学科分类
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500 个结果
  • 简介:Halfsandwichirondicarbonylcomplex[η5-C5H3(t-Bu)2]Fe(CO)2Cl(1)reactswith1,2-dilithiumdiselenocarboraneLi2Se2C2B10H10(2)togiveabinuclearironcarboranecomplex[η5-C5H3(t-Bu)2]2Fe2(CO)3*Se2C2B10H10(3).TheX-raydiffractionanalysisofcomplex3revealsthatoneoftheironatomsischiral.

  • 标签: Carborane Halfsandwich IRON complex Chirality Molecular
  • 简介:TostudytheintramolecularDiels-Aldercycloadditonof2H-chromen-2-oneasadiene,aseriesofchiralN-allyl-N-benzylamidesthatcontaina2H-chromen-2-onemoietyweredesignedforthesynthesisofbenzo[f]isoindol-l-onesviaanintramolecularDiels-Alderandasubsequentretro-Diels-AldercycloadditionwiththeexpulsionofCO2.Boththeyield(80%-89%)andabsolutestereocontrolofthetandemreactionwerehighwhenanelectron-withdrawinggroupwasattachedtothedienophile.Thedoublebondinthestyrenesubstructureremainedintheproductscouldbefurtherderivatizedbydihydroxylation.

  • 标签: 环加成反应 串联反应 二烯烃 CO2 分子内 吸电子基团
  • 简介:Three-dimensional(3D)flowerlikehierarchicalZn2GeO4andMn2+-dopedZn2GeO4microstructureshavebeenpreparedbyafacilehydrothermalapproach.X-Raydiffraction(XRD),fieldemissionscanningelectronmicro-scopy(FESEM),transmissionelectronmicroscopy(TEM)andphotoluminescence(PL)spectrometrywereemployedtocharacterizethesamples.SuchflowerlikehierarchicalZn2GeO4microstructureswithanaveragediameterof3―4μmwerefoundtobeconstructedbyabundantsinglecrystallinenanorodsofabout90nmindiameter.TheluminescentpropertiesofZn2GeO4:xMnphosphorswithdifferentcontentsofMn2+asanactivatorwereinvestigated.TheMn2+-dopedsamplesshowedgreenluminescencecorrespondingtothed-dtransitionofMn2+undertheirradiationofUVlight.Theredshift(from531nmto538nm)inλemwithincreasingMn2+contentwasobservedintheluminescentspectra,whichshouldbeattributedtoaweakcrystalfieldbecauseofthesubstitutionofZn2+byMn2+atadistortedtetrahedrallatticesite.

  • 标签: 锰掺杂 体系结构 场发射扫描电子显微镜 水热法 透射电子显微镜 X-射线衍射
  • 简介:设P为素数,利用同余及高次丢番图方程的一些结果证明了不定方程组x-1=3py^2,x^2+x+1=3z^2仅有正整数解(p,x,y,z)=(7,22,1,13)。

  • 标签: 不定方程 同余 正整数解
  • 简介:Asimplemethodisappliedtocalculatingtheisotopeshifts(ISs)on5S1/2→4D3/2,5/2transitionsof87,88Sr+.FirstwehavecalculatedtheISsoflowertransitionsonaseriesofalkali-likesystemssuchasB2+,Ca+andBa+,whichareinagreementwithotherworks.ThentheISson5S1/2→4D3/2,5/2transitionsof87,88Sr+,whichareusefultostudytheSr+opticalfrequencystandard,areevaluated.

  • 标签: 原子物理 同位素位移 5S1/2→4D3/2 5/2 精细结构
  • 简介:AseriesofTiO2-XSiO2[Xdenotesthemolarfraction(%)ofsilicainthemixedoxides]withdifferentn(Ti)/n(Si)ratioswaspreparedwithammoniawaterasahydrolysiscatalyst.ThephotocatalystspreparedwerecharacterizedbyXRD,thermalanalysis,FTIR,UV-VisandSPS.ThecharacterizationresultsofFTIRandUV-VisspectrashowthatTiatomsweregraduallychangedfromoctahedralcoordinationtotetrahedralcoordinationwiththeadditionofsilica,whichisnotbeneficialforobtainingstrongBrnstedacidityandhigherphotocatalyticactivity.Thephotocatalyticactivityexperiments,whichwereconductedbyusingheptane(orSO2)asthemodelreactant,showedthatTiO2-SiO2containingasuitableamountofsilicacanexhibitmuchhigherphotocatalyticactivitythanpureTiO2.Theenhancedphotocatalyticactivitycanbeattributedtothreefollowingfactors:(1)smallercrystallinesize;(2)higherthermalstability;(3)thenewstrongBrnstedacidity.

  • 标签: TiO2-SiO2混合氧化物 二氧化钛 二氧化硅 光催化氧化 光催化活性 庚烷
  • 简介:CarbonylationofAllylChlorideCatalyzedbyPdCl(TPPTS)inTwo-phaseMediumCarbonylationofAllylChlorideCatalyzedbyPdCl(TPPTS)in...

  • 标签: TPPTS
  • 简介:ForquadraticnumberfieldsF=Q(√2pl…pt-1)withprimespj≡1mod8,theauthorsstudytheclassnumberandthenormofthefundamentalunitofF.TheresultsgeneralizenicelywhathasbeenfamiliarforthefieldsQ(√2p)withaprimep≡1mod8,includingdensitystatements.Andtheresultsarestatedintermsofthequadraticformx2+32y2andillustratedintermsofgraphs.

  • 标签: 古典群 雷代矩阵 二次数域 素数 初级子群
  • 简介:设α是正实数,[α0;α1,α2。…]是α的简单连分数;d是非平方整数,d1、d2是适合d1d2=d,1≤d12,gcd(d1,d2)=1的正整数,本文证明了:当且仅当α=(d2/d1)(1/2)时,α=[α0α1,…αn-1,2α0],其中α0>0,αi=αn-1(i=1…,α-1).

  • 标签: 简单连分数 正整数 渐近分数 当且仅当 定理 引理
  • 简介:Takingadvantageofthelargeγ-detectorarrayGammasphereandtherecoilmassseparatorFMA,highspinstatesin117Bawereinvestigatedthroughtherecoil-β-delayedprotondecaytaggingtechniqueviatheheavy-ioninducedfusion-evaporationreaction64Zn(58Ni,2p3n)117Ba,atabeamenergyof305MeV.Promptγraysbelongingto117Bahavebeenidentifiedfurthermore,arotationalbandhasbeenidentifiedforthefirsttimeandpresentedasbandAinFig.1.

  • 标签: ADVANTAGE FMA VIA HAS
  • 简介:Anewmethodforfabricatingorderedporoussiliconisreported.Atwo-dimensionalsilicananospherearrayisusedasatemplatewithahydrofluoricacid-hydrogenperoxidesolutionforetchingthenanospheres.Theinitialdiameteranddistributionoftheholesintheresultingporoussiliconlayeraredeterminedbythesizeanddistributionofthesilicananospheres.Thecorrosiontimecanbeusedtocontrolthedepthsoftheholes.ItisfoundthatthepresenceofaSiO_2layer,formedbytheoxidationoftheroughinternalsurfaceofthehole,istheprimaryreasonallowingthecorrosiontoproceed.Ultravioletreflectionandthermalconductivitymeasurementsshowthatthediameteranddistributionoftheholeshaveagreatinfluenceonpropertiesoftheporoussilicon.

  • 标签: 二氧化硅层 制备方法 多孔硅 有序 模板 二维
  • 简介:ElectrolyticfixationofCO2wasinvestigatedbyelectrocarboxylationoforganichalides(RX),andfourestersⅠ,ⅡⅢ,Ⅳ)wereobtainedinmoderateyields.ElectrochemicalreductionesterificationsofRXinthepresenceofCO2werecarriedoutonnanocry'stallineTiO2-Ptelectrode.TheelectrochemicalbehaviorofRXinthepresenceofCO2wasinvestigatedbythetechniqueofcyclicvoltammetry,andtheprobablereactionmechanismw,asproposed.

  • 标签: 二氧化碳 电解羧化作用 二氧化钛负载铂电极 纳米晶体 电解固定 有机卤化物
  • 简介:Emissionquenchingof[Ru(bpy)2(4,4’-dcbpy)](PF6)2(1)bybenzenamine,4-[2-[5-[4-[4-dimethylamino]phenyl]-4,5-di-hydro-1-phenyl-1H-pyrazol-3-yl]-ethenyl]-N,N-dimetyl(2)or1,5-diphenyl-3-(2-phenothiazine)-2-pyrazoline(3)wasobserved.Measurementsoftheemissiondecayof1beforeandafteradditionof2or3bysinglephotoncountingtechniquecon-finnedtheobservations.Theemissionquenchingof1by2or3wassubmittedtoStern-Volmerequation.Itwascalculatedthatthequenchingrateconstants(kq)are5.5×109(mol/L)-1s-1for2and4.0×109(mol/L)-1s-1for3,respectively.Theseresultsindicatedacharacterofdynamicquenchingprocess.Thesinglet-stateof2or3wasalsoquenchedby1.ThequenchingbehaviorsdidnotconformtotheStern-Volmerequationandinvolvedbothstaticanddynamicquenchingprocesses.Theapparentquenchingrateconstant(kapp)wascalculatedtobe3×109(mol/L)-1fortheinteractionofexcited2with1,and1.2×109(mol/L)-1forthatofexcited3wit

  • 标签: RUTHENIUM COMPLEXES PYRAZOLINE compounds electrontransfer dynamic
  • 简介:.Thesingle2dilationorthogonalwaveletmultipliersinonedimensionalcaseandsingleA-dilation(whereAisanyexpansivematrixwithintegerentriesand|detA|=2)waveletmultipliersinhighdimensionalcasewerecompletelycharacterizedbytheWutamConsortium(1998)andZ.Y.Li,etal.(2010).Butthereexistnomoreresultsonorthogonalmultivariatewaveletmatrixmultiplierscorrespondingintegerexpansivedilationmatrixwiththeabsolutevalueofdeterminantnot2inL2(R2).Inthispaper,wechoose2I2=(2002)asthedilationmatrixandconsiderthe2I2-dilationorthogonalmultivariatewaveletY={y1,y2,y3},(whichiscalledadyadicbivariatewavelet)multipliers.Wecallthe3×3matrix-valuedfunctionA(s)=[fi,j(s)]3×3,wherefi,jaremeasurablefunctions,adyadicbivariatematrixFourierwaveletmultiplieriftheinverseFouriertransformofA(s)(cy1(s),cy2(s),cy3(s))?=(bg1(s),bg2(s),bg3(s))?isadyadicbivariatewaveletwhenever(y1,y2,y3)isanydyadicbivariatewavelet.Wegivesomeconditionsfordyadicmatrixbivariatewaveletmultipliers.TheresultsextendedthatofZ.Y.LiandX.L.Shi(2011).Asanapplication,weconstructsomeusefuldyadicbivariatewaveletsbyusingdyadicFouriermatrixwaveletmultipliersandusethemtoimagedenoising.

  • 标签: Multi-wavelets FOURIER multipliers image denoising.
  • 简介:我们揭示并且解释thermopowerS/T的可伸缩的行为展出了由典型重费米子(HF)金属YbRh2在在温度T的磁场B的申请下面的Si2。我们证明一样的可伸缩被不同HF混合物例如表明?-YbAlB4和强烈相关的分层的钴氧化物[BiBa0.66K0.36O2]CoO2。用YbRh2是的Si2一个例子,,我们证明S/T的可伸缩的行为在antiferromagnetic阶段转变被违背剩余抵抗力0和状态的密度,N,经验在阶段转变跳,引起thermopower做二跳并且改变它的符号。我们的说明基于深刻地影响0和N的单个粒子的光谱变平。描绘S/T行为的主要特征,我们构造TBYbRh2Si2。我们为HF混合物的计算S/T在对试验性的事实的好同意并且支持我们的观察。

  • 标签: 标度行为 重费米子 热电势 金属 原型 铁磁相变
  • 简介:采用量子化学方法研究了CH2ClO2与NO反应机理.计算结果表明,CH2ClO2+NO反应的主导产物为CH2ClO+NO2,CHClO+HNO2,CHClO+trans-HONO,CH2O+trans-ClONO和CH2O+cis-ClONO.其他产物由于需要跨越的能垒太高或者产物不稳定,对整个反应来讲可以忽略.

  • 标签: CH2ClO2 NO 大气反应 反应机理.