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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:AnovelSr2CuInO3Soxysulfidep-typesemiconductorphotocatalysthasbeenpreparedbysolidstatereactionmethodanditexhibitsintriguingvisiblelightabsorptionpropertieswithabandgapof2.3eV.Thep-typesemiconductorcharacterofthesynthesizedSr2CuInO3SwasconfirmedbyHallefficientmeasurementandMott-Schottkyplotanalysis.First-principlesdensityfunctionaltheorycalculations(DFT)andelectrochemicalmeasurementswereperformedtoelucidatetheelectronicstructureandtheenergybandlocations.Itwasfoundthattheas-synthesizedSr2CuInO3Sphotocatalysthasappreciateconductionandvalencebandpositionsforhydrogenandoxygenevolution,respectively.Photocatalytichydrogenproductionexperimentsunderavisiblelightirradiation(λ>420nm)werecarriedoutbyloadingdifferentmetalandmetal-likecocatalystsonSr2CuInO3SandRhwasfoundtobethebestoneamongthetestedones.

  • 标签: 半导体光催化剂 可见光照射 Mott-Schottky图 P型 制氢 密度泛函理论
  • 简介:CorrelativeMeasurementsofFissionFragmentsandLightParticles(α,)in Reactionsof40Ar+209Bi,natAgat25MeV/u¥WuE?..

  • 标签: Ag Ar BI Correlative FISSION FRAGMENTS
  • 简介:S^p1p≤∞)空间为导数属于Hardy空间H^p的复平面单位圆盘D上所有解析函数组成的空间.令函数φ和φ是D上的解析函数且φ(D)D,则将算子W(φ,φ):f→φfoφ称为加权复合算子.文章给出了当1≤q≤p≤∞,φ∈S^∞时,加权复合算子W(φ,φ)从空间S^p到S^q上的有界性的充要条件.然后通过推广经典的Fejer-Riesz不等式证明了当1p≤∞时,S^p到圆盘代数A上的嵌入映射是紧的.

  • 标签: S^p空间 HARDY空间 加权复合算子 Fejer-Riesz不等式 嵌入映射
  • 简介:研究p-致凸Banach空间中渐近半压缩映象的修正的Mann迭代过程和修正的Ishikawa迭代过程的强收敛性.本文始终假设X是P-致凸Banach空间.最近,r-渐近半压缩映象的概念被引入,并给出了X中该映象(此时,r=P)的修正的Mann迭代过程和修正的Ishikawa迭代过程的强收敛性定理,文章所得结果改进、推广和统一了近期相关结果.

  • 标签: 一致凸BANACH空间 r-渐近半压缩映象 修正的Mann迭代 修正的Ishikawa迭代
  • 简介:ThecompressionbehaviourofPd39Ni10Cu30P21bulkmetallicglassisivestigatedatroomtemperatureupto23.5GPausinginsituhighpressureenergydispersivex-raydiffractionwithasynchrotronradiationsource.Pressureinducedstrucuralrelaxationofthebulkmetallicglassisexhibitedwithinthepressurerange.Itisfoundthatbelowabout5GPa,theexistenceofexcessfreevolumecontributestorapidstructuralrelaxation,whichgivesrisetorapidvolumeticchange.Underhigherpressure,furtherrelaxationresultsinstructuralstiffness.

  • 标签: 高压 Pd39Ni10Cu30P21玻璃 室温 发光行为 X射线衍射 同步辐射
  • 简介:目前,国内没有关于半钢发热剂的国家标准检测方法,只能根据组分范围分别检测各个组分,不仅耗时而且使用的大量化学试剂对环境造成污染。故研究了X-射线荧光光谱法快速测定半钢发热剂中Si,P,S的方法。采用粉末压片制样,研究其制样条件,包括磨样时间、压样时间和压力对测定结果的影响。采用其它方法定值提供的检测样品,作为x-射线荧光光谱法内控标准样品,采用经验系数法进行基体校正,通过解谱拟合建立校准曲线,校准曲线建立后仪器建立漂移校正程序。实验结果精密度好,各元素的相对标准偏差在0.15%-1.3%。准确度满足生产需求,实验方法可用于快速检测半钢发热剂化学组分。

  • 标签: X-射线荧光光谱法 快速测定 半钢发热剂 方法研究
  • 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