简介:采用LFA(LandscapeFunctionAnalysis)方法,通过调查7种地类35组样本,评价植被类型、人类活动对林地景观功能和土壤性能的影响,并验证LFA方法在黄土区的适用性。结果表明:不同植被类型对林地土壤结构稳定性、渗透性能、养分循环性能的影响显著,其中,天然次生林改良土壤结构稳定性、渗透性和养分循环性能的作用最好,其次是刺槐人工林、油松人工林,荒草坡最差;人类活动对人工林地景观功能和林地土壤结构稳定性有显著影响;LFA方法能够较好地评价植被类型对林地土壤性能的影响,以及人类活动对人工林地景观功能和林地土壤结构稳定性的影响,在黄土残塬沟壑区有较好的适用性。
简介:LFA-1andMac-1,twoβ2integrinmembersconstitutivelyexpressedonneutrophils,mediateleukocyterecruitmentcascadebybindingtothesameligandofICAM-1.TheslowrollingandfirmadhesionofleukocytesrelyonLFA-1whilethecellcrawlingisdependentonMac-1.Wehypothesizedthattheirdistinctroleswerelikelyattributedtothedifferencesinthebindingkineticsorinthediverseresponsesofoutside-inandinside-outsignaling.Inthisstudy,wecomparedtheICAM-1bindingfeaturesbetweensolubleormembrane-expressedLFA-1andMac-1withdifferentaffinityconformationsusingopticaltraptechnique.Ourdataindicatethattheaffinityup-regulationfromwidetype(WT)tohighaffinity(HA)isoff-ratedependentforLFA-1buton-ratedependentforMac-1.Thestructuralbasesofthisnewfindingwerefoundtobeconsistentwithourprevioussimulations.Theseresultsfurtheredourunderstandingontheirfunctiondifferencesundershearflow.
简介:老师说:“豆豆,你来回答这个问题:秦始皇灭六国的先后顺序是什么?”豆豆回答:“韩赵魏楚燕齐。”老师说:“不错,和同学们说说你是怎么背的吧。”豆豆说:“喊赵薇去演戏。”