学科分类
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25 个结果
  • 简介:WhilenegativetransferofthenativelinguisticknowledgeinSLAiscloselystudied,otheraspectsofthelearner’snativeknowledgehavebeenignored.Thefollowingisaninvestigationandstudyinthisrespect,revealingthatnegativetransfernoton-lyhappensintheaspectofthelearner’snativelinguisticknowl-edgesuchasthatofthenativegrammaticalrulesandlexicalcon-ception,butalsohappensinaspectsofculturalconventionsandthinkingpatterns.Itisalsofoundthatnegativetransferoflin-guisticknowledgedecreaseswiththelearner’sprogressinstudywhiletheothertwoaspectshavenoobviousdecrease.WithLevel3asacontrolgroup,thispaperconfirmedtheeffectivenessandnecessityinofferingclassesdealingwiththeothertwoaspectsofnegativetransfer.

  • 标签: 环扣
  • 简介:Inthispaperweconsidersomerelatednegativehypergeometricdistributionsarisingfromtheproblemofsamplingwithoutreplacementfromanurncontainingballsofdifferentcoloursandindifferentproportionsbutstoppingonlyaftersomespecificnumberofballsofdifferentcolourshavebeenobtained.Withtheaidofsomesimplerecurrencerelationsandidentitiesweobtaininthecaseoftwocoloursthemomentsforthemaximumnegativehypergeometricdistribution,theminimumnegativehypergeometricdistribution,thelikelihoodrationegativehypergeometricdistributionandconsequentlythelikelihoodproportionalnegativehypergeometricdistributiuon.TotheextentthatthesamplingschemeisapplicabletomodellingdataasillustratedwithabiologicalexampleandinfactmanysituationsofestimatingBernoulliparametersforbinarytraitswithinafinitepopulation,theseareimportantfirst-stepresults.

  • 标签: 数理统计 加权可能性 负超几何分布 最大值
  • 简介:Inthispaperweconsidertheclass∑[p,α,β,k,c]consistingofanalyticfunctionswithnegativecoefficientsandfixedsecondcoefficient.Theobjectofthepresentpaperistogivecoefficientestimates,convexlinearcombinations,somedistortiontheoremsandradiiofstarlikenessandconvexityforf(z)intheclass∑[p,α,β,k,c].

  • 标签: 分析函数 亚纯函数 否定系数 变形理论
  • 简介:Small-angleX-rayscattering(SAXS)usingsynchrotronradiationasX-raysourcehasbeenemployedtocharactcizcthemicroscopicstructrureoforgano-modifiedmesoporousmolecularsieves(organo-MSU-X)preparedbyaone-pottemplate-directedsynthesis.ItisshownthattheSAXSprofileishardlyconstantwithPorod’slawshowinganegativeslope,i.e.,negativedeviation.Thissuggeststhatthereisdiffuseinterfaciallayerlocatedbetweentheporesandthematrix.Thissuggeststhattheorganicgroupsremaincovalentlylinkedtothematrix,asindicatedby^29SiCPMASNMRandFT-IR.Theaveragethicknessoftheinterfaciallayerwasfoundtobeabout1nmforeachofthethreesampleswithdifferentkindsandthesameamounts(20?oforganicgroups.Thiskindofmaterialhasalsobeenprovedtopossessbothsurfaceandmassfractalstructureoftheamophousporoussilicamaterials.2001ElsevierScienceB.V.Allrightsreserved.

  • 标签: 中孔材料 SAXS 小角X射线散射分析 界面层 结构特征 有机中孔分子筛
  • 简介:AccumulatingevidencehasdemonstratedthatregulatoryT(Treg)cellsplayanimportantroleinthemaintenanceofimmunologicself-toleranceandindown-regulatingvariousimmuneresponses.Thus,therehasrecentlybeenanincreasinginterestinstudyingthebiologyofTregcellsaswellastheirpotentialapplicationintreatingimmunediseases.ManytypesofTregcellsubsetshavebeenreportedinavarietyofdiseasemodels.Amongthesesubsets,αβ-TCR+CD3+CD4-CD8-doublenegative(DN)TregcellsaredefinedbytheircapabilityofinhibitingimmuneresponsesviadirectlykillingeffectorTcellsinanantigenspecificfashion.Furthermore,DNTregcellshavebeenshowntodevelopregulatoryactivityafterencounteringspecificantigens,partiallymediatedbytheacquisitionofMHC-peptidecomplexesfromantigenpresentingcells(APCs).ThepresentationofacquiredalloantigensonDNTcellsallowsforthespecificinteractionbetweenDNTregcellsandalloantigenreactiveeffectorTcells.OncetheDNTregandtargetcellshavecomeintocontact,killingisthenmediatedbyFas/Fas-ligandinteractions,andperhapsthroughotherunidentifiedpathways.Furthercharacterizationofthefunctions,molecularexpressionandmechanismsofactivationofDNTregcellswillhelpinthedevelopmentofnoveltherapiestoinduceantigenspecifictolerancetoselfandforeignantigens.Cellular&MolecularImmunology.2004;1(5):328-335.

  • 标签: 双负性调节T细胞 抑制作用 免疫反应 细胞移植 Fas配合体 免疫学
  • 简介:INTRODUCTIONItiscommonknowledgethatthedevelopmentandoccurrenceofanearthquakeisaverycomplicatedgeophysicalprocess.Anearthquakeiscausedbythelocalfailureoftheearthcrustmedium,andearthquakesaredistributedinhomogeneouslyinspace.Seismicactivities,however,arearealreflectionoftheinteractionofthefaults,whichprovidesussomeinformationconcerningtheearthcrustmediumandmayhelpuspredicttheearthquake.Therefore,thestudyoftheseismicitypatterncanbecomeameansofearthquakeprediction.Inordertoreflectdirectlythespacialdistributionofseismicactivities,thesketchofepicentraldistributionhasbeenwidetyusedinthestudy

  • 标签: CRUST GEOPHYSICAL SKETCH epicenter concerning QUAKE
  • 简介:Mostpatientswithtrauma-hemorragicshock,priortoICUadmission,havebeenresuscitatedandstabilizedintheemergencyroom(ER)and/oroperationroom(OR).Manyofthemsufferfromsystemicedema.Thisextra-vascularfluidiscausedbymassiveinfusionoffluidandbloodforthemaintenanceofbloodpressure.Duringtherecoverystage,thepatientsexhibitspontaneousdiuresisfollowedbynegativefluidbalance.Urinevolumesofsomepatientsaremorethan10000ml/d.Doweneedtomaintainabalancebetweendailyinputandoutputofwateratthissituation?

  • 标签: 创伤性失血性休克 体液平衡 自发性多尿症 系统性水肿 临床特点
  • 简介:Thecut-offnegativepressuremethodisoneofeffectiveapproachestosolvetheseepageflowwithfreesurface.Accordingtothecharacteristicsofthismethod,however,ithasbeenfoundoutthatthedeficiencyofthealgorithmsistoeasilycauseinaccuratesimulationinthevicinityoffreesurfaceowingtothepenaltyfunctionwithonlyonecontrollingpenaltyparameter.Therefore,animprovedcut-offpressuremethodwaspresentedbyconstructingpenaltyfunctionwithtwocontrollingpenaltyparameters.Theimprovedalgorithmswereillustratedtobeabletoimprovethesimulationaccuracyandraisetheconvergencespeedthroughconsideringtheeffectsofthepartiallysaturatedorunsaturatedelementsmorereasonablyandcalculatingthenodalexternalforcesmoreaccurately.Finally,theimprovedcut-offnegativepressuremethodwasappliedtothesimulationofunsteadyseepageflowwithfreesurface,andthecorrespondingprogramcodesweredevelopedwithvalidationofsomecases.

  • 标签: 自由表面 定点压力 渗流 有限元分析 处罚函数
  • 简介:Weintroduceanewmodelofone-dimensional(1D)photoniccrystalcomposedofalternatelyarrangedRHMandLHMlayerswithpositiveandnegativerefractiveindicesrespectively,forwhichthetransmissionspectraofthemodelarecalculatednumericallywiththetransfermatrixmethod,andtheband-gapstructureandthepolarizationpropertiesareanalyzed.Wefoundthattheintroductionofnegativerefractiveindexlayers(i.e.LHMmediumlayers)givesrisetosomepeculiarband-gapstructureandpolarizationpropertiesasfollows.Firstly,theforbiddenbandsareextremelywideandthetransmissionbandsareverysharpwithoutoscillation;andsecondly,thechangeofincidentanglehasdifferentinfluencesontheforbiddenbandsofTEandTMmodes.FortheTMmode,theforbiddenbandwidthdecreasessubstantiallyandfinallyvanishes,andfortheTEmodewithcentralwavelength,thetotalreflectionhappensatanyincidentangle.

  • 标签: 光子晶体 光谱传输 折射系数 能隙带 偏振性质
  • 简介:Thetargetofthelargenegativeionsourcebasedonneutralbeaminjection(N-NBI)istoproduceneutralbeamcurrentof22Aandbeampowerof10MWat500keVwithdurationtimeof10s.Sinceitwassuccessfullyoperatedin1996,the5.3MWneutralbeampowerat380keVwithdurationtimeof3shasbeenachieved.Inrecentyearsimprovingandenhancingthebeampoweraregoingon.Severalreasonssuchasplasmanon-uniformity,higherbeamdensityattheupperregioninthebeamprofile,

  • 标签: 能量限制 能量分配 负离子 中性电子束 等离子体
  • 简介:Thebandgappropertiesofone-dimensionalphotoniccrystalswithadefectlayerofnegativerefractiveindexmaterialsarestudied.Thedefectmodewidthisbiggerthanthatofconventionalone-dimensionalphotoniccrystalswithadefectlayerofpositiverefractiveindexmaterials.Thedefectmodeoftheformerisdifferentfromthatofthelatter,shiftstowardsthedirectionofhighfrequency(shortwavelength),andhasabiggershiftingvelocity.Furthermoretheeffectsonthetransmissionpropertiesoftheformerphotoniccrystalscausedbychangeinthepositionofthedefectlayerofnegativerefractiveindexareinvestigated.Finallytheopticalenhancementoftheformerphotoniccrystalsisalsoinvestigated.

  • 标签: 光学晶体 折射系数 能隙带 光学材料