joural of soe-gel science and technonlogy

joural of soe-gel science and technonlogy
joural of soe-gel science and technonlogy

ORIGINAL PAPER

Formation and characterization of c -Fe 2O 3@SiO 2@Ag

I.G.Blanco-Esqueda ?G.Ortega-Zarzosa

?

J.R.Mart?

′nez ?A.L.Guerrero-Serrano ?J.A.Matutes-Aquino

Received:2October 2014/Accepted:5February 2015óSpringer Science+Business Media New York 2015

Abstract Fe 2O 3@SiO 2@Ag composites were synthe-sized,using the coprecipitation method to obtain maghe-mite nanoparticles coated with SiO 2using the Sto

¨ber method to avoid the oxidation,and ?nally silver nanopar-ticles were incorporated by a chemical method.The sam-ples were characterized by X-ray diffraction,transmission electron microscopy,IR spectroscopy and vibrating sample magnetometry.

Keywords Coated nanoparticles áSol–gel áCoprecipitation ác -Fe 2O 3@SiO 2@Ag

1Introduction

Recently the magnetic nanoparticles (NPs)provide some attractive applications in different disciplines such as in physics,biology,chemistry and medicine.The reason is that at this scale,the magnetic NPs show a super-paramagnetic behaviour [1],allowing that we can

manipulate them easily with an external magnetic ?eld.

Recent studies about the coating of the magnetic NPs with different materials allow designing composites with special properties,which depend on the requirements that we wish [2].For example,it is common to ?nd the coating with organic surfactants and polymers to provide them stability and biocompatibility [1].To enhance these properties,we can use a shell of silica that helps to avoid the degradation,changes in phase or agglomeration of the magnetic nanoparticles.

In particular,silica coating has been identi?ed as a promising route to screen the magnetic dipolar interactions between the magnetic NPs [3–5].Several methods have been developed for the preparation of silica-coated mag-netic NPs with core–shell structures including reverse mi-croemulsion synthesis [6–8],arc-discharge [9]and sol–gel processes [10–12].In particular,maghemite nanoparticles synthesized by the co-precipitation technique and coated with silica shells using sol–gel method have been carried out by some authors [13,14].

Incorporation of the magnetic NPs with metallic nanoparticles allows obtaining functional composites with magnetic properties associated with the properties of the metallic nanoparticles.In particular,the silver NPs have been proved to be the most effective antimicrobial agent [15,16].

To improve the chemical stability of Ag nanoparticles,core–shell-typed Ag@SiO 2nanoparticles have been syn-thesized and tested [17–19].In this kind of systems,the SiO 2shell serves as a protecting layer for Ag nanoparticles and can also easily bind to glass substrates,thus forming a durable coating [17].

We can ?nd researches about the bactericide activity of the silver nanoparticles against some different bacteria such as Escherichia coli ,Staphylococcus epidermis y

I.G.Blanco-Esqueda áJ.A.Matutes-Aquino

Centro de Investigacio

′n en Materiales Avanzados S.C.,Chihuahua,Mexico

G.Ortega-Zarzosa áJ.R.Mart?

′nez (&)Facultad de Ciencias,Universidad Auto

′noma de San Luis Potos?′,78000San Luis Potos?′,SLP,Mexico

e-mail:?ash@fciencias.uaslp.mx

J.R.Mart?

′nez Departamento de F?

′sico-Matema ′ticas,Universidad Auto ′noma de San Luis Potos?

′,78000San Luis Potos?′,SLP,Mexico A.L.Guerrero-Serrano

Instituto de F?

′sica,Universidad Auto ′noma de San Luis Potos?′,78000San Luis Potos?

′,SLP,Mexico J Sol-Gel Sci Technol

DOI 10.1007/s10971-015-3656-x

Bacillus subtilis[20,21].So that it exists many applica-tions for these silver NPs such as in deodorants,coatings on medical instruments and water disinfectants.For this last application,there exists one problem:the recuperation of the silver NPs is very dif?cult,and in some concentrations the silver induces a disease called argyria[22,23].One solution is the functionalization of magnetic NPs with sil-ver to facilitate the recuperation with the help of a mag-netic external?eld.

We propose the functionalization of magnetic NPs of maghemite(c-Fe2O3)with a silica shell(SiO2)and the incorporation of silver(Ag)NPs as antibacterial agent by a simple chemical method.That allows the manipulation by means of magnetic?eld of the bactericidal agent and their subsequent recovery,minimizing their negative impact on the environment.

In the present study,we employ chemical methods to fabricate functional Fe2O3@SiO2@Ag particles with paramagnetic comportment for eventually that can be using in antibacterial applications and can be recuperated.

Magnetic nanoparticles were synthesized by the copre-cipitation method[24,25].Then these nanoparticles were coated with silica using the Sto¨ber method to avoid their oxidation[26,27].After this procedure,we incorporated the nanoparticles with silver by chemical method,and we characterize their structural and magnetic properties.

2Experimental procedure

In order to fabricate Fe2O3@SiO2@Ag composite, maghemite nanoparticles were?rst prepared using the co-precipitation method.The chemical precursors used for synthesis of the maghemite were as follows:ferric chloride (FeCl3á6H2O),ferrous chloride(FeCl2á4H2O)and ammo-nium hydroxide(NH4OH).In a solution of10ml of deoxygenated water was mixed0.3936g of iron chloride (II)with1.080g of iron chloride(III)in molar ratio of Fe(II)/Fe(III)=0.5,and then ammonium hydroxide was added until was reached a pH=10.To form the maghe-mite nanoparticles,the precipitate was left at room tem-perature in an open vessel for their ventilation.

The Sto¨ber method was used to coat the maghemite nanoparticles with SiO2.For that,we prepared two solu-tions:the?rst one with30ml of ethylic alcohol and2ml of TEOS,and this solution was added to a second solution composed of38ml of water,38ml of ethylic alcohol,5ml of NH4OH and10ml of the obtained solution with maghemite.Then,the mix was stirred for3h.

Once the maghemite NPs were coated with silica,a fraction of the sample was taken to incorporate silver nanoparticles in their surface.For that,the magnetic nanoparticles with silica were stirred during10min.At this point,it is common to aggregate TEOS in order to have a small layer that acts as adhesive between the magnetic nanoparticles and the silver when reacting with the sodium borohydride to form the silver NPs;however,in our case, this procedure is not necessary since we obtained a good bonding between core shell and silver NPs by adding6ml at0.01M of silver nitrate and stirred for30min with the magnetic particles;and then6ml of sodium borohydride at 0.2M was added and stirred during30min.The procedure is shown schematically in Fig.1.

X-ray diffraction(XRD)patterns were obtained using a GBC-Difftech MMA diffractometer.The nickel-?ltered Cu K a(k=1.54A?)radiation was used.The re?nement was ?tted very well with the phase of maghemite(tetragonal symmetry and spacial group P43212).The analysis was started assuming the structure of trigonal SiO2(trigonal, space group P3221)for the amorphous phase.

Infrared(IR)spectra were recorded with a FT-IR spec-trometer Nicolet system model Avatar360using the dif-fuse re?ectance(DR)mode,for which0.05g of powder sample was mixed with0.3g of KBr.The magnetic characterization was done acquiring the hysteresis loop on a Micromag,AGM2900Princeton Measurements Mag-netometer.Transmission electron microscopy(TEM)ana-lysis was performed on a JEOL JEM-1230at an accelerating voltage of100kV.

3Results and discussion

Magnetic iron oxide nanoparticles are?rst coated with silica to isolate the magnetic core from the surrounding.To con?rm the composition of the magnetic particles,XRD pattern for Fe2O3nanoparticles coated with SiO2was measured.Figure2shows the X-ray diffractogram of the magnetic nanoparticles coated with silica.The observed peaks correspond very well to the maghemite phase,which has being corroborated by the Rietveld re?nement analysis. It has been shown that the method works also well to calculate the amorphous/crystalline fraction in composites with crystalline phases,as in the current case[28].In any case,very good agreement between experimental and cal-culated amorphous/crystalline fraction of composites was obtained[29].

This re?nement indicates that the core–shell nanoparti-cles were pure c-Fe2O3.For these2h values,although the intensity is lower than the diffractogram for pure Fe2O3, the peaks corresponding to maghemite are not obscured by the very broad SiO2peak centred at2h=21°.This means that X-ray might penetrate through the core.Thus the showed peaks did not completely vanish,but its intensity decreased.The Rietveld re?nement assuming the structure

J Sol-Gel Sci Technol

of trigonal SiO 2for the amorphous phase and the very well ?tted indicate us the presence of cover silica.

In summary,we observed the presence of SiO 2amor-phous phase and maghemite phase.The presence of these

two phases is con?rmed by the Rietveld re?nement for amorphous SiO https://www.360docs.net/doc/474102897.html,ing the above re?nement process,the Bragg pattern and the peak position of the diffractograms correspond to the phases identi?ed according to the spatial group Fd-3m:2for the maghemite and (P3221)for the quartz-like amorphous.

The weight per cent of phases calculated by Rietveld re-?nement were 91.45%of SiO 2,and 8.54%of c -Fe2O3.The former phase leads to a lattice parameter of 8.3495±0.0047A

?′and a crystallite size of 16.6±0.4nm,these parameters being in agreement with previous reported values for maghemite particles coated with SiO2[13].

To determine the presence of the silica shell,we acquire the IR spectrum and we did a deconvolution study to de-termine the presence of maghemite as core.

The IR spectrum (Fig.3)shows evidently the presence of characteristic absorption bands of SiO 2.We can identify the vibrational bands of Si–O–Si around 1085cm -1(main

Fig.2X-ray diffractogram and Rietveld re?nement of the maghe-mite particles coated with SiO 2

Fig.3IR absorption spectrum of the magnetic nanoparticles with SiO 2,a in the region from 400to 1200cm -1and

b deconvolution at the range from 400to 1000cm -1

J Sol-Gel Sci Technol

band of SiO2)and453cm-1.Other vibrational bands are the silanols(Si–OH)around950cm-1,as well as extended well de?ned bands in the range from about450to 1000cm-1;these bands have been assigned to vibrational modes of Fe–O bonds in Fe2O3[30,31].These IR features indicate the formation of the iron oxide species.

This last contribution can be observed in the deconvo-lution performed of the IR spectra in the region between of 450and1000cm-1,which is observed a very broad ab-sorption band.

In the spectra,one observes that the peaks at about 480cm-1are very sharp.This fact and the presence of the peaks obtained in the deconvolution process at about453, 555,634and773cm-1indicate the formation of spinel phase in accordance with the X-ray results.

In Fig.4,the TEM images show the shell of the silica covering the magnetic nanoparticles,and we can note that the magnetic nanoparticles were successfully coated with a good de?ne shell of silica with diameters of around70nm. Inside of the shell,the magnetic nanoparticles remain ei-ther isolated or form small agglomerates.

The image clearly shows the presence of iron in the core region and its total absence in the shell region,indicating that the magnetic cores are embedded within the silica spheres.Inter-particle distances are modulated by the SiO2 shell thickness,and this determines the fraction volume of the particles in core[32,33].

When the inter-particle interaction becomes non-negli-gible,structural and magnetic behaviour of the system can radically be changed by forming compact aggregates in the case of strong interactions or by haring a spin glass-like behaviour in the case of weak interactions[14].

In our case,we obtain a weight of8.54%of maghemite so that the inter-particles distance is lower than that ob-tained by Pereira et al.[13],who obtained a weight per-centage of5%for maghemite.This prompted the NPs

to Fig.4TEM images of c-Fe2O3@SiO2

J Sol-Gel Sci Technol

present some agglomeration conducting to obtain a ferro-magnetic behaviour.

In contrast to the maghemite nanoparticles that have a superparamagnetic behaviour,c -Fe 2O 3@SiO 2and c -Fe 2-O 3@SiO 2@Ag present a ferromagnetic behaviour with coercivity of 9.8and 5.2Oe,respectively,and the hys-teresis loop is shown in Fig.5.The effect of the small ferromagnetism observed in the composites is due to the agglomeration of superparamagnetic nanoparticles inside the silica shell.In this sense,agglomerated nanoparticles act as a big particle [34,35].Moreover,the extremely low remanence and coercivities do not affect the magnetic manipulation of the composites because the magnetic nanoparticles are wrapped in a thick layer of silica,which prevents magnetostatic interactions between particles.Figure 6shows the re?nement diffractograms with the incorporation of silver.In the ?gure,we can observe the characteristic peaks of silver.The diffractogram shows the peaks corresponding to elemental silver (JCPS 17004-0783),which have no response to an external magnetic

?eld,and it is dif?cult to identify any peak of the magnetic nanoparticles.In this diffractogram,the peaks of maghe-mite are obscured by the presence of silver that covers the composite c -Fe 2O 3@SiO 2,and in the re?nement process,we can observe the very low intensity of maghemite peaks,due to the presence of silica as cover shell.

The structural parameters for Ag calculated by the Ri-etveld re?nement,which used the spatial group Fm-3m,

lead to a lattice parameter of 4.0920±0.0003A

?′,and a crystallite size of 75.9±2.2nm,whereas for the maghe-mite phase,we obtain a grain size of 16.6±0.4nm,with a

lattice parameter of 8.3495±0.0047A

?′,similar to the values obtained for Fe 2O 3@SiO 2,which indicates the sta-bility of the core shell.

The presence of the composite Fe 2O 3@SiO 2@Ag can be corroborated by the IR spectrum shown in Fig.7.

Because Ag nanoparticles do not have absorption in the infrared region,the IR spectrum of Fe 2O 3@SiO 2@Ag is almost the same as that the Fe 2O 4@SiO 2sample.

However,

Fig.5Hysteresis loop for c -Fe 2O 3@SiO

2

Fig.6X-ray diffractograms and Rietveld re?nement of the Fe 2O 3@SiO 2@Ag

sample

Fig.7IR absorption spectrum of the composite Fe 2O 3@SiO 2@Ag,compared with Fe 2O 3@SiO 2

J Sol-Gel Sci Technol

in agreement with previous results in samples with Ag embedded in silica xerogel matrix[36],the structural ef-fects caused by the incorporation of Ag can be observed, indicating their presence.

From the IR spectrum,one can observe the bands as-sociated with stretching,bending and rocking vibration corresponding to SiO2,and the bands corresponding to Fe–O.Also we can note the effects caused by the incorporation of Ag over silica where the bands of SiO2were modi?ed due to the presence of the metallic silver.In particular, Fig.7shows that the position of the main band shifts from about1080(this position is typical for the conventional silica gel)to1100cm-1[36,37].These results are in agreement with studies of the structure of silica gels using different sources by Kamiya et al.[38,39].

From the IR spectrum,it is possible to see an incipient band at620cm-1,a regular phase of SiO2,a low-cristo-balite in this case[40]and sharp peaks about787,1162, 1207and1239cm-1,which effects are due to the presence of silver in the silica coating,in agreement with previous reports[36].

4Conclusions

Fe2O3@SiO2@Ag composite was synthesized in order to obtain functionalization of magnetic nanoparticles with silver to facilitate their recuperation with the help of a magnetic external?eld.For that,maghemite super-paramagnetic nanoparticles were coated with a silica shell and silver nanoparticles with antibacterial properties were ?xed in the silica layer.Hysteresis loops show that the composite has paramagnetic behaviour and can be easily manipulated by means of an external?eld.

References

1.Harris L(2002)PhD Thesis,Virginia Polytechnic Institute and

State University(19April2002)

2.Pankhurst QA(2006)BT Technol J24(3):33–38

3.Lu AH,Salabas EL,Schu¨th F(2007)Angew Chem Int Ed

46:1222

4.Jeong U,Teng X,Wang Y,Yang H,Xia Y(2007)Adv Mater

19:33

https://www.360docs.net/doc/474102897.html,urent S,Forge D,Port M,Roch A,Robic C,Elst LV,Muller

RN(2008)Chem Rev108:2064

6.Yi DK,Lee SS,Papaefthymiou GC,Ying JY(2006)Chem Mater

18:614

7.Santra S,Tapec R,Theodoropoulou N,Dobson J,Hebard A,Tan

W(2001)Langmuir17:2900

8.Yi DK,Selvan ST,Lee SS,Papaefthymiou GC,Kundaliya D,

Ying JY(2005)J Am Chem Soc127:4990

9.Ferna′ndez-Pacheco R,Arruebo M,Marquina C,Ibarra R,Arbiol

J,Santamar?′a J(2006)Nanotechnology17:1188

10.Philipse AP,Van Bruggen MPB,Pathmamanoharan C(1994)

Langmuir10:92

11.Lu Y,Yin Y,Mayers BT,Xia Y(2002)Nano Lett2:183

12.Barnakov YA,Yu MH,Rosenzweig Z(2005)Langmuir21:7524

13.Pereira C,Pereira AM,Quaresma P,Tavares PB,Pereira E,

Araujo JP,Freire C(2010)Dalton Trans39:2842–2854

14.El Mendili Y,Bardeau JF,Grasset F,Greneche JM,Cador O,

Guizouarn T,Randrianantoandro N(2014)J Appl Phys 116:053905

15.Taylor PL,Ussher AL,Burrell RE(2005)Biomaterials

26:7221–7229

16.Mart?′nez-Castan?o′n G,Nin?o-Mart?′nez N,Mart?′nez-Gutie′rrez F,

Mart?′nez-Mendoza JR,Ruiz F(2008)J Nanopart Res10:1343.

doi:10.1007/s11051-008-9428-6

17.Gao T,Jelle BP,Gustavsen A(2013)J Nanopart Res15:1370

18.Graf C,Vossen DLJ,Imhof A,van Blaaderen A(2003)Langmuir

19(17):6693–6700

19.Chauhuri RG,Paris S(2012)Chem Rev112(4):2373–2433

20.Gong P,Li H,He X,Wang K,Hu J,Tan W,Zhang SS,Yang X

(2007)IOP Publishing Nanotechnology,18:285604,p7

21.Tang D,Yuan R,Chai Y(2006)J Phys Chem B

110:11640–11646

22.Rosenman KD,Moss A,Kon S(1979)J Occup Med21:430–435

23.Cohen SY,Quentel G,Egasse D,Cadot M,Ingster-Moati I,

Coscas GJ(1993)Retina13:312–316

24.Tartaj P,Morales M,Veintemillas-Verdaguer S,Gonza′lez-Car-

ren?o T,Serna C(2003)J Phys D36:R182–R197

25.Hyeon T(2003)Chem Commun,927–934

26.Shi-Yong Yu,Zhang Hong-Jie,Jiang-Bo Yu,Wang Cheng,Sun

Li-Ning,Shi Wei-Dong(2007)Langmuir23:7836–7840

27.Zhang Lihua,Liu Baifeng,Dong Shaojun(2007)J Phys Chem

111:10448–10452

28.Palomares-Sa′nchez SA,Ponce-Castan?eda S,Mart?′nez JR,Ruiz F,

Chumakov Y,Dom?′nguez O(2003)J Non Cryst Solids325:251

29.Le Bail A(1995)J Non Cryst Solids183:39

30.Kandori K,Ohkoshi N,Yasukawa A,Ishikawa T(1998)J Mater

Res13:1698

31.Li Liping,Li Guangshe,Smith RL Jr,Inomata H(2000)Chem

Mater12:3705

32.Papaefthymiou GC,Devlin E,Simopoulos A,Yi DK,Riduan SN,

Lee SS,Ying JY(2009)Phys Rev B80:024406

33.Hiroi K,Komatsu K,Sato T(2011)Phys Rev B83:224423

34.Vollath D,Szabo′DV,Taylor RD,Willis JO(1997)J Mater Res

12:2175

35.Paine TO,Mendelson LI,Luborsky FE(1955)Phys Rev

100:1055

36.Mart?′nez JR,Ortega-Zarzosa G,Dom?′nguez-Espino′s O,Ruiz F

(2001)Low temperature devitri?cation of Ag/SiO2and Ag(CuO)/SiO2composites.J Non Cryst Solids282(2–3):317 37.Duhan S,Devi S,Srivastava M(2010)Indian J Pure Appl Phys

28:271–275

38.Kamiya K,Dohkai T,Wada M,Hashimoto T,Matsuoka J,Nasu

H(1998)J Non Cryst Solids240:202

39.Kamiya K,Oka A,Nasu H,Hashimoto T(2000)J Sol-Gel Sci

Technol19:495

40.Brawer SA,White WB(1975)J Chem Phys74:2421

J Sol-Gel Sci Technol

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Web of Science数据库的检索与利用

Web of Science 数据库的检索与利用 解放军医学图书馆杜永莉 一、引文检索概述 (一)基本概念 1. 引文(Citation):文献中被引用、参考的文献(Cited Work),也称施引文献,其作者称为被引著者(Cited Author)。 2. 来源文献(Source):提供引文的文献本身称为来源文献,其作者称为引用著者(Citing Author)。 3. 引文索引(Citation Index):通过搜集大量来源文献及其引文,并揭示文献之间引用与被引用关系的检索工具。 4. 引文检索:是以被引用文献为检索起点来查找引用文献的过程。 (二)引文的历史回顾 引文的创始人Dr.Eugene Garfield博士是美国科学信息研究所(ISI)的创始人,现在仍然是科学信息研究所的名义董事长,还是美国信息科学协会的前任主席、The Scientist 董事会的主席、Research America董事会的成员。另外他还是文献计量学的创始人。 Dr.Garfield于1955年在Science上发表了具有化时代意义的学术论文:“Citation Indexes for Science: A New Dimension in Documentation through Association of Ideas.”他在这篇文章中描述科研人员可以利用引文加速研究过程、评估工作影响、跟踪科学趋势;阐明引文是学术研究中学术信息获取的重要工具。1957 他创建了美国科学信息研究所(Institute for Scientific Information, ISI)。

1961 年, ISI 推出了 Science Citation Index , SCI 。一种5卷印刷型刊物,包括613种期刊140万条引文的索引。1966年,ISI发布磁带形式的数据,1989年推出CD-ROM 光盘版,1992年ISI为汤姆森科技信息集团接管(Thomson Scientific),1997年推出系列引文数据库(Web of Science),2001年建立具有跨库检索功能的(ISI Web of Knowledge)。 20世纪30年代中期,另外一个著名计量学家布拉德福(S.C.Bradford)在对大量的期刊分布进行研究之后,得出了布拉德福定律(二八定律),揭示出各学科核心期刊的存在,这些核心期刊组成了所有学科的文献基础,重要论文会发表在相对较少的核心期刊上;因此从文献学的角度,没有必要将已经出版的所有期刊全部收录,从数据库的质量上说,则需要有一套科学的流程筛选高质量期刊,为读者提供高质量的学术信息。 Garfield 博士从建立引文数据库开始,经过几十年的时间,建立了一整套期刊筛选的工作流程,每年从全球出版的学术期刊中,筛选出各学科中质量高、信息量大、使用率高的核心期刊。由于这套流程对期刊一些客观指数的长期跟踪,衍生出了另外两个数据库:期刊引证报告(Journal Citation Reports,JCR)和基本科学计量指标(Essential Science Indicators)。 (三)引文的作用 了解某一课题发生、发展、变化过程;查找某一重要理论或概念的由来;跟踪当前研究热点;了解自已以及同行研究工作的进展;查询某一理论是否仍然有效,而且已经得到证明或已被修正;考证基础理论研究如何转化到应用领域;评估和鉴别某一研究工作在世界学术界产生的影响力;发现科学研究新突破点;了解你的成果被引用情况;引文检索为科研人员开辟了一条新颖、实用的检索途径;同时为文献学、科学学、文献计量学等分析研究提供参考数据,如衡量期刊质量、测定文献老化程度、观察学科之间的渗透交叉关系、评价科研人员的学术水平,引文数据库是不可缺少重要工具。 二、Web of Science的检索途径 (一)科学引文索引简介

Web of Science数据库的检索与利用

1、引文的创始者是(A) A、Eugene Garfield B、S.C.Bradford C、Billings,S.A D、Harris,C.J 2、引文的创始单位是(A) A、ISI B、NLM C、CDC D、NIH 3、ISI推出系列引文数据库(Web of Science)的时间是(D ) A、1956年 B、1989年 C、1990年 D、1997年 4、SCI的局限性不包括(B ) A、主要限于基础科学方面 B、不能囊括多数国际多学科高质量科学期刊 C、收录第三世界国家期刊较少 D、论文被引用情况复杂 5、ISI推出了SCI的时间(C) A、1950年 B、1955年 C、1961年 D、1970年 6、关于引文的作用,以下说法错误的是(D ) A、了解某一课题发生、发展、变化过程 B、引文检索为科研人员开辟了一条新颖、实用的检索途径 C、为文献学、科学学、文献计量学等分析研究提供参考数据 D、直接查找全文数据 7、Web of Knowledge包含的数据库有(D) A、Web of Science B、科学会议录索引、化学反应数据库 C、化学索引数据库、Medline数据库 D、以上皆是 8、关于Web of Science的特点,以下说法错误的是(D ) A、跨学科、精选内容,可以进行引文检索

B、增加了分析、跟踪、写作和管理功能 C、从文献相互关系的角度,提供新的检索途径 D、从著者、标题、分类等角度提供检索途径 9、ISI推出CD-ROM光盘版的时间是(A ) A、1970年 B、1961年 C、1982年 D、1991年 10、在SCI中公共卫生所在的数据库是(B ) A、Web of Science Expanded B、Social Sciences Citation Index C、Arts & Humanities Citation Index D、其他

Web of Science使用方法

Web of Science系统 在科技发展与竞争力 分析中应用 周宁丽 2012.10

内容提纲 1.WOS及其功能简介 2.科技文献检索以及分析概念与术语 3.WOS文献检索功能及其利用 4.WOS文献分析功能及其应用 5.WOS引文分析功能及其应用

1. WOS 及其功能简介 ?WOS 简介 WOS(Web of Science)数据库是汤森路透科技集团创建的WOK(ISI web of Knowledge)信息平台中的一个系统。 ?WOS 数据资源 3个引文数据库:Science Citation Index Expanded (SCI-EXPANDED) --1900-至今 (涵盖8,200种核心期刊) Social Sciences Citation Index (SSCI) --1996-至今(涵盖2,800种核心期刊) Conference Proceedings Citation Index -Science (CPCI-S) --1990-至今(涵盖60,000个会 议录) 1个化学数据库: Current Chemical Reactions (CCR-EXPANDED) --1986-至今 ?WOS 主要功能 1.收录、引用、主题文献检索 2.文献与引文统计分析 3. 文献管理与跟踪 ?WOS 学科领域 (1)自然科学、工程技术、生物医 学等150 多个学科领域 (2)人文社科50多个学科领域

2. 1 科技文献收引检索概念 ?科技论文收录检索 选用权威的文献检索系统(如:WOS、ISTP、EI、PUMED、 SCOPAS、CSCD、CSSCI),对其数据库系统收录所发表的期刊、会议文献进行检索 ?科技论文引文检索 利用权威的文献检索系统(如:WOS、ISTP、EI、PUMED、 SCOPAS、CSCD、CSSCI),对其数据库系统收录的期刊、会议文献的引用频次进行查询,对其引文进行检索 ?课题(主题)文献检索 利用权威的文献检索系统(如:WOS、ISTP、EI、PUMED、 SCOPAS、CSCD、CSSCI),对某学科、研究主题进行相关文献检索

Web of Science 各种标号详解

web of Science数据库几个标识(DOI、UT、IDS Number、ISSN、ISBN)的含义 无论是检索机构还是文章作者,对于web of Science数据库记录格式中出现的DOI、UT、IDS Number、ISBN ISSN等英文标识不尽了解,经咨询ISI公司及相应的检索后,把这些标识的意思做简要说明。 (1)DOI(Digital Object Unique Identifier):对象唯一标识符 传统方式是采用URL对因特网上数字资源进行标识,用户点击URL链接即可访问对应的数字资源。然而URL所代表的只是数字资源的物理位置,并不是数字资源本身,一旦资源的物理位置发生变化,原来的URL将成为―死链‖。因此,仅仅使用URL来代表数字对象和链接已经不能适应分布式动态环境的要求。数字对象唯一标识符(Digital Object Unique Identifier)由此产生,它并非只是一个不重复的字符串,真正有用的唯一标识标符系统应该是一套包括名称空间、唯一标识符、命名机构、命名登记系统和解析系统5 个部分的完整体系。 简要地说,对所标识的数字对象而言,DOI相当于人的身份证,具有唯一性。保证了在网络环境下 对数字化对象的准确提取,有效地避免重复。一个网络对象(各种数字资源)一个编号例如——DOI:10.1134/S1061920808010020 (2)UT(Unique Article Identifier)是文章的唯一识别符——收录号 UT –Unique Article Identifier字段是ISI (现在公司名称Thomson Reuters)分配给一篇文章的唯一识别符。可以唯一地识别一条参考文献。它没有显示在Web of Science文章的全记录页里,当输出记录保存为HTML格式时,可以看到UT字段文章的唯一标识符。一篇文章一个编号 例如——UT ISI:000259889100041 (3)IDS Number——检索号 Thomson Reuters Document Solution? 编号。此号码是识别期刊和期号的唯一编号,用于订阅Document Solution 中的文献的全文。一本期刊每一期发表的文章都是一个IDS号。一个期刊的一期对应一个编号 例如——IDS Number:358AR (4)ISSN 国际标准期刊号(International Standard Serial Number),是标识定期出版物(如期刊)和电子出版物的唯一编号,共八位。一个期刊一个编号 (5)ISBN 国际标准书号(International Standard Book Number) 是一种机器读取的唯一标识符,可准确无误地标识书籍。 例如——ISBN:7-5023-4424-1

Web of Science(SCI,SSCI,AHCI,CPCI)数据库资源介绍

Web of Science (SCIE,SSCI,AHCI,CPCI) 登录https://www.360docs.net/doc/474102897.html, 资源简介: Web of Science 是汤森路透科技集团(Thomson Reuters)的产品,Web of Science 包括著名的三大引文索引数据库(SCIE,SSCI,A&HCI)。本馆开通试用的数据库如下: 科学引文索引(Science Citation Index Expanded,简称SCIE),被公认为世界范围最权威的科学技术文献的索引工具,能够提供科学技术领域最重要的研究成果。提供8600多种涵盖176 个学科的世界一流学术科技期刊的文献信息。 社会科学引文索引(Social Sciences Citation Index,简称SSCI),收录3100多种涵盖56个学科的世界一流学术性社会科学期刊的文献信息。 艺术与人文引文索引(Arts & Humanities Citation Index,简称A&HCI),收录艺术与人文学科领域内1,600多种学术期刊,数据可回溯至1975年。同时还从Web of Science 收录的8,000多种科技与社会科学期刊中,筛选出与艺术人文相关的学术文献。 会议论文引文索引(Conference Proceedings Citation Index,简称CPCI),汇聚了全球最重要的学术会议信息,包括专著、丛书、预印本以及来源于期刊的会议论文,提供了综合全面、多学科的会议论文资料。其内容分为两个版本:Conference Proceedings Citation Index - Science (CPCI-S,原ISTP);Conference Proceedings Citation Index - Social Science & Humanities (CPCI-SSH,原ISSHP)。 Web of Science (SCIE,SSCI,A&HCI,CPCI)数据库的特色 利用Web of Science可以快速检索科研信息,可以全面了解有关某一学科、某一课题的研究信息。在提供文献的书目与文摘信息的同时,Web of Science(SCIE,SSCI,AHCI,CPCI)设置了"引文索引"(Citation Index),提供该文献所引用的所有参考文献信息以及由此而建立的引文索引,揭示了学术文献之间承前启后的内在联系,帮助科研人员发现该文献研究主题的起源、发展以及相关研究。还可通过Email和RSS定制主题及引文跟踪服务,随时把握最新研究动态,跟踪国际学术前沿。 Web of Science收录各学科领域中权威、有影响力的期刊,由于其严格的选刊标准和引文索引机制,使得Web of Science(SCIE,SSCI,AHCI,CPCI)在作为文献检索工具的同时,也成为文献计量学和科学计量学的最重要基本评价工具之一。 免费学习资源: 数据库使用指南下载:https://www.360docs.net/doc/474102897.html,/productraining/

web of science课题检索技巧

点击查看更多应用技巧 应用技巧 1.1怎样了解某研究课题的总体发展趋势? 检索结果告诉我们找到了152篇“侯建国”院士的文章。(如果有重名的现象,请参考我们随后提供的有关作者甄别工具的应用技巧。) 1.访问Web of Science数据库检索论文 请访问:https://www.360docs.net/doc/474102897.html,,进入ISI Web of Knowledge平台;选择Web of Science数据库,(以下图示为WOK4.0版新界面)。 示例:如果我们希望检索“中国科技大学”“侯建国”院士在Science Citation Index (SCI)中收录文章的情况。 2.生成引文报告 在检索结果界面上,通过右侧的生成引文报告功能,您可以快速了解该课题的总体研究趋势,并且找到本课题的国际影响力年代变化情况。

结论:通过Web of Science提供的强大的引文报告功能,您可以点击创建引文报告,自动生成课题引文报告,从而提高您的科研效率。 3 利用分析功能了解课题发展趋势 除了自动创建引文报告之外,您也可以利用分析功能生成论文出版年的图式。并且,利用分析功能您可以任意查看某些出版年的论文情况。

结论:通过Web of Science提供的强大的引文报告功能,您可以点击创建引文报告,自动生成课题引文报告,对总体趋势一览全局。而分析功能可以让您更清晰的了解本课题论文每年的发文量,分属于哪些学科,主要集中在哪些国家地区,以哪些语种发表,哪些机构或哪些作者是本课题的引领者,收录本课题论文最多的期刊和会议有哪些等详细信息。

点击查看更多应用技巧 应用技巧 1.2 如何找到某个课题的综述文献? 在科学研究过程中往往需要从宏观上把握国内外在某一研究领域或专题的主要研究成果、最新进展、研究动态、前沿问题或历史背景、前人工作、争论焦点、研究现状和发展前景等内容,如何快速获取这些信息呢?您可以通过检索综述性文献来方便高效地找到信息。 1.访问Web of Science数据库检索课题 请访问:https://www.360docs.net/doc/474102897.html,,进入ISI Web of Knowledge平台;选择Web of Science数据库。如:我们想快速找到有关2007年诺贝尔物理奖获奖课题“巨磁电阻效应-Giant Magnetoresistance”的综述文献。 2.精炼检索结果 在检索结果界面上,通过左侧的精炼检索结果功能您可以快速的了解该课题涉及的学科、文献类型、作者、机构、国家等,甚至通过文献类型选项锁定该课题的高质量综述文献。

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