专业英语重点语句译文
第一章1①Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs (C).电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。
②We also know that the charge e on an electron is negative and equal in magnitude to 1.60210×10 19C, while a proton carries a positive charge of the same magnitude as the electron.我们还知道电子的电量是负的并且在数值上等于1.602100×10-12C，而质子所带的正电量在数值上与电子相等。
③A unique feature of electric charge or electricity is the fact that it is mobile; that is, it can be transferred from one place to another, where it can be converted to another form of energy.电荷或电的特性是其运动的特性，也就是，它可以从一个地方被移送到另一个地方，在此它可以被转换成另外一种形式的能量。
④Although we now know that current in metallic conductors is due to negatively charged electrons, we will follow the universally accepted convention that current is the net flow of positive charges.虽然我们现在知道金属导体中的电流是由负电荷引起的，但我们将遵循通用的惯例，即把电流看作是正电荷的单纯的流动。
⑤The way we define current as i in Eq. (1-l) suggests that current need not be a constant-valued function, charge can vary with time in several ways that may be represented by different kinds of mathematical functions.我们通过方程（1－1）定义电流的方式表明电流不必是一个恒值函数，电荷可以不同的方式随时间而变化，这些不同的方式可用各种数学函数表达出来。
⑥The voltage u ab between two points a and b in an electric circuit is the energy (or work) needed to move a unit charge from a to b;电路中a、b两点间的电压等于从a到b移动单位电荷所需的能量（或所需做的功）。
⑦The power absorbed or supplied by an element is the product of the voltage across the element and the current through it.某一元件吸收或提供的功率等于元件两端电压和通过它的电流的乘积。
第一章2①An ideal independent source is an active element that provides a specified voltage or current that is completely independent of other circuit variables一个理想的独立源是产生完全独立于其它电路变量的特定电压或电流的有源元件。
②The symbol for a voltage source having u volts across its terminals is shown in Fig.1-4(a).该电压完全独立于流过元件的电流，在其端部具有u伏电压的电压源的符号如图1－4（a）所示③Another symbol that is often used for a constant voltage source, such as a battery with U volts across its terminals, is shown in Fig.1-4(b).对于恒定电压源我们通常使用另一种符号，例如在两端只有U伏电压的电池组，如图1－4（b）所示。
④We might observe at this point that the polarity marks on Fig.1-4(b) are redundant since the polarity could be defined by the positions of the longer and shorter lines.我们可能已经注意到这一点，即图1－4（b）中的极性标号，是多余的因为我们可以根据长天线的位置符，确定电池极性。
⑤Thus if u is the voltage across the source and its current i is directed out of the positive terminal, then the source is delivering power, given by p = ui, to the external circuit.因此如果u是电源两端的电压而电流i直接从其正端流出，那么该电源正在向对电路释放功率，由式p＝ui 算出。
⑥Since the control of the dependent source is achieved by a voltage or current of some other element in the circuit, and the source can be voltage or current, it follows that there are four possible types of dependent sources,由于控制受控源的控制量来自于电路中其他元件的电压或电流，同时由于受控源可以是电压源或电流源。
⑦It should be noted that an ideal voltage source (dependent or independent) will produce any current required to ensure that the terminal voltage is as stated, whereas an ideal current source will produce the necessary voltage to ensure the stated current flow.应该注意的是：一个理想电压源（独立或受控）可向电路提供以保证其端电压为规定值所需的任意电流，而电流源可向电路提供以保证其电流为规定值所必须的电压。
All the simple circuit elements that will be considered in the work that follows can be classified according to the relationship of the current through the element to the voltage across the element.在下面进行的工作中我们要研究的简单电路元件可以根据流过元件的电流与元件两端的电压的关系进行分类。
Furthermore, we shall need to define special kinds of sources in which the source voltage or current depends upon a current or voltage elsewhere in the circuit; such sources will be termed dependent sources or controlled sources此外，我们还要定义一些特殊类型的电源，这些电源的电压或电流取决于电路中其他的电流或电压，这样的电源将被称为非独立源或受控源。
第一章3①The circuit element used to model the current-resisting behavior of a material is the resistor.用来模拟材料阻流性能的电路元件是电阻，电阻是最简单的无源元件。
②Obviously, a straight line is the only graph possible for which the ratio of u(t) to i(t) is constant for all i(t).显然，当u（t）与i（t）的比值对于所有的i（t）都为一恒定值时，其唯一可能的图形就是一条直线③Resistors whose resistances do not remain constant for different terminal currents are known as nonlinear resistors.对于不同端部电流而具有不同电阻的电阻器被称为非线性电阻器。
④In reality, all practical resistors are nonlinear because the electrical characteristics of all conductors are affected by environmental factors such as temperature.事实上，所有实际电阻器都是非线性的，因为所有电阻器的电气性能会受到例如温度等的环境因素所影响。
①"Resistors" may be easily purchased or manufactured, but it is soon found that the voltage-current ratio of this physical device is reasonably constant only within certain ranges of current, voltage, or power and depends also on temperature and other environmental factors.我们可以很容易地买到或制造电阻器，但很快我们发现这种物理元件只有当电流、电压或者功率处于特定范围时其电压——电流之比才是恒定的，并且这个比值也取决于温度以及其它环境因素。
英语模块复习必背句子翻译250句（所有的必修）
英语模块复习必背句子翻译250句（所有的必修）复习必背句子翻译(250句)决定一个人英语水平的不只是单词量，更重要的是句子量，永远追求句子量，互相比赛句子量。
根据括号内的提示将下列句子翻译成英语。
Module 1 Unit 11. 在三鹿有毒奶粉事件曝光后，家长们为该给孩子吃什么而忧虑。
(expose; be concerned about)After the serious poisoning of Sanlu milk powder was exposed to the public, parents become even more concerned about what their children can eat.2. 好朋友就是能和你分享快乐和忧伤的人。
(share…with)A best friend is someone who can share happiness and sorrow with you.3. 我很感激你的建议，它帮助了我与同学们融洽相处。
(be grateful, advice, get along with)I’m grateful for your advice, which has helped me get along well with my classmates.4. 这是他第一次用电子邮件与笔友交流。
（the first time, communicate with）This is the first time that he has used an e-mail to communicate with his pen friend.5. 当我们在游泳池边玩的时候, 那个淘气的男孩故意把我推到了水里。
（while… doing, on purpose）While we were playing at the swimming pool, the naughty boy pushed me into the water on purpose.6. 爱好是不会让你感到厌倦的——你投入的时间越长，乐趣越多(the more… the more; devote to; get tired of).A hobby is something that you never get tired of—the moretime you devote to it, the more fun you will have.7. 计算机使人们即使身处世界的不同角落也能面对面地交流, 这彻底改变了我们的生活。
大学英语重点句子翻译
1、Once the secret is uncovered ,spouses usually fight the problem alone,bleeding inside,because the stories are too humiliating to share.秘密一旦被揭穿，配偶就要独自承受心头剧痛，因为这种事太丢人了，没法跟别人说。
2、Anybody who is living with a compulsive gambler is totally overwhelmed”,says Tom Tucker,president of the California Council on problem Gambling .”they’re steeped in anger,resentment,depression,confusion.”与嗜赌成瘾的人一起生活都会陷入绝望，加利福尼亚问题赌博委员会主任汤姆塔克说。
他们沉浸在愤怒、怨恨、沮丧、困惑之中。
3、One Los Angeles woman,whose husband’s gambling was tearing at her sanity,says she slept with her fists so tightly clenched that her nails sliced into her palms.一个洛杉矶妇女，她的丈夫嗜赌成瘾，自己几乎神经崩溃，她说他睡觉的时候双手紧握成拳头，指甲把自己的手掌都掐破了。
4、There were times the pain was so much I thought being in jail,or being in electric chair,would be less than this.那种伤害太痛苦了，觉得哪怕坐牢、上电椅，也不至于那么痛苦。
5、With drug or alcohol abusers,there is the hope of sobering up,an accomplishment in itself,no matter what problems may have accompanied their addictions.吸毒者或酗酒者尚有清醒起来的希望，不管他们的毒瘾、酒瘾造成了什么麻烦，会清醒起来本身就是一项成就。
英语好词好句摘抄大全带翻译
英语好词好句摘抄大全带翻译1. "The early bird catches the worm." 早起的人能抓住虫子。
2. "Actions speak louder than words." 行动胜于言语。
3. "When life gives you lemons, make lemonade." 当生活给你柠檬时，就做柠檬水。
4. "Don't put all your eggs in one basket." 不要把所有的鸡蛋放在一个篮子里。
5. "Time is money." 时间就是金钱。
6. "Where there's a will, there's a way." 有志者事竟成。
7. "Birds of a feather flock together." 物以类聚，人以群分。
8. "No pain, no gain." 没有痛苦，就没有收获。
9. "Every cloud has a silver lining." 每一朵乌云背后都有银边。
10. "A stitch in time saves nine." 及时处理，可以避免更大的麻烦。
11. "Better late than never." 迟到总比不到好。
12. "A friend in need is a friend indeed." 患难见真情。
13. "All work and no play makes Jack a dull boy." 只工作不玩耍，聪明孩子也变傻。
15. "Knowledge is power." 知识就是力量。
专业英语翻译作业译文
专业英语翻译作业译文1.科学家们认为，这样微弱的粒子正则轨道实际上是不存在的。
的想法现在已被事实否定了。
2.虽然小行星很小很微弱，天文学家已经知道很多关于它们的大小，形状和组合物，通过使用各种直接和间接的技术。
例如，它是已知的许多小行星的亮度的周期性变化。
3.随着疾病的进展，大肌肉也稳步增长疲软。
如果不治疗，患者变得瘫痪有呼吸非常困难，并最终死亡。
4.将信息从计算机的一部分转移到另一个取决于电流进行了线。
5.只有两件事是天文观测----站立的地方和地方看需要。
6.太阳风严重扭曲地球磁场，把它拖了一个长长的尾巴。
7.使用计算机，我们组成了一系列的合成歌曲的混合自然音节为不同的模式。
8.苍头燕雀的显示，找出正确的声音模仿的本能，这表明本能学习鸟类作为他们发展他们的歌曲一样重要。
9.We know from the fossil record that our ancestors and other intelligent creatures,the australopithecines,branched off from an apelike creature 2.5 million to 3 million years ago ,and coexisted until the australopithecines died out a little less than a million years ago.Stone tools and other evidence at campsites that date form about 2,000,000 B.C.indicate that some form of australopithecine performed human activities ------ making tools,sharing food and working together.我们知道从化石记录我们的祖先和其他智能生物，猿，分枝从远古的生物2500000到3000000年前，南方古猿和共存直到死了比一百万年前少了一点。
英语句子及翻译经典3篇
英语句子及翻译经典3篇英语句子翻译篇一1、谷雨不雨，交回田主。
If it rains, return it to the landlord.2、桐叶马蹄大，稻种下泥无牵挂。
Tongye horseshoe big, rice seed mud without concern.3、六月六，晒得鸭蛋熟。
On June 6, duck eggs were cooked in the sun.4、星星眨眼，有雨不起。
The stars blink, but it can't rain.5、春雷十日阴，春雷十日寒。
Spring thunder is cloudy on the tenth day and spring thunder is cold on the tenth day.6、山中无老虎，猴子称大王。
There are no tigers in the mountains. Monkeys are called kings.7、四月不拿扇，急煞种田汉。
April does not take a fan, anxious farmer.8、人合心，马合套。
People fit in, horses fit in.9、水多成河，粪多成禾。
More water makes rivers, more feces make grains.10、柱石脚下潮有雨。
At the foot of the pillars there was rain and tide.11、病来如山倒，病去如抽丝。
Diseases come down like mountains and go away like threads.12、走的多了成道路，吃的多了成习惯。
The more you walk, the more you eat, the more you become a habit.13、右是目，左是眼。
Right is the eye, left is the eye.14、乐时想往他处走，悲时想往自家回。
西安邮电大学 专业英语重点
1. We see Cloud Computing as a computing model, not a technology. In this model “customers” plug into the “cloud” to access IT resources which are priced and provided “on-demand”. Essentially, IT resources are rented and shared among multiple tenants much as office space, apartments, or storage spaces are used by tenants. Delivered over an Internet connection, the “cloud” replaces the company data center or server providing the same service. Thus, Cloud Computing is simply IT services sold and delivered over the Internet. Refer to section of Types of Cloud Computing.译文：我们看到，云计算作为一种计算模式，而不是技术。
在这个模型中的“客户”插入到“云”访问IT资源定价，并提供“按需”。
从本质上讲，IT资源租用及使用多个租户之间共享办公空间，公寓，或存储空间高达租户。
“云”交付了一个互联网连接，取代该公司的数据中心或服务器提供相同的服务。
因此，云计算是简单的在互联网上出售及交付的IT服务。
参考部分云计算的类型。
2. PaaS（platform as a Service)Delivers virtualized servers on which customers can run existing applications or develop new ones without having to worry about maintaining the operating systems, server hardware, load balancing or computing capacity. These vendors provide APIs or development platforms to create and run applications in the cloud –e.g. using the Internet. Managed Service providers with application services provided to IT departments to monitor systems and downstream applications such as virus scanning for e-mail are frequently included in this category.译文：提供虚拟化服务器上，客户可以运行现有应用程序或者开发新的，无需担心维护操作系统，服务器硬件，负载均衡或计算能力。
专业英语重点句子(带单词翻译版)
Unit 1 (5个)1.Materials science and engineering (MSE) is an interdisciplinary field concerned with inventing new materials and improving previously known materials by developing a deeper understanding of the microstructure-composition-synthesis-processing relationships.2.Materials scientists and engineers not only deal with the development of materials, but also with the synthesis and processing of materials and manufacturing processes related to the production of components.3.One of the most important functions of materials scientists and engineers is to establish the relationships between a material or a device’s properties and performance and the microstructure of that material, its composition, and the way the material or the device was synthesized and processed.4.In materials science, the emphasis is on the underlying relationships between the synthesis and processing, structure, and properties of materials.5.In materials engineering, the focus is on how to translate or transform materials intoa useful device or structure.Unit 2（3个）6.What is also fascinating about van der Waals forces is that they begin as inter actions between atoms and molecules that ultimately lead to considerable forces between fine particles of any material.7. We make use of metal and ceramic powders (dry or slurries) in processing many ceramic and metallic materials through routes collectively known as powder processing (Processing technique for metals involving the solid-state bonding of a fine grained powder into a fully dense product).8.We can accomplish this by introducing like charges on the particles (electrostatic stabilization) or adsorbing soap like surfactant molecules on the surfaces of particles (steric stabilization).Unit 3（8个）9.The Si-O bond in the SiO44- structure in about 50 percent covalent and 50 percent ionic according to calculations from Pauling’s equation.10.The tetrahedral coordination of SiO44- satisfies the directionality requirement of covalent bonding and the radius ratio requirement of ionic bonding.11.If two corners of each SiO44-tetrahedron are bonded with the corners of othertetrahedra, a chain or ring structure with the unit chemical formula of SiO32- results.12.Silicate sheet structure form when three corners in the same plane of a silicate tetrahedron are bonded to the corners of three silicate tetrahedra.13.The mineral['mɪnərəl](矿物的,矿物) kaolinite['keɪəlɪnaɪt] (高岭石) consists (in its pure form) of every small, flat plates roughly hexagonal[hek'sæɡənəl](六边的，六角形的) in shape, with their average size being about 0.7um in diameter[daɪ'æmɪtə](直径)and 0.05 um thick.14.Another example of a sheet silicate is the mineral talc [tælk](滑石；云母), in which a sheet of Mg3(OH)24+ bonds with two outer-layer Si2O52- sheets (one on each side) to form a composite['kɒmpəzɪt](复合的；合成的)sheet with the unit chemical formula['fɔːmjʊlə](公式,方程式) Mg3(OH)2(Si2O5)2.15.Crystalline['krɪst(ə)laɪn](结晶的)silica exists in several polymorphic[,pɒlɪ'mɔːfɪk](多态的)forms that correspond to different ways in which the silicate tetrahedral are arranged with all corners shared.16.The most stable forms of silica and the temperature ranges in which they exist at atmospheric pressure are low quartz[kwɔːts](石英) below 573℃, high quartz between 573 to 867℃, high tridymite['trɪdɪmaɪt](鳞石英)between 867 and 1470℃, and high cristobite[kris'təu,bəlait](方石英) between 1470 and 1710℃.Unit 4（15个）17.Point defects(点缺陷)are localized['lokə'laɪzd](局部的；地区的；小范围的) disruptions[dɪs'rʌpʃən](破坏)in otherwise perfect atomic or ionic arrangements in a crystal structure.18.These imperfections, may be introduced by movement of the atoms or ions when they gain energy by heating, during processing of the material, by introduction of impurities, or doping[dop](掺杂).19.An important "point" about point defects is that although the defect occurs at one or two sites, their presence is "felt" over much larger distances in the crystalline material.20. When atoms or ions are missing (i.e., when vacancies are present), the overall randomness['rændəmnɪs](随意；无安排；不可测性) or entropy['entrəpɪ](熵) of the material increases, which increases the thermodynamic[,θɜːməʊdaɪ'næmɪk](热力学的)stability of a crystalline material.21.Vacancies['vekənsi](空位)play an important role in determining the rate at whichatoms or ions can move around, or diffuse[dɪ'f juːz](弥散,扩散)in a solid material, especially in pure metals.22.If we conduct(管理；引导；表现) this sintering['sɪntərɪŋ](烧结) treatment in a reducing or inert atmosphere (e.g., hydrogen or nitrogen), some of the oxygen ions from BaTiOa will leave the material in the form of oxygen gas.23.In some cases, we can introduce vacancies at specific ion sites so as to enhance the movement of ions in ceramic materials, which can help sinter ceramics[ɪn'hɑːns](提高；加强；增加) at lower temperatures.24.At room temperature(~298K), the concentration [kɒns(ə)n'treɪʃ(ə)n](集中,浓度)of vacancies is small, but the concentration of vacancies increases exponentially[,ɛkspo'nɛnʃəli](以指数方式) as we increase the temperature, as shown by the following Arrhenius type behavior:25.Interstitial[,ɪntə'stɪʃ(ə)l](间质的；空隙的；填隙的) atoms or ions，although much smaller than the atoms or ions located at the lattice['lætɪs](晶格；格子) points，are still larger than the interstitial sites that they occupy; consequently, the surrounding crystal region['riːdʒ(ə)n](范围) is compressed and distorted[dɪs'tɔrtɪd](扭曲).26.Interstitial atoms such as hydrogen['haɪdrədʒ(ə)n](氢)are often present as impurities; whereas[weər'æz](然而；鉴于；反之) carbon atoms are intentionally added to iron to produce steel.27.If there are dislocations(变位；位移；断错) in the crystals trying to move around these types of defects, they face a resistance to their motion, making it difficult to create permanent deformation(永久性变形) in metals and alloys.28.Substitutional[,sʌbstə'tjʊʃənl](置换)atoms or ions may either be larger than the normal atoms or ions in the crystal structure, in which case the surrounding inter-atomic spacings are reduced, or smaller causing the surrounding atoms to have larger inter-atomic spacings.29.Whether atoms or ions added go into interstitial or substitutional sites depends upon the size and valence of guest atoms or ions compared to the size and valence of host ions.Unit 5（10个）30.Semiconductors(半导体) which do not contain appreciable[ə'priːʃəb(ə)l](可感知的；可评估的；相当可观的) levels of dopants or impurities are known as intrinsic[ɪn'trɪnsɪk](本质的，固有的)semiconductors, When we add small concentrations of P or B to silicon crystal, these atoms occupy crystallographic[,krɪstəlɑ'ɡræfɪk](结晶的)sites where silicon atoms usually reside(住，居住；属于).31.The result is each P atom added has one "extra" electron that cannot pair with a Si atom to form a fifth Si-P bond.32.The entire microelectronics[,maɪkrəʊɪlek'trɒnɪks]微电子学) industry, as we know it today, would not exist if we did not have a good understanding of the diffusion of different atoms into silicon or other semiconductors.33.Strong covalent[,ko'velənt](共价的)and ionic bonds along with microstructural features contribute to the relatively poor electrical conductivity exhibited[ɪg'zɪbɪt] by many ceramics.34.The ability of ions to diffuse and provide a pathway for electrical conduction plays an important role in enabling these applications.35.This is one of the major reasons why we use polyethylene terephthalate (PET聚对苯二甲酸乙二醇酯) to make bottles which ensure that the carbonated beverages['bev(ə)rɪdʒ](饮料) they contain will not loose their fizz(兴奋，活力；嘶嘶声；充气饮料) for a reasonable period of time.36.In reality, aluminum[ə'ljuːmɪnəm] oxidizes['ɒksɪdaɪz](氧化) (rusts) more easily than iron. However, the aluminum oxide (Al2O3) forms a very protective but thin coating on the aluminum’s surface preventing any further diffusion of oxygen and hindering(妨碍) further oxidation of the underlying aluminum.37.We distinguish[dɪ'stɪŋgwɪʃ](区分)between the movement of atoms, molecules['mɑlə,kjʊl], ions, electrons, holes, etc. as a result of concentration gradient['greɪdɪənt](梯度) and temperature (diffusion) or some other driving force, such as gradients in density['densɪtɪ](密度), electric field, or magnetic field gradients.38.This equation is derived from(来自，源自于) a statistical analysis(统计分析) of the probability that the atoms will have the extra energy Q needed to cause movement. 39.The disorder vacancies create (i.e., increased entropy) helps minimize the free energy and, therefore, enhance the thermodynamic stability of a crystalline material.40.In chapter 3, we have seen that for many ceramics with ionic bonding the structure can be considered as close packing(密集流水) of anions(阴离子)with cations(阳离子；正离子) in the interstitial sites.41.At higher temperatures, the thermal['θɜːm(ə)l](热的) energy supplied to the diffusing atoms permits the atoms to overcome the activation energy(活化能) barrier and more easily move to new sites in the atomic arrangements.Unit 6（9个）42.Since melting, casting, and thermomechanical[,θə:məumi'kænikəl](热] 热机的，[热] 热机械的)processing is not a viable['vaɪəbl](可行的；能养活的；能生育的)option for polycrystalline[,pɑlɪ'krɪstə'laɪn](多晶)ceramics, we typically process ceramics into useful shapes starting with ceramic powders.43.In this process, the green ceramic is heated to a high temperature, using a controlled heat and atmosphere, so that a dense material is obtained.44.Powders consist of particles that are loosely bonded, and powder processing involves the consolidation [kən,sɒlɪ'deɪʃən](巩固；合并；团结)of these powders into a desired shape.45.In some cases, very large pieces (up to a few feet in diameter and six to eight feet long) can be produced using a process called cold isostatic pressing (CIP冷等静压制) where pressure is applied using oil.46.Similarly, large pieces of metals and alloys compacted['kɔmpæktid]( . 压实的；压紧的) using CIP can be sintered under pressure in a process known as hot isostatic pressing (HIP热等静压；高温等静力压制).47.Some recent innovative['ɪnəvetɪv](革新的，创新的)processes that make use of microwaves (similar to the way food gets heated in microwave oven) have also been developed for the drying and sintering of ceramic materials.48.Some ceramics, such as silicon nitride['naɪtraɪd](氮化物) (Si3N4), are produced by reaction bonding(反应粘合).49.Reaction bonding, which can be done at lower temperatures, provides better dimensional[dɪ'menʃənəl](空间的,尺寸的) control compared with hot pressing; however, lower densities and mechanical properties are obtained.50.This mixture has a clay(粘土)-lake consistency[kən'sɪst(ə)nsɪ](一致性；稠度；相容性), which is then fed to an extruder[ɛk'strudɚ](挤出机；挤压机) where it is mixed well in a pug mill(搅拌机), sheared[ʃɪəd](修剪), deaerated[di'ɛret](出去空气), and then injected(注入的) into a die(冲模，钢模；骰子)where a continuous shape of green ceramic is produced by the extruder.Unit 7（2个）51.The combination of transparency[træn'spær(ə)nsɪ](透明，透明度)and hardness at room temperature along with sufficient(足够的；充分的) strength and excellent corrosion [kə'rəʊʒ(ə)n](腐蚀)resistance to most normal environments make glasses indispensable for many engineering applications such as construction and vehicle glazing(上釉；玻璃装配业).52.However, in borosilicate[,bɔːrəʊ'sɪlɪkeɪt] glasses(硼硅酸盐玻璃) that have additions of alkali['ælkəlaɪ](碱；可溶性无机盐) and alkaline earth(碱土金属) oxides, BO33- triangles can be converted(转化) to BO44- tetrahedra, with the alkali or alkaline earth cations providing the necessary electroneutrality.Unit 8（14个）53.It reacts relatively quickly with water, and in normal Portland cements(波特兰水泥，硅酸盐水泥，普通水泥) is the most important of the constituent[kən'stɪtjʊənt](成分；选民；委托人)phases for strength development; at ages up to 28 days, it is by far the most important.54.The rate at which it reacts with water appears to be somewhat variable, perhaps due to differences in composition or other characteristics, but in general is high initially[ɪ'nɪʃ(ə)lɪ](起初的) and low or very low at later ages.55.The standard specifications(标准技术规范；标准规格) with which such cements(水泥；胶合剂) must comply[kəm'plaɪ](遵守) are similar, but not identical[aɪ'dentɪk(ə)l](同一的；完全相同的), in all countries and various names are used to define the materials, such as Class 42.5 Portland cement in current European and British standards (42.5 is the minimum 28-days compressive strength in MPa), Type I and II Portland cement in the ASTM (American Society for Testing and Materials) specifications used in USA, or Ordinary Portland Cement(OPC) in former British standards.56.Standard specifications are, in general, based partly on chemical composition or physical properties such as specific surface area, and partly on performance tests, such as setting time or compressive strength developed under standard conditions.57.The content of MgO is usually limited to 4%--5%, because quantities of this component in excess of about 2%can occur as periclase (magnesium oxide), which through slow reaction with water can cause destructive expansion of hardened concrete['kɒŋkriːt](具体物；凝结物).58.Many other minor['maɪnə](次要的,未成年的) components are limited in content by their effects on the manufacturing process, or the properties, or both, and in some cases the limits are defined in specifications.59.Rapid-hardening Portland cements have been produced in various ways, such as varying the composition to increase the alite['eilait](硅酸三钙石；A-水泥石) content, finer grinding['ɡraɪndɪŋ](磨的)of the clinker['klɪŋkə](渣块；炼砖), and improvements in the manufacturing process, e.g., finer grinding or better mixing of the raw materials. 60.The alite contents of Portland cements have increased steadily over the one and a half centuries during which the latter have been produced, and many cements thatwould be considered ordinary today would have been described as rapid hardening only a few decades ago.61.For both ordinary and rapid-hardening cements, both lower and upper limits may be imposed on(利用；欺骗；施加影响于) strength at 28 days, upper limits being a safeguard against poor durability[,djʊrə'bɪləti](耐久性；坚固；耐用年限)resulting from the use of inadequate[ɪn'ædɪkwət](不充分的，不适当的) cement contents in concrete.62.63.Destructive expansion from reaction with sulfates['sʌlfet](硫酸盐)can occur not only if the latter are present in excessive [ɪk'sesɪv](过多的，极度的) proportion(比例) in the cement, but also from attack on concrete by sulfate solutions.64.The reaction involves the Al2O3-containging phases in the hardened cement, and in sulfate-resisting Portland cements its effects are reduced by decreasing the proportion of the aluminate phase, sometimes to zero.65.The reaction of Portland cement with water is exothermic[,eksə(ʊ)'θɜːmɪk](发热的), and while this can be advantage under some conditions because it accelerates hardening, it is a disadvantage under others, such as in the construction of large dams or in the lining of oil wells, when a cement slurry(水泥渣) has to be pumped over a large distance under pressure and sometimes at a high temperature.66.lower heat evolution[,iːvə'luːʃ(ə)n](演变；进化论；进展)can be achieved by coarse [kɔːs](粗糙的)grinding, and decreased total heat evolution by lowering the contents of alite and aluminate.67.The ASTM specifications include definitions of a Type II or “moderate heat of hardening” cement, and a more extreme Type IV or “low heat” cement.Unit 9（无）Unit 10（7个）posites(复合材料) are combinations of two materials in which one of the materials, called the reinforcing[,riɪn'fɔrs](增强的) phase, is in the form of fibers(纤维), sheets, or particles and is embedded[ɪm'bed](栽种,嵌入) in the other material, called the matrix['meɪtrɪks](基质) phase.69. If the composite is designed and fabricated['fæbrɪ,ket](制造，组装)correctly, it combines the strength of the reinforcement with the toughness(韧性；强健；有粘性) of the matrix to achieve a combination of desirable properties not available in any single conventional material.70.Because of the variety of available reinforcement and matrix materials, as well asthe ability to combine them in a wide range of volume['vɒljuːm] fractions['frækʃ(ə)n](体积分量), composites can be produced with a broad range of properties, notably['notəbli](显著的) elastic[ɪ'læstɪk] modulus['mɒdjʊləs] (弹性系数；弹性模数), strength, and toughness combinations.71.A composite is a combination of a reinforcing phase present in the form of particles, whiskers, or fibers in a matrix that holds the discrete[dɪ'skriːt]( . 离散的，不连续的) reinforcement pieces together and provides them with lateral support.72.Many composites occur naturally。
考试必备--英语高级翻译必备语句
英译汉：1、 All living things must, by reason of physiological limitations die.由于生理上的局限，一切生物总是要死亡的。
2、 When a person sees, smells, hears, or touches something, then he is perceiving.当一个人看到某种东西，闻到某种气味，听到某个声音或触到某物时，他是在运用感官在感受。
3、 We can get more current from cells connected in parallel.电池并联时提供的电流更大。
4、 There are some metals which possess the power to conduct electricity and ability to be magnetized.某些金属具有导电和被磁化的能力。
5、 The speech synthesis process typically begins with recording a human voice and analyzing it to extract important frequency andamplitude data.语言合成过程一般是先记录人的说话声并通过分析获得重要的频率和振幅数据。
6、 The shadow cast by an object is long or short according as the sun is high up in the heaven or near the horizon.物体投影长短取决于太阳是高悬天空还是靠近地平线。
7、 Much less is connected with the separation of genera, and there is considerable uniformity of opinion as to the delimitation of families.这与属的划分关系不大，而在科的划分上观点是相当一致的。
化学专业英语译文
化学专业英语修订版译文目录：1、THE ELEMENTS AND THE PERIODIC TABLE元素和周期表在原子核中质子的数目被称为原子序数,或质子数,Z;电中性原子中的电子数目也等于原子序数,Z;一个原子的总质量几乎由它的原子核中的质子和中子的总数所决定;此总量称为质量数,A;原子中中子的数目,中子数,其值由下式给出：A-Z;元素这一术语指的是,由单一种类的原子所组成的纯物质;对化学家来说“类”是由其原子序数指定的,因为这是个决定了它的化学行为的属性;目前,所有的原子从Z = 1,Z = 107都为人所知了；共有107种化学元素;每个化学元素被赋予一个名称和一个特定的符号;对于大多数的元素来说符号是简单的英文名称的缩写,由一个或两个字母组成,例如：氧==O 氮== N 氖==Ne 镁==Mg 已经为人所知了很长一段时间的一些元素,其符号是基于其拉丁语中的名称,例如：铁==Feferrum铜==Cucuprum铅==Pbplumbum在表1中可以找到的元素的完整列表;早在17世纪末期,罗伯特.波义尔就开始了这项工作,他提出了现在公认的元素概念,大量的研究使我们对元素及其化合物的性质有了相当的研究;1869年,和,各自通过独立的工作,提出了周期性规律;在现代的形式中,该规律表明元素的属性和原子序数呈周期性的函数关系;换句话说,当元素依照原子序数的升序排列时,具有大致相同的特性的元素将沿着列表中的一定间隔降序排列;因此,将具有类似性质的元素排成纵列,从而将元素排成表格的形式是可能的;这种安排被称为一个周期表;每个一行中的元素构成一个周期;应当指出的是周期表的长度是变化的;有一个很短的周期只由2个元素组成,随后的两个周期各有8个元素,接下来的两个长周期各有18个元素;再接下来的一个周期包括32个元素,最后一个周期显然是不完整的;这样的安排,使得相同的垂直列中的元素具有类似的特性;这些列构成的化学族或群;那些以两个八元素周期为首的族中的元素被指定为主族元素,和其他各组的成员被称为过渡或内过渡元素;在周期表中,一条重重的阶梯线把元素们划分成金属和非金属;这条线除氢外左侧的是金属元素,而在右边是非金属元素;这种划分只是为了方便;那些与分隔线邻近的元素——准金属,既有金属的性质,又有非金属的性质;可以看出,大部分的元素,包括所有的过渡与内过渡元素,是金属元素;除氢元素——一种气体元素外,IA族的元素组成了碱金属族;它们是非常活泼的金属,它们从未在自然界中以单质状态被发现;然而,它们的化合物是广泛分布的;碱金属族的所有成员,只能形成具有1 +价的离子;与此相反,IB族的元素铜,银,和金的元素相对来说是惰性的;它们和碱金属是相似的,因为它们在化合物中以1 +的离子存在;但是,和大多数过渡元素具有的特性一样,它们形成也能形成其它价的离子;IIA族的元素就是通常所说的碱土金属;它们离子的特征价态是2 +;这些金属,尤其是组中的最后两个元素,几乎和碱金属一样活泼; IIB组元素,锌,镉,和汞比那些IIA的元素活性低,但比邻近的IB族元素活泼;它们的特征离子价态也是2 +;除硼以外,第IIIA族元素也相当活泼的金属;铝与空气反应后是惰性的,但这一表现源于这一事实：在金属表面形成了一个薄的,不可见的铝的氧化膜,该膜保护大部分金属不会进一步氧化;IIIA族的金属形成3 +价的离子;IIIB族由金属钪,钇,镧和锕组成;第IVA族由一个非金属,碳,两个准金属,硅和锗和两种金属,锡和铅组成;这些元素中的每一个都形成一些化合物,这些化合物的分子式表明四个其它的原子出现在每个IVA族原子周围;例如,四氯化碳,CCl4; IVB族金属——钛,锆和铪,也形成每个IVB族原子与四个其它原子结合的化合物,这些化合物纯的时候是非电解质;VA族的元素包括三个非金属元素——氮,磷,砷和两个金属——锑和铋;尽管它们存在分子式为N2O5,PCL5,和AsCl5的化合物,但它们都不是离子型化合物;这些元素形成的化合物——氮化物,磷化物和砷化物,其中离子的价态都是负三价; VB族的所有元素都是金属;这些元素形成这样的多种不同的化合物,它们的特点是不容易总结归纳的;除钋以外,VIA族元素是典型的非金属;他们有时也被称为硫族,来自希腊字,意思是“灰源体”;在他们与金属形成的二元化合物中它们以2-的离子价存在;ⅦA族的所有元素都是非金属元素,被称为卤素;来自希腊文,意思是“盐源体”;他们是最活泼的非金属,并能够与几乎所有的金属和大部分非金属,包括它们自己反应;ⅥB,ⅦB,VIIIB的所有元素都是金属;它们形成各种不同的化合物,在这一点上我们甚至不能举出任何能表现各族元素典型变化的例子;化学行为的周期性可以通过这样的事实阐明：不包括第一个周期,每个周期的开始,是一个非常活泼的金属;周期中的连续元素,金属性逐渐降低,最终成为非金属,最后,在ⅦA族,一个非常活泼的非金属就出现了;每个周期以惰性气体家族的一个成员结束;-------------------------------------------------------------------6、THE CLASSIFICATION OF INORGANIC COMPOUNDS无机化合物的分类化合物的分类今天成千上万的化合物已被化学家所认识;如果根据个别化合物来了解这么多化合物的性质和行为,即使其中的很小一部分也不可能;所幸的是,大多数化合物可以被归为几类;这样,如果我们能正确地对一个化合物进行分类,就可以根据已知这类化合物的性质知道这个化合物的一般性质;例如,盐酸是一种酸,因为已经熟悉酸的性质,我们就可以立即知道这一化合物的一般性质;我们学过的大多化合物可以分为酸,碱,盐,金属氧化物,非金属氧化物;在这5类化合物中,前3种—酸,碱,盐—是最重要的;如果一种酸,碱或盐溶于水中形成的溶液是电流的导体,就被称为电解质;如果没有电流产生则此化合物是非电解质;普通化合物的分类通过观察化学式我们可以将许多普通化合物分类如下：⒈⒉通常碱中存在的氢氧根写在分子式的后面;分子式的前面一般是金属;例如,OHOH3;⒊盐由金属组成,写在前面,结合非金属或基团,写在化学式的后面;如SOClO2;⒋氧化物仅包括氧和其它一种元素;如果这种元素除了氧以外是非金属,这种氧化物称为非金属或酸酐;酸酐的命名是因为在特定的条件下将水溶液加入到非金属氧化物中会生成酸;同样,如果水从含氧酸中被转移走就会生成酸酐;另一类氧化物,金属氧化物或碱酐,由氧结合金属组成;当在适当的条件下将水加入到碱酐中,有碱生成,反之亦然;酸按传统的观念,所有的酸都包含H,它可以被金属取代;在酸分子中负价的基团由非金属或基团组成负价基团;这些负价的基团被称为酸根除了氧和氢氧根;所有的酸都是共价化合物,它们的原子通过共用电子连接;当酸溶于水时,由于酸中的氢离子转移到水分子中所以形成离子——例如：H ‥‥‥‥ H﹕Cl﹕+H﹕O﹕H→H﹕O﹕H++﹕Cl﹕-这是一种配位价,水中未成对的电子结合氢离子形成水合离子;水合离子是水合物H+ 或称质子,根据这种形式酸在水溶液中电离时,我们可以利用简单的H+来写方程式;此方程式变得简单而且容易配平;酸的主要性质是提供H+的能力,因此,我们把能够提供H+的物质定义为酸; 酸的性质,一般来说,酸的水溶液的性质如下：⒈它们都有酸味;柠檬,桔子以及其它的柠檬水果由于柠檬酸的存在而具有酸味；酸奶的酸味也是因为乳酸的存在;⒉它可以使蓝石蕊变红;石蕊是一种染料,它在酸溶液中显红色,在碱溶液中显蓝色；将纸浸泡在石蕊中制成石蕊试纸;这类物质,能够确定所给的溶液是酸还是碱,我们称之为指示剂;甲基橙和酚酞是其它两种常用的指示剂;⒊它可以和某些金属反应生成氢气;这类反应经常被用来制氢气;⒋它和碱反应生成盐和水;一般的强酸有硫酸,硝酸,盐酸,氢溴酸和氢碘酸;其它的一些酸仅仅部分电离从而仅仅是中强酸或弱酸;碱所有金属的氢氧化物被分类于碱类;一般的碱如氢氧化钠,氢氧化钾,氢氧化钙和氢氧化钡可以溶于水中;如果这些化合物可以溶解于水中,所有的溶液中都会有OH- ;氨的水溶液也属于碱类,因为溶液中存在OH-;每种这类化合物都是由金属或铵根离子结合氢氧根离子形成的;正如显示酸特性的部分是H+,因此显示碱特性的部分是OH-;因此碱的概念就扩展为不能提供质子的物质; 碱的性质;一般来说金属氢氧化物的水溶液显示出以下的性质：⒈味道苦;⒉具有滑腻性;⒊可以使红色石蕊变蓝;⒋和酸生成盐和水;⒌大多数金属氢氧化物都是可溶的;一般情况下氢氧化钠,氢氧化钾,氢氧化钙,氢氧化钡和氨是可溶的;一般的强碱有氢氧化钠,氢氧化钾,氢氧化钙和氢氧化钡;盐酸和碱反应生成盐和水;酸中的氢离子结合碱中的氢氧根离子形成水分子;酸和碱的反应是中和反应;如果在反应后所有的水通过蒸发移走,碱中的正离子和酸中的负离子形成晶格的固体;证据显示化合物氯化钠,一种盐,是一种电价的化合物,可以在固体或晶体状态下电离;这种晶体由钠离子和氯离子通过定向模式组成的;一般来讲,大多数盐在晶体状态下是电价的;由定向离子通过确定的方法组成;-------------------------------------------------------------------7、The Nomenclature of Inorganic Compounds无机化合物的命名随着上千种新无机化合物的发现,我们有必要修改传统命名的规则;国际委员会已经推荐了一套化合物命名的规则,并且现在世界各地都采用了;许多旧的名字仍然在使用,但是我们将讨论新旧规则的许多例子,但以新规则为讨论重点;其中主要的变化就是被Albert Stock提出的为一些存在多种氧化态的金属的化合物氧化物、氢氧化物、盐命名的Stock方法;在这种情况下,金属氧化态是紧接着金属的英语名称之后在圆括号中用罗马数字表示,该数字与金属的氧化数一致;如果金属只有一个常见的氧化数,则不使用罗马数字;另一个重要的变化是在命名复杂的离子和配位化合物;我们推迟后者的命名直到我们讨论这些化合物;金属氧化物、酸碱、盐的命名一个学生如果掌握了给出离子电荷和较常见离子名称的价表3,他在掌握命名方面就必定有了一个好的开端;阴阳离子以恰当的比例来平衡电荷组成了化合物,并且化合物的名字来自于离子的名称,例如NaCl叫氯化钠;AlOH3叫氢氧化铝,FeBr2叫溴化铁Ⅱ或者溴化亚铁;CaC2H3O22叫乙酸钙,Cr2SO43叫硫酸铬Ⅲ或者硫酸铬,等等;表4给出一些额外金属化合物命名的例子;两种常见的系统被使用时,Stock系统是首选;注意的是,即使在这个系统中,然而阴离子的名称仍需要查化合价表4;带负电荷的离子,阴离子,可能是单原子的或者是多原子的;所有单原子的阴离子都有以 ide结尾的名字;氢氧根离子OH-和氰根离子CN-的两个多原子离子也有以ide结尾的名字;许多多原子离子除了其他元素还包含了氧元素;在这些含氧阴离子中氧原子的数量以后缀ite和ate来表示,ite和ate分别意味着较少和较多的氧原子;在某些情况下,有必要表示多于两个相同元素的氧阴离子,分别表示更少和更多氧原子的前缀hypo和per 可能被使用;一系列的氧阴离子被命名在表5中;非金属氧化物的命名仍被广泛使用的旧的命名系统使用希腊语前缀表示氧原子的数目和化合物中其他的元素;被使用的前缀有lmono-, 有时简称成 mon-, 2di-, 3tri-, 4tetra-, 5penta-, 6 hexa-, 7hepata-, 8octa-, 9nona-and 10deca-;当命名一个非金属氧化物时,渐渐地的字母a在前缀中被省略tetra并且常常mono-在所有的名称中也一起被省略;Stock系统也被用于非金属氧化物,这里的罗马数字指的是除了氧元素其他元素的氧化态;在两个系统中,除了氧元素的其他元素被首先命名,整个名称后面加上一个OXide;表6中展示了一些例子;酸的命名酸的名字可以直接从化合价表3的知识中得到,只要以下面表的形式改变酸离子阴离子的名字即可;表7展示了这种关系的例子;还有少数情况下,酸的名字可以由酸根稍稍的改变得到;例如：H2SO4是sulfuric而不是sulfic;相似的,H3PO4是phosphoric而不是phosphic;一些很少见的阴离子不包括在化合价表3中;例如：BO33-是硼酸根的离子并且H3PO3是硼酸;TeO42-是碲酸盐离子并且H2TeO4是碲酸,等等;酸式盐和碱式盐可以想象,在酸和碱的中和反应中,只有一部分氢离子被中和；因此NaOH + H2SO4-----→NaHSO4 + H2O化合物NaHSO4有酸的性质,因为它当中有氢离子,它也是一个盐,因为它既有金属阳离子有酸根;像这样的含酸性氢离子的盐叫做酸式盐;磷酸H3PO4可以逐渐的被中和成盐,NaH2PO4, Na2HPO4 和 Na3PO4;前两种是酸式盐,因为它们包含可置换的氢;一种命名这些盐的方法是把NaH2PO4叫做磷酸二氢钠,把Na2HPO4叫做磷酸氢二钠;这种算是磷酸盐在控制血液酸碱度方面起着重要作用;第三种化合物,磷酸钠Na3PO4,其中没有可置换的氢,通常被叫做正磷酸钠,或磷酸三钠用以区别前两种酸式盐;历史上,前缀bi-被用来命名一些酸式盐;在工业上,例如,NaHCO3被叫做碳酸氢钠而CaHSO32被叫做亚硫酸氢钙;因为bi-有点令人误解,故上面讨论的命名系统更可取;如果碱中的氢氧根逐渐被氢离子所中和,就很可能形成碱式盐：CaOH2 + HCl-----→CaOHCl + H2O碱式盐有碱的性质并且可以和酸反应生成正盐和水;OH基团是一个碱性基团叫做羟基集团;BiOH2NO3的名字叫做碱式硝酸铋;混盐如果酸中的氢被两种或两种以上不同的金属所替换,就形成了混盐;因此H2SO3中的两个氢原子被钠和钾取代从而生成混盐,NaKSO4硫酸氢钾;NaNH4HPO4是一个酸式混盐,它可以从尿中结晶出来;-------------------------------------------------------------------9、The coordination complex配位化合物配位化合物形成的化学基础是配位键,形成时必须有一个电子对受体和一个电子对给体;因此,配位反应是路易斯酸碱的中和过程;中心离子是路易斯酸或电子对受体,而周围的基团,叫做配体,它们是路易斯碱或电子对给体,总的来说,这个反应可以这样来表述：Mn+ + x:L -----→ M:Lxn+正向反应是配位反应而逆向反应是解离反应,不管是配位反应还是解离反应,当x大于1时,这个反应都是逐级的,所以上面的方程式是几个逐级反应的总和;配位键本质上在介于共价键包括在一些情况下双键的性质和离子键之间,例如在水溶液中的化合物NaH2Ox +,钠离子和配位水分子的相互作作用就强于在氯化钠晶体中和周围氯离子的相互作用;而在另一个极端,像FeCN64-这样的化合物就主要包含基础的共价键;这种性质上的不同由表9中的化合物说明;表中前四种化合物是类盐物质,它们的阴离子和阳离子只有一个是络合物;这显然是对于它们的水相组成来说的;然而,相同的离子在固相中依然是存在的,尽管正如表中所示,它们的分子式都被写成复盐的形式;在上面的每种情况中络合离子都在溶解过程中存在,但是在溶解过程中很少有自由配离子和水合单原子离子的踪迹;值得注意的是,配离子可以是分子,像NH3,也可以是离子的,像CN-,NO2- 或F-,在VF4H2O2-的例子中,钒就既和分子型,也和离子型的配体配位了;第五个化合物Pt2Cl44NH3,在水溶液中既包含络合阳离子也络合配位阴离子;最后一个化合物有一个表明CuCl42-络合离子存在的晶体构型,然而,当该物质溶解于水中时,混合的水合单分子离子就形成了;这清楚的说明了Cu II 和水配体形成了一种比和氯离子配体更稳定的化合物;高度的离子性使得水合Cu II 在溶液中快速的转换,在溶解过程中没有CuCl42-存在并不能证明它在固相中不存在;配位场理论已证实在配位化合物中有用的新理论是晶体场或配位场理论,该理论说明配位体被配位化合物的中心离子拉住,主要是由于中心离子的原有电荷和配位体的极性间的静电吸引力;吸引力的强弱程度决定了络合物的稳定程度;也取决于中心离子和配体的价态和尺寸; 运用这个理论,计算很多价态和尺寸等因素的能量影响,并且最终获得键能的值;后者对预测大部分化合物的性质和构型来说十分有用;配体配体必须是极性的或者是可极化的非极性配体是弱配体,并且它们通常含有能和中心离子形成配位键的未共用电子对;配体可以基于它们和金属离子形成一个键键单齿的或两个键双齿的的能力进行分类,二价的或有两个给体原子的配体,像乙二胺H2N—CH2—CH2 — NH2,是二配位的,因为它们包含两个位点,并以此和中心原子成键;配体可能还要复杂,三齿的、四齿的、甚至六齿的配体都已为人所知;多齿配体可能同时含有可与中心离子配位的中性和负电性的位点,就像甘氨酸离子：在这里含氧负离子和中性的含氮原子都有未共用的电子对并且都可以和给定的阳离子配位;其中一个例子是络合物Co H2NCH2CO2 3,在这个络合物中钴和甘氨酸离子中的一个氧都发生了配位,当多齿配体和中心离子在两个或两个以上的位点配位的时候,就形成了上述钴的乙二胺配合物那样的环状结构,这种络合物叫做螯合物,而多齿配体则叫做螯合体;配位化合物的命名和实例1、阳离子最先命名,阴离子最后命名;2、负离子的名称以o结尾,就如表10所举之例;它们是cyano-, hydroxo-,chloro-,carbonato-.按照字母顺序排列;3、中性单元历史上自有其结尾,像ammine氨, aqua-水以前是 aquo-, carbonyl 羰基, nitroso-亚硝基;4、络合物中中心离子的氧化数由元素后面括号中的罗马数字表示,当络合离子是阴离子时中5、中性络合物和阳离子的命名方法相同;6、如果该络合物是正电性的,那么要以络合物中不包含的阳离子的名称来补全化合物的名称; 这些规则将由下面的例子说明：-------------------------------------------------------------------10、Alkanes烷烃异构体的数目现在总称为烷烃的化合物也被称为饱和碳氢化合物和链烷烃;链烷烃这个词来源于拉丁文,指的是物质的化学惰性,也被用于能从石油中获得由高级烷烃组成的石蜡;已经证明戊烷三种异构体,己烷五种异构体,庚烷九种异构体等结构式的多样性随着碳含量的增加急剧增加;常见的烷烃这一系列中的所有烷烃的区别在于他们的组成上含有递增的CH2基团,并构成了一个同系列;因此,庚烷和辛烷是同一系列的烃,二十烷是甲烷的更高级同系物;饱和无支链的链状化合物及其一价基团前四个饱和的无支链的无环状的碳氢化合物被称作甲烷,乙烷,丙烷和丁烷;这一系列中更高级成员的名称是由去掉数字末尾的”a”再加上”-ane”的数字术语构成;下列表中是这些名称的例子;饱和非环碳氢化合物支链或无支链的总称为“烷烃”;饱和有支链的碳氢化合物的命名是把支链的名称加到最长链的名称前面;最长链是用阿拉伯字母从一端向另一端编号,这样选择编号方向时尽可能使支链位次具有最低的编号;当逐一比较包含着相同碳原子数目的许多位次时,根据第一个位次差异,含最低数字的是最低者;这一原则的应用与取代基的性质无关;例如：2,3,5——三甲基己烷用适当的词缀2,3,4...等作前缀表示相同的未被取代的基团;例：3,3——二甲基戊烷饱和的非环状碳氢化合物末端碳原子上去掉氢而衍生的一价基团,在命名时是将碳氢化物名称末尾的“-ane”用”yl”替换;含有自由价的碳原子被编号为“1”位,作为一类,这些基团被称作常规的或无支链的烷基;例：1—甲基戊基,2—甲基戊基,5—甲基戊基异丁基,仲丁基,叔丁基,辛戊基稳定性—化学上,烷基是相对惰性的,因为对于那些很易与烯烃和炔烃反应的试剂;它们却显出很高的惰性;例如,正己烷,不能与浓硫酸,沸腾的硝酸,熔融的氢氧化钠,高锰酸钾或铬酸反应;除了氢氧化钠外,这些试剂在常温下都易与烯烃反应;能和烷烃发生的少数几个反应几乎都需要较高的温度或特殊催化剂;卤代作用—如果把一个盛有正己烷的试管放在暗处,并用一滴溴处理,几天后原有颜色仍保留不褪色;假如将溶液暴露在太阳光下,颜色几分钟就会褪去,并且可以在试管口产生呈现出来的雾状冷凝物溴化氢;这个反应是光化学取代反应：C6H14+Br→C6H13Br+HBr烷烃的氯代比溴代更普通更有用,它不仅在光化学条件下实现,而且可以利用其它方法实现;光引发烷烃的氯代反应是将氯气分子通过均裂过程转变为氯原子,在均裂过程中,一个共价键断裂,形成这个键的每个原子仍保留一个电子;一个氯原子有奇数个或未成对的电子,它是一种自由基;由于原子具有达到最外层价电子饱和的趋势;任何自由基都是非常活泼的;光化学氯代反应是通过一系列自由基的传递进行的;它是自由基的链反应;链引发阶段1,即氯分子的均裂,产生了氯自由基；在链传递阶段,一个氯自由基和烷烃分子反应,产生氯化氢和一个烷基自由基2,这个自由基依次再和氯分子反应产生氯代烷和氯自由基3,由于第二阶段需要的氯自由基在第三阶段再生,这两个反应合起来组成链反应;在链反应中如果两个反应以极高的效率进行,将不需要进一步的光能而自动传递;然而这种效率并不是很高,因为氯自由基可能重新结合4,或与烷基自由基结合5,或与器壁碰撞消耗能量6;因此,需要持续提供光照保证引发自由基需要的充足能量;链引发阶段需要输入的光能总计为+mol;但第二阶段是放热的;因为断裂碳氢键所需的能量比氢氯键所需的能量小;第二阶段的链传递3也是放热的;事实上烷烃的氯代反应是爆性式的进行;裂解—加热到500-700℃时,更高级的烷烃经历热裂解或裂化生成小分子混合物,其中一些是饱和的,一些是不饱和的;特殊的石油馏分通过选择性的断裂产生的不饱和的碳氢化合物在化学合成上是很有用的;裂解断裂的是碳碳键而不是碳氢键;因为打开碳碳键需要的能量是247KJ/mol,而断裂碳氢键所需能量是364KJ/mol;氧化物—碳氢化合物和氧气反应放出能量,这是内燃机使用汽油作燃料的依据;一个给定的碳氢化合物释放的能量用燃烧热来表示, 用KJ/mol来表示;气态碳氢化合物的不充分燃烧在生产碳黑方面是很重要的,尤其是生产灯芯,墨汁颜料,槽法碳黑,被应用于橡胶工业的填料;天然气因为价廉,易得而被使用；炭黑的产量随。
英语专业英译汉课件
Chinese-English Translation CourseUnit OneError Analysis:Part One On the test paperI. Choose the one which is proper and idiomatic .1. Our home, once full of laughters, now deafens us with its silence.译文A: 我们的家，曾经充满了欢声笑语，现在却充满了令人震耳欲聋的沉寂。
译文B: 我们的家，曾经充满了欢声笑语，现在却十分安静。
2. There are few of us but admire his courage.译文A: 我们人人都佩服他的勇气。
译文B: 我们中很少有人佩服他的勇气。
3. All cities did not look like as they do today.译文A: 在过去，城市面貌并不都像今天这样千篇一律。
译文B: 过去，城市面貌与现在完全不同。
4. To starve oneself emotionally is a mistake.译文A: 不满足自己感情上的需要是一种错误。
译文B: 使自己的感情挨饥受饿是一种错误。
5.The boss‘s girl Friday called me.译文A: 老板的女儿星期五打电话给我了。
译文B: 老板的女秘书打电话给我了6. Marriage bed is full of roses and thorns.译文A: 婚姻总是有苦有甜。
译文B: 婚姻的花坛里既长鲜花也生荆棘。
7. I never go past that kindergarten but think of my happy childhood there.译文A: 每当我走过那所幼儿园，我就回想起在那里度过的幸福童年。
译文B: 尽管我从未经过那所幼儿园，但是我回想起在那里度过的幸福童年8. And soon over the whole surface of the marsh, a great cloud of birds hung screaming and circling in the air.译文A: 很快就有一块乌云似的一大群野鸟在沼泽上空惊叫着，盘旋着。