学科分类
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11 个结果
  • 简介:AccordingtotheUnitedNationspopulationprojections,thepopulationoftheelderlyisexpectedtoroughlytripleinChinafrom2000to2050,particularlywhenthegenerationswhowerebornbetweenthe1950sand1970smovethroughtheagestructure,andalsobecausepeoplearelivinglongerandfertilityrateshavefallen,populationagingisexpectedtoputpressureongovernment'sfiscalbalancethroughhigherold-agesecuritybenefitsandhealth-careexpenditures.Thisworkdrawstogetherthebroadrangeofelementsinvolvedwithinaconsistentframework,basedonacomputabledynamicgeneralequilibriummodelwithanoverlappinggenerationstructure.Furtheranalysisusingmodelsimulationillustratesthatthealternativeschemesforthebenefitrate,retirementageandtechnologicalprogressarelikelytobebeneficial,andthatanobviousslow-downinthegrowthoflivingstandardsislikelytobeavoided.

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  • 简介:Strainageinginsteelwasfirstobservedduringthe19thcenturywhenthemaximumloadcarryingcapacityofatestpiecewasincreasedafterithadbeenretestedfollowingapreviousseriesoftestinginaplasticrange.Overthelastdecades,agreatdealofresearchhasbeenperformedtogaindeeperinsightsintothephenomenonofstrainageing.Thesynergisticdevelopmentoftheoreticalhypothesisandnewexperimentalevidenceshaspromotedtheunderstandingofthemechanismsunderlyingstrainageing.Thecontentofthispaperisorganizedintofourcomponents.First,wehavecomparedthemaintheoriesdevelopedinrecentyears.Second,wehavesummarizedthemetallurgicaleffectsonthestrainageingbehaviorobservedinexperiments.Moreover,wehavemadeanattempttocorrelatetheexperimentalresultsandtheabove-mentionedtheories.Third,wehaveproposedafeasiblesolutiontocontrolstrainageinginlowcarbonsteels.Finally,wehaveelaboratedthepotentialityoftheatomprobetechniqueinfacilitatingdirectcharacterizationofthedistributionofsoluteatoms.

  • 标签: 应变时效 低碳钢 实验证据 溶质原子 承载试验 最大负荷
  • 简介:Thisstudyinvestigatesthemicrostructuresofmicroalloyedsteelsbeforeandafterstrainageingtreatment.Itwasfoundthatthemicrostructureconsistedofbothlathferriteandpearlite.Mostofthecarbidesand/ornitridesofmicroalloyingelementsweredistributedinsidethegrainswithasmallamountdistributedatthegrainboundaries.Theprecipitatedphasesinsidethegrainsweremuchsmallerinsizethanthoseatthegrainboundaries.Theprecipitatesareeithercircularorshortbar-like,ofsizesfromafewnanometerstoseveralhundrednanometers.Afterageing,onlycarbonatomssegregatearoundthedislocationsandnitrogendoesnotparticipateinproducingtheCottrellatmospherebecauseitwasfixedbyalloyingelementsbeforeageing.

  • 标签: 微合金钢 老龄化 微结构 微合金元素 压力 应变时效处理
  • 简介:ByadoptingtheAECIIndexMethodproposedbytheauthorandusingmethodofpopulationsimulation,thispaperanalyzesquantitativelythetrend,intensityandregulationoftheeconomicpressureofpopulationageinginChina,andcomparesChinawithothercountries.Itdrawsthefollowingconclusions:(1)Chinawillfacegreateconomicpressureduetopopulationageinginthefirsthalfofthiscentury.Accordingtothemediumprojection,thepressurewillincreasemostrapidlyduringtheperiodfromthemiddleof2020stotheendof2030s,andreachitspeakaround2040whentheintensityofthepressuremayquadruplethatin2010.(2)ThegreateconomicpressureofpopulationageingmayremarkablyreduceChina'sdevelopmentmomentum.(3)Toeasethepressure,weshouldrelymainlyoneconomicmeasures,supplementedbypopulationcontrolmeasures.(4)TograduallyliberalizetheprevailingbirthcontrolpolicyonthepremiseofstickingtothestatepolicyoffamilyplanningisarationalapproachtoregulatetheeconomicpressureofpopulationageinginChina.Ontheonehand,thiscaneasethepossibleeconomicpressureofageinginthefuture,andontheotherhand,itcancontrolthepressureofpopulationsizewithinanendurablelimit.

  • 标签: 人口老龄化 中国经济 压力强度 规制 人口控制 计划生育
  • 简介:影响在海水沉浸,以及结果在潮湿散开上把聚合物矩阵composites的厚度压成薄片为glass/isopolyester(G/IPE)的composites的机械性质降级,carbon/isopolyester(C/IPE),glass/vinylester(G/VE)和carbon/vinylester(C/VE),在这份报纸被调查。把3压成薄片并且在厚度的10mm,使用湿手上篮技术制作,被描绘因为在人工的海水媒介的潮湿吸收,和他们的曲折力量和interlaminar砍力量(ILSS)降级被学习。潮湿散开被观察是到Ficks的anamolous为3的法律和10mm在散开的以后的阶段的厚样品。10mmthick样品的潮湿渗透是比3mm的大的二~三份订单厚的,当潮湿浸透的时间仍然保持未改变时。随增加把厚度压成薄片,1.4%为C/VE增加的潮湿浸透并且7%为G/IPE。剩余曲折力量和ILSS在10mm的情况下是更大的在200天暴露以后的厚标本。折断的标本的SEM检查在10mm显示出纤维/矩阵debonding的更大的层次厚标本。

  • 标签: 复合材料层压板 水分扩散 聚合物基体 人工海水 厚度 层间剪切强度
  • 简介:October5,theninthdayoftheninthlunarmonth,wasthedayofthetraditionalDoubleNinthFestival.SanshuiDistrictofFoshanCityinGuangdongorganizeda1000-old-menfeastthatday.Morethan1000localseniorcitizensjoinedaseriesofactivitiesduringtheCulturalFestivalofLongevity.Duringthefeast,GuangdongCommitteeonAgeingtoldourreporterthatGuangdongwouldestablishtheold-ageallowance(OAA)systemthroughouttheprovinceby2015.

  • 标签: 广东省佛山市 委员会 津贴 老龄 养老 重阳节
  • 简介:Peltophorumdubiumseedsweresettoimbibewithfourtreatments,soakedwithsolutionCaptan0.2%under10and27℃,PEG6000-1.0MPaunder10and27℃.Foreachtreatmenttherewerefourreplicateswith40seedsincubatedin9-cmPetridisheswithdoublefilterpapermoistenedwithtestingsolution.Theimbibitioncurvesshowedthatthefinalweightincreasewerefrom70%to150%inthetreatmentswhenimbibitionenteredalagphase.Seedsweretestedforeffectsongerminationoffivetreatments:controlgroup(nonprimed),primedwithPEG6000-1.0MPaat10and27℃,primedwithCaptan0.2%at10and27℃.Foreachtreatment,therewerethreesub-treatments:seedsweresoakedindistilledwaterfor12,24and36hbeforetheenergytest.GerminationpercentagesofnonprimedseedsandprimedinPEG27℃soakedindistilledwaterduring12hwerethehighest,reaching100%.ThelowestgerminationpercentageoccurredprimedseedswithPEG600027℃andsoakedindistilledwaterduring36h,whichwasonly52%.GerminationmeantimeofprimedseedsinPEGat10℃,soaked24hwas1.08days,meantimeofprimedseedsinPEGat27℃soaked12hwas2.42days.Acceleratedageingresultsshowedlowornogerminationafterageing72h.Controlgrouphadahighergerminationpercentageandseedsweremoreresistanttodeteriorationthanthoseinprimedgroups,bothinPetridish(27℃)andvermiculate(roomtemperature).

  • 标签: 巴西盾柱木 种子处理 种子吸涨 种子活力 种子萌发率 种子老化
  • 简介:Inordertostudyseedqualitychangesofmainafforestationspeciesunderhightemperatureandhighrelativehumidity,thedeteriorationmechanismofseedsofRobiniapesudoacaciaandPinustabulaeformisfromaridandsemiaridareasofNorthernChinawaselucidatedinthisstudy.Theseedswereartificiallyagedfor2and6datthetemperatureof45oCandtherelativehumidity(RH)of50%,75%and100%,respectively.Theresultsshowedthatthegerminabilitydecreasedandthecellmembranedeteriorated...

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  • 简介:TheZnOquantumdots(QDs)weresynthesizedwithimprovedchemicalsolutionmethod.ThesizeoftheZnOQDsisexceedinglyuniformwithadiameterofapproximately4.8nm,whicharehomogeneouslydispersedinethanol.Theopticalabsorptionedgeshiftsfrom370nmofbulkmaterialto359nmofQDmaterialsduetothequantumsizeeffect,whilethephotoluminescencepeakshiftsfrom375nmto387nmwiththeincreaseofthedensityofZnOQDs.ThestabilityofZnOQDswasstudiedwithdifferentdispersiondegreesat0?Candatroomtemperatureof25?C.Theagglomerationmechanismsandtheirrelationshipwiththeemissionspectrawereuncoveredforthefirsttime.WiththeageingofZnOQDs,theagglomerationisaggravatedandthesurfacedefectsincrease,whichleadstothedefectemission.

  • 标签: 量子点材料 团聚机理 发射光谱 老化时间 氧化锌 温度