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500 个结果
  • 简介:WeuseamodifiedBecke-JohnsonexchangeplusalocaldensityapproximationcorrelationpotentialwithinthedensityfunctionaltheorytoinvestigatetheelectronicstructuresofHg1-xCdxTeandIn1-xGaxAswithxbeing0,0.25,0.5,0.75,and1.Forbothofthetwoseries,ourcalculatedenergygapsanddielectricfunctions(realpartε1andimaginarypartε2)areinagreementwiththecorrespondingexperimentalresultswithxbeingbetween0and1.Thecalculatedzero-frequencyrefractiveindexvariesgreatlywithxforHg1-xCdxTe,butchangeslittlewithxforIn1-xGaxAs,whichisconsistentwiththerealpartsoftheirdielectricfunctions.Therefore,thisnewapproachissatisfactorytodescribetheelectronicstructuresandtheopticalpropertiesofthesemiconductors.

  • 标签: HG1-XCDXTE 密度泛函理论 光学性质 能隙 HG1-XCDXTE 局域密度近似
  • 简介:New[1+1]and62-membered[2+2]Schiffbasemacrocyclescontaininga2,6-diamidopyridinesubunithavebeensynthesizedbycondensationreactionoftheprecursorspyridine-2,6-dicarboxamideand1,10-bis(20-formylphenyloxy)decaneinthepresenceofphosphoricacidviaaone-potprocess.Thecyclocondensedproductswereeffectivelyisolatedbygelcolumnchromatographyandcharacterizedby~1HNMR,FTIR,massspectrometryandX-rayanalysis.Thetwomacrocycleshaveatwistedstructure,andnotanopen‘circular’conformationinthesolidstate.

  • 标签: 大环化合物 一锅法合成 凝胶柱层析 X射线分析 反应合成 FTIR
  • 简介:The1,1'-binaphtholbasedoligomers3and7with3,3'-acetylene-phenylene-acetylenespacerwerepreparedfromBINOL1.ThehighopticalrotationvalueandCDspectrademonstratedthemainchainchiralityoftheoligomermolecule.TheUV-VISandfluorescentspectraevidencethecharacteristicsofconjugatedstructure.Incomparisonwitholigomer2bearing3,3'-acetylenespacer,theoligomers3and7havelongerefficientconjugationsegment,andtheirfluorescentquantumyields(φ)increased(0.60-0.65versus0.14).Extendingtheeffectiveconjugationsegmentwouldimprovethephotophysicalpropertiesofchiralconjugatedpolymers.``

  • 标签: CHIRAL CONJUGATED oligomer BINOL 3 3'-Acetylene-phenylene-acetylene SPACER
  • 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。

  • 标签: 证明方法 误差估计 证法 近似计算 初等方法 算术平均
  • 简介:WeinvestigateindetailtheeffectsofR-parityleptonnumberviolationonthedecay~↑b1→b~↑x1^0intheR-parityviolatingminimalsupersymmetricstandardmodel(Rp-MSSM)underthepresentexperimentalconstraintsonRpparameters.Inournumericalcalculationsweconsidertwocasesofinputparametersofthesquarkandsleptonsectors,MsquarkMslepton,forcomparison.TheresultsshowthattherelativeR-parityviolatingcorrectionisnotverysensitivetothemassofthelightestneutralino-0↑x1andthedegenerateR-parityviolatingcouplingparameterλ2′,butstronglydependsonMsquark,Mslepton,tanβandthedegenerateR-parityviolatingcouplingparameterλ1′.Therelativecorrectionisabout-4~3%andcanexceed-6%insomeregionofparameterspace.Therefore,preciseexperimentanalysesonthedecay~↑b1→b~↑x1^0mayprovideaprobeoftheR-parityviolation.

  • 标签: R-奇偶效应 最小超不对称模型 质子 稳定性 重子数
  • 简介:SYNTHESISANDANTI-HUMANIMMUNODEFICIENCYVIRUS-(HIV-)ACTIVITYOF9-(2-PHOSPHONYLMETHOXYETHYL)ADENINE()ANDITSREGIOISOMER3-(2-PHO...

  • 标签: HIV-1
  • 简介:TwopossiblereactionmechanismsofVS~+(~3∑~-,~1Γ)withCOinthegasphasehavebeenstudiedbyusingB3LYP/TZVPandCCSD(T)/6-311+G(3dr,3pd)methods:theO/Sexchangereaction(VS~++CO→VO~++CS)andtheS-transferreaction(VS~++CO→V~++COS).Thetworeactionsproceedviatwo-stepandone-stepmechanism,respectively.ThebarriersofthetripletandsingletPESsare30.6and50.9kcal/mol,respectively,forO/Sexchangereactionand7.3and50.2kcal/mol,respectively,fortheS-transferreaction.Theresultsindicatethatthetripletgroundstatereactionismorefavorable,andtheS-transferreactionismorefavorablethantheO/Sexchangereaction,whichisingoodagreementwiththeexperimentalobservation.

  • 标签: 钒元素 铅矿 硫化物 理论研究
  • 简介:Inthispaperasimulatedannealing(SA)algorithmispresentedforthe0/1mul-tidimensionalknapsackproblem.Problem-specificknowledgeisincorporatedinthealgorithmdescriptionandevaluationofparametersinordertolookintotheperfor-manceoffinite-timeimplementationsofSA.ComputationalresultsshowthatSAper-formsmuchbetterthanageneticalgorithmintermsofsolutiontime,whilsthavingamodestlossofsolutionquality.

  • 标签: 模拟退火 运算法则 静态冷却表 执行时间
  • 简介:ThispapershowsthattheC1-curvedfiniteelementdevelopedbyBernadoningeneralcannotsatisfytheessentialboundaryconditionsonapproximateboundary.Furthermore,amodifiedC1-curvedfiniteelementisgiven,whichiscompatiblewiththeelementofArgyristriangleandcansatisfythehomogeneousDirichletboundaryconditionsonapproximateboundary.

  • 标签: Curved boundary DOMAIN Argyris TRIANGLES C1-curved
  • 简介:TheCMSregionalcalorimetertriggersystemdetectssignaturesofelectrons/photons,taus,jets,andmissingandtotaltransverseenergyinadeadtinmesspipelinedarchitecture.Thissystemreceives7000calorimetertreggertowerenergieson1.2Gbanddigitalcoppercableseriallinksandprocessestheminalow-latencypipelineddesignusingcustom-builtelectronics.AttheheartofthesystemistheReceiverCardwhichusesthenewgenerationofgigabitethernetreceiverchipsonamezzaninecardtoconvertserialdatatoparalleldatabeforetransmissionona160MHzbackplaneforfurtherprocessingbycardsthatsumenergiesandidentifyelectronsandjets.Wedescribethealgorithmsandhardwareimplementation,andsummarizethesimulationresultsthatshowthatthissystemiscapableofhandlingtheraterequirementswhiletriggeringonphysicssignalswithhighefficiency.

  • 标签: CMS实验 热量计 解发系统
  • 简介:Fourteennew1-acyl-5-arylbiuretsweresynthesizedbythereactionofarylureaswithacylisocynantes.Thelatterwasobtainedfromacylchlorideandleadcyanateindichloromethane,usingpyridineascatalyst.Thestructuresofcompounds3a-nwereconfirmedbyIR,1HNMRandMSspectra.

  • 标签: 1-Acyl-5-aryl BIURET acylisocyanate arylurea SYNTHESIS
  • 简介:Itisoftenstatedthatevencleantokamakdischargesdisruptathighdensity.Onepossibilityisthatsuchdisruptionresultfromtheenergylossarisingfromhydrogenrecyclingattheedgeoftheplasma.thisenergylosscouldleadtoacontractionofthecurrentchannelandtheproductionofadisruptivelyunstableconfiguration.

  • 标签: 循环效应 HL-1M 托卡马克装置 放电分布 等离子体
  • 简介:这份报纸基于图1拉普拉斯算符为Cheeger切割论述理论和算法的详细评论。在可行集合的房间结构的优点,我们建议一个房间下降(CD)为完成Cheeger的框架切了。当插松驰在可行集合保证客观价值的减少时,从哪个反的力量(IP)方法和最陡峭的降下(SD)方法能也被恢复,我们能得到二个指定CD方法。所有这些方法的比较在几张典型的图上被进行。[从作者抽象]

  • 标签: 算法 细胞结构 最速下降法 可行集 功率法