简介:Regionaldevelopmentisacourseofaccumulationbasedonmanyfactors,whichisdirectlyrelatedtoresourcesutilizationandconversion.Andmaterialwealthproductionandaccumulationembodytheoutcomeofregionaldevelopment.Thus,focusingonmaterialwealth,regionaldevelopmentcanbeevaluatedfromresourcesandperspectiveofresourcesconversion.Takingtheinfrastructurallevel,transportationaccessibilityandeconomicdevelopmentlevelintofullaccount,theconceptof'material-baseddevelopment'waspresentedandthematerial-baseddevelopmentindex(MDI)modelwasestablished.ByusingtheMDImodel,geographicinformationsystemtechnologyandmathematicmethods,thisarticlethencalculatedMDIofeachcountyandprovinceofChinain2005andsystematicallyevaluatedthematerial-baseddevelopmentofChinaatcountyandprovincialscales,soastobringsomescientificreferencesandpolicy-makingsupportstothepopulationdevelopmentfunctionorientedzoningandpopulationspatialdistributionplanningofChina.Theresultshowedthat:(1)Atcountyscale,thematerial-baseddevelopmentofcountieswithinChinain2005wassignificantlydifferent,inwhichtherewere1876countiesbelongingtothemid-levelmaterial-baseddevelopmentandaccountedfor78.10%ofthetotal.Thenumbersofhigh-levelandlow-levelcountieswere144and382andaccountedfor6.00%and15.90%respectively,demonstratingaspindleshapeingeneral.Thespatialdistributionofmaterial-baseddevelopmentwasunbalanced,anditwasmuchbetterinsoutheasternpartofthelineof'Daxinganling–Yinshan-Liupanshan–southeastedgeofQinghai–TibetPlateau'thanthatofnorthwestern.Furthermore,therewerealsodifferencesofthesub-indexbetweendifferentmaterial-baseddevelopmentlevels.Therefore,fordifferentregions,keyissuesandmeasuresadaptabletolocalconditionshouldbeprioritizedandtakeninordertorealizeregionalbalancedevelopment.(2)Atprovincialscale,therewasalsosignificantdifferen
简介:彗星实验是瑞典科学家Ostling和Johanson于1984年发明的检测毒物DNA损伤效应的方法。它经历了从最初的微电泳技术、中性彗星实验、碱性彗星实验、酶切彗星实验和双向垂直彗尾彗星实验等不断完善的发展过程。在毒理学、遗传学和环境生态科学等领域有着重要的应用,是经济合作与发展组织(OECD)和欧洲食品安全局等国际组织推荐的测定遗传毒性的方法之一。彗星实验的关键点包括单细胞悬液的制备、细胞裂解液的成分与比例,低熔点琼脂糖凝胶的浓度,电泳条件等。在典型应用领域,如蚯蚓、鱼、两栖动物、鼠和人的彗星实验很难找到标准实验方案。成功的彗星实验还需关注,实验设计时必须包括阳性对照,结果表述时必须有图为证,实验方案可能因物种或细胞而异。