首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   972篇
  免费   16篇
  国内免费   10篇
电工技术   7篇
综合类   30篇
化学工业   349篇
金属工艺   125篇
机械仪表   71篇
建筑科学   107篇
矿业工程   5篇
能源动力   40篇
轻工业   27篇
水利工程   5篇
石油天然气   31篇
武器工业   6篇
无线电   20篇
一般工业技术   62篇
冶金工业   36篇
原子能技术   6篇
自动化技术   71篇
  2024年   1篇
  2023年   5篇
  2022年   8篇
  2021年   14篇
  2020年   16篇
  2019年   5篇
  2018年   7篇
  2017年   6篇
  2016年   10篇
  2015年   24篇
  2014年   51篇
  2013年   58篇
  2012年   73篇
  2011年   97篇
  2010年   69篇
  2009年   62篇
  2008年   57篇
  2007年   50篇
  2006年   49篇
  2005年   54篇
  2004年   47篇
  2003年   44篇
  2002年   32篇
  2001年   26篇
  2000年   25篇
  1999年   26篇
  1998年   12篇
  1997年   14篇
  1996年   13篇
  1995年   11篇
  1994年   5篇
  1993年   7篇
  1992年   4篇
  1991年   3篇
  1990年   2篇
  1989年   7篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1982年   1篇
排序方式: 共有998条查询结果,搜索用时 187 毫秒
51.
彭爱华  吴彪 《化肥工业》2006,33(1):45-47
介绍了与Shell煤气化配套的耐硫变换装置采用重油裂化气开车及运行情况。通过对设计数据与实际运行数据对比以及节能效益与存在的问题分析,指出了该套装置的优越性以及用于Shell粉煤气化原料气变换的可行性。  相似文献   
52.
本文介绍了一种汽车安全气囊气体发生器的壳体强度设计方法,采用该方法对某气体发生器壳体进行了设计,强度达到了USCAR标准要求.  相似文献   
53.
阐述了在壳牌煤气化装置中使用CO2气体替换N2气做为输送粉煤的气源,进入气化炉的CO2还原成C0以提高合成气中的有效气体成分。同时为了减少CO2排放和CO2综合利用,但要充分考虑不同煤种的反应活性也不同,有效的利用煤的反应活性。  相似文献   
54.
熔模铸造中经常出现毛刺缺陷,是造成铸件次品的重要原因.毛刺的出现与制壳过程中面层型壳的开裂有关.讨论了型壳间温湿度、风力对型壳开裂的影响,并提出了监控的具体措施.使用快干增强硅溶胶也有助于降低毛刺缺陷.  相似文献   
55.
The aim of this study was to investigate whether total carotenoid content (TCC) in noble scallop Chlamys nobilis is related to body tissue, shell colour, and gender. TCC was determined by a UV–vis recording spectrophotometer in tissue of gonad, adductor, mantle, and gill separately sampled from male and female individuals with orange and brown shell colours from the same cultured population. TCC was significantly different among body tissues, depending on shell colour and gender, ranging from 0.73 to 59.85 μg g−1. In general, TCC was greater in the order of gonad > mantle > adductor > gill. In the same gender, orange shell colour individuals contained significantly higher TCC than brown ones in all four tissues (P < 0.05). In the same shell colour, female contained significantly higher TCC than male in gonad and adductor tissues (P < 0.05).  相似文献   
56.
We consider the free vibration problem of thin shells of revolution of constant type of geometry, focusing on the asymptotic behaviour of the lowest eigenfrequency, as the thickness tends to zero. Numerical experiments are computed using two discretization methods, collocation and finite elements, each corresponding to a different shell model. Our results are in agreement with theoretical results obtained using interpolation theory and cited in literature.  相似文献   
57.
In this study we present the results of an intersex survey of Littorina littorea along the Belgian coast. Levels of female intersex and sterility were determined to assess TBT related adverse effects. In addition, we determined the levels of male penis shedding and trematode infestation and investigated the morphology of the shell. Significant differences were found for all these variables which clearly differentiated periwinkles from Zeebrugge (B2) from those at other locations. Intersex index (ISI) values were relatively low (i.e. 0.00-0.39), except at B2 where they ranged up to 3.52, the highest value ever reported in literature. Consequently, female reproductive impairment at B2 was severe. Indeed, up to 95% of female periwinkles were sterile at B2. In addition, 61% of the male periwinkles had shed their penis. Furthermore, no trematode infestation could be detected at B2 and specimens from this location had the largest and heaviest shells, which may be related to population demography and/or a different use of energy budgets.  相似文献   
58.
In civil engineering, shell structures are widely used as liquid-containment vessels. Understanding how the shell responds to relevant loading conditions is important for the design of safe and economical liquid-containment shell structures. This paper reviews recent research on the strength, stability and vibration behaviour of liquid-containment shell structures, and traces the developments pertaining to the design of these facilities to withstand various loading and environmental effects such as liquid pressure, wind pressure, ground movement and thermal effects. Results of recent feasibility studies of non-conventional shell forms for liquid containment are also reported, and areas of focus for future research are suggested.  相似文献   
59.
Liquid storage steel tanks are vertical above-ground cylindrical shells and as typical thin-walled structures, they are very sensitive to buckling under wind loads, especially when they are empty or at low liquid level. Previous studies revealed discrepancies in buckling resistance of empty tanks between the design method proposed by the American Standard API 650 and the analytical formulas recommended by the European Standard EN1993-1-6 and EN1993-4-2. This study presents a comparison between the provisions of current design codes by performing all types of numerical buckling analyses recommended by Eurocodes (i.e. LBA-linear elastic bifurcation analysis, GNA-geometrically nonlinear elastic analysis of the perfect tank and GNIA-geometrically nonlinear elastic analysis of the imperfect tank). Such analyses are performed in order to evaluate the buckling resistance of two existing thin-walled steel tanks, with large diameters and variable wall thickness. In addition, a discussion is unfolded about the differences between computational and analytical methods and the conservatism that the latter method imposes. An influence study on the geometric imperfections and the boundary conditions is also conducted. Investigation on the boundary conditions at the foot of the tank highlights the sensitivity to the fixation of the vertical translational degree of freedom. Further, it is indicated that the imperfection magnitude recommended by the EN1993-1-6 is extremely unfavorable when applied to large diameter tanks. Comments and conclusions achieved could be helpful in order to evaluate the safety of the current design codes and shed more light towards the most accurate one.  相似文献   
60.
介绍管壳式反应器格栅计算程序的设计原珲、设计步骤及部分代码。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号