为你找到 1000 条关于 材料1 的结果
低碳钢材料在拉伸实验过程中,不发生明显的塑性变形时,承受的最大应力应当小于()的数值,A、比例极限B、许用应力C、强度极限D、屈服极限
没有明显屈服平台的塑性材料,其破坏应力取材料的()。A、比例极限σpB、名义屈服极限σ0.2;C、强度极限σbD、根据需要确定。
材料的屈服应力取决于外力的大小。
一般塑性材料在动载荷情况下不考虑应力集中的影响。脆性材料或塑性差的材料在动载荷情况下需要考虑应力集中的影响。
无屈服阶段的塑性材料,以卸载后产生数值为0.2%塑性应变(残余应变)的应力值称为名义屈服极限(屈服强度)
一般塑性材料在静荷载下不考虑应力集中的影响。脆性材料或塑性差的材料在动荷载下需要考虑应力集中的影响。
二只50mL容量瓶,分别为(1)、(2),在(1)号容量瓶中加入Cd2+未知液5.0mL,测得扩散电流为10μA,在(2)号容量瓶中加入Cd2+未知液5.0mL,再0.005mol/LCd2+标准溶液5.0mL,测得扩散电流为15μA,未知溶液中Cd2+的浓度是多少(mol/L)()
注意题目中的容量瓶,意思是将溶液要稀释至50mL然后再开始测定
用钙离子选择性电极直接测定中的血清钙,若Mg2+的浓度为1.300×10-6mol·L-1,Ca2+的浓度为4.00×10-6mol·L-1,钙电极对镁的选择性系数是0.014,则由于镁离子的干扰产生的相对误差为()
钙离子为待测离子,镁离子为干扰离子,0.46%
当相对保留值为1的时候说明两组分的分离很好()
等于1的话,说明二者的保留时间相同,峰重叠
ReadingComprehension(90minutes)Directions:Thereare4passagesinthissection.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA),B),C)andD).YoushoulddecideonthebestchoiceandmarkthecorrespondingletteronAnswerSheet.PassageOneQuestions1to5arebasedonthefollowingpassage.Althoughmanyofusmayfeelair-conditionersbringrelieffromhot,humidorpollutedoutsideair,theyposemanypotentialhealthhazards.Muchresearchhaslookedathowthemovementofairinsideaclosedenvironment---suchasanofficebuilding---canspreaddiseaseorexposepeopleinthebuildingtoharmfulchemicals.OneofthemorewidelypublicizeddangersisthatofLegionnaire’sdisease,whichwasfirstrecognizedinthe1970s.Thiswasfoundtohaveaffectedpeopleinbuildingswithair-conditioningsystemsinwhichwarmairpumpedoutofthesystem’coolingtowerswassomehowsuckedbackintotheairintake(通风口),inmostcasesduetopoordesign.Thewarmair,filledwithbacteria,wascombinedwithcooled,conditionedairandwasthencirculatedaroundvariouspartsofthebuilding.Studiesshowedthatevenpeopleoutsidesuchbuildingswereatriskiftheywalkedpastairexhaustpipes.Largeair-conditioningsystemsaddwatertotheairtheycirculatebymeansofhumidifiers(湿度调节器).Inoldersystems,thewaterusedforthisprocessiskeptinspecialreservoirs,thebottomsofwhichprovidebreedinggroundsforbacteriawhichcanfindtheirwayintotheventilation(通风)system.Therisktohumanhealthfromthissituationhasbeenhighlightedbythefactthattheimmunesystems(免疫系统)ofapproximatelyhalfofworkersinair-conditionedofficebuildingshavedevelopedtheabilitytofightofftheorganismsfoundatthebottomofsystemreservoirs.Butchemicalscalled“biocides”areaddedtoreservoirstomakethemgerm-free,andtheyaredangerousintheirownrightinsufficientquantities,astheyoftencontaincompoundsstronglylinkedtocancers.Finally,itshouldbepointedoutthattheartificialclimaticenvironmentcreatedbyair-conditionerscanalsoaffectus.Inanaturalenvironment,whetherindoororoutdoor,therearesmallvariationsintemperatureandhumidity.Indeed,thehumanbodyhaslongbeenaccustomedtothesenormalchanges.Inanair-conditionedlivingorworkingenvironment,however,bodytemperaturesremainwellunder37℃,ournormaltemperature.Thisleadstoaweakenedimmunesystemandthusgreaterexposuretodiseasessuchascoldsandflu.1.WhatdoweknowaboutLegionnaire'sdiseasefromthepassage?
1.Gettingaroundacityisonething—andthenthere’sthematterofgettingfromonecitytoanother.
ReadingComprehension(90minutes)Directions:Thereare4passagesinthissection.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA),B),C)andD).YoushoulddecideonthebestchoiceandmarkthecorrespondingletteronAnswerSheet.PassageOneQuestions1to5arebasedonthefollowingpassage.Althoughmanyofusmayfeelair-conditionersbringrelieffromhot,humidorpollutedoutsideair,theyposemanypotentialhealthhazards.Muchresearchhaslookedathowthemovementofairinsideaclosedenvironment---suchasanofficebuilding---canspreaddiseaseorexposepeopleinthebuildingtoharmfulchemicals.OneofthemorewidelypublicizeddangersisthatofLegionnaire’sdisease,whichwasfirstrecognizedinthe1970s.Thiswasfoundtohaveaffectedpeopleinbuildingswithair-conditioningsystemsinwhichwarmairpumpedoutofthesystem’coolingtowerswassomehowsuckedbackintotheairintake(通风口),inmostcasesduetopoordesign.Thewarmair,filledwithbacteria,wascombinedwithcooled,conditionedairandwasthencirculatedaroundvariouspartsofthebuilding.Studiesshowedthatevenpeopleoutsidesuchbuildingswereatriskiftheywalkedpastairexhaustpipes.Largeair-conditioningsystemsaddwatertotheairtheycirculatebymeansofhumidifiers(湿度调节器).Inoldersystems,thewaterusedforthisprocessiskeptinspecialreservoirs,thebottomsofwhichprovidebreedinggroundsforbacteriawhichcanfindtheirwayintotheventilation(通风)system.Therisktohumanhealthfromthissituationhasbeenhighlightedbythefactthattheimmunesystems(免疫系统)ofapproximatelyhalfofworkersinair-conditionedofficebuildingshavedevelopedtheabilitytofightofftheorganismsfoundatthebottomofsystemreservoirs.Butchemicalscalled“biocides”areaddedtoreservoirstomakethemgerm-free,andtheyaredangerousintheirownrightinsufficientquantities,astheyoftencontaincompoundsstronglylinkedtocancers.Finally,itshouldbepointedoutthattheartificialclimaticenvironmentcreatedbyair-conditionerscanalsoaffectus.Inanaturalenvironment,whetherindoororoutdoor,therearesmallvariationsintemperatureandhumidity.Indeed,thehumanbodyhaslongbeenaccustomedtothesenormalchanges.Inanair-conditionedlivingorworkingenvironment,however,bodytemperaturesremainwellunder37℃,ournormaltemperature.Thisleadstoaweakenedimmunesystemandthusgreaterexposuretodiseasessuchascoldsandflu.1.WhatdoweknowaboutLegionnaire'sdiseasefromthepassage?
ReadingComprehension(90minutes)Directions:Thereare4passagesinthissection.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA),B),C)andD).YoushoulddecideonthebestchoiceandmarkthecorrespondingletteronAnswerSheet.PassageOneQuestions1to5arebasedonthefollowingpassage.Although many of us may feel air-conditioners bring relief from hot, humid or polluted outside air, they pose manypotential health hazards. Much research has looked at how the movement of air inside a closed environment---such as anoffice building---can spread disease or expose people in the building to harmful chemicals.One of the more widely publicized dangers is that of Legionnaire’s disease, which was first recognizedinthe 1970s. This was found to have affected people in buildings with air-conditioning systems in which warmair pumped out of the system’ cooling towers was somehow sucked back into the air intake (通风口),in mostcases due to poor design. The warm air, filled with bacteria,was combined with cooled, conditioned air andwas then circulated around various parts of the building. Studies showed that even people outside such buildings were at risk if they walked past air exhaust pipes.Large air-conditioning systems add water to the air they circulate by means of humidifiers(湿度调节器).Inolder systems, the water used for this process is kept in special reservoirs, the bottoms of which providebreedinggrounds for bacteria which can find their way into the ventilation (通风)system. The risk to human health from this situation has been highlighted by the fact that the immunesystems (免疫系统)of approximately half of workers in air-conditioned office buildings have developed the ability to fight off the organisms found at the bottom of system reservoirs. But chemicals called “biocides”are added to reservoirs to make them germ-free, and they are dangerous in their own right in sufficient quantities, as they often contain compounds strongly linked tocancers.Finally, it should be pointed out that the artificial climatic environment created by air-conditioners canalso affect us. In a natural environment, whether indoor or outdoor, there are small variations in temperature and humidity. Indeed, the human body has long been accustomed to these normal changes. In an air-conditioned living or workingenvironment, however, body temperatures remain well under37℃, our normal temperature. This leads to a weakened immune system and thus greater exposure to diseases such as colds and flu.1.What do we know about Legionnaire's disease from the passage?
根据时间价值理论,在普通年金现值系数的基础上,期数减1、系数加1的计算结果,应当等于
当事人受胁迫,当事人自知道或者应当知道撤销事由之日起1年内没有行使撤销权,撤销权消灭