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   358531篇
  免费   29687篇
  国内免费   21710篇
电工技术   57109篇
技术理论   28篇
综合类   37805篇
化学工业   18266篇
金属工艺   12553篇
机械仪表   30527篇
建筑科学   32026篇
矿业工程   14564篇
能源动力   11910篇
轻工业   8737篇
水利工程   11033篇
石油天然气   11470篇
武器工业   5698篇
无线电   32541篇
一般工业技术   18374篇
冶金工业   13339篇
原子能技术   3160篇
自动化技术   90788篇
  2024年   1319篇
  2023年   3552篇
  2022年   6474篇
  2021年   8149篇
  2020年   9175篇
  2019年   6954篇
  2018年   6281篇
  2017年   9088篇
  2016年   10473篇
  2015年   12039篇
  2014年   23168篇
  2013年   19802篇
  2012年   26213篇
  2011年   28129篇
  2010年   21264篇
  2009年   21535篇
  2008年   21863篇
  2007年   27332篇
  2006年   24504篇
  2005年   21686篇
  2004年   17885篇
  2003年   16052篇
  2002年   12524篇
  2001年   10407篇
  2000年   8745篇
  1999年   7025篇
  1998年   5325篇
  1997年   4540篇
  1996年   3838篇
  1995年   3188篇
  1994年   2661篇
  1993年   1856篇
  1992年   1528篇
  1991年   1127篇
  1990年   891篇
  1989年   760篇
  1988年   545篇
  1987年   325篇
  1986年   211篇
  1985年   220篇
  1984年   236篇
  1983年   196篇
  1982年   170篇
  1981年   122篇
  1980年   92篇
  1979年   91篇
  1978年   70篇
  1977年   66篇
  1976年   28篇
  1959年   28篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
This paper presents an overview and personnal perspective on recent developments and current practice in computer process model. The basic concepts behind conventional process control are reviewed to provide a starting point for the non-control specialist and process engineer. The ensuing sections on Internal Model Control (IMC), Model Predictive Control (MPC) and adaptive control illustrate the evolution of control technology from the traditional multiloop strategies to the modern, multivariable, model-based, computer control systems now being used in industry. The paper does not provide a complete, critical review of process control. However, the discussion and the recommended references should provide a good starting point for anyone wanting to become familiar with current practice and some of the new directions of process control.  相似文献   
94.
95.
A multivariable control system design approach in the frequency domain is presented. The issue of control system redesign in an adaptive control scheme is discussed. Expert system techniques have been used for the automated design of controllers for multivariable systems. Design knowledge has been represented using rules, facts and objects. The design process consists of a sequence of operations obtained by heuristics and experience in the the design techniques. An automated design session of a multivariable plant using the expert system demonstrates that the expert system appears to work well in its prototype implementation.  相似文献   
96.
Pole shifting of multivariable control system over finite dimensional real algebras is studied. The main results are expressed in terms of the minimal polynomial of A + BF, where F is a feedback.  相似文献   
97.
Often companies in the (petro‐) chemical industry claim that all possible countermeasures against potential accidents have been taken and therefore accidents are unforeseeable. In this paper we question this statement by analysing the pre‐warning signals (precursors) preceding a number of industrial accidents. 17 accidents that occurred in the (petro‐) chemical industry have been investigated by exploring FACTS, an accident database containing information about industrial accidents worldwide. This paper will demonstrate that the existence of precursor information could have been used to foresee and even prevent these accidents if a proper control action had been initiated. The accidents are analysed further, according to a control model, which was adapted from that of C. Argyris. It demonstrates the ineffectiveness of several elements of business process control loops and that the so‐called ‘double‐loop learning’ cycle is more important than the ‘single‐loop learning’ cycle if one considers safety improvement. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
98.
Extracted and unextracted black cherry (Prunus serotina), red oak (Quercus rubra), and red pine (Pinus resinosa) wood specimens were exposed to artificial weathering, and their discoloration process was investigated to obtain basic understanding on the role of wood extractives in the weathering of hardwoods and softwoods. Color measurements were made with a spectrometer according to ISO 2470 standards, using the CIELAB system. Results obtained showed that the rate of whiteness was not significantly affected by extractives removed with organic solvents, but were significantly affected when organic solvent extraction was followed by water extraction. The total discoloration rate had the same pattern, and chromaticity coordinates were less affected by wood extractives. These results confirm the hypothesis that some extractives contained in wood act as antioxidants and are able to provide some protection to wood surfaces against weathering degradation. However, more work is needed to understand the chemistry and mechanism of action of these extractives so as to develop any practical use for this property. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 425–434, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20248  相似文献   
99.
100.
In this paper, we employ a nonlinear adaptive mechanism to globally stabilize nth-order reactions.  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