英语写作：如何写好引言

HowtoWritetheIntroductionS1020489王华斌S1010133陈方城S1010104张李巧Thispptconcludes:definitionandpurpose(定义)rulesforagoodIntrodutionandsomeexceptions(好的引言的原则和例外).reasonsfortherules(原则的解释).tense(时态).people(人称).citationandabbreviations(引用和缩写).definitionandpurposeThefirstsectionofthetextSupplysufficientbackgroundinformation(背景知识)toallowthereadertounderstandandevaluatetheresultsofthepresentstudyPrevioustherationale(原理)

forthepresentstudyandyourpurpose(目的)

inwritingthepaper.RulesforagoodIntrodutionpresentfirst,withallpossibleclarity,thenatureandscopeoftheprobleminvestigated(主题).Brieflyreviewthepertinentliteraturetoorientthereader(背景).Statethemethodoftheinvestigation.ifdeemednecessary,thereasonsforthechoiceofaparticularmethodshouldbestated(方法和原因).Statetheprincipalresultsoftheinvestigation(结果).Statetheprincipalcnclusionsofsuggestedbytheresults(结论).Example

Thebloodbrainbarrier(BBB)formedbytightendothelialcelljunctionsofbraincapillarypreventsalargenumberoftherapeuticcompoundsfromcentralnervoussystem(CNS),includingantibiotics,antineoplasticagentsandCNSactivedrugs.

Methotrexate(MTX)isapromisingantitumordrug.Unfortunately,itisverydifficultforMTXtopenetrateBBBsothattheadministrationofintrathecalinjectionisemployedinclinicaltreatmentforbraintumors.However,thisroutesubjectspatientstooperationwoundsandhighrisks.介绍研究领域及其一般进展，提供背景资料背景：以前研究中存在的问题ExampleSeveralpharmaceuticalmethodshavebeentriedtoovercomeBBB.First,drugswithproperchemicalstructurescanbemodifiedtoenhancebrainuptakeusuallybyintroductionoflipophilicgroups.Besides,anovelchemicaldeliverysystemhasalsodeveloped(Yoshikawaetal.,1999).However,thisstrategyislargelylimitedbythechemicalstructureofcompounds.Atthesametime,alargenumberoflipophiliccompoundsthatcanpassthroughBBBarerapidlypumpedbackintobloodstreambymulti-drugresistanceproteins(MRPs)includingmultipleorganicaniontransporter(MRP2)andP-glycoprotein(Pgp).Theexistenceofsucheffluxpumpsprovestobeanotherlimitationtothismethod.Second,stericallystabilizedimmunoliposomesareusedforbothchemicaldrugsandgenesdeliverytobrain(Huwyleretal.,1996;ShiandPardridge,2000).However,humanderivedantibodyistooexpensiveandtheefficacyofsuchtechnologyisnotremarkable.文献回顾：一直在研究的相关的药理方法两个However指出仍然需要研究的地方ExampleTheobjectiveofthepresentstudywastodeterminewhetherthesizeofnanoparticleshadanyinfluenceonbraintargeting.Noexperimentsconcerningthisaspecthavebeenreported.PBCAnanoparticleswithdifferentsizecouldbepreparedbyadjustingthepolymerizationconditionssuchasmediapH,concentrationofemulsifierandmonomerplusstirringrate.MTXwasusedasthemodeldrugsandinvivoexperimentswerecarriedouttoobtainsomepharmacokineticresults.介绍作者研究目的和活动：PBCA纳米质粒研究选择特定方法和选择的原因：用MTX做对照药物Reasonsfortherules

ThefirstruleisthecardinaloneIftheproblemisnotstatedinareasonable,understandableway,readerwillhavenointerestinyoursolution(简明扼要的介绍你的主题).Key:whydidyouchoosethatsubject,andwhyisitimportant?ReasonsfortherulesThesecond(literaturereview)andthird(choiceofmetheod)rulesralatetothefirst(背景和方法).Key:MakereaderunderstandwhattheproblemwasandhowyoutriedtoresolveReasonsfortherulesThestatementofprincipalresultsandconclusions——thecapstoneoftheIntroduction(介绍结果和结论很重要)AbitofredundancywiththeabstractisoftendesirableThemistaketheauthorsmaymake:Holdingbacktheirmoreimportantfindingsuntillateinthepaper.(引言中不提重要的发现，而放到论文最后)

“Rendingascientificarticleisn’tthesameasreadingadetectivestory.Wewanttoknowformthestart”(Ratnoff,1981).SomeexceptionInsomereseachareasandjournals,scientificpapersfollowonlythefirstthreerulesKey:lookingatpapersinyourtargetjournalasmodelsSomeexceptionSomefields,theIntroductionhasa“funnel”shape(漏斗状结构，先介绍大的背景，再介绍小的研究方向).

优点：Aintroductionthusstructuredcanprovideahelpfulandhospitablewelcome(给读者帮助性的和“好客”的态度).tense

MuchoftheIntroductionshouldbewritteninpresenttense,becauseyouwillberefferringtoyourproblemandtheestablishedknowledge(一般现在时为主).可以适当用过去时描述前人已经做过的工作，用现在完成时描述一直持续到现在的工作或研究程度。tensetensetense

Gurkovskayaetal.(2009)foundthattheneuroactivesteroiddehydroepiandrosterone(DHEA)candosedependentlydecreasevoluntaryintakeofethanolinmalerats.Inthatstudy,subjectstrainedtoconsumeethanolreceiveddosesoftheneuroactivesteroidspregnanoloneandDHEAtocomparetheireffectsonethanolconsumption.ThatstudyshowedthatDHEAdecreasedethanolintakemoreeffectivelythanpregnanolone.DHEAproducesawidearrayofphysiologicaleffects,acharacteristicthatmakesdeterminingthespecificmechanismbywhichitaltersethanolintakedifficult.Forinstance,DHEAisaprecursorforestradiolandtestosteroneinperipheraltissues(Lardyetal.,2005)andhasintrinsicandrogenicactivity(Moetal.,2006).DHEAisalsoanegativeallostericmodulatoroftheGABAAreceptorcomplex(Majewskaetal.,1990)thatcanincreasethelevelsofotherneuroactivesteroidsthatmodulatethisreceptor,suchasallopregnanolone(Bernardietal.,2005).ThefactthatDHEAcanserveasaprecursorforestradiolandtestosteroneinperipheraltissuesmaybeproblematicforitsuseinaclinicalsetting(Lardyetal.,2005).AdministrationofexogenousDHEAhasbeenfoundtocauseacne,hirsutism,andalteredmensesinwomenbecauseofitscapacityforincreasingtestosteronelevels(vanVollenhovenetal.,1999;PanjariandDavis,2007).Furthermore,alterationsinthelevelsofsexsteroidshavebeenreportedtoaffectethanolconsumption(LakozaandBarkov,1980;Juarezetal.,2002).Thepresentstudycomparedtheeffectsof3b-acetoxyandrost-5-ene-7,17-dione(7-ketoDHEA)onethanolintakewiththeeffectsofDHEAreportedpreviouslyinthesamegroupofrats(Gurkovskayaetal.,2009).7-ketoDHEAisametaboliteofDHEAthatisnotconvertedtosexhormones(Lardyetal.,1998).7-ketoDHEAistheacetylesterof7-oxoDHEA,anaturallyoccurringmetabolite

ofDHEA(seeFig.1).Invivo,widespreadtissueesteraseshydrolyze7-ketoDHEAtofree7-oxoDHEA(Lund-Peroetal.,1994).person适当地使用“I”，“We”或“Our”,“Thispaper”等词,以明确地指示作者本人的工作;如：——Weconductedthisstudytodeterminewhether…(Thisstudywasconductedtodeterminewhether…);——Thispaperwillpresent(presents)anewapproachthatprocessthedatamoreefficiently.(Insummary,previousmethodsareallextremelyinefficient.Henceanewapproachisdevelopedtoprocessthedatamoreefficiently.)Citationandabbreviati