(完整word版)英语短文练习(word文档良心出品).doc

短文一Theatomisabasicunitofmatterthatconsistsofadensecentralnucleussurroundedbyacloudofnegativelychargedelectrons.Theatomicnucleuscontainsamixofpositivelychargedprotonsandelectricallyneutralneutrons.Theelectronsofanatomareboundtothenucleusbytheelectromagneticforce.Anatomcontaininganequalnumberofprotonsandelectronsiselectricallyneutral,otherwiseitispositivelyornegativelychargedandisknownasanion.Anatomisclassifiedaccordingtothenumberofprotonsandneutronsinitsnucleus:thenumberofprotonsdeterminesthechemicalelement,andthenumberofneutronsdeterminestheisotopeoftheelement.原子是物质的基本单位，由密集的中央核周围有云带负电荷的电子。原子核包含一个组合的带正电的质子和电中性的中子。一个原子的电子被电磁力约束的核。原子含有相同数目的质子和电子是电中性的，否则它是正或负电荷，称为离子。根据其原子核的质子和中子的数量分类：质子数决定元素，而中子数决定元素的同位素。短文二Analyticalchemistryisthestudyoftheseparation,identification,andquantificationofthechemicalcomponentsofnaturalandartificialmaterials.Analyticalmethodscanbeseparatedintoclassicalandinstrumental.Classicalmethodsuseseparationssuchasprecipitation,extraction,anddistillationandqualitativeanalysisbycolor,odor,ormeltingpoint.Quantitativeanalysisisachievedbymeasurementofweightorvolume.Instrumentalmethodsuseanapparatustomeasurephysicalquantitiesoftheanalytesuchaslightabsorption,fluorescence,orconductivity.Theseparationofmaterialsisaccomplishedusingchromatography,electrophoresis.分析化学是研究的分离，鉴定，以及自然和人工材料的化学成分定量分析。分析方法可分为经典和仪器。传统的方法使用的分离，如沉淀，萃取，蒸馏和定性分析的颜色，气味，或熔点。定量分析是以重量或体积测量的实现。仪器方法使用一个测量装置的被分析物，如光吸收，荧光的物理量，或电导率。材料的分离是通过使用色谱法，电泳。短文三Chromatographyisaseparationandanalysistechnique.Themixtureisdissolvedinafluidcalledthemobilephase,whichcarriesitthroughanothermaterialcalledthestationaryphase.Thevariousconstituentsofthemixturetravelatdifferentspeeds,causingthemtoseparate.Theseparationisbasedondifferentialpartitioningbetweenthemobileandstationaryphases.Subtledifferencesinacompound'spartitioncoefficientresultindifferentialretentiononthestationaryphase.Chromatographymaybepreparativeoranalytical.Thepurposeofpreparativechromatographyistoseparatethecomponentsandfurthergetpurifiedcomponents.