学科分类
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500 个结果
  • 简介:由全国大学生数学建模竞赛组委会、中国工业与应用数学学会数学模型专业委员会和教育委员会共同举办的"第14届全国数学建模教学和应用会议"于2015年8月15日-17日河北省保定市举行。本次会议由河北大学承办,全国大学生数学建模竞赛河北赛区组委会协办,共有来自全国多所高校的500余位师生代表参加了会议。8月15日上午,会议新校区邯郸音乐厅开幕,河北大学数学与信息科学学院院长孟宪礼教授主持开幕式。河北大学党委常委、副校长康书生,党委常委、河北省数学学

  • 标签: 数学建模教学 数学建模竞赛 党委常委 信息科学学院 长康 应用数学研究
  • 简介:14-fluorophenyl-14H-dibenzo的灵巧、有效的合成[一,j]氧杂蒽被氟化的benzaldehydes的一个壶冷凝作用面对p-TSA景倠扳?牰瑯楥?戠瑵渠瑯椠?桴?敲敬獡?景倠扳?湡?獐兢瀠潲整湩?湩琠敨渠湯瀭潨灳潨祲慬整?湡?桰獯桰牯汹瑡摥倠?与萘粉开发了?敭扭慲敮s

  • 标签: 无溶剂条件合成 二苯并 氟化 苯基 微波辐射 衍生物
  • 简介:Inthisresearch,alucunaryKegginstructure,[PMo2W9O39]7-wasselectedasanefficienthomogenouscatalystfordegradationofanazodye(directblue71)andasimplemethodwasdevelopedfordegradationofDB71.ThemethodisbasedontheoxidationofazodyeinthepresenceofalucunaryKegginformofpolyoxometalates,K7[PMo2W9O39]?19H2O,asahomogenouscatalystatroomtemperature.Thereactionismonitoredspectrophotometricallybymeasuringtheabsorbanceofdyeatλ=585nm.Someparametersincludingconcentrationofcatalyst,concentrationofH2O2,pHandreactiontimewereinvestigatedandoptimized.ResultsshowthatK7[PMo2W9O39]?19H2Oismoreefficientinthepresenceofhydrogenperoxide.DegradationofdyeinthepresenceofthecatalystandH2O2couldleadtothedisappearanceapproximately65%ofdyeafter60min.ButdegradationforthesameexperimentperformedintheabsenceofcatalystorintheabsenceofH2O2was22%or5%respectively.Approximately87%azodyeshasbeeneliminatedafter90mininthepresenceofcatalyst,H2O2andoptimizeconditions(0.6g/LofK7[PMo2-W9O39H9H2O,0.08mol/Lhydrogenperoxideandroomtemperature).

  • 标签: 杂多阴离子 催化作用 KEGGIN结构 多金属氧酸盐 偶氮染料 含钼
  • 简介:TheprecursoryprojectofADSprotonlinearacceleratoristhedevicetoprovideintenseprotonbeamsfortheentiretransmutationsystem,whichhasthefiguresofintensebeamandhighenergy.Asaresult,acontinuousdeflectedbeamwithacertainintensitywoulddeclinetheperformanceoftheacceleratordevicesorevenmakedamageswithin20s.Inordertopreventthiskindofproblem,anintegratemachineprotectionsystemwithfunctionsofstatemonitoringandtimelybeamcuttingisrequiredtoprotectacceleratordevices.

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  • 简介:DigitaldecayspectroscopyofactinideisotopesatthegasfilledseparatorSHANSAlloverthechartofnuclides,theregiontothe“north-east”of208Pb,withZ≥84andN=128~130,hoststheshortest-livedαradioactivities,withhalf-livesintherangeofnanosecondstomicroseconds.Synthesisanddetectionofneutron-deficientisotopesabovethoriuminthisregionarechallengingduetotheirlowproductioncrosssectionsandshorthalf-lives.

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  • 简介:Thestrategyofsequentiallyspin-coatingaperovskitefilmfromtheperovskiteprecursorandanelectrontransportinglayerof[6,6]-phenyl-C71-butyricacidmethylester(PC71BM)isdevelopedtosimplifythefabricationprocedureofperovskitesolarcells.X-raydiffractionandscanningelectronmicroscopyindicatethatPC71BMfilmonperovskitelayercanretardtheevaporationofdimethylsulfoxide(DMSO)efficiently,thusprolongingthetransformationofintermediatephasetoperovskitecrystals,leadingtoahighqualityperovskitethinfilm.Thesolarcellswiththestructureofindiumtinoxides(ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/CH3NH3PbI3/PC71BM/bathocuproine(BCP)/Agmadefromthissimplifiedmethodexhibitahigherefficiency(12.68%)thanthosefromtheconventionalone-stepmethod(9.49%).

  • 标签: Perovskite 太阳能电池 简化准备过程 结晶化
  • 简介:此文系由国际物理教育委员会(ICPE)主席E.L.Jossem,教授推荐,他认为这是一篇十分好的有关物理教育研究的总结性文章,读者可从此文章中了解美国物理教育研究工作的进展情况。认真细读此文,对大、中学物理教师都是很有裨益的.

  • 标签: 物理教育 中学物理教师 读者 文章 国际 教授
  • 简介:讨论一类总数依赖非线性年龄结构种群模型的动力特性,给出了系统的一个等价问题,并讨论了系统的平衡解和非平衡解,得到了平衡解和非平衡解存在的充要条件.

  • 标签: 非线性 年龄结构 种群模型 平衡解
  • 简介:Thephotonpolarizationtensorcarriesthefundamentalinformationofmagnetizedvacuumormedium[1{5].Acompletedescriptionofthevacuumpolarizationtensorisparticularlycomplicatedtoapproach,sincethevacuumphotonpolarizationtensorisexpressedintermsofadoublesummationofinfiniteserieswithrespecttotwoLandaulevelsoccupiedbyvirtualchargedparticles.MostworkswerefocusingonthestrongfiledlimitwithanassumptionofLowestLandauLevel(LLL)[2,6]InRef.[7]weobtainedafulldescriptionofvacuumpolarizationtensorinresponsetoalltheLandaulevelsatanyfieldstrengthofBforthefirsttimebeyondLLLapproximation,andwefoundoutthattheimaginarypartofthephotonpolarizationtensorξΠbecomesnonzeroatthetimelikemomentaregionQ2>4(M2+2neB)atT=0,i.e..,theLLLapproximationisanalyticallysatisfied[3,7].

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  • 简介:Thenovelcomplex[K(18-C-6)]2[Cd(mnt)2][18-C-6-18-crown-6,nmt=1,2-dicyanoethene-1,2-dithiolate,C2S2-(CN)2^2-]wassynthesizedandcharacterizedbyelementalanalysis,IRspectrumandX-raydiffractionanalysis.Thecomplexdisplaystwo-dimensionalnetworkstructureof[K(18-C-6)]complexsegmentsand[Cd(nmt)2]complexsegmentbridgedbyS-K-S,S-K-NandN-K-Ninteractionsbetweenadjacent[K(18-C-6)]and[Cd(mnt)2]units.

  • 标签: 二维网络 合成 晶体结构 18-冠醚-6络合物 镉络合物 1 2-二氰基乙烯-1 2-连二硫酸镉
  • 简介:由于CAD系统与虚拟现实系统在建模以及实时应用等方面的差异,使得作为虚拟现实应用的虚拟装配系统不能直接使用CAD系统中的零件模型信息。因此有必要使用CAD系统提供的API开发—个接口程序来提取零件的模型信息供虚拟装配系统使用。虚拟装配系统需要从CAD系统提取的信息包括零件或部件的名称、零部件在装配中出现的次数、零部件在装配完成后的位置与姿态、零部件装配特征、几何参数信息以及零件或部件的图形信息。

  • 标签: 虚拟装配 计算机辅助制造 零件模型信息 接口程序
  • 简介:HIRFL-CSRacceleratorfacilityhasbeenoperatingwith3ionsources,whichareLAPECR1,LECR3andSECRAL.Theseionsourcescanprovidedifferentkindsofionswithdifferentenergy.Forexample,LAPECR1mainlyprovidesH+andHe+witheextractionvoltageabove25keV,LECR3canprovidetheionbeamswithlowtomediumchargestates,includingthemetallicionswithlowmass,suchasC^4+,Ar^11+,B^3+,Mg^7+,etc.,whileSECRALaimstoproduceintenseandhighlychargedionbeams,especiallymetallicones,suchlikeKr^19+,Xe^31+,Ni^19+,Bi^31+,U^33+,andsoon.

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  • 简介:Thestudyonthedecaypropertiesofnewisotopeslocatedfarfromthebetastabilitylineiscurrentthefocusofnuclearphysics.ForisotopesintheregionZ>82andN<126,-emissionprevailsasradioactivedecaymodeand-spectroscopyisthemostimportanttooltoobtaininformationonthenuclearstructure.IntheheavynucleiregionwithN=124and126isotones,anintruderstate(h9=2.f7=2)8+basedontheattractiveinteractionoff7=2protonsandf5=2neutronshasbeensignificantlyobserved,whichincreasesthebindingenergyofthisconfigurationwithincreasingprotonnumber.

  • 标签: Multi-nucleon TRANSFER REACTIONS