学科分类
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49 个结果
  • 简介:DiamondfromLiaoning,Chinawasstudiedbysynchrotronradiationandinfraredspectrum.Thedistributionofdislocationsinthespecimenthasbeenrevealed.Anewmethodtodeterminetheorientationofcrystaldefectshasbeenproposedandtheorientationindexesofthedislocationsinthespecimenwerecalculatedbythismethod.Ithasbeenfoundthatthedislocationsinthespecimentarenearbutnotpreciselyparallelto{111}planes,Themaximumanglebetweendislocationand{111}planeisabout16°.AlmostallthedislocationsinthespecimenthavethesameBurgersvector1/2[101]andimplythesamenessoftheirorigination.

  • 标签: 天然金刚石 缺陷 位错 X射线
  • 简介:烷基配糖物1并且芳基glycosides24stereospecifically高度从商业地可得到的开始的材料在46步上被综合。acetobromo的联合反应--有unprotectivedihydroxyaglycon的D葡萄糖面对钠氢氧化物面对银氧化物,或与芳香的aglycon生产了关键中介。仅仅配置glycosides在这个过程被形成。所有这些glycosides的合成第一次被报导。

  • 标签: 立体合成 芳基β-D-葡萄糖苷 耦合反应 天然葡萄糖苷
  • 简介:我们试验性地学习微观结构和自然奶牛皮革的机械行为。张力的测试用皮革脱衣被执行观察他们的变丑,爬并且失败。奶牛皮革的微观结构是从一些的不同尺寸的纤维的一个分层的、复杂网络到在直径的一些几百纳米,这被发现。他们显示出非线性的压力紧张关系和粘弹性的行为。湿度的效果也被检验。一根multilayered横梁的一个简单理论模型被建议描述最在紧张的基本行为。

  • 标签: 力学性能 天然 牛头 应力应变关系 显微组织 粘弹行为
  • 简介:Supposethat{Xn(ω)}areindependentrandomcomplexvariablesequence,E(Xn)-0andThenthecircle{|Z|=ρ}isalmostsurelyanaturalboundaryoftherandomseriessumfromn=1to∞Xn(ω)Zn-1

  • 标签: circle RADIUS 石电 二万 丁面 林价
  • 简介:Naturalsurfacecoatingscollectedfromnaturalsubstances(NSCsNS)wereemployedtostudytherolesofthemainchemicalcomponents(ironoxides,manganeseoxides,andothercomponents)incontrollingtheadsorptionoflead(Pb)andcadmium(Cd)inaquaticenvironments.TheselectivechemicalextractionfollowedbytheadsorptionofPbandCdexperimentsandstatisticalanalysis,wereusedtoinvestigatetheadsorptionpropertyofeachcomponent.Hydroxylaminehydrochloridewasusedtoremovemanganeseoxidesselectively,andsodiumdithionitewasusedtoextractironoxidesandmanganeseoxides.TheresultindicatedthatironoxidesandmanganeseoxidesplayedanimportantroleintheadsorptionofPbandCdonNSCsNS,andtherelativecontributionwasabouttwo-thirds.Thecontributionofmanganeseoxideswasthegreatest,withalesserroleindicatedforothercomponents.TheadsorptionabilityofmanganeseoxidesforPbandCdwasgreaterthanthatofironoxidesorothercomponentsforPbandCd.ThePbadsorptionobservedineachcomponentwasgreaterthanCdadsorption.

  • 标签: 氧化铁 氧化锰 吸附 表面涂层
  • 简介:Directconversionofmethanetohigherhydrocarbonsisaneffectiveprocesstosolvetheproblemofnaturalgasutilization.Althoughremarkableprogresshasbeenachievedonthedehydro-aromatizationofmethane(DAM),lowconversioncausedbyseverethermodynamiclimitations,cokeformation,andcatalysisdeactivationremainimportantdrawbackstothedirectconversionprocess.MolybdenumcatalystssupportedonHZSM-5typezeolitesupportareamongthemostpromisingcatalysts.Thisreviewfocusesontheaspectsofdirectmethaneconversion,intermsofcatalystscontainingmetalandsupport,reactionconditions,andconversionindifferenttypesofreactors.Thereactionmechanismforthiscatalyticprocessisalsodiscussed.

  • 标签: 天然气利用 直接转换 催化剂失活 甲烷转化 ZSM-5型
  • 简介:Awidevarietyofdifferenttypesofmicroorganismsareknowntoproduceintracellularenergyandcarbonstorageproducts,whichhavebeengenerallydescribedasbeingpoly(β-hydroxybutyrate),PHB,butwhichare,moreoftenthannot,copolymerscontainingdifferentalkylgroupsattheβ-position.Hence,PHBbelongstothefamilyofpoly(β-hydroxyalkanoastes),PHA,allofwhichareusuallyformedasintracellularinclusionsinbacteriaunderunbalancedgrowthconditions.Recently,itbecameofindustrialinteresttoevaluatethesePHApolyestersasnaturalbiodegradableandbiocompatibleplasticsforawiderangeofpossibleapplications,suchassurgicalsuturesorpackagingcontainers.Forindustrialapplications,thecontrolledincorporationofrepeatingunitswithdifferentchainlengthsintoaseriesofcopolymersisdesirableinordertoproducepolyesterswitharangeofmaterialpropertiesbecausephysicalandchemicalcharacteristicsdependstronglyonthepolymercomposition.Such"tailor-made"copolymerscanbeproducedundercontrolledgrowthconditionsinthat,ifadefinedmixtureofsubstratesforacertaintypeofmicroorganismsissupplied,awelldefinedandreproduciblecopolymerisformed.

  • 标签: COPOLYMER BIODEGRADABLE belongs ALKYL incorporation MONOMER
  • 简介:AmmoniumcanchangethetypeofnaturalclinoptilolitefromJinyunofZhejiangProvinceofChina.Thecharacterofexchangeandselectivityofammoniumtypeclinoptilolitetothealkaliandalkaline-earthmetalwereinvestigated,theheatresistanceandnitricacid-resistanceofnaturalclinoptilolitewerediscussed.AlltypesofclinoptilolitewereresearchedbymeansofX-ray,IRspectroscopy,DTAanalyses.Theionexchangewasexperimentedbycolumnoperation,indicatingthatthevalidamountofexchangecapacityofNH4^+typeclinoptilotiesismorethan25mg/g.

  • 标签: 离子交换 天然倾斜发光沸石 钾盐
  • 简介:Thethermalperformanceofarectangularloopwithahorizontalheatingsegmentandapartlycoolingverticallegisstudied.Byone-dimensionalapproach,traditionalfrictionfactorandempiricalcorrelation,amodifiedGrashofnumberGr^*whichturnsouttobeveryimportantinthedescriptionofcirculationflowisintroduced.AnewcorrelationforNusseltnumberofthehorizontalheaterisobtainedandthecomparisonwithexperimentalvaluesshowsgoodagreement.

  • 标签: 热自然对流 环形热虹吸管 分析
  • 简介:Naturalfreshwatersurfacecoatings(biofilmsandassociatedminerals),whichweredevelopedintheNanhuLake,Changchun,P.R.China,wereusedasanefficientbiosorbentfortheremovalofCd(Ⅱ)fromaqueoussolutions.ThebatchexperimentswerecarriedouttodeterminetheadsorptionpropertiesofCd(Ⅱ)ontothenaturalsurfacecoatings.TheclassicalLangmuiradsorptionisothermwasappliedtoestimatingtheequilibriumcoefficientsofCd(Ⅱ)adsorbedonthesurfacecoatings.Theresultsshowthatthemaximumadsorptioncapacityofthesurfacecoatingsis434.78μmolCd/m2(beingequalto0.17mmolCd/gofsurfacecoatingsor10.38mmolCd/gFe)andtheCd(Ⅱ)removalfromsolutionmediabythenaturalsurfacecoatingswasshowntobestronglyaffectedbysolutionpHandionstrength.TheresultedinformationalsoindicatesthatthemaximumCdremovalefficiency(CRE)wasdeterminedtobeapproximately90%atinitialCdmassconcentrationof0.1mg/L(theconcentrationlimitofCd(Ⅱ)inwastewatersfordischargeinaquaticmediainChineselegislation),andthekineticadsorptionofCd(Ⅱ)ontothesurfacecoatingsisfastwitharound70%ofthetotaladsorption-takingplacein150mininsolutionunderthecontrolledlaboratoryconditions(mineralsaltssolutionwithdefinedspeciation,ionicstrength0.05mol/L,and25℃).WiththeadvantageofhighCdadsorptioncapacity,thenaturalsurfacecoatingsappeartobeapotentiallyeffectivebiosorbentfortheremovalandrecoveryofCd(Ⅱ)frompollutedwater.

  • 标签: 废水处理 Cd(Ⅱ) 水溶液 离子迁移 生物吸附 氧化铁
  • 简介:ThenaturalconvectiveheattransferperformanceofanaluminumhexagonalhoneycombactingasanovelheatsinkforLEDcoolingisexperimentallyinvestigated.Theconceptofaddinganadiabaticsquarechimneyextensionforheattransferenhancementisproposed,andtheeffectsofchimneyshape,height,anddiameterarequantified.TheaverageNuavofaheatedhoneycombwithstraightchimneyissignificantlyhigherthanthatwithoutchimney,andtheenhancementincreaseswithincreasingchimneyheight.Atagivenchimneyheight,honeycombswithdivergentchimneysperformbetterthanthosewithconvergentones.Forafixeddivergentangle,theNuavnumberincreasesmonotonicallywithincreasingchimneyheight.Incontrast,withtheconvergentanglefixed,thereexistsanoptimalchimneyheighttoachievemaximumheattransfer.

  • 标签: 烟囱高度 自然对流 性能实验 六角形 蜂窝 强化传热
  • 简介:AccordingtotheThomsonReuterreporton20June2013,the2012ImpactFactorofJournalofNaturalGasChemistry,renamedasJournalofEnergyChemistryin2013,is1.405,whichranksfirstamongchemistryjournalsinChina.WewouldliketoexpressourappreciationtoalltheauthorswhohavecontributedtheirgoodworktotheJournal.Thefollowingisthelistofthearticlespublishedin2010and2011whichreceivedthemostcitationsandthuscontributedthemosttothenewimpactfactor.

  • 标签: 化学期刊 天然气 作者 中国 引文 影响因子
  • 简介:Naturalconvectionheattransferinahorizontalenclosurefilledwithanisotropicporousmedia,beingisothermallyheatedatbettomandcooledattopwhiletheverticalwallsbeingadiabatic,isnumericallystudiedbyapplyingtheBrinkmanmodel-amodifiedformofDarcymodelgivingconsideratiointotheviscouseffect.Theresultsshowthat:(1)alargerpermeabilityratio(K^*)causesalowerflowintensityintheenclosureandasmallerNusseltnumber,allNusseltnumbersapproachunityinthelimitofK^*→∞;alargerthermalconductivityratio(λ^*)causesastrangerdistortionofisothermsintheenclosureandahigherflowvelocitynearthewalls,alltheNusseltnumbersapproachunityinthelimitofλ^*-→0,thepermeabilityandthermalconductivityratiosgenerallyhaveopposingeffectsontheNusseltnumber.(2)anincreasingDarcynumberdecreasestheflowintensityandheattansferrates,whichismoresignificantatalowerpermeabilityratio.Inparticular,withK^*≤0.25,theNusseltnumberforDa=10^-3woulddifferfromthatofDarcyflowuptoanamountof30%,ananalysisneglectingthenon-Daricaneffectwillinevitablybeofconsiderableerror.

  • 标签: 热传导 自然对流 多孔介质