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   1844篇
  免费   132篇
电工技术   28篇
综合类   1篇
化学工业   572篇
金属工艺   30篇
机械仪表   37篇
建筑科学   151篇
矿业工程   8篇
能源动力   75篇
轻工业   261篇
水利工程   26篇
石油天然气   5篇
无线电   117篇
一般工业技术   261篇
冶金工业   89篇
原子能技术   19篇
自动化技术   296篇
  2023年   17篇
  2022年   44篇
  2021年   79篇
  2020年   48篇
  2019年   64篇
  2018年   91篇
  2017年   74篇
  2016年   79篇
  2015年   51篇
  2014年   92篇
  2013年   141篇
  2012年   110篇
  2011年   134篇
  2010年   100篇
  2009年   97篇
  2008年   76篇
  2007年   94篇
  2006年   74篇
  2005年   46篇
  2004年   50篇
  2003年   29篇
  2002年   31篇
  2001年   24篇
  2000年   28篇
  1999年   33篇
  1998年   24篇
  1997年   13篇
  1996年   16篇
  1995年   15篇
  1994年   19篇
  1993年   14篇
  1992年   11篇
  1991年   8篇
  1990年   9篇
  1989年   6篇
  1988年   9篇
  1987年   10篇
  1985年   11篇
  1984年   5篇
  1983年   9篇
  1982年   6篇
  1981年   6篇
  1980年   5篇
  1979年   7篇
  1978年   9篇
  1977年   5篇
  1976年   4篇
  1975年   6篇
  1954年   3篇
  1940年   4篇
排序方式: 共有1976条查询结果,搜索用时 15 毫秒
1.
Water Resources Management - The water evaluation and planning (WEAP) approach and the invasive weed optimization algorithm (IWOA) are herein employed to determine the optimal operating policies in...  相似文献   
2.
3.
4.
5.
6.
In the approach to a cycle-invariant state in the forced feed concentration cycling of the CO oxidation over a NiO catalyst, a very long transient has been observed lasting 80 ks or more. This transient appears to be associated only with CO pretreatment of the catalyst and is not a general phenomenon. The slow convergence to the cycle-invariant state reported in certain modelling calculations in the literature appears to have a different cause.  相似文献   
7.
The water and oil uptake of mesquite and arabic gums in powdered form was studied at temperatures of 23, 35 and 45°C. A previously proposed equation to predict osmotic equilibrium was tested using the experimental data with both gums and a good statistical fit was obtained. Mesquite gum showed the highest water and oil absorption at all temperatures studied. Temperature dependence of the reciprocal of the S1 and WL were determined using an Arrhenius equation. The activation energy for water and oil absorption for gum arabic was 21.98 and 39.57 kJ mol−1, compared to that of mesquite gum having values of 15.79 and 46.16 kJ mol−1, respectively. A second order kinetic model was obtained for water and oil absorption for both gums.  相似文献   
8.
In this letter, we will evaluate the performance degradation of a 40 km high‐speed (40 Gb/s) optical system, induced by optical fiber variations of the chromatic dispersion induced by temperature changes. The chromatic dispersion temperature sensitivity will be estimated based on the signal quality parameters.  相似文献   
9.
Focused ion beam (FIB) and nano-probing were applied for failure analysis of three-dimensional stacked circuits with copper through-silicon-vias between the stacked chips. The failure analysis was done after high temperature storage and thermal cycling tests. Passive voltage contrast in FIB allowed to pinpoint the open sites. FIB cross-sections showed the presence of opens at the bottom of the copper vias. The failure cause was suspected to be an interlayer particle, which was confirmed by optical profilometry. Nano-probing was used on another sample to pinpoint the failure location through the measurement of the local resistance within the daisy chains. The failure was traced out to be related with surface contamination.  相似文献   
10.
An evaluation of the Spanish CSIC performance in Biotechnology, as compared with those of the French CNRS and the Italian CNR, has been carried out to determine the balance between the generation of scientific knowledge and the transfer of technology. This study shows a high scientific productivity mostly in journals with moderate impact factor, a low generation of patents and an insufficient transfer of knowledge to the Spanish companies. Other indicators confirm the existence of competitive human resources in biotechnological research producing scientific knowledge of interest for the development of patents and that cooperates successfully at European level.  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