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500 个结果
  • 简介:Aseriesofpolybenzoxazoles(co)polymersbearingcrankshaftunitsinthemainchainwassynthesizedbytheconventionalsolutionpolycondensationof4,6-diaminorescinoldihydrochloride,terephthalicacid(TA)and2,6-naphthalenedicarboxylicacid(NDA).Allofthepolymersshowlyotropicliquidcrystalbehaviorinpolyphosphoricacid(PPA)andmethanesulfonicacid(MSA).Thepolybenzoxazolesexhibitanexcellentthermalresistancealthoughthecrankshaftmonomerhasbeenintroducedintothepolymerbackbone.Thetemperatureforthe5%weightlossofallthepolymersisabove600℃.TheX-raydiffractionanalysisresultsshowthattheseriesofthepolymershasahighcrystallinity.TheintroductionofNDAmakesaslightdecreaseinthethermalresistanceofthepolymers.ThemaximumabsorptionpeakintheUV-Visspectracanbeadjustedaccordingtotheamountof2,6-naphthaleneunitsinthepolymers,whichindicatesthepotentialapplicationofthepolymersasoptoelectriematerials.

  • 标签: 2 6-萘 2 6-萘二羧酸 对苯二酸 聚磷酸 聚苯并唑 共聚物
  • 简介:Theorientationalorderoftwoliquidcrystals,namely,6-[4-(4-nitrophenylazo)phenyloxy]hexyldiethanolamines(C6)and10-1-bromo[4-(nitrophenylazo)phenyloxy]alkane(B10)wasstudiedbymeansof2HNMRspectroscopywithhexamethylbenzene-d18astheprobemolecule.TheresultsshowthatthedirectorsinthesmecticAphaseofC6andthenematicphaseofB10couldbealigned,whichwasparalleltothemagneticfield.TheorientationalorderparameterofthesolutemoleculesinC6wasabout0.2,whileitisonly0.1inB10,whichisexpectedbecausethemoreorderedsmecticphasetendstoalignsolutemoleculestoahighlevel.ComparedtotheorientationalorderparameterofthesoluteintheSmCphaseof4[3,4,5-tris(4-dodecyloxybenzyloxy)-benzoyloxy]-4-(4′-dodecyloxybenzoyloxy)biphenyl(Ⅰ)(P2=0.14),itislargerinSmAphaseofC6.TherelativelyhigherorientationalorderparameterofthesoluteinC6isattributedtotheformationofintermolecularH-bondsintheSmAphaseofC6.

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  • 简介:Fe2O3/activecarbon(Fe2O3/AC)nanocompositeswerereadilyfabricatedbypyrolyzingFe3+impregnatedactivecarboninanitrogenatmosphere.Theas-preparedcompositeswerestudiedbyX-raypowderdiffraction(XRD),X-rayphotoelectronspectroscopy(XPS)andtransmissionelectronmicroscopy(TEM).Thecapacitivepropertyofthecompositeswasinvestigatedbycyclicvoltammetry(CV)andgalvanostaticcharge-dischargetest.Physicalcharacterizationsshowthattheγ-Fe2O3finegrainsdispersedintheACwell,withameansizeof21.24nm.Electrochemicaltestsin6mol/LKOHsolutionsindicatethattheas-preparednanocompositesexhibitedimprovedcapacitiveproperties.Thespecificcapacitance(SC)ofFe2O3/ACnanocompositeswasupto188.4F/gthatwasderivedfrombothelectrochemicaldouble-layercapacitanceandpseudo-capacitance,whichwas78%largerthanthatofpristineAC.AsymmetriccapacitorwithFe2O3/ACnanocompositesaselectrodeshowedanexcellentcyclingstability.TheSCwasonlyreducedbyafactorof9.2%after2000cyclesatacurrentdensityof1A/g.

  • 标签: 纳米复合材料 电容特性 制备 X-射线光电子能谱 X-射线粉末衍射 透射电子显微镜
  • 简介:Aseriesofaromaticimineswerereducedtocorrespondingaminesinexcellentyieldsby2-phenyl-N,N-dimethylbenzimidazoline(PDMBI)photochemicallyinthepresenceofmagnesiumperchloride(Mg(ClO4)2).AMg2+mediatedphotoinducedelectrontransfermechanismwasproposed.

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  • 简介:Anovelflower-likehydratedmagnesiumcarbonatehydroxide,Mg_5(CO_3)_4(OH)_2·4H_2O,withmicro-structurecomposedofindividualthinnano-sheetswassynthesizedusingafacilesolutionroutewithouttheuseoftemplateororganicsurfactant.Reactiontimehasanimportanteffectonthefinalmorphologyoftheproduct.Themicro-structureandmorphologyofMg_5(CO_3)_4(OH)_2·4H_2OwerecharacterizedbymeansofX-raydiffractometry(XRD),field-emissionscanningelectronmicroscopy(FE-SEM).Brunauer-Emmett-Teller(BET)surfaceareasofthesampleswerealsomeasured.Theprobableformationmechanismofflower-likemicro-structurewasdiscussed.ItwasfoundthatMg_5(CO_3)_4(OH)_2·4H_2Owithflower-likemicro-structurewasanovelandefficientcatalystforthesynthesisofdiphenylcarbonate(DPC)bytransesterificationofdimethylcarbonate(DMC)withphenol.

  • 标签: 碳酸镁氢氧化 合成 微观结构 催化活性 酯交换反应
  • 简介:韩国蔚山,2007年10月11日一继本年度早些时候推出一系列新型抗氧化剂和紫外光吸收剂后,日前,松原集团再次高兴地宣布,进一步扩充这一关键产品范围,以满足专业行业需求。这些新产品在2007年K展6号馆C79展台上展出,新产品包括:

  • 标签: 紫外光吸收剂 产品范围 抗氧化剂 行业需求
  • 简介:Quasiclassicaltrajectorycalculation(QCT)isusedfrequentlyforstudyingcollisionalenergytransferbetweenhighlyvibrationallyexcitedmoleculesandbathgases.Inthispaper,theQCToftheenergytransferbetweenhighlyvibrationallyexcitedC6F6andN2,O2andgroundstateC6F6wereperformed.TheresultsindicatethathighlyvibrationallyexcitedC6F6transferredvibrationalenergytovibrationaldistributionofN2,O2andgroundstateC6F6,sotheyareV-Venergytransfer.EspeciallyitismainlyV-VresonanceenergytransferbetweenexcitedC6F6andgroundstateC6F6,excitedC6F6transfersmorevibrationalenergytogroundstateC6F6thantoN2andO2.ThevaluesofQCT,-〈△Evib〉ofexcitedC6F6aresmallerthanthoseofexperiments.

  • 标签: 准经典轨道计算 碰撞能转换 C6F6 N2 O2 氟苯
  • 简介:研究了考虑溶剂效应后2,1,3-苯并噻二唑衍生物中S原子被CH2—、O—和NH—取代引起电子性质和光谱性质变化,结果表明,与母体分子相比,O—取代引起最高占据轨道能量(EHOMO)和最低空轨道能量(ELUMO)变化很小,而CH2—和NH—取代引起EHOMO和ELUMO变化较明显,且CH2—和NH—取代后分子EHOMO变化小于ELUMO变化.CH2—取代导致最大吸收波长(λabs)和最大发射波长(λem)明显红移,而O—和NH—取代导致λabs和λem明显蓝移;而且取代后分子吸收和发射光谱振子强度都增大.

  • 标签: 有机电致发光 2 1 3-苯并噻二唑 溶剂效应 电子性质 光谱性质
  • 简介:利用2,3-二甲基吡嗪与硝酸铜及氯化铜合成了铜配位聚合物[Cu(Mepz)]2n+(Mepz=2,3-二甲基吡嗪),并通过单晶X射线衍射方法进行了表征.该晶体属于正交晶系,空间群为:Cmca,相关晶胞参数为:a=0.68617(11)nm,b=1.3652(2)nm,c=1.9533(3)nm,V=1.8297(5)nm3.该配位聚合物中Cu原子与2个N原子、2个O原子和2个Cl原子配位,形成了一个稍微畸变配位八面体,每相邻2个配体之间通过Cu离子与吡嗪环上2个N原子配位连接成无限延伸一维链状结构,并通过分子间氢键作用进一步将其连接成为二维超分子网络结构.

  • 标签: 铜配合物 2 3-二甲基吡嗪 晶体结构 超分子 聚合物
  • 简介:利用室温液相还原、晶种生长方法,成功制备了大小形貌均一、性能稳定且具有磁性Fe3O4@Cu2O复合纳米粒子,并且对制备Fe3O4@Cu2O纳米粒子进行了光催化性能研究.在以紫外光为光源照射下,合成Fe3O4@Cu2O纳米粒子对有机染料甲基蓝溶液起到很好降解作用.更重要,在外加磁场作用下,Fe3O4@Cu2O纳米粒子容易回收,具有良好可循环利用性能.

  • 标签: Fe3O4@Cu2O纳米粒子 晶种生长 催化剂 循环利用性
  • 简介:基于密度泛函理论(DFT)平面波超软赝势方法,对MgF:晶体近邻F位进行双空穴调制掺杂,选择PBE泛函进行计算,对比N单掺杂MgF:晶体和N近邻双掺杂MgF。晶体晶体结构、电子结构以及吸收光谱.通过对电子结构比较,研究了N近邻双掺杂对MgFz光催化活性影响,给出了离子之间协同作用机理.通过对比可以看出,N近邻双掺杂对MgF:晶体光学性能具有较佳调制效果,其效果优于(N,Fe)双掺杂调制.

  • 标签: 密度泛函理论 双空穴调制 电子结构 光学性质
  • 简介:在他们photocatalytic/photoelectro-catalytic表演之上TiO2nanotube数组(TNA)结构参数效果被把词法特征和物理化学性质与不同试管长度从三种电解质准备了作比较学习。结果证明与试管长度增长转移红TNA和短TNA紫外力吸收边拥有更高bandgap精力。TNA电气化学窗户变化趋势DMSO(5.5V)>市民(3.2V)>HF(1.8V)。长TNA拥有更高photocatalytic(PC)反应建议表面粗糙因素PC效率主要决定因素,尽管,为长TNA有明显再结合效果。从一样电解质为TNA由在试管长度和photoelectrocatalytic(PEC)效率之间积极关联证实了,试管长度改进能导致更好PEC反应,但是当试管长度在某个价值上时,PEC降级率不再增加,但是减少。有从市民和DMSO电解质准备大表面粗糙因素长TNA与从HF电解质准备短TNA相比展出比较或平更低PEC性能,显示TNAPEC表演被费用分离和光电子转移性质而非表面粗糙系数和试管长度统治。

  • 标签: 光催化反应 纳米管阵列 光电性能 结构参数 TiO2 表面粗糙度
  • 简介:Thecrystalstructureof[Ni(TAAB)(py)2](BF4)2,whereTAABisthetetradentatemacrocyclicligandtetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecine,hasbeendeterminedfromX-raydiffractionanalysis.Thecrys.taibeiongstomonoclinic,spacegroupP21/nwithcellparameters

  • 标签: MONOCLINIC shaped BRIDGED PYRIDINE BENZALDEHYDE editorial
  • 简介:Anewcytotoxicpyrrolidinoindolinediketopiperazinedimer,cristatuminE(1),wasisolatedfromthefermentationbrothofthealgalfungusEurotiumherbariorumHT-2associatedwiththemarinealgae,Enteromorphaprolifera.ThestructurewasdeterminedbyspectroscopicanalysesandMarfey’saminoacidanalysis.CristatuminE(1)showedcytotoxicityagainstK562tumorcelllineandantibacterialactivityagainstEnterobacteraerogenesandEscherichiacoliwithIC50andMICvaluesof8.3,44.0and44.0mmol/L,respectively.

  • 标签: 细胞毒性 散囊菌 二聚体 藻菌 哌嗪 二酮
  • 简介:Underdifferentreactionconditions,theexpectedandunexpectedreactionproducts(ofwhichX-raycrystallographicstructurewaspresented)ofetherificationof2-per(poly)fluoroethyl4-substitutedphenolwithβ-haloethanolcanbeobtainedrespectively.

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  • 简介:Inthiswork,viaafacilesolvothermalroute,wesynthesizedananodematerialforlithiumionbatteries(LIBs)—SnS_2nanoparticle/graphene(SnS_2NP/GNs)nanocomposite.ThenanocompositeconsistsofSnS_2nanoparticleswithanaveragediameterof4nmandgraphenenanosheetswithoutrestacking.TheSnS_2nanoparticlesarefirmlyanchoredonthegraphenenanosheets.AsananodematerialforLIBs,thenanocompositeexhibitsgoodListorageperformanceespeciallyhighrateperformance.Atthehighcurrentrateof5,10,and20A/g,thenanocompositedeliveredhighcapacitiesof525,443,and378mAh/g,respectively.ThegoodconductivityofthegraphenenanosheetsandthesmallparticlesizeofSnS_2contributetotheelectrochemicalperformanceofSnS_2NP/GNs.

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  • 简介:4,4-Dialkyl-2-oxazolin-5-onesarepreparedbyonestepreactionof2-oxazolin-5-onewiththemagnesiummethylcarbonate(MMC)andalkyIhalides.Itisanovelandconvenientmethodforsynthesisofα,Υ-disubstitutcdα-aminoacidbyhydrolysisof4,4-dialkyl-2-oxazolin-5-ones.

  • 标签: carbonate HYDROLYSIS ACID DISUBSTITUTED CONVENIENT STARTING
  • 简介:NewrareearthvanadatesYSrQ-xCaxV3O9-y(x=0.0,0.67,1.0,1.33and2.0)havebeensynthesizedbyanewsimplemethod.X-raypowderdiffractionresultsshowthattheyaremono-phase.Theybelongtoorthorhombicstructureandtheirlatticeconstantsarecalculated.TheresultsofweightgainsinTGcurvesshowthatthelowervalentvanadiumisoxidizedtohighervalentstateathighertemperature.Theoxygencontentsofnewcompoundsarecalculatedfromtheweightgains.BothV3+andV4+coexistinYSr2-xCaxV3O9-y.Thesecompoundsexhibitlowelectricresistivityatroomtemperature.

  • 标签: valent constants vanadium OXIDIZED gains coexist