简介：TcellhomeostasiscommonlyreferstothemaintenanceofrelativelystableTcellnumbersintheperipherallymphoidorgans.AmongthelargenumbersofTcellsintheperiphery,Tcellsexhibitstructuraldiversity,I.e.,theexpressionofadiverserepertoireofTcellreceptors(TCRs),andfunctionaldiversity,I.e.,thepresenceofTcellsatna(I)ve,effector,andmemorydevelopmentalstages.AlthoughthehomeostasisofTcellnumbershasbeenextensivelystudied,investigationofthemechanismsunderlyingthemaintenanceofstructuralandfunctionaldiversityofTcellsisstillatanearlystage.ThefundamentalfeaturethroughoutTcelldevelopmentistheinteractionbetweentheTCRandeitherselforforeignpeptidesinassociationwithMHCmolecules.Inthisreview,wepresentevidenceshowingthathomeostasisofTcellnumberanddiversityismediatedthroughcompetitionforlimitingresources.ThenumberofTcellsismaintainedthroughcompetitionforlimitingcytokines,whereasthediversityofTcellsismaintainedbycompetitionforself-peptide-MHCcomplexes.Inotherwords,diversityoftheself-peptiderepertoirelimitsthestructural(TCR)diversityofaTcellpopulation.Wespeculatethatcognatelowaffinityself-peptides,actingasweakagonistsandantagonists,regulatethehomeostasisofTcelldiversitywhereasnon-cognateornullpeptideswhichareextremelyabundantforanygivenTCR,maycontributetothehomeostasisofTcellnumberbyprovidingsurvivalsignals.Moreover,self-peptidesandcytokinesmayformspecializednichesfortheregulationofTcellhomeostasis.
简介：<正>PolandconfrontedmanyspecialproblemswhenitaccesstotheGATTasasocialistcountrysinceithadimplementedplannedeconomyforaratherlongtimeaftertheliberation.TheAgreementsofGATTandPoland’sAccessionTheGATTmembertookuptherightsandthedutiesbasicallyinastateofequilibrium.IfacountrywantedtogainthebenefitasaGATTmember,itmusttakecertainduties.Allmar-
简介：本文重点研究了大别山潜山，牌楼地区榴辉岩Ｐ－Ｔ－ｔ轨迹，探讨了大别山地区榴辉岩成因，认为榴辉岩原岩主要是碱性玄武岩，少部分洋脊拉斑玄武岩岩浆早期结晶分异堆晶岩及部分钙质沉积岩。它们在华北与杨子板块碰撞时（２６０±３０Ｍａ），地壳向下俯冲到４０－６０ｋｍ处，温度５５０°－８３０°Ｃ，压力１．１－２．１ＧＰａ的条件下形成的。在构造抬升过程中，榴辉岩产生了角闪岩相、绿片岩相退变质作用，角闪岩相温压条件：４６０°－５７０℃，０．４－０．７ＧＰａ。流体包裹体研究表明：流体包体成分主要为ＮａＣｌ－Ｈ＿２Ｏ，Ｈ＿２Ｏ，ＮａＣｌ－ＣＯ＿２－Ｈ＿２Ｏ体系，变质作用过程从早至晚由氧化向还原环境转化。熔融包体的发现表明：榴辉岩形成具有局部深熔作用。从榴辉岩产状、岩石化学、地球化学特征表明本地区榴辉岩不是一种成因，同时具有Ｂ类、Ｃ类榴辉岩特征。
简介：如果彩显有开机烧行管的问题，通常可以使用分段切割法来排除，分段切割法，就是在检修过程中，通过拔掉部分转接插座或新开某一电路，有的也可甩掉某一电路或幕些元器件来缩小故障范围，最后把故障元件找出来，一般对于大电流短路的故障，采用切割击效果最为显著，如开机烧行管，可先将+B电压断开接一假负载。其目的是将负载断开，看故障部位是出在电源电路还是行电路，这是最为常用的一种电路切割法，再如一台无80V视放电压的机器，其真实故障为视放电路一电容短路导致电源电路保护，行无法工作。采用这种方法，将P904座拔开后，行电路工作，高压正常。这无疑是视放板上的问题，通过缩小故障范围，直到查出坏的元器件，排除故障。
简介：Halfsandwichirondicarbonylcomplex[η5-C5H3(t-Bu)2]Fe(CO)2Cl(1)reactswith1,2-dilithiumdiselenocarboraneLi2Se2C2B10H10(2)togiveabinuclearironcarboranecomplex[η5-C5H3(t-Bu)2]2Fe2(CO)3*Se2C2B10H10(3).TheX-raydiffractionanalysisofcomplex3revealsthatoneoftheironatomsischiral.
简介：ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｒｅｃｅｎｔｄｉｓｃｏｖｅｒｙｏｆａｃｌａｓｓｏｆｃａｒｂｏｎｃｏｎｔａｉｎｉｎｇｍｏｌｅｃｕｌｅｓｋｎｏｗｎａｓｔｈｅｆｕｌｅｒｅｎｅｓｈａｓｐｒｏｄｕｃｅｄａｓｅｒｉｅｓｏｆｍａｔｅｒｉａｌｓｗｉｔｈａｗｉｄｅｒａｎ...
简介："他奶奶的!"当华本海发现鲁镇论坛上讨论一百多年前鲁迅小说的帖子的时候,心中就窝了一股无名之火.当年自己爷爷的爷爷华老栓那愚昧无知的举动让刚刚痛斥过陈水扁狂骂过小日本的网虫们"义愤填膺",不到半个月的时间,这篇的帖子就已经提到鲁镇论坛的首页,点击率一路飙升.
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![Synthesis, Structure and Characterization of a Novel Asymmetrical Half-sandwich Binuclear Iron Carborane Complex [η5-<b style='color:red'>C</b>5H3(<b style='color:red'>t</b>-Bu)2]2Fe2(CO)3Se2<b style='color:red'>C</b>2B10H10](/image/thesis13 "Synthesis, Structure and Characterization of a Novel Asymmetrical Half-sandwich Binuclear Iron Carborane Complex [η5-<b style='color:red'>C</b>5H3(<b style='color:red'>t</b>-Bu)2]2Fe2(CO)3Se2<b style='color:red'>C</b>2B10H10")
