简介：本文研究E^n＋1的中闭超曲面上的Lr（0≤r≤n）算子，得到其第一非零特征值心的两个上界估计，改进和推广了Alias等人的相应结论。

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简介：ＥＸＩＳＴＥＮＣＥＯＦＷＥＡＫＳＯＬＵＴＩＯＮＳＯＦ２－ＤＥＵＬＥＲＥＱＵＡＴＩＯＮＳＷＩＴＨＩＮＩＴＩＡＬＶＯＲＴＩＣＩＴＹω＿０∈Ｅ（ｌｏｇ￣＋Ｌ）￣α（α＞０）ＪＩＵＱＵＡＮＳＥＮ（ＩｎｓｔｉｔｕｔｅＯｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ｔ...

简介：数列{(1+1/n)~2}的极限是数学上最重要的极限之一,关于它的存在性的证明方法已有多种,参见文[1]、[2]、[3],本文提供这个极限存在性的两种证法,并且给出用常用对数的工具计算e的近似值及进行误差估计的初等方法。

简介：Anovelseriesofpyrido[1,2-e]purin-4(3H)-onederivativescontainingpolarsubstituentson5'-positionweredesignedandpreparedaspotentialPDE5inhibitors.Thispaperreportsthesyntheticroutes,1H-NMRdata,andthePDE5inhibitoryactivitiesofthetargetcompounds.Thepolarpiperazinylgroupcontained(on5'-position)compound,3B2,showedthehighestactivityamongthetestedderivativesbutlesspotencythansildenafil1.

简介：DrivenbycuriosityaboutpossibleflightoptionsfortheChang’e-2spacecraftafteritremainsattheSun-EarthL2point,effectiveapproachesweredevelopedfordesigningpreliminaryfuel-optimalnear-Earthasteroidflybytrajectories.Theapproachesincludetheuseofmodifiedunstablemanifolds,gridsearchofthemanifolds’parameters,andatwo-impulsemaneuverfororbitalphasematchingandz-axisbiaschange,andaredemonstratedtobeeffectiveinasteroidtargetscreeningandtrajectoryoptimization.Asteroidflybysareexpectedtobewithinadistanceof2×107kmfromtheEarthowingtotheconstrainedEarth-spacecraftcommunicationrange.Inthiscase,thespacecraft’sorbitalmotionissignificantlyaffectedbythegravitiesofboththeSunandtheEarth,andtherefore,theconceptofthe"heliocentricoscillating-Keplerorbit"isproposed,becausetheclassicalorbitalelementsoftheflybytrajectoriesreferencedintheheliocentricinertialframeoscillatesignificantlywithrespecttotime.Theanalysisandresultspresentedinthisstudyshowthat,amongtheasteroidswhoseorbitsarethemostaccuratelypredicted,"Toutatis","2005NZ6",or"2010CL19"mightbeencounteredbyChang’e-2inlate2012or2013withtotalimpulseslessthan100m/s.

简介：用微分法则和矢量代数由Ｅ＝－ｄΦｄｔ在一定条件下直接导出感生电动势和动生电动势表达式，说明其具有等价性

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简介：Startedfrom5-hydroxy-2-pentanone,(R)(E)-3,7-dimethyl-2-octene-1,8-dioicacid,callosobruchusicacid,wassynthesizedviafivestepswithD-(-)-camphorsultamasthechiralauxiliary.Itwasofgoodopticalpurityandyield.

简介：Theeffectandmechanismofcarmustine(BCNU)combinedwithall-transretinoicacid(ATRA)ontheapoptosisofhumanglioblastomaU251cellswereinvestigatedbymeansof3-(4,5-dimethylthiazol-2-yl)-2,5-diphe-nyltetrazoliumbromide(MTT)assay,flowcytometry,reversetranscription-polymerasechainreaction(RT-PCR)andWesternblotanalysis.TheresultsshowthatBCNUorATRAshowstime-anddose-dependentinhibitioneffectsonhumanglioblastomaU251cellsandthecombinationofBCNUwithATRAshowsansynergisticinhibitioneffectonhumanglioblastomaU251cells,andthecombinedBCNUandATRAcansignificantlyinhibittheproliferationofhumanglioblastomaU251cells,andinducetheapoptosisofthem,makingthecellsarrestinthestageofG1phase,thestageofSandG2phasesdecline,therateoftheapoptosisofhumanglioblastomaU251cellsincrease,thecorrespondingmRNAexpressionofcyclinEandcyclin-dependentkinase2(CDK2)downregulatedandthecorrespon-dingmRNAexpressionofp27kip1unregulated.Inaddition,thecombinedBCNUandATRAreducedtheproteinexpressionofnuclearfactorkappaB(NF-κB).Takentogether,theseresultssuggestthatthetreatmentofhumanglioblastomaU251cellswithacombinationapplicationofATRAandBCNUcanexertsynergisticeffect,thecourseofthiskindofcombinationchemotherapymaylikelybeassociatedwithmultiplemolecularmechanismsforapoptosis,furthermore,thecyclinEandp27kip1shouldbeconsideredasnoveltargetsforcontrollingthegrowthofglioblastomacells.

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简介：该规划的目的是重新研究物理教育的内容和结构，这是由于在三个方面有了重大的发展：①过去的三十年里，物理知识爆炸性地增长；③认知心理学的研究，对学习进程有了新的认识，③计算机技术及其功能不断提高。

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简介：<正>§1引言[1,2]中,我们对两参数马尔科夫过程的三点转移函数族{Pijkr（s,t）}的解析性质进行了研究,包括可测性,连续性,可微分性等,以及恒正性及状态对的分解定理等。我们发现,两参数马尔科夫过程与单参数马尔科夫过程虽然有某些相似,但更重要的是本质上的不同。本文对两参数马尔科夫过程的三点转移函数族的解析性质作进一步的探讨。