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   241297篇
  免费   2629篇
  国内免费   427篇
电工技术   4292篇
综合类   257篇
化学工业   39373篇
金属工艺   9380篇
机械仪表   7393篇
建筑科学   5448篇
矿业工程   1391篇
能源动力   5157篇
轻工业   24838篇
水利工程   2476篇
石油天然气   5092篇
武器工业   32篇
无线电   25046篇
一般工业技术   44780篇
冶金工业   45348篇
原子能技术   5950篇
自动化技术   18100篇
  2021年   2108篇
  2019年   2020篇
  2018年   3490篇
  2017年   3426篇
  2016年   3690篇
  2015年   2236篇
  2014年   3900篇
  2013年   10196篇
  2012年   6154篇
  2011年   8297篇
  2010年   6546篇
  2009年   7235篇
  2008年   7585篇
  2007年   7713篇
  2006年   6887篇
  2005年   6046篇
  2004年   5815篇
  2003年   5600篇
  2002年   5676篇
  2001年   5561篇
  2000年   5384篇
  1999年   5302篇
  1998年   12574篇
  1997年   8899篇
  1996年   6858篇
  1995年   5329篇
  1994年   4735篇
  1993年   4624篇
  1992年   3667篇
  1991年   3387篇
  1990年   3593篇
  1989年   3472篇
  1988年   3303篇
  1987年   2895篇
  1986年   2932篇
  1985年   3373篇
  1984年   3219篇
  1983年   2892篇
  1982年   2738篇
  1981年   2821篇
  1980年   2719篇
  1979年   2624篇
  1978年   2684篇
  1977年   2949篇
  1976年   3805篇
  1975年   2368篇
  1974年   2242篇
  1973年   2376篇
  1972年   1970篇
  1971年   1858篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
This research was supported under project No. 6.02.02/128-93 as part of the state scientific-technical program on future information technologies and systems by the Ukrainian State Committee, of Science and Technology.  相似文献   
133.
134.
135.
In the editorial by J.C. Bezdek (ibid., p.1), an example is presented to demonstrate differences between fuzzy membership and probability. The authors argue that probability can be used in a way much more closely analogous to this use of fuzzy membership, weakening the argument for the latter  相似文献   
136.
Family nursing, always a component of nursing, has been recently receiving increased attention through publications, educational programs, clinical practice settings and family nursing research. Nurses are in the best position to assist families experiencing the illness of a loved one, but often lack the skills and confidence necessary to assist with the psychosocial needs. The purpose of this paper is to describe the development and implementation of a family nursing program within a large, tertiary care facility. The program's evaluation is ongoing but early outcomes indicate that day-to-day nursing practice has been positively influenced and improved job satisfaction may result.  相似文献   
137.
Carstensen and Rhodes1 have suggested that when, in stability programs, assays cannot be performed immediately after the protocol-designated storage time, then freezing them until such a time when assays can be performed would be a reasonable manner to retain the protocol schedule. They caution, however, that such a procedure may not be valid for dissolution data. The article to follow deals with real-time data showing that such a process is feasible for Nalidixic Acid tablets (and presumably for other tablets as well), and that, furthermore, the dissolution pattern would seem to be “frozen” as well.  相似文献   
138.
139.
140.
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   
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