学科分类
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29 个结果
  • 简介:2006年1月6日上午,国务院台湾事务办公室正式公布赠台大熊猫的最终遴选结果:16,19熊猫为大陆赠送台湾的熊猫。

  • 标签: 大熊猫 大陆 办公室 国务院 台湾省
  • 简介:公元前202年,刘邦打败了项羽,结束了长时期群雄割据的战乱局面,完成了汉帝国的大一统。为了巩固其统治地位,咸阳城的新主人一方面采取“与民休息”、“轻徭薄赋”的宽柔政策发展农商,另一方面则对各路诸侯论功行赏,分封爵位和赏赐领地。特别是“文景之冶”后的汉王朝经济繁荣,百废俱兴。“京师之钱累巨万,贯朽而不可校。太仓之粟陈陈相因,充溢露积于外,至腐败不可食。”

  • 标签: 咸阳 割据 诸侯 赏赐 大一统 刘邦
  • 简介:全球知名的以生态保护为宗旨的绿色和平组织、其船长最近又添新力军,购自原俄国的消防船(MVEsperanza),将取代老旧的“绿色和平”,正式投入使用。2003年9月4日和5日,“希望”抵访加拿大温哥华市,笔者闻讯赶到码头,不料却扑了一空,急询在场的绿色和平组织的义工,方得知“希望”因前一天的抗议活动被码头管理公司下了逐客令,我和一群参观者马不停蹄地又赶到新的泊船地点,却是在温哥华的英格兰海湾中,经由小气艇驳接,终于在秋

  • 标签: “希望号”船 环境保护 绿色和平组织 废水回收系统
  • 简介:为了阐明哺期全氟辛烷磺酸(perfluorooctanesulfonate,PFOS)染毒对大鼠及其仔鼠海马细胞钙稳态的影响,将妊娠Wist-ar大鼠30只,从妊娠第1天开始对实验组分别以7.2mg.kg-1(low,L)、14.4mg.kg-1(high,H)(以饲料中的PFOS计)的PFOS进行染毒至仔鼠生后35d。采用固相萃取-高效液相色谱/质谱联机法(HPLC/MS-MIS)检测脑组织中PFOS浓度,使用Fura-2/AM荧光探针法测定母鼠和仔鼠海马细胞内游离钙离子浓度([Ca2+]i)。结果表明:PFOS可以在仔鼠海马组织中发生蓄积作用;7.2mg.kg-1、14.4mg.kg-1实验组母鼠海马细胞[Ca2+]i分别为(175.4±11.9)、(313.4±18.7)nmol.L-1,均显著高于对照组(155.6±11.9)nmol.L-1(p〈0.05);在仔鼠出生后第1天(postnatalday1,PND1),高剂量PFOS染毒组仔鼠海马细胞[Ca2+]i显著高于对照组(p〈0.01)。在PND28和PND35时,出生前后均进行高剂量PFOS染毒组仔鼠海马细胞[Ca2+]i均显著高于对照组及出生前后均进行低剂量PFOS染毒的组别(p〈0.01)。在PND28和PND35时,仅出生前高剂量PFOS染毒的仔鼠海马细胞[Ca2+]i均显著高于对照组及仅出生前低剂量PFOS染毒的组别(p〈0.01)。此外,随着仔鼠年龄的升高,仅出生前、仅出生后和出生前后均进行PFOS染毒的仔鼠海马细胞[Ca2+]i均有显著升高(p〈0.05)。研究结果表明,哺期PFOS染毒可以诱导大鼠及其仔鼠海马细胞[Ca2+]i升高,这可能对大鼠及仔鼠的神经系统产生影响。

  • 标签: 全氟辛烷磺酸 海马 钙离子 神经毒性
  • 简介:为探讨纳米MnO2与常规MnO2粉末对细胞DNA损伤作用的差别,采用不同浓度的纳米MnO2与常规MnO2粉末(0、100、200、400μg·mL^-1)对Hela细胞进行染毒,应用单细胞凝胶电泳(彗星实验)检测Hela细胞的损伤效应.结果表明,与对照组相比,纳米MnO2和常规MnO2各染毒组细胞尾部DNA百分率(TailDNA%)和尾矩(TailMoment)均显著增加(p〈0.01);同一浓度下,纳米MnO2组细胞尾部DNA百分率和尾矩显著高于常规MnO2组(p〈0.01).以上结果表明,纳米MnO2和常规MnO2粉末均能导致Hela细胞DNA损伤,且纳米MnO2的损伤作用强于常规MnO2.

  • 标签: 纳米MNO2 常规MnO2 DNA损伤 单细胞凝胶电泳
  • 简介:Globalclimatechangeisoneofthemajorenvironmentalissuesfacedbyhumans.Existingevidenceindicatesthattheanthropogenicpushforariseintheatmosphericconcentrationofgreenhousegases(GHGs)(particularlyCO2)hasbeenaprimarycauseforglobalwarming.Asidefromeconomicandteclinologicalfactors,demographicdynamics(includinghumanconsumptioninabroaddemographicsense)hasbeenamajordriverforCO2emissions.Inthispaper,weperformedbothnonlinearregressionanalysis(basedontheSTIRPATmodel)andgraycorrelationdegreeanalysis(basedongraysystemtheory)ontheimpactofdemographicdynamicsonCO2emissions.OurresultsrevealthatCO2emissionsarepositivelycorrelatedwithpopulationsizeandGDPpercapitaandnegativelycorrelatedwithenergyintensity.WealsoshowthatgraycorrelationdegreewithCO2emissionsforfivevariables(i.e.,householdconsumption,urbanizationrate,householdsize,populationagingrate,populationsize)variessubstantially:householdconsumption>urbanizationrate>householdsize>populationagingrate>populationsize,withhouseholdconsumptionbeingthehighest,andpopulationsizethelowest.TomitigatetheimpactofdemographicdynamicsonCO2emissions,itisofvitalsignificancetonurturepeople’sawarenessofsustainableconsumptionandtoadheretocurrentpopulationcontrolpolicies.

  • 标签: DEMOGRAPHIC DYNAMICS CO2 EMISSIONS GRAY
  • 简介:HouseholdconsumptionisoneoftheimportantfactorsthatinduceCO2emission.Basedoninput-outputmodel,thisarticlecalculatedtheintensityofCO2emissionofdifferentincomegroupsandsevenprovincesinChina,andthenestimatedtotalCO2emissioninducedbyurbanhouseholdconsumptionfrom1995to2004inChinabasedonstatisticdataofhouseholdlivingexpenditure.TheresultsshowthatCO2emissionpercapitainducedbyhouseholdconsumptionhadincreasedfrom1583to2498kgCO2during1995-2004.Theratioofconsumption-inducedCO2emissiontototalCO2emissionhadrisenfrom19%to30%inthepastdecade.IndirectCO2emissionaccountedforanimportantpartoftheconsumption-inducedemission,theratioofindirectemissiontoconsumption-inducedemissionhadrisenfrom69%to79%duringthesameperiod.Asignificantdifferenceinconsumption-inducedCO2emissionacrossdifferentincomegroupsanddifferentregionshasbeenobserved.CO2emissionpercapitaofhigherincomegroupsanddevelopedregionsincreasedfasterthanthatoflowerincomegroupsanddevelopingregions.ChanginglifestylehasdrivensignificantincreaseinCO2emission.Especially,increasesinprivatetransportexpenditure(forexample,vehicleexpenditure)andhousebuildingexpenditurearekeydrivingfactorsofgrowthinconsumption-inducedCO2emission.TherearebigdifferencesintheamountofCO2emissioninducedbychangeinlifestyleacrossdifferentincomegroupsandprovinces.Itcanbeexpectedthatlowerincomehouseholdsanddevelopingregionswillincreaseconsumptiontoimprovetheirlivingswithincomegrowthinthefuture,whichmayinducemuchmoreCO2emission.AreasonablelevelofCO2emissionisnecessarytosatisfyhumanneedsandtoimprovelivingstandard,butanoticeablefactisthatCO2emissionpercapitainducedbyhouseholdconsumptionindevelopedareasofChinahadreachedaquitehighlevel.Adjustmentinlifestyletowardsalow-carbonsocietyisinurgentneed.

  • 标签: 资源 二氧化碳 城市环境 大气污染
  • 简介:为探究并比较淡水鱼种日本青鳉早期发育阶段对Cu2+和Cd2+等重金属胁迫的响应,在实验室通过半静态方式,对日本青鳉受精卵和仔稚鱼分别进行了48h和96h急性毒性实验。结果表明:Cu2+对日本青鳉胚胎24、48h-LC_(50)分别为8.164mg·L(-1)和6.965mg·L(-1);Cd2+对日本青鳉胚胎24、48h-LC_(50)分别为63.084mg·L(-1)和53.093mg·L(-1);较低浓度组Cu(2+)(≤1.97mg·L(-1))时日本青鳉胚胎的发育速率快于对照组,而较高浓度组(≥3.87mg·L(-1))胚胎的发育速率则慢于对照组;与Cu(2+)略有不同,无论浓度高低Cd(2+)对胚胎的孵化速率均产生抑制作用;Cu(2+)和Cd(2+)质量浓度分别高于1.97mg·L(-1)和19.68mg·L(-1)时,两种重金属离子均显著降低胚胎的孵化率(P〈0.05)。Cu(2+)对日本青鳉初孵仔鱼24、48、72和96h-LC_(50)分别为5.361mg·L(-1)、2.844mg·L(-1)、2.020mg·L(-1)和1.352mg·L(-1);Cd(2+)对日本青鳉初孵仔鱼24、48、72和96h-LC_(50)分别为15.907mg·L(-1)、10.550mg·L(-1)、7.986mg·L(-1)和6.346mg·L(-1);Cu(2+)对日本青鳉稚鱼24、48、72和96h-LC_(50)分别为5.732mg·L(-1)、4.037mg·L(-1)、2.498mg·L(-1)和1.955mg·L(-1);Cd(2+)对日本青鳉稚鱼的24、48、72和96h-LC_(50)分别为16.419mg·L(-1)、11.745mg·L(-1)、8.516mg·L(-1)和6.776mg·L(-1)。与其它淡水水生生物相比,日本青鳉仔稚鱼对铜和镉离子较为敏感。

  • 标签: 日本青鳉 重金属 发育阶段 急性毒性
  • 简介:为了解大蒜鳞茎浸提液对种子萌发和幼苗生长的化感作用,实验采用不同浓度大蒜鳞茎浸提液对金秋红二菜苔的种子进行处理,观察对种子萌发、幼苗根长、茎长和幼苗根重、苗重的影响.实验结果表明,大蒜鳞茎浸提液对金秋红二菜苔种子的发芽率和发芽指数的化感作用随着大蒜鳞茎浸提液浓度的升高而增强;大蒜鳞茎浸提液对金秋红二菜苔幼苗的根和苗都有抑制作用,且对根的化感作用强于苗的化感作用.

  • 标签: 大蒜 鳞茎浸提液 化感作用 金秋红二号菜苔
  • 简介:AftertheKyotoProtocolwasimplemented,carbonleakageexertsgreatinfluencesoninternationaltradeandeconomy.Tradecreatesamechanismforconsumerstoshiftenvironmentalpollutionassociatedwiththeirconsumptiontoothercountries.ChinahasovertakentheU.S.astheworld'sbiggestCO2emittersince2006.AsChina'ssecondlargesttradepartner,theU.S.hasthebiggesttradedeficitwithChinawhichhasarousedalotofdisputesbetweenthetwoparties.ButsofartheassessmentsofthetradeimbalanceofChina-U.S.havepaidlittleattentiontoenvironmentalimpactsassociatedwiththetradeimbalance.Appliedaninput-outputapproach,thearticleestimatestheamountofCO2embodiedinChina-U.S.tradeduring1997-2007.ItwasfoundthatthroughtradewithChina,theU.S.reduceditsCO2emissionscomparedwithanon-tradescenario.Duetothegreatercarbon-intensityandrelativelylessefficientproductionprocessesofChineseindustry,China-U.S.traderesultedinmoreCO2emissionsinChinaandtheworld.Intheend,thearticlegivessomesuggestions:itisequalandsustainablethattheinternationalaccountingmethodologiesshouldbeimproved,forCO2emissionsresponsibilitymustbedesignedtoaccountforthedynamicnatureofinternationaltrade.

  • 标签: 二氧化碳排放量 国际贸易 中国 京都议定书 环境污染 环境影响
  • 简介:EstablishingpositiveandurgenttargetsforCO2reductionandemissionpeak,andpromotingenergyconservationandenergystructureadjustmentareamongthestrategiestoaddressglobalclimatechangeandCO2emissionsreduction.Theyarealsomeanstobreakthroughtheconstraintsofdomesticresourcesandenvironment,andinternalneeds,toachievesustainabledevelopment.Generallyspeaking,acountry’sCO2emissionpeakappearsafterachievingurbanizationandindustrialization.Bythen,connotativeeconomicgrowthwillappear,GDPwillgrowslowly,energyconsumptionelasticitywilldecrease,andenergyconsumptiongrowthwillslowdown-dependentmainlyonnewandrenewableenergies.Fossilfuelconsumptionwillnotincreasefurther.WhenCO2emissionreachesitspeak,theannualreductionrateofCO2intensityofGDPisgreaterthanGDPannualgrowthrate;andtheannualreductionrateofCO2intensityofenergyuseisgreaterthantheannualgrowthrateofenergyconsumption.Therefore,threeimportantapproachestopromotionofCO2emissionpeakcanbeconcluded:maintainingreasonablecontrolofGDPgrowth,strengtheningenergyconservationtosignificantlyreducetheGDPenergyintensity,andoptimizingtheenergymixtoreducetheCO2intensityofenergyuse.Byaround2030,Chinawillbasicallyhavecompleteditsrapiddevelopmentphaseofindustrializationandurbanization.ConnotativeeconomicgrowthwillappearwiththeaccelerationofindustrialstructureadjustmentThetargetofGDPenergyintensitywillstillbetomaintainanaverageannualreductionof3%orhigher.Theproportionofnon-fossilfuelswillreach20-25%,andtheaimwillbetomaintainanaverageannualgrowthrateof6-8%.Thetotalannualenergydemandgrowthof1.5%willbesatisfiedbythenewlyincreasedsupplyofnon-fossilfuels.TheannualdeclineinCO2intensityofGDPwillreach4.5%orhigher,whichiscompatiblewithanaverageannualGDPgrowth

  • 标签: CO2 emission PEAK ADDRESSING CLIMATE change
  • 简介:Inthispaper,weconstructamodelinwhichtheimpactofpollutiononhealthisexertedthroughbothdirectandindirectchannels.Theindirectchanneliscapturedbyaproductionfunc-tioninwhichtheprincipalhealth-improvingfactor,incomegrowth,canberealizedonlyinthecostofpollutionincrease.Thismodelisthentestedbytheaggregatedchroniclediseasedatainover78Chinesecounties.Ourresultsshow,afterattainingthethresholdof8μg/m2,continuousincreaseinindustrialSO2emissiondensitywillleadtheratioofpopulationsufferingchroniclediseases,amongwhichrespiratorydiseasesoccupyasignificantproportion,torise.However,owingtotechnologicalprogressinpollutioncontrolactivities,theneededSO2emissiontoproduceoneunitofGDPdiminisheswithtime.Therefore,thenegativeeffectfrompollutionaugmentationonpublichealthseemstoberecompensedmoreandmorebythepositiveeffectofeconomicgrowth.

  • 标签: 工业污染 环境 公共健康 中国 二氧化硫 工业废气
  • 简介:ThispaperproposestouseDEAmodelswithundesirableoutputstoconstructtheMalmquistindexthatcanbeusetoinvestigatethedynamicchangesofCO2emissionperformance.Withtheindex,theauthorshavemeasuredtheCO2emissionperformanceof28provincesandautonomousregionsinChinafrom1996to2007;withtheconvergencetheoryandpaneldataregressionmodel,theauthorsanalyzetheregionaldifferencesandtheinfluencingfactors.ItisfoundthattheperformanceofCO2emissionsinChinahasbeencontinuouslyimprovedmainlyduetothetechnologicalprogress,andtheaverageimprovementrateis3.25%,withacumulativeimprovementrateof40.86%.Inaddition,theCO2emissionperformancevariesacrossfourregions.Asawhole,theperformancescoreofeasternChinaisthehighest.ThenortheasternandcentralChinahasrelativelylowerperformancescores,andthewesternChinaisrelativelybackward.Theregionaldifferencesaredecreasing,andtheperformanceofCO2emissionsisconvergent.TheinfluenceofsomefactorsontheperformanceofCO2emissionsissignificant,suchasthelevelofeconomicdevelopment,thelevelofindustrialstructure,energyintensity,andownershipstructure.Theinfluenceofsomefactors,suchasopening-uptotheoutsideworld,ontheperformanceofCO2emissionsisnotsignificant..

  • 标签: 二氧化碳排放量 排放性能 中国东部 区域差异 动态变化 影响因素
  • 简介:WhenaccountingtheCO2emissionsresponsibilityoftheelectricitysectorattheprovinciallevelinChina,itisofgreatsignificancetoconsiderthescopeofbothproducers’andtheconsumers’responsibility,sincethiswillpromotefairnessindefiningemissionresponsibilityandenhancecooperationinemissionreductionamongprovinces.Thispaperproposesanewmethodforcalculatingcarbonemissionsfromthepowersectorattheprovinciallevelbasedonthesharedresponsibilityprincipleandtakingintoaccountinterregionalpowerexchange.Thismethodcannotonlybeusedtoaccounttheemissionresponsibilitysharedbyboththeelectricityproductionsideandtheconsumptionside,butitisalsoapplicableforcalculatingthecorrespondingemissionresponsibilityundertakenbythoseprovinceswithnetelectricityoutflowandinflow.ThismethodhasbeenusedtoaccountforthecarbonemissionsresponsibilitiesofthepowersectorattheprovinciallevelinChinasince2011.Theempiricalresultsindicatethatcomparedwiththeproduction-basedaccountingmethod,thecarbonemissionsofmajorpower-generationprovincesinChinacalculatedbythesharedresponsibilityaccountingmethodarereducedbyatleast10%,butthoseofotherpower-consumptionprovincesareincreasedby20%ormore.Secondly,basedontheprincipleofsharedresponsibilityaccounting,InnerMongoliahasthehighestcarbonemissionsfromthepowersectorwhileHainanhasthelowest.Thirdly,fourprovinces,includingInnerMongolia,Shanxi,HubeiandAnhui,havethehighestcarbonemissionsfromnetelectricityoutflow-14milliontin2011,accountingfor74.42%oftotalcarbonemissionsfromnetelectricityoutflowinChina.Sixprovinces,includingHebei,Beijing,Guangdong,Liaoning,Shandong,andJiangsu,havethehighestcarbonemissionsfromnetelectricityinflow-11milliontin2011,accountingfor71.44%oftotalcarbonemissionsfromnetelectricityinflowinChina.Lastly,thispaperhasestimatedtheemissionfactorsofelectricity

  • 标签: SHARED RESPONSIBILITY power GENERATION efficiency carbon
  • 简介:Thispaperquantifiesadecompositionanalysisofenergy-relatedCO2emissionsintheindustrialsectorsofShanghaiovertheperiod1994-2007.TheLog-MeanDivisiaIndex(LMDI)methodisappliedtothisstudyintermsofsixfactors:laborforce,labormobility,grosslaborproductivity,energyintensity,fuelmix,andemissioncoefficient.Inaddition,thedecouplingeffectbetweenindustrialeconomicgrowthandCO2emissionsisanalyzedtoevaluateCO2mitigationstrategiesforShanghai.TheresultsshowthatalllaborproductivityhasthelargestpositiveeffectonCO2emissionchangesintheindustrialsectors,whereaslabormobilityandenergyintensityarethemaincomponentsfordecreasingCO2emissions.OtherfactorshavedifferenteffectsonCO2mitigationindifferentsub-periods.AlthougharelativedecouplingofindustrialCO2emissionsfromtheeconomicgrowthinShanghaihasbeenfound,ShanghaishouldkeeppacewiththeindustrialCO2emissionsreductionbyimplementinglow-carbontechnology.Theseresultshaveimportantpolicyimplications:PlanCisthereasonablechoiceforShanghai.

  • 标签: 二氧化碳排放量 能源强度 上海 分解 工业部门 劳动生产率
  • 简介:为研究水生生物对水体中重金属和有机磷农药毒性的响应,研究了锯齿新米虾暴露在Cu2+、毒死蜱单一溶液和毒性1:1混合溶液下的响应状况,同时采用相加指数法对混合毒性进行了评价。单一毒性试验结果表明:毒死蜱对锯齿新米虾的毒性显著高于Cu(2+)(p〈0.01);Cu(2+)对锯齿新米虾未觉察反应浓度(NOEC)和最低觉察反应浓度(LOEC)分别为1.78mg·L(-1)、2.40mg·L(-1),24、48、72和96h的LC_(50)分别为6.41、4.75、4.20和3.44mg·L(-1);毒死蜱对锯齿新米虾NOEC和LOEC分别为0.04μg·L(-1)、0.07μg·L(-1),24、48、72和96h的LC50分别为035、0.17、0.11和0.06μg·L(-1);参考鱼类毒性分级标准,Cu(2+)对锯齿新米虾为高毒,而毒死蜱为剧毒。混合毒性试验结果表明:采用Cu(2+)和毒死蜱毒性1:1进行试验时,暴露时间为24、48、72和96h的相加指数(AI)分别为0.02、0.45、1.86和223,即混合毒性为协同作用。通过研究锯齿新米虾对Cu(2+)、毒死蜱单一和联合毒性的响应,可为水环境污染与防治、物种多样性保护提供科学依据。

  • 标签: 锯齿新米虾 CU2+ 毒死蜱 毒性响应
  • 简介:为了探讨纳米与微米尺度SiO2对雄性大鼠的生殖毒性作用,选择不同剂量的纳米SiO2(20~40nm)与微米SiO2(1~10μm)采用气管滴注方式对雄性Wistar大鼠分组染毒.于染毒5周后处死大鼠,检查附睾精子形态,并检测睾丸组织和血清中睾丸功能标志酶活性变化以及性激素含量的变化.结果表明:1)高、低剂量的纳米和微米SiO2染毒均可使大鼠发生程度不同的精子数量减少、精子活动率降低、精子畸形率升高;2)纳米SiO2染毒可使大鼠睾丸组织SDH、LDH和血清中ACP活性显著降低,而微米SiO2染毒对这些指标的影响不显著;3)纳米SiO2和高剂量微米SiO2染毒可使大鼠血清T和睾丸匀浆T浓度显著降低,而对血清LH没有显著影响;4)与微米SiO2相比,纳米SiO2对大鼠生殖功能的损伤有更严重的趋势,但相同剂量下,纳米SiO2和微米SiO2相比,各指标均无显著性差异.以上结果表明,微米和纳米尺度SiO2染毒均可使大鼠生殖功能产生损伤,使部分生殖功能指标发生显著变化;与微米SiO2相比,纳米SiO2对大鼠生殖功能的损伤有更严重的趋势.

  • 标签: 纳米SIO2 微米SiO2 雄性大鼠 生殖损伤
  • 简介:焦化废水中含有大量毒性物质,具有较强的生物毒性。本文以实验室构建的A2/O焦化废水处理系统为研究对象,考察废水处理过程化学成分和急性毒性的变化。采用紫外扫描和三维荧光光谱分析考察了处理系统各阶段出水的物质组分,并采用固相萃取和超滤膜分离等手段对水样各组分的发光细菌急性毒性进行研究。结果表明,伴随着芳香族物质等毒物的去除,焦化废水的急性生物毒性在该处理系统中被逐步削减,最终出水的毒性当量仅为原水的28%;不同组分的生物毒性测试结果显示,废水水样的强极性和中等极性有机组分贡献了绝大部分的毒性当量,而这些物质主要在缺氧段及好氧段被削减;结合三维荧光光谱的分析结果,可推断焦化废水中一类很难在A2/O处理系统中被完全去除的芳香族蛋白质类似物(Ⅱ区)很可能具有较强的生物毒性,是构成出水毒性的主要物质。

  • 标签: 焦化废水 A2 O工艺 急性毒性 组成变化 因果关系分析
  • 简介:随着环境重金属污染的加剧和营养学的发展,人们越来越重视对重金属元素及营养金属元素肠道吸收过程的探讨及其生物有效性影响因素的研究.Caco-2细胞模型能有效的模拟人体小肠上皮细胞的转运与吸收过程,可结合基因技术、分子技术等手段用于研究人体肠道吸收物质的机制和影响因素.首先,总结了近年来利用Caco-2模型对镉、铬、铅、砷等多种重金属及铜、铁、锌、钙等多种营养金属在小肠内的吸收、转运方式、代谢机制及影响吸收、转运过程的各类条件等的研究工作,然后对Caco-2细胞模型研究方法及其在未来评估金属人体生物有效性的应用进行了展望.

  • 标签: CACO-2细胞 金属 体外试验 生物有效性 转运与吸收 健康风险评估