学科分类
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376 个结果
  • 简介:Wepropose,inthispaper,touseseveralmultivariateanalysismethodeandanewkindofvariablestoseparatebetweenfourclassesofeventsproducedatLEP2:theeventswith2jets,3jets,4jetsandthosehavingamoreabundantjettopology(njets,n>4)Neuralnetworkhaveproventhemselvestobemoreefficientclassifierthantheothertechniques.Theefficienciesandpuritiesachievedwiththeoptimizedneuralnetworkareinaverage1to7%higherthanthoseobtaindwiththeothermethods.

  • 标签: e^+e^-碰撞实验 神经网络 喷射注数
  • 简介:设计了一种结构简单、噪声低、功耗小的溴化镧(LaBr3:Ce)γ谱仪前端读出电子学电路。该电路包括电压灵敏前置放大电路、谱仪放大电路和供电电源3部分,电路的设计基于传统核电子学方法和较新的电子元器件,采用低噪声设计技术,在能谱测量中获得了较高的能量分辨率。文中首先介绍了电路的设计方案,包括各部分电路原理、功能和设计要点;然后开展了电路仿真和电路板设计;最后通过实验进行电路功能验证。实验表明:基于研制的前端读出电子学电路、溴化镧(LaBr3:Ce)探测器及数字多道分析器组成的γ谱仪系统,对137Cs662keVγ能峰的能量分辨率可达2.7%,谱仪系统性能稳定。

  • 标签: 溴化镧 (LaBr 3:Ce) Γ谱仪 前置放大电路 谱仪放大电路
  • 简介:Radiotherapy,astandardadjuvanttosurgery,improvessurvivalratesinpatients,butresistancetotreatmentbysomegliomaslimitsthesuccessofclinicalapplication.Emergingevidenceindicatesthatthetumormicroenvironmentcontributestoradiationresistancebyregulatingthelevelsofcytokinesandgrowthfactors[1;2].

  • 标签: MIGRATION THROUGH Modulating
  • 简介:PhotoelectrochemicalandelectrochemicalreductionofCO2intoorganicchemicalsispromisingfordirectlyorindirectlytransformingsolarenergyintochemicalenergyforfurtherutilization.However,researchontheelectroactivespeciesintheseprocesseshasbeenratherlimited.Inthiswork,weinvestigatedpossibleelectroactivespecies(CO2orHCO3–)involvedintheelectrochemicalreductionofKHCO3atelevatedtemperatureswithoutCO2bubbling.TheresultsshowedthatCO,CH4,andC2H4wereproducedafterelectrochemicalreductionof3.0mol/LKHCO3atelevatedtemperatureonaCuelectrodeevenwithoutCO2bubbling,althoughtheirfaradaicefficiencieswerelow(<6%).MeasurementsforCO2generationfromthedecompositionofHCO3–showedthatelevatedtemperatureandhighHCO3–concentrationstronglypromotedthisprocess.Theseresultssuggestedthatthein-situproducedCO2fromthedecompositionofHCO3–wasprobablytheelectroactivespeciesintheelectrochemicalreductionofHCO3–withoutCO2bubbling.ChangesoftheGibbsfreeenergy,rateconstant,andactivationenergyofthedecompositionofHCO3–intoCO2werealsoinvestigatedandcalculatedfromtheexperimentaldata.

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  • 简介:Muscovitemicasheetswithathicknessof12mwereirradiatedbyswiftheavyionsKrandBifromHeavyIonResearchFacilityinLanzhou(HIRFL).Theuencesrangefrom11010to11012ions/cm2.Theelectronicenergyloss(dE/dx)eincreasesfrom5.9to31.5keV/nm.ThevibrationalmodicationsinirradiatedmicawereinvestigatedbyFourier-transforminfraredspectroscopyandthelatenttrackswereobservedbytransmissionelectronmicroscope(TEM).Theinfraredspectrumshowsthatmotionsfromallatomtypesinthemuscovitemicastructurecouldbefoundinmodesforallvibrations.AsshowninFig.1,theintensityofallvibrationalmodesinmica,includingtheOHstretchmotionat3621cm??1,decreasedwiththeincreasing(dE/dx)e.Thesimilartendencyisfoundinsamplesirradiatedbyswiftheavyionswithincreasingionuence.Itisindicatedthatdefectsandstructuralmodicationsgeneratedduringswiftheavyionirradiation,andmoredefectsareintroducedbyirradiationwithhigherionuence.

  • 标签: TRACK VIBRATIONAL MUSCOVITE
  • 简介:Understandingthehealtheffectsofexposuretospaceradiationisofparticularimportancebecauseofthemountinginterestindeepspaceexploration.Heavyionssuchas56Fearemainradiationsourcesindeepspace,whichcouldposeasignificanthazardtospaceflightcrewsduringandaftermissions[1].ComparedtoX-rays,56FeionshasthemostdeleteriouseffectsonsurvivalandlevelsofDNAdamage[2].

  • 标签: FE ION RADIATION
  • 简介:Nuclearmassisoneofthefundamentalquantityofatomicnucleus.Thetotalbindingenergyofanucleusderivedfromtherelatedmassvaluesreflectsalltheinteractionsamongtheconstitutingnucleons.Massesofshort-livedA=2Z+3nucleiof112SnprojectilefragmentshavebeenmeasuredattheexperimentalcoolerstorageringCSRe,employingtheIsochronousmassspectrometry(IMS).TheexperimentwasconductedattheHeavyIonResearchFacilityinLanzhouatthebeginningof2016.Theprimarybeamof112Sn35+wasaccumulatedinthesynchrotronCSRmandacceleratedto467.91MeV/u.Secondarybeamwereproducedbyimpingingthehighintensity112Sn35+beamontoa10mmberylliumtargetwhichwaslocatedattheentranceoftheradioactivebeamlineRIBLL2.Theprojectilefragmentsof112Snemergedfromthetargetwerethentransmitted,separatedinflightthroughRIBLL2andfinallyinjectedintoCSRe.

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  • 简介:AnewgeneralizedJacobiellipticfunctionmethodisusedtoconstructtheexacttravellingwavesolutionsofnonlinearpartialdifferentialequations(PDEs)inaunifiedway.Themainideaofthismethodistotakefulladvantageoftheellipticequationwhichhasmorenewsolutions.Morenewdoublyperiodicandmultiplesolitonsolutionsareobtainedforthegeneralized(3+1)-dimensionalKronig-Penny(KP)equationwithvariablecoefficients.Thismethodcanbeappliedtootherequationswithvariablecoefficients.

  • 标签: 椭圆方程 孤立解 行波解 非线性偏微分方程 计算数学
  • 简介:Menofreproductiveageundergoingradiotherapyareoftenconcernedaboutthepossibleeffectsonfertilityandfuturechildren[1].Inthisinvestigation,serumtestosteronewasmeasuredfollowingwhole-bodyirradiationwitha2Gycarbonionradiation(CIR),andimmunofluorescencewereusedtoinvestigateproteinlocalizationthatevaluatetheunderlyingtoxicologicalmechanismofacuteinjuryinducedbyCIRinpubertalmicetestes.

  • 标签: ACUTE INJURY INDUCED
  • 简介:TheDNA-dependentproteinkinasecatalyticsubunit(DNA-PKcs)playsamajorroleinDNAdamagesignalingandrepair,andisalsofrequentlyover-expressedintumormetastasis.WeusedisogeniccelllinesexpressingdifferentlevelsofDNA-PKcstoinvestigatetheroleofDNA-PKcsinmetastaticdevelopment.Interestingly,ourresultsshowedthatX-rayirradiationinducedthemetastasisofDNA-PKcspositive(M059K)butnotnegative(M059J)cells;however,genisteincouldsuppresstheradiation-inducedmetastaticpotentialofM059Kcells(Fig.1).Theconcretemechanismsunderlyingthisphenomenonwillbeinvestigatednextyear.

  • 标签: DNA-PKCS POSITIVE CELLS
  • 简介:Thispaperreportsthathexagonal-phaseLaF3:Yb30.20,Er30.02andLaF3:Yb30.20,Tm30.02nanocrystals(NCs)weresynthesizedviaahydrothermalmethod.Thetransmissionelectronmicroscopy,selectedareaelectrondiffraction,powderx-raydiffraction,andthermogravimetricanalysisareusedtocharacterizetheNCs.Under980nmexcitation,theYb3/Er3andYb3/Tm3codopedNCscolloidalsolutionspresentbrightgreenandblueupconversionfluorescence,respectively.TheseNCsshowefficientinfrared-to-violetandinfrared-to-visibleupconversion.TheupconversionfluorescencemechanismsofLaF3:Yb30.20,Er30.02andLaF3:Yb30.20,Tm30.02NCsareinvestigatedwitha980-nmdiodelaserasexcitationsource.

  • 标签: 可见红外线 荧光性 调查研究 RE离子
  • 简介:Thisworkpresentsthesaturableabsorption(SA)propertiesofCsPbBr3perovskitequantumdots(QDs).TheperovskiteQDsshowexcellentSAperformancewithanonlinearabsorptioncoefficientof-35×10-2cm∕GWandafigureofmeritof3.7×10-14esucm.Further,theiruseassaturableabsorbersinapassivelyQ-switchedvisiblesolid-statelaserforthegenerationofsolitonpulsesisdemonstrated.TheseresultsdemonstratethepotentialfortheperovskiteQDstoactassaturableabsorbers.

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