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   471073篇
  免费   6215篇
  国内免费   1368篇
电工技术   8198篇
综合类   319篇
化学工业   73741篇
金属工艺   19196篇
机械仪表   14722篇
建筑科学   11339篇
矿业工程   2860篇
能源动力   11915篇
轻工业   41387篇
水利工程   5109篇
石油天然气   10043篇
武器工业   20篇
无线电   53380篇
一般工业技术   93423篇
冶金工业   84080篇
原子能技术   11287篇
自动化技术   37637篇
  2021年   4091篇
  2019年   3763篇
  2018年   6444篇
  2017年   6471篇
  2016年   6935篇
  2015年   4568篇
  2014年   7662篇
  2013年   20944篇
  2012年   12328篇
  2011年   16673篇
  2010年   13360篇
  2009年   15139篇
  2008年   15301篇
  2007年   14970篇
  2006年   13091篇
  2005年   12131篇
  2004年   11436篇
  2003年   11089篇
  2002年   10866篇
  2001年   10682篇
  2000年   10258篇
  1999年   10500篇
  1998年   24848篇
  1997年   18130篇
  1996年   14253篇
  1995年   10608篇
  1994年   9623篇
  1993年   9316篇
  1992年   7191篇
  1991年   7030篇
  1990年   6689篇
  1989年   6767篇
  1988年   6590篇
  1987年   5598篇
  1986年   5539篇
  1985年   6398篇
  1984年   6035篇
  1983年   5534篇
  1982年   5102篇
  1981年   5311篇
  1980年   5053篇
  1979年   5041篇
  1978年   5115篇
  1977年   5874篇
  1976年   7658篇
  1975年   4607篇
  1974年   4389篇
  1973年   4413篇
  1972年   3781篇
  1971年   3475篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
101.
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 14–15, February, 1989.  相似文献   
102.
A direct method is described for computing a hysteresis point (double turning point) corresponding to a cusp point of a system ofn nonlinear equations inn variables depending on two parameters. By addition of two equations a minimally extended system ofn+2 nonlinear equations is constructed for which the hysteresis point is an isolated solution. An efficient implementation of Newton's method is presented not requiring evaluations of second derivatives of the original problem. Two numerical examples show the efficiency of theQ-quadratically convergent method.  相似文献   
103.
104.
Consideration was given to the decision making procedures based on the fuzzy messages of experts whose preferences on the set of collective decisions can also be fuzzy.  相似文献   
105.
106.
Flame structure and NO emission characteristics in counterflow diffusion flame of blended fuel of H2/CO2/Ar have been numerically simulated with detailed chemistry. The combination of H2, CO2 and Ar as fuel is selected to clearly display the contribution of hydrocarbon products to flame structure and NO emission characteristics due to the breakdown of CO2. A radiative heat loss term is involved to correctly describe the flame dynamics especially at low strain rates. The detailed chemistry adopts the reaction mechanism of GRI 2.11, which consists of 49 species and 279 elementary reactions. All mechanisms including thermal, NO2, N2O and Fenimore are taken into account to separately evaluate the effects of CO2 addition on NO emission characteristics. The increase of added CO2 quantity causes flame temperature to fall since at high strain rates a diluent effect is prevailing and at low strain rates the breakdown of CO2 produces relatively populous hydrocarbon products and thus the existence of hydrocarbon products inhibits chain branching. It is also found that the contribution of NO production by N2O and NO2 mechanisms are negligible and that thermal mechanism is concentrated on only the reaction zone. As strain rate and CO2 quantity increase, NO production is remarkably augmented. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
107.
108.
Fuzzy logic was first suggested as the mechanism by which humans drive cars. This paper addresses the use of fuzzy logic and algorithms towards the intelligent autonomous motion control of land vehicles. To cope with vehicle complexities, internal parametric changes, and with unpredictable environmental effects, the controllers that are presented, whilst heuristic in nature, are self-organizing or self-learning in that they generate automatically by observation an experiential rule base that models the vehicle, and via an appropriate performance index an optimal control rule base that is robust to large parametric changes. The methodology presented is applicable to any complex process which is too difficult to model or control using conventional methods, or which has relied on the experience of a human operator. An overview of fuzzy logic and static fuzzy logic control (akin to expert systems) is provided, together with illustrative examples.  相似文献   
109.
Translated from Atomnaya Énergiya, Vol. 67, No. 2, pp. 97–100, August, 1989.  相似文献   
110.
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