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   587163篇
  免费   6923篇
  国内免费   1979篇
电工技术   11099篇
综合类   454篇
化学工业   86573篇
金属工艺   23109篇
机械仪表   18591篇
建筑科学   13251篇
矿业工程   2810篇
能源动力   16661篇
轻工业   44144篇
水利工程   5873篇
石油天然气   10101篇
武器工业   29篇
无线电   73499篇
一般工业技术   117651篇
冶金工业   110981篇
原子能技术   12513篇
自动化技术   48726篇
  2022年   3583篇
  2021年   5435篇
  2020年   4125篇
  2019年   5192篇
  2018年   8693篇
  2017年   8760篇
  2016年   9257篇
  2015年   5948篇
  2014年   9900篇
  2013年   28189篇
  2012年   15627篇
  2011年   21241篇
  2010年   16986篇
  2009年   19223篇
  2008年   19893篇
  2007年   19610篇
  2006年   17503篇
  2005年   15647篇
  2004年   14912篇
  2003年   14954篇
  2002年   14032篇
  2001年   14272篇
  2000年   13305篇
  1999年   14042篇
  1998年   35968篇
  1997年   24915篇
  1996年   19245篇
  1995年   14412篇
  1994年   12707篇
  1993年   12635篇
  1992年   9079篇
  1991年   8680篇
  1990年   8560篇
  1989年   8078篇
  1988年   7775篇
  1987年   6716篇
  1986年   6554篇
  1985年   7241篇
  1984年   6627篇
  1983年   6170篇
  1982年   5676篇
  1981年   5684篇
  1980年   5365篇
  1979年   5136篇
  1978年   4971篇
  1977年   5807篇
  1976年   7778篇
  1975年   4266篇
  1974年   4068篇
  1973年   4087篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
92.
93.
Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 172–176, May–June, 1994  相似文献   
94.
95.
Nutrient uptake by the hindlimb was investigated utilising the arteriovenous difference technique in 5 Thoroughbred horses fed to maintenance a diet of 100% roughage or 52% oat grain and 48% roughage. Arterial blood was obtained from a catheter inserted into the carotid artery while venous blood was simultaneously collected from a catheter placed into the iliac vein via the medial saphenous vein. The arteriovenous difference for glucose was significant and represented a mean extraction of 10 +/- 1% with no effect of diet. If fully oxidised, glucose uptake (corrected for lactate and pyruvate arteriovenous difference) was sufficient to account for 78 +/- 13% or 107 +/- 15% of the oxygen consumed by the hindlimb in horses fed a roughage or 52% oat grain diet respectively. Acetate was also a major metabolite of the hindlimb, showing a 39 +/- 5% extraction with no effect of diet. However, the 52% oat grain diet did induce a significant decline in the concentration of acetate in arterial blood. The potential contribution to oxidation in the hindlimb was significantly reduced from 32 +/- 4% in horses fed roughage to 21 +/- 3% when fed 52% oat grain. D-3-Hydroxybutyrate uptake could account for 9 +/- 1% of the oxidation by the hindlimb with no effect of diet. The technique for measuring nutrient uptake across the hindlimb using the arteriovenous difference is relatively simple and would be valuable in investigating fuel use by muscle during exercise.  相似文献   
96.
An extended logistic model with a varying asymptotic upper bound for long-range peak demand forecasting is described. The model has been applied to a typical fast growing system, the Saudi Consolidated Electric Company. The forecasts are compared with actual demands and with those obtained from classical forecasting methods. The model gave relatively accurate peak demand forecasts compared with other classical methods. The model with a single load observation is capable of producing several peak demand forecasts corresponding to different levels of maximum temperature and various levels of social activity. The forecasts produced by the model were also stable irrespective of the length of the ex-post simulation period  相似文献   
97.
Studies static-state feedback control of discrete-event systems under partial observation. The authors present a necessary and sufficient condition for the existence of a static-state feedback controller. A static controller is a special case of a dynamic controller studied by Kumar et al. The authors' condition, however, has computational advantage in contrast to those obtained by Kumar et al. The authors also present a necessary and sufficient condition under which the modular feedback synthesis is possible  相似文献   
98.
Surveyed 70 practicing attorneys and 150 law students to determine the extent to which they felt it was their responsibility to inform clients they referred for psychological testing about the testing process and about the validity scales on tests. Results showed that almost 50% of the attorneys and over 33% of the students believe that clients referred for testing always or usually should be informed of validity scales on tests. These results suggest that many test takers, particularly in forensic settings, may have information about validity scales that facilitates their giving biased responses without detection. Psychologists doing forensic evaluations should be alert to this possibility and should consider using more than one approach to detect response distortions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
99.
100.
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