简介：ErdǒsandSósconjecturedin1963(see[1],Problem12in247)thateverygraphGonnverticeswithsizee(G)>1/2n(κ-1)containseverytreeTofsizek.Inthispaper,weprovetheconjectureforgraphswhosecomplementscontainnocyclesoflength4.

简介：Inthispaperwereportachemicaloscillationcatalyzedby[Ni(Me2[14]1,3-dieneN4)]2+(Me2[14]l,3-dieneN4denotes2,3-dimethyl-l,4,8,ll-tetraazacyclotetradeca-1,3-diene)inBrO3--pyruvicacid-H2SO4system.Thedomainoftheexistenceoftheoscillationwasobtained.Theeffectsofinitialconcentrationofthecomponentsontheoscillationwerestudied.Thefeaturesoftheoscillationsweredescribedindetail.WealsoexaminedtheeffectsofAg+,Hg2+,CCl4,freeradicalinhibitors,etc.ontheosillations.

简介：为高功率脉冲功率装置设计了4MV同轴-三平板型水介质自击穿开关作为脉冲输出开关。脉冲输出开关指在脉冲功率装置中脉冲形成线输出端的开关，它是脉冲形成线和传输线的连接部件，对传输电脉冲进行二次压缩。脉冲输出开关常常是自击穿开关，由于其前面的主开关对Marx发生器输出电脉冲进行了初步压缩，脉冲输出开关的输入脉冲前沿上升较快，故脉冲输出开关常常是多通道开关。

简介：Theabinitiomolecularorbitalmethodisemployedtostudytheenantioselectivereductionofacetophenonewithboranecatalyzedbythiszolidino[3,4-c]oxazaborolidine.Computationresultshowsthatthecontrollingstepforthereductionisthedecompositionofthecatalyst-alkoxyboraneadductandthereductionleadstoS-alcohols.ThetransitionatateofthehydridetransferfromtheboranemoietytothecarbonylcarbonofacetophenoneisatwistedchairstructurewithaB(2)-N(3)-BBH3-HBH3-CCo-OCO6-memberedring.

简介：ＭｉｃｒｏｄｏｓｉｍｅｔｒｉｃＳｐｅｃｔｒｕｍａｎｄＲａｄｉａｌＤｏｓｅＤｉｓｔｒｉｂｕｔｉｏｎｏｆ２３９ＰｎｏｒＲａｙｉｎＣＨ４Ｇａｓ￥ＺｈｕＬｉａｎｆａｎｇ；ＬｉＸｕｅｋａｎ；ＣｈｅｎＸｕｅｂｉｎｇ；ＨｅＹｕｓｈｅｎｇ；ＳｕＹｏｕｗｕａｎｄ...

简介：Wedemonstratedamonolithic,compact,diode-pumpedgain-switchedNd:YVO4laserat1.064μmwavelengthwithcontrollablerepetitionrateof1Hzto25kHz.Stablegain-switchedpulsetrainwithmaximumrepetitionrateof25kHzandpulsewidthof16nswasobtained.

简介：ＳＹＮＴＨＥＳＩＳＯＦ３－ＡＲＹＬ－１（２Ｈ，４Ｈ）ＡＣＲＩＤＯＮＥＳＡＮＤＴＨＥＩＲＤＥＲＩＶＡＴＩＶＥＳ￥ＲｏｎｇＹＩＮ；ＧｕａｎｇＦａｎＨＡＮ；ＹｕＴｉａｎＬＩ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｄｉｃａｌＬａｂｏｒａｔｏｒｙ，ＪｉｌｉｎＭｅｄｉｅａ...

简介：TheenergyresponsesofKaoftwotypesofcylindricalG-Mcountertubeswerecalculatedusinganelectron-photoncascadeMonteCarlocode,EGS4.OnetypeoftheG-McountertubeswasGJ4401(sensitivelength9cm,diameter1cm),theotherwasJ5(sensitivelength2cm,diameter0.3cm),therestrictedsamplingtechniqueofsourcephotonwasused.Goodtendencyagreementsbetweenthesimulationsandexperimentswereachievedforgammaradiationwithenergiesrangingfrom40keVto1.25MeV.ForGJ4401,thedifferenceofresponsebetweensimulationsandexperimentsat662keVwas34%andforJ5thedifferencewas27%.

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简介：Thedifferentregioselectiveandstereoselectiveproductswereobtainedbythereductionofstigmast-4,22-dien-3,6-dionewithNaBH4-CH3OHwhendifferentkindsofmetalionswasaddedtothereaction.

简介：ＳＹＮＴＨＥＳＩＳ　ＡＮＤ　ＳＰＥＣＴＲＡ　ＳＴＵＤＩＥＳ　ＯＦ　ＴＲＡＮＳＩＴＩＯＮ　ＭＥＴＡＬ　ＣＯＭＰＬＥＸＥＳ　ＤＥＲＩＶＥＤ　ＦＲＯＭ　２，　４－ＤＩＮＩＴＲＯＰＨＥＮＹＬ　ＨＹＤＲＡＺＩＮＥＳＹＮＴＨＥＳＩＳＡＮＤＳＰＥＣＴＲＡＳＴＵＤＩ...

简介：Thetreatmentandresourcereuseof1,2,4-acidproducingwastewaterbyself-mademacroporousadsorptionresinND,A-107wasstudiedinthispaper.Optimumadsorptionanddesorptionprocessparameterswereacquiredbysystematicallystudy.ThepolymericresinNDA-107indicatedgoodadsorption&desorptionof1,2,4-acidinthewastewater.Theremovalefficiencyof1,2,4-acid,CODerisabout78%,72%respectively.Itisevidentthatthisadsorptionprocessisanefficienttreatmentmethodfor1,2,4-acidproducingwastewater.Atthesametime,theaccumulationandresourcereuseofl,2,4-acidcanberealizedinthisprocess.

简介：ＥＬＥＣＴＲＯＮ　ＴＲＡＮＳＦＥＲ　ＢＥＴＷＥＥＮ　Ｅｕ３＋　ＡＮＤ　Ｃｅ３＋　ＩＮ　ＳｒＭｇＦ４　ＭＡＴＲＩＸＥＬＥＣＴＲＯＮＴＲＡＮＳＦＥＲＢＥＴＷＥＥＮＥｕ３＋ＡＮＤＣｅ３＋ＩＮＳｒＭｇＦ４ＭＡＴＲＩＸ￥ＹｉｎｇＷＵ；Ｃｈ...

简介：Ti6Al4Visawidelyappliedinmedicalimplantssuchasbone,joint,andteethduetoitsexcellentmechanicalproperties,corrosionresistance,plasticityandthebiocompatibilityofthesurfaceoxide.However,thenativesurfaceoxidefilmisquitethin(about5nm)andtechniquessuchasmicroarcoxidation,plasmasprayedhydroxyapatitaeandplasmaimmersionionimplantationareusedtosynthesizethickersurfacetitaniumoxide.

简介：YbxY1-xAl3(BO3)4(x=0.1,0.07and0)crystalshavebeengrownbythefluxmethod.ThegrowthdefectsofYbxY1-xAl3(BO3)4crystalsweredetectedbyX-raytopography.ItisfoundthattheperfcetionofYbYABcrystalwithlowYbdopantisbetterthanthatwithhighYbdopant.InYb0.1Y0.9Al3(BO3)4crystal,growhtbands,growthboundaries,grown-indislocationsandinclusionswereobserved.Howver,thedensitiesofgrowthdefectsforYb0.07Y0.93Al3(BO3)4andYAl3(BO3)4arelowandnoobviousinclusionsareobservedinthesecrytals.Inaddition,growthtwinswrerdetectedinYbxY1-xAl3(BO3)4crystalbyusingthechemicaletchingmethod.ItisfoundthatthegrowthtwinsoccurfrequentlyinYb0.01Y0.9Al3(BO3)4crystalwhereasnogrowthtwinappearsinYAl3(BO3)4crystal.Basedontheexperimentalobservations,theformationmechanismofgrowthtwinsisdiscussed.Inthemeantime,theeffectivemeasuresforreducingthegrowthtwinsanddefectsareproposed.2001ElsevierScienceB.V.Allrightsreserved.

简介：Lophenol,cholest-4α-methyl-7-en-3β-ol(1),obtainedfromDracaenacochinchinensis(Lour.)S.C.Chen,wasstructurallymodified.Itwasacetylatedtoprotect3β-hydroxylgroup,andthenoxidisedbyseleniumdioxideinaceticacidtogivecholest-4a-methyl-8-en-3β,Ta-dioldiacetate(3).Thiscompound3isunstableinchloroformsolutionorwhenheatedandeasilyconvertedtoadienecompound,cholest-4a-methyl-7,14-dien-3β-olacetate(4).Thestructuresof3and4wereelucidatedbymeansofIR,^1HNMR,^13CNMRandMS,andtheabsoluteconfigurationof3wasestablishedbyX-raycrystallography.Thepropertyof3wasalsodiscussedinthispaper.Both3and4arenewcompoundsandwerereportedforthefirsttime.

简介：3-(2-Hydroxyphenyl)-6-(4-nitrophenyl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine,C16H11N5O3S,waspreparedbythecyclizationof3-(2-hydroxyphenyl)-4-amino-5-mercapto-1,2,4-triazolewith2-bromo-4-nitroacetophenone.Thecompoundwascharacterizedbymeansofelementalanalysis,IR,1HNMR,13CNMR,massspectrometry,andX-raydiffraction.ThecompoundcrystallizesinamonoclinicsystemwithspacegroupCc,a=2.1853(4)nm,b=2.1192(5)nm,c=1.3526(3)nm,β=95.21(2)°,V=6.238(2)nm3,Dcalcd.=1.505Mg/m3,Z=16,F(000)=2916,R1=0.0501,wR2=0.0427.Acomparisonbetweenthecrystalstructuresof1,2,4-triazolo[3,4-b][1,3,4]thiadiazineand1,2,4-triazolo[3,4-b][1,3,4]thiadiazolewasmadeinthestructuralview.Atwo-dimensionalnetworkisformedbyhydrogenbondsandπ-πstackinginteractions.

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简介：′93桂林中外物理教师学术交流会于7月31日至8月3日在广西师范大学举行。来自日本、美国、德国、韩国、菲律宾、泰国和香港等国家和地区的38名外方代表与来自国内25个省，市、自治区的159名中方代表出席了会议，中国物理学会、物理通报等单位发来了贺信。

简介：Asimpleeffectivesynthesisofbis(dihydropyrimidinone-4-yl)benzenederivatives,usingboricacidascatalyst,fromisophthalicaldehydeorterephthalicaldehyde,1,3-dicarbonylcompoundsandureaorthioureainglacialaceticacidwasdescribed.AstheexpansionoftheclassicalBiginellireaction,thismethodhastheadvantageofexcellentyields83%-94%andshortreactiontime0.5-1.5h.