学科分类
/ 25
500 个结果
  • 简介:the most important technique a teacher can use to guide students toward grammatically correct writing is to let them write,teachers are encouraged to adopt a more moderate approach to error. If the teacher over-corrects the students’ mistakes,it is more helpful to select one or two kinds of errors the individual student is making than to point out every error in the paper. The teacher can identify a selected error

  • 标签:
  • 简介:Consideringthatinamagneticresonancesystem,ifthedetectioncoilcontributesdominantlytothesystemnoise,theperformanceofthewholesystemcancertainlybeimprovedbyswitchingtoadetectioncoilmadeofahigh-temperaturesuperconductor,andusingYBa2Cu3O7thinfilmson25×25mm^2LaAlO3substrates,wehavepreparedtwokindsofdetectioncoils:single-coilandtwo-coil.encouragingly,theirqualityfactorsaremeasuredtobeQ>2500fortwo-coil(at22.566MHzand77K)andQ>5500forsingle-coil(at92.3MHzand77K),respectively,Here,wedescribethedetailsofthedesign,fabricationandtestingofthecoils.

  • 标签: 超导电体 高压超导体探测线圈 磁共振系统
  • 简介:Newacetylenemonomers,6-{[(1-naphthylethynyl-4-phenyl)carbonyl]oxy}-l-phenyl-l-hexyne(1),2,5-diethynylthiophene(3),and4,4′-diethynylbiphenyl(6)weresynthesized.Homopolymerizationof1andcopolycyclotrimerizationsof3and6with1-heptyneandl-octynehavebeenachievedwithWCI6-andTaC15-Ph4Sncatalysts,respectively,givingsolublelineardisubstitutedpolyacetylene(2)andhyperbranchedpolyarylenes(5and8)withhighmolecularweights(upto1.2×105)inhighyields(upto98%).ThestructuresandpropertiesofthepolymersarecharacterizedandevaluatedbyIR,NMR,TGA,UV,photoluminescence(PL),andelectroluminescence(EL)analyses.Allthepolymerspossesshighthermalstabilityandemitstrongbluelightuponphotoexcitation.Theintensityoftheemittedlightisgreaterthanthatofpoly(1-phenyl-1-octyne),awell-knownhighlyluminescentdisubstitutedpolyacetylene.Littleaggregation-inducedredshiftinthePLwasobservedinthethinfilmsofthepolymers.Byconstructingamulti-layerELdevice,highELquantumyield(0.18%)hasbeenachievedin2,whicharethebestresultsforsubstitutedpolyacetylenesattainablesofar.

  • 标签: DISUBSTITUTED polyacetylene HYPERBRANCHED polyarylene LIGHT EMISSION
  • 简介:Inthispaper,wereviewthestatusofthemultifunctionalexperimentalplatformattheNationalLaboratoryofHighPowerLaserandPhysics(NLHPLP).Theplatform,includingtheSG-IIlaserfacility,SG-II9thbeam,SG-IIupgrade(SG-IIUP)facility,andSG-II5PWfacility,isoperationalandavailableforinterestedscientistsstudyinginertialconfinementfusion(ICF)andabroadrangeofhigh-energy-densityphysics.Thesefacilitiescanprovideimportantexperimentalcapabilitiesbycombiningdifferentpulsewidthsofnanosecond,picosecond,andfemtosecondscales.Inaddition,theSG-IIUPfacility,consistingofasinglepetawattsystemandaneight-beamnanosecondsystem,isintroducedincludingseverallasertechnologiesthathavebeendevelopedtoensuretheperformanceofthefacility.RecentdevelopmentsoftheSG-II5PWfacilityarealsopresented.

  • 标签: HIGH-POWER laser FACILITY INERTIAL CONFINEMENT fusion
  • 简介:ONTHEHIGHPRECISIONADAPTIVEOPENBOUNDARYCONDITIONSFORTRANSIENTWAVES¥ZouGuang-yuan(Dept.ofMechanicsandEngineeringSciences,Peking...

  • 标签: ADAPTIVE open BOUNDARY conditions high PRECISION
  • 简介:Itisexpectedthatinthenewcentury,tocopewithdevelopmentsofnewhightemperaturetechnologies,anewgenerationofhighperformancerefractoryceramicswillemergeandflourishwhichshouldincludethefollowing(1)oxideandnonoxidecompositescharacterizedbyauniquecombinationofhighhotstrength,highthermalshockresistanceandhighcorrosionresistance;(2)freeCaObearingbasicrefractoriescapableofpurifyingmoltenmetalforimprovingcleanlinessandofabsorbingcontaminantsfromwastegasesforreducingenvironmentalpollution;(3)freeflowingzerocementcastableswithimprovedthermomechanicalproperties,thermalshockresistanceandcorrosionresistanceandgradientcastableswithvaryingmatrixcompositionandvaryingtexture.

  • 标签: 耐火陶瓷材料 氧化复合材料 氧化钙 非氧化复合材料
  • 简介:in the teaching of reading teachers often do just that. Rather than let the students into,teachers can offer their students texts,When the teachers give reading class to students

  • 标签:
  • 简介:Withtherapiddevelopmentofdeepsubmicron(DSM)VLSIcircuitdesigns,manyissuessuchastimeclosureandpowerconsumptionaremakingthephysicaldesignsmoreandmorechallenging.InthisreviewpaperweprovidereaderswithsomerecentprogressoftheVLSIphysicaldesigns.Therecentdevelopmentsoffloorplanningandplacement,interconnecteffects,modelinganddelay,bufferinsertionandwiresizing,circuitorderreduction,powergridanalysis,parasiticextraction,andclocksignaldistributionarebrieflyreviewed.

  • 标签: VLSI 结构设计 互连 线径号 缓冲器插入
  • 简介:大学校园的生活多姿多彩,大学生活的快乐多种多样,有些快乐只能一个人独享,如埋头读书的快乐、独自沉思的快乐、,有些快乐要两个人一起才能获得,如偎依缠绵的快乐、布阵对弈的快乐,但还有一些快乐,要大家一起来,才够high!

  • 标签: 大学生活 大学校园 快乐 个人
  • 简介:Wepresentapseudo-inverseghostimaging(PGI)techniquewhichcandramaticallyenhancethespatialtransverseresolutionofpseudo-thermalghostimaging(GI).IncomparisonwithconventionalGI,PGIcanbreakthelimitationontheimagingresolutionimposedbythespeckle’stransversesizeontheobjectplaneandalsoenablesthereconstructionofanN-pixelimagefrommuchlessthanNmeasurements.Thisfeaturealsoallowshigh-resolutionimagingofgray-scaleobjects.Experimentalandnumericaldataassessingtheperformanceofthetechniquearepresented.

  • 标签:
  • 简介:Neutralbeaminjectionisoneofthemainplasmaheatingmethodsinnuclearfusiondevices.InordertosupportthescientificstudyoftheExperimentalAdvancedSuperconductingTokamak(EAST),amegawatt-levelhighcurrentionsourceisdesignedandmanufacturedintheASIPP,andtheprogressandpreliminarytestresultswillbepresentedinthispaper.

  • 标签: 强流离子源 兆瓦级 超导托卡马克 核聚变装置 中性束注入 ASIPP
  • 简介:Thispaperintroducestwokindsofmethodswithhighaccuracyforfi-niteelementprobabilitycomputingmethod,bywhichthefunctionvalueononeorafewnodescanbecalculatedwithoutformingthetotalstiffnessmatrix.

  • 标签: finite element mathematical EXPECTATION random WALK
  • 简介:B_2O_3-P_2O_5-SiO_2(BPS)three-dimensional(3D)high-organizedpolystyrene(PS)opalsandinverseopalswithlargedomainwerefabricatedandcharacterized.Scanningelectronmicroscope(SEM)showsthreeorfoursmall'windows',indicatingthataverywellinterconnectionbetweenPSspheresofopal.Theultraviolet-visible(UV-vis)spectraindicatethatthephotonicbandgaps(PBGs)areabout710and604nmfor320-and270-nmspheresrespectively.WhileaccordingtoBragg'sequation,thesimulationresultsshouldbe762and643nm,whichmeanthat52and39nmwereshiftedtoblueregion,respectively.

  • 标签: 光子晶体 聚苯乙烯 有机物 光谱
  • 简介:暑假到了!暑假可是撒开欢儿玩乐的时候,都到上海来看世博会吧!这一期我们发布两个任务,或者说是游乐的兴奋点,带上小伙伴们,出发!如果马力不够,就充足电吧!

  • 标签: 世博会 指南 兴奋点 暑假 伙伴
  • 简介:

  • 标签: