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17 个结果
  • 简介:Thispapercontainsadetailed,selfcontainedandmorestreamlinedproofofthel~2decouplingtheoremforhypersurfacesfromthepaperofBourgainandDemeterin2015.TheauthorshopethiswillserveasagoodwarmupforthereadersinterestedinunderstandingtheproofofVinogradov'smeanvaluetheoremfromthepaperofBourgain,DemeterandGuthin2015.

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  • 简介:TheLaboratoryforIntenseLasers(L2I)isaresearchcentreinopticsandlasersdedicatedtoexperimentalresearchinhighintensitylaserscienceandtechnologyandlaserplasmainteraction.Currentlythelaboratoryisundergoinganupgradewiththegoalofincreasingtheversatilityofthelasersystemsavailabletotheusers,aswellasincreasingthepulserepetitionrate.Inthispaperwereviewthecurrentstatusofthelaserresearchanddevelopmentprogrammeofthisfacility,namelytheupgradedcapabilityandtherecentprogresstowardstheinstallationofanultrashort,diode-pumpedOPCPAlasersystem.

  • 标签: DIODE-PUMPED SOLID-STATE LASER and APPLICATIONS FEMTOSECOND
  • 简介:Inthiswork,wewillprovetheexistenceofboundedsolutionsinW_0~(1,p)(Ω)∩L~∞(Ω)fornonlinearellipticequations-div(a(x,u,▽u))+g(x,u,▽u)+H(x,▽u)=f,wherea,gandHareCaratheodoryfunctionswhichsatisfysomeconditions,andtherighthandside/belongstoW~(-1,q)(Ω).

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  • 简介:我们综合了一系列Nb2Pd1xRuxS5多晶的样品由一固态反应方法并且系统地由运输和磁性的大小在超导性上调查了做Ru效果。超导性被提高,Ru做并且在混乱之上是相当柔韧的,这被发现。霍尔系数大小显示费用运输被类似于做的红外的案例的洞类型费用搬运人统治,建议多乐队超导性。在Ru或红外做之上,Hc2/Tc展出重要改进,超过泡利不相容原理由约4的一个因素的顺磁的限制价值。Tc和上面的关键字段的比较(在Pd地点上的不同的做元素之中的Hc2),揭示联合的纺纱轨道的一个重要角色。

  • 标签: 掺杂效应 超导电性 空穴 电荷输运 固相反应法 多晶样品
  • 简介:通过DSC和同步辐射WAXS技术测定了结晶温度对iPP和TMB-5/iPP结晶行为的影响.结果表明,随等温结晶温度升高,iPP总结晶度变化不大,但是β晶型含量降低的同时α晶型含量增加.TMB-5是一种具有温度依赖的选择性成核剂,当等温结晶温度高于140℃时,含TMB-5成核剂的iPP的β晶型的含量急剧降低.本文进一步探讨了TMB-5对iPP结晶行为影响的机理.

  • 标签: 等规聚丙烯 Β成核剂 结晶温度
  • 简介:Zn/ZSM-5(NZ2)andZn/Ni/ZSM-5(NZ3)asthecatalystsformethanoltoaromatics(MTA)weresynthesizedbyasimpleultrasonicimpregnation.ThetexturalandacidpropertiesofallcatalystswerecharacterizedusingXRD,HRTEM,NH3-TPD,Py-IR,XPS,XRFandTGtechniques.TheXRDandHRTEMresultsshowedthatthebasiczeolitestructureswerenotaffectedmuchwiththeincorporationofZnandNispecies.However,greatchangeshavetakenplaceinacidproperties.ThePy-IRandXPSresultsindicatedthattheZn-Lewisacidsites(ZnOH+species),whichhavestrongerinteractionwiththezeoliteframeworkcomparedwithZnOspecies,weregeneratedattheexpenseofBacidsiteswiththeincorporationofzincspecies.Moreover,theproductanalysisresultsshowedthattheincorporationofzincspeciespromotedtheprimaryaromatizationbyenhancingthedehydroaromatizationandsuppressingthecrackingandsubsequentH-transferreaction.Furthermore,theadditionofNispecieswellinhibitedthelossofzincspeciesbyconvertingpartialZnOspeciestoZnOH+species,andthusimprovedthearomatizationactivityandcatalyststability.ThecatalyticperformanceresultsshowedthattheNZ3possesshigherconversionofmethanolinalongertimeandloweraveragerateofcokeformationcomparedwithNZ2.Inaddition,theNZ3alsoexhibitedthehighestyieldofBTXasthereactionproceeds.

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  • 简介:CarbondepositionduringmethanoltohydrocarbonsleadstothequickdeactivationofZSM-5catalystanditisoneofthemajorproblemsforthistechnology.DecreasingthecrystalsizeorintroducingmesoporesintoZSM-5zeolitescanimproveitsdiffusionpropertyanddecreasethecokeformation.Inthispaper,nano-sizedZSM-5zeolitewithintercrystallinemesoporescombiningthemesoporousandnanosizedstructurewasfabricated.Forcomparison,themesoporousZSM-5andnano-sizedZSM-5werealsoprepared.ThesecatalystsampleswerecharacterizedbyXRD,BET,NH3-TPD,TEM,Py-IRandTGtechniquesandusedontheconversionofmethanoltogasolineinafixed-bedreactoratT=405°C,WHSV=4.74h-1andP=1.0MPa.Itwasfoundthattheexternalsurfaceareaofthenano-sizedZSM-5zeolitewithintercrystallinemesoporesreached104m2/g,largerthanthatofmesoporousZSM-5(66m2/g)andnanosizedZSM-5(76m2/g).Catalyticlifetimeofthenano-sizedZSM-5zeolitewithintercrystallinemesoporeswas93h,whichwasonlylongerthanthatofmesoporousZSM-5(86h),butshorterthanthatofnanosizedZSM-5(104h).Strongaciditypromotedthecokeformationandthusdecreasedthecatalyticlifetimeofthenano-sizedZSM-5zeolitewithintercrystallinemesoporesthoughitpresentedlargeexternalsurfacethatcouldimprovethediffusionproperty.Thespecialzeolitecatalystwasfurtherdealuminatedtodecreasethestrongacidity.Afterthis,itscokeformationratewasslowedandcatalyticlifetimewasprolongedto106hbecauseofthelargeexternalsurfaceareaanddecreasedweakacidity.Thisspecialstructuralzeoliteisapotentialcatalystformethanoltogasolinereaction.

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  • 简介:一系列1,3二度(2-alkyltetrazol-5-yl)triazenes被钠亚硝酸根的处理在高收益综合了并且盐酸有substituted-5-aminotetrazoles的酸。所有混合物充分用红外光谱学被描绘,1HNMR和13CNMR光谱学和高分辨率团分光计(HRMS)。大多数这些triazenes展出与TNT可比较、低的好爆炸性能融化从81的点??????獩硯穡汯湩吗?

  • 标签: 三氮烯 烯类 合成 官能化 NMR光谱 表征
  • 简介:Unlikeorganic–inorganichybridperovskites,all-inorganiccesiumleadhalideperovskitesholdgreatpromisefordevelopinghigh-performanceoptoelectronicdevices,owingtotheirimprovedstability.Herein,weinvestigatetheperovskite-relatedCsPb2Br5nanoplatelets(NPLs)withtunableemissionwavelengthsviachangingthereactiontemperaturesto100°C,120°C,and140°C.ReactiontemperatureplaysakeyroleindeterminingtheshapesandthicknessesoftheresultingCsPb2Br5NPLs.AhighertemperatureisinfavoroftheformationofsmallerandthickerNPLs.Todeveloptheirpotentialapplicationsinoptoelectronicdevices,greenlightemittingdiodes(LEDs)andphotodetectorsbasedonCsPb2Br5NPLsarefabricated.ThegreenLEDsbasedonCsPb2Br5NPLssynthesizedat140°Cexhibitanexcellentpuregreenemission(fullwidthathalf-maximumof<20nm)anddisplayaluminousefficiencyof34.49lm∕Wunderanoperationcurrentof10mA.Moreover,thephotodetectorbasedonCsPb2Br5NPLssynthesizedat100°Chasbetterperformancewitharisetimeof0.426s,adecaytimeof0.422s,andaratioofthecurrent(withandwithoutirradiation)of364%.

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  • 简介:Aserialofprotonatedandlayeredtransitionmetaloxides,includinglayeredHTaWO6,HNbMoO6aswellasHNbWO6,weresynthesizedbysolid-statereactionandion-exchange.ThelayeredHTaWO6hasbeensystematicallystudiedasasolidacidtorealizethedehydrationoffructoseto5-hydroxymethylfurfural(HMF).ThetransitionmetaloxidesampleswerecharacterizedwithICP-OES,EDS,XRD,XPS,SEM,TGA,FT-IR,N2adsorption–desorptionandNH3-TPD.Theinfluentialfactorssuchasreactiontemperature,reactiontime,solvent,catalystamountandsubstrateconcentrationweredeeplyinvestigated.Theoptimizedfructoseconversionrateof99%withHMFyieldof67%wereachievedafter30minat140°Cindimethylsulfoxide.

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  • 简介:NanosizedGa-containingZSM-5zeoliteswerepreparedviaisomorphoussubstitutionandimpregnationfollowedbycharacterizedusingvarioustechniques.Thecatalyticperformanceofthezeolitesforthearomatizationof1-hexenewasinvestigated.TheresultsindicatethatisomorphoussubstitutionpromotestheincorporationofGaheteroatomsintotheframeworkalongwiththeformationofextra-frameworkGaO+species([GaO+]a)thathavestrongerinteractionswiththenegativepotentialoftheframework.Inaddition,basedonthePy-IRresultsandcatalyticperformance,the[GaO+]aspecieswithstrongerLewisacidsitesproducedabettersynergismwithmoderateBr?nstedacidsitesandthusimprovedtheselectivitytoaromaticcompounds.However,theimpregnationresultsintheformationofGa2O3phaseandsmallamountsofGaO+speciesthataremainlylocatedontheexternalsurface([GaO+]b),whichcontributetoweakerLewisacidsitesduetoweakerinteractionswiththezeoliteframework.During1-hexenearomatization,thenanosizedGaisomorphouslysubstitutedZSM-5zeolitesamples(Gax-NZ5)exhibitedbettercatalyticperformancecomparedtotheimpregnatedsamples,andthehighestaromaticyield(i.e.,65.4wt%)wasachievedovertheGa4.2-NZ5sample,whichcontainedwiththehighestGacontent.

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  • 简介:建立了一种电感耦合等离子体质谱(ICP-MS)法测定环境水样中Cu、Zn、Mn、Pb、Cd5种重金属元素含量的方法。经过仪器条件优化和干扰校正后,方法中5种元素的工作曲线的相关系数均大于0.999,检出限为0.014-0.22μg/L。对加入国家标准物质作为质控样15个批次的环境水样进行统计分析并绘制质控图。同时与原子吸收光谱法测定结果进行对比分析,测定值与标准值基本一致,质控样的测定值基本都在控制线范围之内。结果表明,方法精密度和准确度均能满足环境水样的分析,ICPMS法更适用于大批量、多样化环境水样的监测分析。

  • 标签: 电感耦合等离子体质谱法 原子吸收光谱法 环境水样 重金属
  • 简介:Theneworganic-inorganiccompound,[C_6H_7N_2O_2]_3TeCl_5·2Clwassynthesizedanditsstructurewasdeterminedatroomtemperatureinthetriclinicsystem(P~-1)withthefollowingparameters:a=10.5330(11)?,b=10.6663(11)?,c=15.9751(16)?,α=82.090(2)°,β=71.193(2)°,γ=68.284(2)°andZ=2.ThefinalcycleofrefinementledtoR=0.057andRw=0.149.ThecrystalstructurewasstabilizedbyanextensivenetworkofN--H···Clandnon-classicalC--H···Clhydrogenbondsbetweenthecationandtheanionicgroup.Severalthermalanalysistechniquessuchasthermogravimetricanalysis,differentialscanningcalorimetricanalysisandevolvedgasanalysiswereused.Weusedisoconversionalkineticsmethodstodeterminethekineticsparameters.Weobservethatthedecompositionof[C_6H_7N_2O_2]_3TeCl_5·2Clentailstheformationhydrochloricacidofnitroanilineasvolatiles.Theinfraredspectrawererecordedinthe4000–400cm~(-1)frequencyregion.TheRamanspectrawererecordedintheexternalregionoftheanionicsublatticevibration50–1500cm~(-1).TheopticalbandgapwascalculatedfromtheUV-VisabsorbancespectrausingclassicalTaucrelationwhichwasfoundtobe3.12and3.67eV.

  • 标签: 结构分析 光学性质 合成 化合物 紫外-可见吸收光谱 差示扫描量热分析