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500 个结果
  • 简介:Inthisarticle,nano-scaleAl/Fe2O3compositeswithdifferentmorphologiesweresuccessfullyobtainedbyasimpleelectrospinningtechnique,whichisbasedonasurfactant(polyvinylpyridine,PVP)inamixtureofN,N-dimethylformamide(DMF)and2-propanol.TheelectrospunAl/Fe2O3compositesexhibitedacrystalstructureandphasecompositionbyX-raydiffractionanalysis.ThedifferentmorphologiesoftheAl/Fe2O3compositeswerealsoobservedthroughscanningelectronmicroscopyandtransmissionelectronmicroscopy.Itwasfoundthattherathersimpleelectrospinningmethodusedtopreparethemorphology-controlledAl/Fe2O3compositesmayhavethepotentialforpreparationofpropellants,explosives,andpyrotechnicsinthefuture.

  • 标签: 下线 服务 迁移
  • 简介:Thispaperreportsonthelongevityofglycerol-dry(CO2)reformingoverthelanthanum(La)promotedNi/Al2O3catalysts.TheXRDresultsshowedthattheNiparticlewaswell-dispersedinthepresenceofLapromoter.Inaddition,viatheNH3-TPDanalysis,itwasfoundthattheLapromoterhasreducedtheacidityofNicatalystwhichmayhaveexplainedthemitigationofcarbonlaydown.Itwasdeterminedthatthe3.0wt%La-promotedNi/Al2O3catalystpossessedthelargestBETspecificsurfaceareaof97m2g-1.Consequently,ityieldedthebestcatalyticlongevityperformancewithconversionattainedmorethan90%,evenafter72hofreactionduration.Significantly,itcanbeconfirmedthatthepresenceofCO2duringtheglyceroldryreformingwasessentialinreducingcarbondeposition,mostlikelyviagasificationpathway.Thishasensuredastabilityofcatalyticactivityforalongreactionperiod(72h).

  • 标签: 镍催化剂 Al2O3 CO2 甘油 重整 长寿
  • 简介:摘要在装置的射线源射线检测过程中,会对周围环境产生一定的辐射危害,因而必须从技术和制度上对其进行辐射防护,从而对射线源操作人员及周围群众提供符合国家标准的辐射防护,保障相关人员的身心健康,使射线检测工作顺利完成。

  • 标签: 射线源 屏蔽防护 安全管理
  • 简介:HotcompressionbehaviorofTiC–Al2O3/AlcompositeswasstudiedusingtheGleeble-1500systematatemperaturerangeof300–550°Candatstrainraterangeof0.01–10.00s-1.TheassociatedstructuralchangeswerestudiedbyTEMobservations.Theresultsshowthatstressleveldecreaseswithdeformationtemperatureincreasingandstrainratedecreasing,whichcanberepresentedbyaZener–Hollomonparameterinanexponent-typeequationwithhotdeformationactivationenergyQof172.56kJ·mol-1.Dynamicrecoveryoccurseasilywhenstrainratesarelessthan10.00s-1.Dynamicrecrystallizationcanoccuratstrainrateof10.00s-1.

  • 标签: TiC–Al2O3/Al COMPOSITES HOT DEFORMATION Flow stres
  • 简介:Theoreticalmodelsofstellarevolutionpredictnegligiblequantitiesof6Li,9Be,and11Binthehydrogenburningphasesofastar’sevolution[1].TheprimordialBig-Bangnucleosynthesis(BBN)modelmightbemoregenerousinitsproductionoftheseelements[2].Theradiative-capturecrosssectionforprotoncaptureon11Bleadingto12CissmallatastrophysicallyinterestingenergiesbecauseofthelargeCoulombbarrier.

  • 标签: FACTORS LOW ENERGIES
  • 简介:沉寂巳久的京东医药城日前重新开张,域名为“yao.jd.com”的京东医药城挂名上药云健康旗舰店,首页打出醒目的“B2B全新上线”字样,并按地区分类,与医药B2B电商的网站式样类似。2015年5月联姻上海医药后,两者达成处方药电商销售的独家合作,并分享处方药电商的数据与资源。业内猜测,京东仍将采取B2C模式,待政策放开后销售处方药,主打B2B模式却是意料之外。但在业内人士看来,随着医药C牌照(营运B2C业务的牌照)井喷,B2C已成为红海。

  • 标签: 医药 处方药 地区分类 业内人士 销售
  • 简介:IDC中国行业研究与咨询服务部研究经理张亚男分析认为,京东建立商采平台,较具意义:首先,打破传统流通业层层代理模式,缩短利润链,降低渠道成本,提升品牌商利润空间;其次,打破时间与空间及地理区域限制,提升分销效率,符合消费电子类产品快速迭代的需求;再次,为企业提供电商采购整体解决方案,加速公共客户(含政府、央企)、KA(大型知名企业)及SMB(中小企业)三类客户电商化采购进程.

  • 标签: 采购模式 B2B 利润空间 整体解决方案 中小企业 电子类产品
  • 简介:PureAl2O3-2SiO2powderswerepreparedbysol-gelandcoprecipitationmethods,andtheiralkaliactivationreactivitieswerecompared.Thealkali-activationreactivityofthepowderpreparedbythesol-gelmethodwashigherthanthatofthepowderpreparedbythecoprecipitationmethod.Thepowderswereinvestigatedby27AIand29Simagic-anglespinningnuclearmagneticresonancespectroscopy(MASNMR)tounderstandtherelationshipbetweentheirstructureandalkali-activationreactivity.The27AlMASNMRdatashowedthatthefive-coordinateAIcontentofthepowderpreparedbythesol-gelmethodwashigherthanthatofthepowderpreparedbycoprecipitation.Thehighercontentoffive-coordinateAlcorrespondedtohigheralkali-activationreactivity.The29SiMASNMRdatashowedthatforthepowderpreparedbythesol-gelmethod,siliconwasreplacedbyaluminumatsecondarycoordinationsitesofthecentralSiatomsduringcalcination.However,forthepowderpreparedbysingle-batchcoprecipitation,themainchangewasfromalowdegreeofpolycondensationtoahighdegreeofpolycondensation.

  • 标签: 魔角旋转核磁共振 活化反应 固体碱 核磁共振光谱 粉末 化学合成
  • 简介:摘要采用溶胶-凝胶法制备了Al2O3-ZrO2复合溶胶膜,研究了化学组成和添加剂对复合溶胶的影响。结果表明,当Al2O3/ZrO2=1,DMF=40vol%时,可得到澄清透明,粘度适中,稳定性好,且凝胶干燥后几乎无开裂的溶胶膜

  • 标签: 无机陶瓷膜 Al2O3-ZrO2复合溶胶
  • 简介:随着微创腔镜技术的发展,CO2气腹的应用也日渐广泛,通过向腹腔内充入CO2,可为术者操作提供一个良好的手术术野。然而由于机体对CO2的吸收,导致了血内的CO2浓度上升,又会对机体产生一系列的不利影响,尤其是CO2极易通过血脑屏障,使脑内H+浓度升高,改变脑血流[1]。本研究旨在探讨应用CO2气腹时因为呼气末二氧化碳分压(PETCO2)的升高而引起的脑动脉血流的变化。

  • 标签: CO2气腹 呼气末二氧化碳分压 脑动脉血流
  • 简介:Differentrareearth(RE)ionsdopantswereaddedintotheSrAl2SiO7:Eu2+phosphorsinordertoenhancethephosphorescenceproperties,andtheeffectoftheREionsincludingYb3+,Ce3+,Nd3+,Dy3+andTm3+,wascomparativelyinvestigated.ItwasfoundthatNd3+additionimprovedthephosphorescencepropertiesobviouslyamongallthestudiedREions.Therefore,Sr1.96–xAl2SiO7:xEu2+,yNd3+phosphorswerestudiedindetail,andtheoptimumEu2+andNd3+concentrationsweredeterminedwiththeafterglowtimeofabout20min.Thephasestructures,photoluminescence(PL)properties,long-lastingphosphorescence(LLP)properties,afterglowdecaycurvesandthermo-luminescence(TL)fortheselectedphosphorsduringthecorrespondingstudywereinvestigated.AllthephosphorsexhibitedgreenPLemissionandLLPemission.ThereweretwoTLbandslocatedatabout325and380Kforthestudiedsamples,andtherelationshipbetweenREadditionandphosphorescencepropertieswasdiscussed.

  • 标签: 稀土掺杂 光性质 荧光粉 磷光 欧盟 稀土离子
  • 简介:摘要本文以CO2气体保护焊的概述为基础,着重分析了CO2气体保护焊各工艺参数对其焊接的影响,以实际为出发点对CO2气体保护焊焊缝裂纹的分类及控制措施进行了探讨。

  • 标签: GMAW CO2气体保护焊 焊接
  • 简介:Inthispaper,quartzcrystalmicrobalance(QCM)gassensorscoatedwithpolyehtyleneimine(PEI)wasutilizedforcarbondioxide(CO2)detection.Thesensingmechanismisbasedontheavailabilityofreversibleacid-basereactionsbetweenCO2moleculesandPEIatroomtemperature.TheexperimentalresultsrevealedthatthePEI/starchsensorexhibitedmuchhighersensitivitythanthatofpurePEI,andshowedapproximatelinearityoveraconcentrationregionrangingfrom500ppmto8000ppm.Theinfluenceofhumidityhadalsobeeninvestigated.Furthermore,theresponseandrecoverytimedeceasedastheoperationtemperaturesincreased.Finally,sensitivitylossafterconservationforseveraldaysandreversibilityofthesensorshadbeendiscussed.

  • 标签: 气体传感器 PEI QCM 检测 二氧化碳分子 石英晶体微天平
  • 简介:ToimprovethemechanicalpropertiesofWC-Al2O3composites,theeffectsoftraceamountofCeO2additivesonthemicrostructureandmechanicalpropertiesoftheWC-Al2O3compositespreparedbyhotpressingwereinvestigated.TheresultsrevealedthattheWC-Al2O3compositesdopedwith0.1%CeO2possessedrefinedmicrostructureandenhancedmechanicalpropertiescomparedwiththatoftheundopedWC-Al2O3composites.TraceCeO2suppressedthedecarburizationofWC,promotedthemicrostructuralrefinement,andimprovedtheinterfacecoherenceoftheWCmatrixandAl2O3.When0.1%CeO2wasaddedtotheWC-Al2O3composites,theeffectofCeO2resultedintheachievementofarelativedensityof98.82%withanexcellentVickershardnessof16.89GPa,combiningafracturetoughnessof9.85MPa·m1/2withanacceptableflexuralstrengthof1024.05MPa.

  • 标签: 复合材料 力学性能 显微组织 CEO2 添加剂 组织细化
  • 简介:Inthepresentstudy,sampleswereextensivelycollectedthroughoutthestainlesssteelmanufacturingprocess.Thethree-dimensionalmorphologyofinclusionswasrevealedbynon-aqueoussolutionelectrolysis.Thehighconcentrationofaluminuminferrosiliconcausedtheincrementof[Al]sinsteelandAl2O3ininclusions,whichledtothehighermeltingtemperatureofinclusions.ItwasconcludedthattheapplicationoflowAlferrosiliconandcalciumtreatmentcouldpreventtheformationofAl2O3-richinclusions.

  • 标签: 奥氏体不锈钢 夹杂物控制 O3 低铝硅铁 水溶液电解 制造过程
  • 简介:CO2methanationhasbeenahottopicbecauseofitsimportantapplicationinthespacecraftandpotentialutilizationofcarbondioxide.Nickelcatalystisactiveforthisreaction.However,itsactivitystillneedstobeimproved.Dielectricbarrierdischarge(DBD)plasma,initiatedatambientconditionandoperatedat~150°C,hasbeenemployedinthisworkfordecompositionofnickelprecursortoprepareNi/MgAl2O4.Theplasmadecompositionresultsinhighdispersion,uniquestructure,enhancedreducibilityofNiparticlesandpromotedcatalyst-supportinteraction.AnimprovedactivityofCO2methanationwithahigheryieldofmethanehasbeenachievedovertheplasmadecomposedcatalyst,comparedtothecatalystpreparedthermally.Forexample,themethaneyieldoftheplasmapreparedcatalystis71.8%at300°Cbutitis62.9%overthethermalpreparedcatalyst.ThecatalystcharacterizationconfirmedthatCO2methanationovertheDBDplasmapreparedcatalystfollowspathwayofCOmethanation.

  • 标签: 甲烷化反应 分解催化剂 等离子体 二氧化碳 镍催化剂 介质阻挡放电
  • 简介:为了提高方镁石-尖晶石砖性能,以电熔镁砂、镁铝尖晶石、金属铝粉和板状刚玉为原料来制备方镁石-尖晶石材料。研究了金属铝粉和板状刚玉添加量对材料体积密度、显气孔率、高温抗折强度、抗热震性的影响。结果表明:随着金属铝粉加入量的增多,材料烧结性能得到提高,加入金属铝粉时材料的高温抗折强度变大,加入金属铝粉1.5%时抗热震性最好;加入板状刚玉2%时烧结性能和抗热震性最好,加入4%板状刚玉时材料的高温抗折强度最大。

  • 标签: 金属铝粉 镁铝尖晶 石物理性能 无铬化
  • 简介:建立了碱熔水浸的方法溶解试样,ICP-AES法同时测定钛铁矿中硅和铝的方法,对分析过程中的一些条件进行了研究,该法用于测定钛铁矿中SiO2Al2O3,得到了满意的结果,相对标准偏差为3.00%~5.04%,回收率在96.5%~103.8%之间。

  • 标签: 碱熔水浸 ICP-AES 钛铁矿 SIO2 AL2O3