当前位置:考试网  > 试卷库  > 职业资格  > 其它  > 焊工  >  常温拉伸试验的合格标准是什么?
试题预览

常温拉伸试验的合格标准是什么?

查看答案
收藏
纠错
正确答案:

焊接接头的抗拉强度不低于母材抗拉强度定值的下限,异种钢焊接接头按抗拉强度规定值下限较低一侧的母材。

答案解析:

暂无解析

你可能感兴趣的试题

氧气顶吹转炉脱硫的热力学条件是()

炼钢炉内氧的存在形式主要是以气态和溶解在炉渣中两种形式存在

硫的危害是()

普碳钢对磷硫的要求有()

被腐蚀报废的金属制品的制造价值往往要比金属本身的价值()

热门试题 更多>
As Gilbert White,Darwin , and others observed long ago, all species appear to have theinnate capacity to increase their numbers from generation to generation. The task forecologistsis to untangle the environmentaand biologicalfactorsthat hold this intrinsiccapacity for population growth in check over the long run. The great variety of dynamicbehaviorsexhibitedby differentpopulationmakes thistaskmore difficult:sompopulations remain roughly constant from year to year; others exhibit regular cycles ofabundance and scarcity; still others vary wildly, with outbreaks and crashes that arein some cases plainly correlated with the weather, and in other cases not.To impose some order on this kaleidoscopeof patterns , one school of thought proposesdividing populations into two groups. These ecologists posit that the relatively steadypopulations havedensity-dependent growth parameters; that is, rates ofbirth , death ,and migrationwhich depend strongly on population density. The highly varying populationshave density-independent growth parameters, with vital rates buffeted by environmentalevents ;these rates fluctuate in a way that is wholly independent of population density.This dichotomy has its uses, but it can cause problems if taken too literally. Forone thing , no population can be driven entirely by density-independent factors all thetime. No matter how severely or unpredictably birth, death , and migration rates may befluctuatingaround theirlong-termaverages , ifthere were no density-dependenteffects ,the populationwould , in the long run , eitherincrease or decrease without bound (barringa miracle by which gains and losses canceled exactly)。 Put another way, it may be thaton average 99 percent of all deaths in a populationarise from density-independentcauses ,and only one percent from factors varying with density.The factorsmaking up the one percentmay seem unimportant, and their cause may be correspondingly hard to determine. Yet,whether recognized or not, they will usually determine the long-term average populationdensity.In order to understand the nature of theecologist ’s investigation, we may think ofthe density-dependent effectson growth parameters as the signal ecologists are trying toisolateand interpret, one that tends to make the population increase from relativelylowvalues or decrease from relatively high ones, while the density-independent effects actto produce noise in the populationdynamics.For populationsthatremain relativelyconstant , or that oscillate around repeated cycles, the signal can be fairly easilycharacterized and its effects described, even though the causative biological mechanismmay remain unknown. For irregularly fluctuating populations, we are likely to have toofew observations to have any hope of extracting the signal from the overwhelming noise.But it now seems clear that all populationsare regulatedby a mixture of density-dependentand density-independent effects in varying proportions. 1. The author of the text is primarily concerned with [A] Discussing two categories of factorsthat controlpopulationgrowth and assessingtheir relative importance. [B] Describinghow growth ratesin naturalpopulationsfluctuateover time andexplaining why these changes occur. [C] Proposing a hypothesisconcerning population size and suggesting ways to test it. [D] Posing a fundamental question about environmentalfactorsin populationgrowth andpresenting some currently accepted answer. 2. It can be inferred from the text that the author considers the dichotomy discussedto be [A] Applicable only to erratically fluctuating populations. [B] instrumental, but only if its limitations are recognized. [C] Dangerously misleading in most circumstances. [D] A complete and sufficient way to account for observed phenomena. 3.to the text , allof the followingbehaviors have been exhibitedby differentpopulations EXCEPT [A] Roughly constant population levels from year to year. [B] Regular cycles of increases and decreases in numbers. [C] Erratic increases in numbers correlated with the weather. [D] Unchecked increases in numbers over many generations. 4. The discussion concerning population in the third paragraph serves primarily to [A] Demonstrate the difficultiesecologistsface in studying density-dependentfactorslimiting population growth. [B] Advocate more rigorous study of density-dependent factors in population growth. [C] Prove that the death rates of any populationare never entirelydensity-independent. [D] underline the importance of even small density-dependent factors in regulatinglong-term population densities. 5. In the text, the author does all of the following EXCEPT [A] Cite the views of other biologists. [B] Define a basic problem that the text addresses. [C] Present conceptual categories used by other biologists. [D] Describe the results of a particular study.
试题分类: 专业英语八级
练习次数:30次
某宾馆装修改造项目采用工程量清单计价方式进行招投标,该项目装修合同工期为3 个月,合同总价为 400 万元,合同约定实际完成工程量超过估计工程量15% 以上时调整单价, 调整后的综合单价为原综合单价的 90% 。合同约定客房地面铺地毯工程量为3800m2 ,单价为 140 元/m2; 墙面贴壁纸工程量为7500m2 ,单价为 88 元/m2 。施工过程中发生以下事件; 1.装修进行 2 个月后,发包方以设计变更的形式通知承包方将公共走廊作为增加项目进行装修改造。走廊地面装修标准与客房装修标准相同,工程量为 980m2; 走廊墙面装修为高级乳胶漆, 工程量为 2300m2 ,因工程量清单中无此项目,发包人与承包人依据合同约定协商后确定的乳胶漆的综合单价为l5 元/m2 。 2.由于走廊设计变更等待新图纸造成承包方停工待料5d ,造成窝工 50 工日 (每工日工资 20 元)。 3.施工图纸中浴厕问毛巾环为不锈钢材质,但由发包人编制的工程量清单中无此项目,故承包人投时未进行报价。施工过程中,承包人自行采购了不锈钢毛巾环并进行安装。工程结算时,承包人按毛巾环实际采购价要求发包人进行结算。 问题: 1.因工程量变更,施工合同中综合单价应如何确定? 2.客房及走廊地面、墙面装修的结算工程款应为多少? 3.由于走廊设计变更造成的工期及费用损失,承包人是否应得到补偿? 4.承包人关于毛巾环的结算要求是否合理?为什么 ?
试题分类: 一级建造师
练习次数:2次
试题分类: 安全员
练习次数:0次
扫一扫,手机做题