatments without secondary adverse effect are needed. Maca (Lepidium meyenii) is a Peruvian plant that belongs to the Brassicaceae family. The edible part of the plant is a radish-like tuber that constitutes the hypocotyl and the root of the plant [4]. Previous studies focused on proving the traditional fertility-enhancing properties of the hypocotyls of maca regarding sperm production [5–8], sexual behavior [9–11], and female fertility [12]. Up to 13 varieties of maca have been described according to the color of its hypocotyls [4, 13] that showed different biological effects [14–16]. Black maca, for example, presented the greatest effect on sperm production in rats [15] and on latent learning in ovariectomized (OVX) mice [16] and red maca significantly reduced prostate size in rats [14]. Furthermore, we have demonstrated that maca can enhance sperm count and sperm motility in normal men without altering serum testosterone, luteinizing hormone (LH) or follicle stimulating hormone (FSH) levels [4]. Recent studies have also shown that extracts of Lepidium meyenii (Maca) (3.5 g/d) can reduce psychological symptoms, including anxiety and depression, and lower measures of sexual dysfunction in post-menopausal women independently of any estrogenic and androgenic activity [17]. In addition, maca improves bone mass and restores bone trabecular area of lumbar vertebrae in OVX rat [18, 19]. Yet, the authors did not mention the variety of maca they used in their studies. The present study aims to evaluate the effect of three different maca varieties (black, yellow and red) on bone structure in OVX female rats, using standardized extracts based on polyphenols content.
© 2010 S. Karger GmbH, Freiburg Fax +49 761 4 52 07 14 Information@Karger.de Accessible online at: /fok
Carla Gonzales Biological and Physiological Science Department, Faculty of Science and Philosophy Universidad Peruana Cayetano Heredia Av. Honorio Delgado 430, Lima 31, Peru Tel. +511 3190000, ext. 2515 carla.gonzalez@upch.pe
Schlüsselwörter Lepidium meyenii · Schwarzes Maca · Rotes Maca · Knochenstruktur · Ovariektomie Zusammenfassung Ziel: Diese Studie wurde entwickelt, um die Wirkung verschiedener Arten von Maca (Lepidium meyenii) auf die Knochenstruktur von Ratten nach Ovariektomie (OVX) zu untersuchen. Material und Methoden: 36 weibliche Ratten wurden zufällig 6 Gruppen zugeteilt: eine scheinoperierte Gruppe sowie Ratten, die nach einer OVX 4 Wochen lang mit destilliertem Wasser, Estradiol (40 mg/kg), schwarzem, rotem oder gelbem Maca (63 mg/ml) behandelt wurden. Am Ende der Behandlung wurden das uterine Gewicht sowie die Histomorphologie des Femurknochens und der Lumbalwirbel erhoben. Ergebnisse: Die Ovariektomie reduzierte Gewicht, Durchmesser und Breite des Femurknochens. Behandlungen mit Estradiol, schwarzem oder rotem Maca reduzierten die Effekte der OVX auf diese Variablen. Histologische Analysen zeigten, dass Behandlungen mit Estradiol, schwarzem und rotem Maca den Effekt der Ovariektomie umkehrten, indem sie die Trabekelzone des zweiten Lumbalwirbels vergrößerten. Das uterine Gewicht war bei den OVX-Ratten reduziert und wurde durch Estradiol, aber weder durch schwarzes noch rotes Maca erhöht. Schlussfolgerung: Rotes und schwarzes Maca haben protektive Effekte auf die Knochenstruktur von OVX-Ratten ohne östrogene Auswirkungen auf das uterine Gewicht.