学科分类
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500 个结果
  • 简介:Anewμ3-Otriiron(Ⅲ)complex[Fe3O(OBz)6(CH3OH)3](NO3)(CH3OH)2(HOBZ=benzoicacid)hasbeensynthesized,itsstructurehasbeendeterminedandvariabletemperaturemagneticsusceptilityhasalsobeenmeasured.Inthemolecule,threeironatomsformedanequilateraltrianglewithu3-Oincenter.ThefittingtothemagneticsusceptibilityshowedthatanintramolecularantiferromagneticexchangeinteractionoccurredbetweenironatomswithJ=-25.51cm-1,andaweakerintermolecularantiferromagneticexchangeinteractionoccurredwithzJ’=-2.30cm-1.

  • 标签: Crystal STRUCTURE MAGNETIC exchange triiron complex.
  • 简介:Pureandneodymium-dopedgadoliniumcalciumoxoboratecrystalsofhighqualityweregrownbytheCzochralskimethod.Theorientationofcrystalwaspreciselydetermined,andthesamplesformeasurementswereprepared.Throughsynchrotronx-raytopographyandhigh-resolutionx-raydiffractometry,thetwinstructurewasdiscovered.Somepropertiessuchasthefigureofmeritvalue,anddielectric,piezoelectric,andelasticconstantsweremeausuredalongwithadiscussionoftheanisotropyofthelaserproperties.

  • 标签: GdCa4O(BO3)3晶体 钕掺杂 硼酸盐晶体 Nd:GdCa4O(BO3)3晶体 晶体生长 形貌学
  • 简介:我们在一个Y3Ga5O12(YGG)主人系统调查Bi3+和RE3+(RE=Tb或Eu)的光性质。Bi3+的另外的做能在这位主人提高Tb3+或Eu3+的光。到Tb3+和Eu3+的从Bi3+的精力转移被观察,精力转移的机制被调查。自从Bi3+排放乐队或Eu3+刺激乐队,转移能作为电的多极相互作用被解释的精力的机制重叠,当Tb3+或Eu3+的紧张随Tb3+或Eu3+集中的增加增加时,Bi3+排放紧张减少。因此,Bi3+离子是到在Y3Ga5O12主人的Tb3+和Eu3+使活跃之物的一种有效sensitizer。

  • 标签: 发光光谱 发光特征 能量传递
  • 简介:At-hyperwheel(t≥3)oflengthl(orW(t)lforbrevity)isat-uniformhypergraph(V,E),whereE={e1,e2,...,el}andv1,v2,...,vlaredistinctverticesofV=∪eii=1lsuchthatfori=1,...,l,vi,vi+1∈eiandei∩ej=P,j∈/{i1,i,i+1},wheretheoperationonthesubscriptsismodulolandPisavertexofVwhichisdifferentfromvi,1≤i≤l.Inthispaper,theminimumcoveringproblemofMCλ(3,W(3)4,v)isinvestigated.DirectandrecursiveconstructionsonMCλ(3,W(3)4,v)arepresented.Thecoveringnumbercλ(3,W(3)4,v)isfinallydeterminedforanypositiveintegersv≥5andλ.

  • 标签: 最小覆盖问题 一致超图 递归结构 Tgt 直接和 覆盖数
  • 简介:Europium(Ⅲ)-dopedYF3ispreparedbyahydrothermalprocessat200℃.X-raydiffraction(XRD)patternidentifiestheformationofYF3phasewithoutdetectableimpurity.Environmentscanningelectronmicroscopy(ESEM)imageshowstheevensizedistributionofthesampleswithcubicmorphology.TheexcitationandemissionspectraoftherareearthionsdopedYF3areinvestigatedbyfluorescencespectrophotometer.Theexcitationspectrumfor591nmemissionhasseveralexcitationbandsat320,365,386,397and467nm,andthemainpeakvaluewas397nm.TypicalEu3+emissionpeaksat591nm(5D0→7F1)and612nm(5D0→7F2)areobservedwhenexcitedby397nm,andthestrongestemissionis591nm,demonstratingthattherareearthionsoccupythecentrosymmetricalsitesinYF3.

  • 标签: HYDROTHERMAL synthesis RARE earth ion YF3
  • 简介:Ca3Y2(BO3)(4):Eu3+黄磷被高温度solid-statereaction方法综合,并且光特征被调查。排放光谱在相应于电的dipoleD-5(0)的613和621nm展出二强壮的红排出物在365nm刺激下面的Eu3+的-F-7(2)转变,原因是Eu3+代替forY3+在Ca3Y2(BO3)(4)的水晶结构占据非中心对称的位置。为613nm的Theexcitation光谱显示黄磷能是有效地激动的由紫外(紫外)(254nm,365nm和400nm)并且蓝色(470nm)光。Ca3Y2(BO3)(4)的排放紧张上的Eu3+集中的效果:Eu3+黄磷被测量,排放紧张与增加Eu3+集中增加的结果表演,然后减少。Ca3Y2(BO3)(4)的CIE颜色坐标:Eu3+黄磷是(0.639,0.357)在15mol%Eu3+。

  • 标签: 发光特征 高温 固体 光谱
  • 简介:[Co3(1,2-S2C6H4)3(PPh3)3][CoBr3(DMF)].sol(1,sol=CHCl3,O(C2H5)2,H2O)wasobtainedfromthereactionofCoBr(PPh3)3withNa2(S2C6H4)inchloroform.TheCo3coreinthecationof1exhibitsametal-metalbondedisoscelestriangle,inwhichthetwolongerCo-CobondsarebothbridgedbyS2C6H4ligandsontwosidesofthetriangleplanerespectively,whilethebottomshortCo-CobondisbridgedbythethirdbidentateS2C6H4ligand.Aseriesofpolynu-clearcobaltclustercompoundswithphosphine,thiolateand/orsulphurligandswerepreparedbylowoxidationstateCo+withthiolatesinorganicsolvents.Thesetri-,tetra-,hexa-,heptanuclearclustercompounds1-8withvarioustypesofcrystalstructurescanbeviewedasthecondensedpolynuclearcobaltcomplexesthatthecobaltatomframeworkswithsulphurbridgedwerebuiltthroughthesmalltriangularunitsof[Co3S3nL3](n=1,2)withorwithout[CoL](L=PR3,Br,Cl,5-C5H5)fragments.

  • 标签: POLYNUCLEAR cobalt THIOLATE PHOSPHINE structure.
  • 简介:Asanimportantmulti-functionalmaterialappliedinsurfaceacousticwavedevices,opticalcommunications,laserandoptoelectronicsduetoitsgoodphotoelectricandpiezoelectricproperties,lithiumtantalate(LiTaO3)hasdrawnextensiveinterests[1].NumerousphysicalpropertiesofLiTaO3,suchasacoustical,electronicstructures,opticalpropertiesandeffectivemass,thermodynamicproperties,havebeenreportedinseveralpapers.Pointdefectswillaffecttheelectronicstructurewhichshouldberesponsibleformanyphysicalproperties,especiallyopticalproperties.

  • 标签: FIRST-PRINCIPLE INVESTIGATION LITAO3
  • 简介:Reactionsofthe6-hydroxy-thiopyrano[3,4-c]pyridine-5-carbonitrilederivative1withα-halo-carbonylcompoundsgavetheortho-substitutedintermediates2a-cwhichwereconvertedintofuro[2,3-b]thiopyrano[4,3-d]pyridines3a-cbyfusionofafuranmoietyunderbasicconditions.Furthercyclizationof3a-cledtoafusionofapyrimidinering,yieldingthetetracyclicproducts6,7and8.Inaddition,condensationof6withvariousaromaticaldehydesaffordedthecorrespondingimines9a,b.Mannichreactionof7gaveproducts10a,b.

  • 标签: Synthesis AROMATIC ALDEHYDES products MANNICH reaction
  • 简介:MP3风靡我们的时候,我们就开始患上MP3疯魔症——眼睛睁开的第一秒,便搜索最爱的MP3,低头走路,孤立进食,默默无语……自始至终,活在一个人的世界里,你说,这不是疯了是怎么了?

  • 标签: MP3 设计 整机 电池
  • 简介:Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/Organophilicmontmorillonite(PHBV/OMMT)nanocompositeswerepreparedandthebiodegradabilityofthePHBV/OMMTnanocompositeswasstudiedbyacultivationdegradingmethodinsoilsuspension.TherelationshipbetweenstructureandbiodegradabilityofPHBV/OMMTnanocompositeswasinvestigated.TheresultsshowedthatthebiodegradabilityofPHBV/OMMTnanocompositesdecreasedwithincreasingamountofOMMTanditwasrelatedtothenumberofPHBVdegradingmicroorganismsindegradationenvironment,theanti-microbialpropertyofOMMTandthedegreeofcrystallinityofthenanocomposites.

  • 标签: 生物降解能力 聚(3-羟基丁酸酯-co-3-羟基戊酸酯) 蒙脱土 纳米复合物 环境友好物质 可降解塑料
  • 简介:DrugsSPD-304(6,7-dimethyl-3-{[methyl-(2-{methyl-[1-(3-trifluoromethyl-phenyl)-1H-indol-3-ylmethyl]-amino}-ethyl)-amino]-methyl}-chromen-4-one)andzafirlukastcontainacommonstructuralelementof3-substitutedindolemoietywhichcloselyrelatestoadehydrogenatedreactioncatalyzedbycytochromeP450s(CYPs).ItwasreportedthatthedehydrogenationcanproduceareactiveelectrophilicintermediatewhichcausetoxicitiesandinactivateCYPs.DrugL-745,870(3-{[4-(4-chlorophenyl)piperazin-1-yl]-methyl}-1H-pyrrolo2,3-β-pyridine)mighthavesimilareffectsinceitcontainsthesamestructuralelement.Weusedmoleculardockingapproachcombinedwithmoleculardynamics(MD)simulationtomodelthree-dimensional(3D)complexstructuresofSPD-304,zafirlukastandL-745,870intoCYP3A4,respectively.Theresultsshowthatthesethreedrugscanstablybindintotheactivesiteandthe3-methylenecarbonsofthedrugskeepareasonablereactivedistancefromthehemeiron.ThecomplexstructureofSPD-304-CYP3A4isinagreementwithexperimentaldata.Forzafirlukast,thecalculationresultsindicatethat3-methylenecarbonmightbethedehydrogenationreactionsite.DockingmodelofL-745,870-CYP3A4showsapotentialpossibilityofL-745,870dehydrogenatedbyCYP3A4at3-methylenecarbonwhichisinagreementwithexperimentinvivo.Inaddition,residuesinthephenylalanineclusteraswellasS119andR212playacriticalroleintheligandsbindingbasedonourcalculations.ThedockingmodelscouldprovidesomecluestounderstandthemetabolicmechanismofthedrugsbyCYP3A4.

  • 标签: 分子对接 甲基吲哚 药物 细胞色素P450 脱氢反应 结构元素
  • 简介:以化学沉淀法制备单相的铕离子掺杂硼铝酸盐红色荧光粉YAl3(BO3)4:Eu3+,考察了焙烧温度、掺铕量等因素对材料性能的影响,用X射线衍射、扫描电镜、激发光谱和发射光谱对荧光粉的结构、形貌和发光性能进行了表征.以尿素为沉淀剂,900℃焙烧沉淀前驱体可得到单相荧光粉YAl3(BO3)4:Eu3+,反应温度比传统高温固相法降低了300℃;沉淀法制备的荧光粉粒径分布范围小,无团聚现象,粒径约300nm.掺铕量为10%(物质的量比)时发光强度最大.在260nIn的紫外光激发下,Eu3+的5D0→F72的电偶极跃迁最强,发射光为618nm的红光.

  • 标签: 稀土 发光性 沉淀法 荧光粉 YAl3(BO3)4