简介:介绍了老牌零售商J.C.佩尼在经营遭遇困境的情况下,积极开展网络零售业务,重振旗鼓,为传统零售商的发展指出一条新路。
简介:Johnson-Cook本构模型是研究材料在动态过程中力学状态的-种常用模型.为标定Johnson-Cook本构模型参数,给出了常规的试验方法及试验条件,并通过理论推导,介绍了利用试验数据求解John-son-Cook本构模型参数的具体方法.在此基础上,以某涂层材料为例,建立了该材料的Johnson-Cook本构模型,验证了文中方法的可行性.
简介:ObjectiveToinvestigatetheearlychangeofcochlearribbonsynapsesoninnerhaircellsinresponsetoaminoglycosideototoxicity.MethodsC57BL/6Jmicereceivedintraperitonealinjectionofgentamicin(100mg/kg/day),andtheapicalcoilorganofCortiwasexaminedonthe4th,7thand10thday(n=10).Litter-mateswithoutgentamicintreatmentservedascontrols(n=10).RIBEYEonthepresynapticmembraneandAMPAreceptorsonthepostsynapticmembranewerelabeledwithCtBP2orGluR2/3respectively.Threedi-mensionreconstructionwasconductedusingthe3DSMAX8.0software.ResultsTherewerenodisruptionsofouterorinnerhaircellsinallgroups.However,thenumberofribbonsynapsesoncochlearinnerhaircellsincreasedsignificantlywithin7daysaftergentamicinexposure(P<0.01),followedbyasignificantde-creaseafter7days.ConclusionDuringtheearlystageofaminoglycosideototoxicity,increasedpopulationofcochlearribbonsynapsesmayindicateasignificantdown-regulationofsynapticfunction.
简介:ObjectiveTostudycharacteristicsofhearinglossafterexposuretomoderatenoiseexposureinC57BL/6Jmice.MethodsMaleC57BL/6Jmicewithnormalhearingatageof5-6weekswerechosenforthisstudy.Themicewererandomlyselectedtobestudiedimmediatelyafterexposure(GroupP0),or1day(GroupP1),3days(GroupP3),7days(GroupP7)or14days(P14)afterexposure.Theirbeforeexposureconditionservedasthenormalcontrol.Allmicewereexposedtoabroad-bandwhitenoiseat100dBSPLfor2hours,ABRthresholdswereusedtoestimatehearingstatusateachtimepoint.ResultsABRthresholdelevationwasseenateverytestedfrequencyatP0(P<0.01).Elevationathigh-frequencies(16kHzand32kHz)wasgreaterthanatlowerfrequencies(4kHzand8kHz,P<0.05).FromP1toP14,ABRthresholdscontinuouslyimproved,andtherewasnosignificantdifferencebetweenP14andbeforeexposure(P>0.05).ConclusionThereisafrequencyspecificresponseto100dBSPLbroad-bandwhitenoiseinC57BL/6Jmice,withthehigh-frequencybeingmoresusceptible.HearinglossinducedbymoderatenoiseexposureappearsreversibleinC57BL/6Jmice.
简介:春节是农历的新年。春,《前汉书·律历志》、《风俗通》诸书的解释。为"春蠢也"。"蠢"是昆虫活动的意思,春来虫动,幼苗吐绿,万物兴旺,《公羊传》又注说:"春者,天地开辟之端,养生之道,法象所出,昏斗指东方曰春。"春又被神化成为春神东君执掌的神,是吉祥幸福的象征。节,多指节气,是按地球在绕地球公转轨道上的位置划分的,地球从春分点出发,每前进15度为一个节气:它反映了季节变化、气候特点、气候现象的规律,春与节连起来,古人称这天是年之首、月之首、日之首。意味着春回大地,一元复始,气象更新。我国古代的春节,指的是二十四节气中的立春,这在《后汉书·杨震传》中记载可佐证:"春节未雨,百僚焦心,而缮修不止,诚致早之征也。"《晋书》亦载:"其时正朔旦立春"。到南北朝时,春节是指整个春季,至于把正月初一定为春节,则是民国初年的事,因其在立春前后,就表示春天的到来或开始,与岁首之意相合。"春节"最早也叫"度岁",有的把农历年的除夕称作"分岁"这也是有其来历的,在夏至殷商时代,人们把木星叫"岁