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21.
应用微模型进行凝胶处理的机理研究   总被引:2,自引:1,他引:2  
张玉萍 Dawe.  RA 《油田化学》1994,11(3):220-225
本文通过应用一种在玻璃上刻蚀的地层孔隙微模型进行凝胶封堵试验,观察油水通过凝胶封堵的孔隙介质和裂缝的方式以及残余油和孔隙介质润湿性对凝胶封堵能力的影响,对聚合物凝胶处理的机理进行研究。研究结果表明,凝胶的堵水能力大大高于堵油能力。原因在于油相穿过凝胶主要是从孔道中部指进,通过沿途带走一些凝胶碎片和凝胶内的部分水份而使凝胶收缩,油相流动通道增大,流动阻力降低。盐水穿过凝胶时则趋于进入凝胶结构内部使凝胶膨胀,使水相流动通道缩小,流动阻力增加。  相似文献   
22.
为探讨保健食品促进排铅作用动物模型饮水染毒的适宜剂量,给小鼠自由饮用Pb^2 浓度为163.9、546.2、l638.7mg/L的醋酸铅溶液30d,每周记录饮用量,周末称重,估算实际铅摄入剂量。实验末取血、肝、脑、肾、股骨,石墨炉原子吸收分光光度法测定全血和组织铅含量。结果显示,163.9、546.2、l638,7mg Pb^2 /L剂量组小鼠实际铅摄入剂量分别为27.9、86.6、169.4mg/kg BW,546.2、1638.7mg Pb^2 /L剂量组小鼠体重增长较对照组显著减少,食物利用率也明显降低;各剂量组小鼠全血、肝、肾、股骨铅及546.2、1638.7mg Pb^2 /L剂量组小鼠脑铅含量显著升高。建议以546.2mg Pb^2 /L作为保健食品促进排铅作用饮水染毒的造模剂量;除骨铅外,建议增测肾脏、脑组织内的铅、锌、铜含量及骨骼内的钙含量。  相似文献   
23.
The built environment needs to develop sustainable, decarbonised, low energy systems and approaches that are socially acceptable and economically beneficial. The UK mainstream house construction industry is being driven, through policy and regulation, towards achieving this end without evidence of how these new systems of provision are used by passively adopting households. In this paper energy use, consequential emissions of CO2, and annual running costs for a case study comprising 14 newly constructed low energy affordable homes are evaluated. Four different energy typologies are compared: ground sourced heat pumps; active solar (thermal and photovoltaic); passive solar and mechanical ventilation with heat recovery; conventional high efficiency gas boiler. The carbon embodied in construction and emitted over a 20 year occupation period for each typology is calculated. Ground source heat pumps have the highest annual primary energy demand, CO2 emission and annual running costs over the 20 year period. The homes with active solar technologies provided most benefit across all three evaluation criteria. Energy and CO2 emissions associated with end uses other than heating were similar to the UK average. This poses significant questions on the probability of policy application in the real world to deliver projected reductions in emissions of CO2.  相似文献   
24.
This paper investigates the consequences of a sudden increase in transportation costs when household behaviors and building inertia are accounted for. A theoretical framework is proposed, capturing the interactions between behaviors, transportation costs and urban structure. Numerical simulations show that changes in households and landowners’ choices reduce significantly the long-term adverse effects of a shock in transportation costs. Indeed, the shock translates, over the long run, into a more concentrated housing that limits households utility losses and maintains landowners’ income. But, because of building inertia, the shock leads first to a long transition, during which the adjustment is constrained by a suboptimal housing-supply structure. Then, households support larger losses than in the final stage, though lower than with no behavior adjustment, and landowners experience a large decrease in their aggregate income and an important redistribution of wealth. Thus, behaviors and building inertia are key factors in determining the vulnerability to transportation price variability and to the introduction of climate policies. Our policy conclusions are that: (i) if a long-term increase in transportation costs is unavoidable because of climate change or resource scarcity, a smooth change prevents to some extent the negative transition effects and (ii) fast-growing cities of the developing world can reduce their future vulnerability to shocks in transportation costs through the implementation of policies that limit urban sprawl.  相似文献   
25.
从物理力学、应力测试、有限元模拟三方面分析计算了SP牌坊的受力及应力情况,再通过对应力及裂纹断口的分析得出:高周疲劳是SP牌坊开裂的根本原因。以理论与现场实际相结合,研究出了SP牌坊开裂有效修补方案,通过该修补方案的实施,牌坊本体上的应力水平降低了40%,且对拍击振动也较不敏感,修补维修策略有效。  相似文献   
26.
Objective: The purpose was to develop a short-form version of the Center for Epidemiologic Studies Depression Scale (CES-D) for the identification of persons with major depressive disorder (MDD) within a population with rheumatoid arthritis (RA). Study Design: Data were analyzed from 337 persons with RA. Forty-six participants met the diagnostic criteria for MDD; 291 participants were classified in the non-MDD category (including 21 participants with dysthymia and 18 participants with minor depressive disorder). A short-form version of the CES-D was developed, and multiple cutoff scores were examined. Results: A cutoff score of ≥5 from a 9-item, short-form CES-D was found to be generally as efficient as the more commonly used full-scale cutoff score of ≥16 for classifying participants with MDD within an RA population. Although the shortened CES-D scale (cutoff score ≥5) was slightly more sensitive, it also exhibited slightly less specificity than the full-scale cutoff score of ≥16. Conclusion: The results suggest that a short-form CES-D can be used to screen for MDD within an RA sample with a degree of efficiency that is generally comparable to that of the full-scale instrument. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
27.
28.
纯电动汽车两挡变速器壳体强度分析与改进   总被引:3,自引:0,他引:3  
在电动汽车变速器优化设计的研究中,变速器壳体的强度对变速器的传动性能有重要影响.纯电动汽车两挡变速器壳体结构较复杂,且受力极不均匀,难以用传统的解析方法对其进行强度计算.针对上述问题,提出利用有限元法对变速器壳体进行强度分析.研究了两挡变速器的结构及工作原理,计算了极限工况下壳体轴承座载荷,建立了壳体的三维实体模型及有限元模型,得到了壳体的应力分布云图,确定了壳体强度的薄弱环节,并据此提出了改进方案.结果表明:改进后的变速器壳体强度得到了改善,并实现了产品的轻量化,为变速器壳体的设计及生产提供了理论依据.  相似文献   
29.
在历经20年的建设后,中国的城市住房在数量和质量方面都有了飞跃发展,但同时,城市的富裕居民和贫困居民在住房条件上的鸿沟也日益加大。有鉴于美国在住房建设方面的经验,文章提出应制定一种侧重于社会发展的住房新政策,并提出“为大众的社区”和“社区建设”的概念。  相似文献   
30.
居住类建筑一直是建筑设计人员关注的重点,关于"住"的思考人们也从未停歇过,将结合一些流行的住宅设计观点展开对于"住"的思考.  相似文献   
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