简介:摘要随着智能终端设备不断增加和网络流量的持续上升,现有的通信技术已无法满足未来通信要求。终端直通(Device-to-Device,D2D)通信作为第五代移动通信网(5G)的关键技术能有效缓解数据压力,提高频谱利用率。本文介绍了D2D的优点,详细分析了D2D通信中的关键技术环节,展望了D2D未来发展重点及主要方向。
简介:Asimplemethodisappliedtocalculatingtheisotopeshifts(ISs)on5S1/2→4D3/2,5/2transitionsof87,88Sr+.FirstwehavecalculatedtheISsoflowertransitionsonaseriesofalkali-likesystemssuchasB2+,Ca+andBa+,whichareinagreementwithotherworks.ThentheISson5S1/2→4D3/2,5/2transitionsof87,88Sr+,whichareusefultostudytheSr+opticalfrequencystandard,areevaluated.
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:Methetraxate(MTX),aclassicaldihydrofolatereductaseinhibitor,wasasuccessfulclinicalantitumoragent,havingpotentinhibitoryactivitiestoseveralkindsoftumors.Unfortunately,thecancercellkswereeasiertoproduceresistancetoMTXwhichendedinthefailureofchemotherapy.Inordertoovercometheresistanceoftumorcells,anewkindofdihydrofolatereductaseinhibitorscallednonclassicalantifolateincludingtriazines,pyrimidinesandquinazolinesweredesignedandsynthesized.Becauseofthedifferentantitumormechanismsbetweenthetwokindsofcompunds,thecancercellsresistanttoMTXmaystillbesensitivetothenonclassicalantifolate.Accordingtothistheory,somenonclassicalantifolate2,4-diamino-5-methyl-6-(substitutedbenzylamino)quinazolineswiththegeneralstructureshowninFIg.1weresynthesizedandtheirantitumoractivitiesweredeterminedinthisthesis.
简介:StudiesontheSynthesis,the2Dand3DQSARAboutLipophilicAntifolate2,4Diamino5methyl6(SubstitutedBenzylamino)QuinazolineComp...
简介:<正>"AirHuarache2k5预计发售时间2005年3月26日,预计官方售价$130。"当这个消息发布之后,所有鞋迷都感到非常高兴,一款人们期盼已久的鞋终于要上市了。之前,由于AirHuarache2k5的前辈AirHuarache2k4时尚的外观,以及其包裹性、保护性、舒适性和鞋的轻量化近乎完美的融和,当之无愧地被鞋迷们评定为2004年最佳鞋款之一,因此人们对2K5的期望值达到了前所未有的高度。从2K5的样品图片面世的那一天起,这款鞋就被人们不断谈论,网上经常出现关于2K5的种种猜测,不过大都掺杂了自己的私人情感,没有什么实际根据。但是值得肯定的一点