简介：(-)-(5R,6S)-6-Acetoxyhexadecan-5-olide1,anaturalmosquitoattractantpheromone,wassynthesizedfromreadilyavailablealdehyde2andcyclopentanone3usingL-proline-catalyzedasymmetricaldolreactionasthekeystep.

简介：分式方程的增根与无解是分式方程中常见的两个概念，学生在学习分式方程后，常常会对这两个概念混淆不清，认为分式方程无解和分式方程有增根是同一回事，事实上并非如此．1分式方程增根与无解的关系分式方程有增根，指的是解分式方程时，在把分式方程转化为整式方程的变形过程中，方程的两边同乘了一个可能使分母为零的整式，从而扩大了未知数的取值范围而产生的未知数的值．

简介：讨论了区间I＝[0,1]上的所有反N型（即减－增－减型）函数的迭代根问题。

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简介：TwonewcoenzymeB12analogues,2’,5’-dideoxycytidylcobalamin(2a)and2’,5’-dide-oxyuridinylcobalamin(2b),andtwoothers,2’,5’-dideoxyadenosylcobalamin(2c),and5’-deoxy-thymidylcobalamin(2d)werepreparedbyanimprovedmethod.AllthefouranalogueswereinvestigatedbyUV-visand2D1HNMRspectroscopy.Thecomparisonsanddiscussionabouttheirspectroscopicpropertiesweredone.

简介：(±)-5,5'-Dihydroxy-7,7'-dimethoxy-8,8'-biflavone((±)-l)wasresolvedintoitsopti-callypureformsviatheformationandrecrystallizationofits(2R)-and(2S)-l-(4-toluenesulfonyl)proly-late,andthemethylatedderivativesof(+)-and(-)-lwerealsoprepared.Theabsoluteconfigurationsofallthese8,8'-biflavoneshavebeenconfirmedbytheirCDspectra.

简介：Reactionsofthe6-hydroxy-thiopyrano[3,4-c]pyridine-5-carbonitrilederivative1withα-halo-carbonylcompoundsgavetheortho-substitutedintermediates2a-cwhichwereconvertedintofuro[2,3-b]thiopyrano[4,3-d]pyridines3a-cbyfusionofafuranmoietyunderbasicconditions.Furthercyclizationof3a-cledtoafusionofapyrimidinering,yieldingthetetracyclicproducts6,7and8.Inaddition,condensationof6withvariousaromaticaldehydesaffordedthecorrespondingimines9a,b.Mannichreactionof7gaveproducts10a,b.

简介：“爱尔兰根纲领”是几何学史上一篇划时代的文献，它提出的“变换下的几何不变量”思想对几何、代数乃至其后整个数学的发展都产生了广泛而深刻的影响．然而，这一重要思想在高等数学中的体现和应用却鲜为人注意．为此，本文详细探讨了“爱尔兰根纲领”的思想在高等数学内容中的体现以及它在高等数学中的应用．

简介：Fourteennew1-acyl-5-arylbiuretsweresynthesizedbythereactionofarylureaswithacylisocynantes.Thelatterwasobtainedfromacylchlorideandleadcyanateindichloromethane,usingpyridineascatalyst.Thestructuresofcompounds3a-nwereconfirmedbyIR,1HNMRandMSspectra.

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简介：Thestructuralproperties,mechanicalbehavior,andelectronicstructureofthenewlydevelopeddiamondlikeBC5(d-BC5)wasinvestigatedusingdensityfunctionaltheory(DFT)calculations.Theresultsindicatethatd-BC5hasgreatbulkmodulusof393GPa,largeshearmodulusof398GPa,andhighhardnessof62Pa,andthussupportthefactthatd-BC5isanultra-incompressibleandsuperhardmaterial.Remarkably,thesuperhardd-BC5exhibitsmetallicfeatures.Furthermore,thetrendthatthemechanicalbehaviorfallswiththeincreaseofboroncontentwasrevealed.Thecombinationofhugestiffness,highhardness,andgoodmetallicitymakesseriesofdiamondlikeBCx(d-BCx)validforwiderapplicationsincomparisonwithpurediamond.

简介：Treatmentof4-amino-3-(1-aryl-5-methyl-1,2,3-triazol-4-yl)-5-mercapto-1,2,4-triazoles/2-amino-5-(1-aryl-5-methyl-1,2,3-triazole-4-yl)-1,3,4-thiadiazoleswithbenzaldehyde,acetoneandω-bromoacetophenonewastestedandcompared.ThetitlecompoundsSchiffbases,amides,imidazolo[2,1-b]-1,3,4-thiadiazolesand7H-s-triazolo[3,4-b]-1,3,4-thiadiazineshavebeenconfirmedbyelementalanalyses,^1HNMR,IRandMSspectra.AllthecompoundshavealsobeenscreenedfortheirantibacterialactivitiesagainstB.subtilis,S.aureusandE.coli.

简介：想一想：期末将近，学校准备在各班评选最爱劳动奖、最尊敬父母奖等，请同学们想一想，怎样才能使评选出的人选具有说服力?把你想到的方法与同学交流。

简介：设v1，v2，v3，…，vn是图G的n个顶点，（d（v1），d（u2），d（u3），…，d（vn））^T是图G邻接矩阵A的特征向量，则称G是调和图，其中d（vi）表示顶点弘的度．1—4圈的调和图已经确定，本文确定了所有的3-调和的5-圈调和图．

简介：DarkMatterParticleExplorer(DAMPE)isapowerfulspacetelescopeforhighenergycosmicraysdetectionsuchas-ray,electronandheavyions.ThemainmotivationofDAMPEistofindtheevidenceofdarkmatterexistence,andthesatelliteisscheduledforlaunchingbeforetheendof2015.ThePlasticScintillatorDetector(PSD),whichisoneofthekeycomponentsoftheDAMPEsystem,hastwomajorfunctionalities:distinguishphotonsfromchargedparticlesbyanti-coincidenceandmeasurethechargeofheavyions.ThePSDisdesignedandfabricatedbytheinstituteofmodernphysics,CAS.Itconsistsof82plasticscintillatorstrips,eachofwhichisreadoutbyPMTatbothends,andadouble-dynodereadoutschemeforPMTisutilizedinordertocoverthelargedynamicrange(fromHtoCa).

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简介：讨论了马体群旗传递作用于斯坦诺5设计上的情况，得到了如下结论：设D=（X，Ω，I）是非平凡的斯坦诺5设计，D的自同构群G旗传递地作用在D上。若G是几乎单群，则（i）基柱Soc（G）不是下列单群：N=Mv，v=11，22，23和N=M11,v=12（ii）若N=M12，v=12，则D是一个5-（12，6，1）设计，且GM12（iii）若N=M24，v=24，则D是一个5-（24，8，1）设计，且GM24。

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简介：5-Amino-1,10-phenanthrolineandthreetypesofnew5-substituted1,10-phenanthrolinederivativesbydifferentalkylamides,phen-NHCOR[phen=1,10-phenanthrolineR=CH=CH2;(CH2)nBr,n=1,3-5(CH2)nCH3,n=9--14],weresynthesized.Theywerecharacterizedbymeansofelementalanalyses,infraredspectroscopy,protonnuclearmagneticresonancespectroscopy,andmassspectroscopy.Thesenewcompoundsareimportantligandsortheactivematerialsofruthenium(Ⅱ)electrochemiluminescent(ECL)sensors.

简介：ThecatalyticactivityofFe/ZSM-5fortheselectivereductionofNOtoN2withmethaneinthepresenceofexcessO2wasstudied.Fe/ZSM-5catalystswithvariousFeloadingswerepreparedbyimpregnationmethod.ItiswellknownthatmethaneisinactivewhenFe/ZSM-5asthecatalystfortheselectivecatalyticreduction(SCR)ofNOwithmethane.However,thispapershowsthatwhenthecontentofFewasabout0.5%,Fe/ZSM-5showedhighercatalyticactivityandselectivityofmethane,andputforwardmeasurableactivationforCH4isanimportantfactorforthereactionofremovalofNOxwithCH4.