简介:“近T”结构是由“近”加上表示时间的语素、词、词组构成的结构体(如近日、近一两天)。表示时间的词语,以说话时间为分界点,有的表过去时间(如昨天、上周四),有的表未来时间(如明天、下周四),有的可表过去也可表未来(如最近、周四)。表过去的称作后指的,表未来的称作前指的。不论后指的还是前指的,它们自身都有方向上的规定性,称作有向的。既能指过去又能指未来的,它们自身没有方向上的规定性,是无向的。“前指、后指、有向、无向”都是时间词语的指向属性。以指向属性为依据,“近T”结构可分为两类:有向后指的和无向的。“近T”结构原本都是有向后指的,后来分化为有向后指的和无向的两类。“近T”结构有时会造成歧义,导致歧义的原因有两个,一是“近”的多义性,二是某些“近T”结构的无向性。
简介:Thereisastorytellingofareligiousmasterallegedlycapableofmovingmountains.Amancametohimaskingforademonstratiom.Themastersatinfrontofamountainforamoment,thenwenttotheothersideofitanddeclaredtheendofthedemonstration.Alltheaudiencesweregreatlypuzzledandbeggedhimforanexplanation.Hesaid:“Therehasneverbeenawayofmovingmountains;whatyoucandoistogotothemountainifitdoesn'tcome”.
简介:今夏的T恤在面料、款式、品牌、风格方面有什么特点呢?面料崇尚自然。今夏T恤面料体现出崇尚自然、崇尚个性的浪漫风情。以前人们很崇尚的化纤、涤纶类T恤,如今已受冷落。而棉纺类T恤却逐渐得到人们的青睬。诸如天然的纯棉、棉涤、棉麻、棉绒类T恤一亘俏销。另外,以真丝和羊毛为主的面料也被市场看好,特别是一些科技含量高、功能特殊、面料质地再符合人体健康要求的产品,成为人们追求的对象。以腾腾们对于棉质T恤的起皱无可奈何,目前通过科学的工艺已完定克服了这一弱点,使棉质T恤具有透气、吸汗、柔软、舒适的特性和自然、免烫、防缩、亮泽、手感好的特点。今夏将出现国产全棉免烫T恤。款式花样繁多。今夏的T恤可谓花样繁多,应有
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.