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   37877篇
  免费   3181篇
  国内免费   3232篇
电工技术   3185篇
技术理论   5篇
综合类   2444篇
化学工业   2468篇
金属工艺   299篇
机械仪表   1409篇
建筑科学   1326篇
矿业工程   186篇
能源动力   1360篇
轻工业   462篇
水利工程   273篇
石油天然气   231篇
武器工业   187篇
无线电   2708篇
一般工业技术   2976篇
冶金工业   958篇
原子能技术   150篇
自动化技术   23663篇
  2024年   159篇
  2023年   613篇
  2022年   466篇
  2021年   742篇
  2020年   1027篇
  2019年   1100篇
  2018年   1030篇
  2017年   1379篇
  2016年   1489篇
  2015年   1325篇
  2014年   2258篇
  2013年   3467篇
  2012年   1820篇
  2011年   2309篇
  2010年   1669篇
  2009年   2170篇
  2008年   2158篇
  2007年   2160篇
  2006年   1878篇
  2005年   1694篇
  2004年   1417篇
  2003年   1340篇
  2002年   1227篇
  2001年   982篇
  2000年   976篇
  1999年   890篇
  1998年   794篇
  1997年   708篇
  1996年   644篇
  1995年   557篇
  1994年   502篇
  1993年   482篇
  1992年   369篇
  1991年   354篇
  1990年   279篇
  1989年   216篇
  1988年   187篇
  1987年   168篇
  1986年   137篇
  1985年   180篇
  1984年   187篇
  1983年   167篇
  1982年   147篇
  1981年   96篇
  1980年   71篇
  1979年   85篇
  1978年   61篇
  1977年   67篇
  1976年   19篇
  1975年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
设计并研制了一种用于压缩式致冷设备的电子式定温域多功能控制装置。它除具有控温范围宽、精度高、控温参数易调等优点外,还实现了低成本的温度显示、半自动除霜控制、加电延时保护、过欠压保护等功能。全部采用无触点控制方式,有良好的性能/价格比。  相似文献   
52.
A necessary and sufficient condition to test the robustness of a regulator of uncertain linear systems with constrained control is given. The candidate regulator for this test is that stabilizing nominal systems. An illustrative example is also given.  相似文献   
53.
In this paper we extend the finite-dimensional results for the H-control problem with measurement-feedback to a large class of infinite-dimensional systems, allowing for a certain type of unboundedness in the input and output operators (the Pritchard-Salamon class). The main result of the paper relates the solvability to the suboptimal H-control problem to the existence of stabilizing solutions to certain operator Riccati equations. Furthermore, a characterization of all suboptimal controllers is given.  相似文献   
54.
The problem of design of minimax robust LQG controllers for linear systems with parameter and noise uncertainties is considered in this paper. Necessary and sufficient conditions for converting this problem to a two-person, zero-sum continuous game problem are presented. A simple procedure for design of a suboptimal minimax robust LQG controller, i.e., the LQG controller for least-favourable model, is proposed. Necessary and sufficient conditions for the existence of a saddle point are established. Under these conditions, the controller obtained is exactly the minimax LQG controller. When there does not exist a saddle point, the worst-case error between the controller obtained and the minimax robust LQG controllers under described uncertainties is bounded.  相似文献   
55.
In this paper we present a numerical method for estimating the current state of a nonlinear control system. We use finite differences to discretize a modified version of the finite-time observer equations in James. The discretized equations are simple and easily programmed. The convergence and accuracy of the scheme is proved, and the scheme enjoys a number of important properties: availability of rate of convergence estimates, good robustness characteristics, and the ability to handle certain types of discontinuities in the observations. The major disadvantage is that the number of grid points required increases exponentially with the number of state dimensions.  相似文献   
56.
57.
Management of multidimensional discrete data   总被引:1,自引:0,他引:1  
Spatial database management involves two main categories of data: vector and raster data. The former has received a lot of in-depth investigation; the latter still lacks a sound framework. Current DBMSs either regard raster data as pure byte sequences where the DBMS has no knowledge about the underlying semantics, or they do not complement array structures with storage mechanisms suitable for huge arrays, or they are designed as specialized systems with sophisticated imaging functionality, but no general database capabilities (e.g., a query language). Many types of array data will require database support in the future, notably 2-D images, audio data and general signal-time series (1-D), animations (3-D), static or time-variant voxel fields (3-D and 4-D), and the ISO/IEC PIKS (Programmer's Imaging Kernel System) BasicImage type (5-D). In this article, we propose a comprehensive support ofmultidimensional discrete data (MDD) in databases, including operations on arrays of arbitrary size over arbitrary data types. A set of requirements is developed, a small set of language constructs is proposed (based on a formal algebraic semantics), and a novel MDD architecture is outlined to provide the basis for efficient MDD query evaluation.  相似文献   
58.
可分2-D系统是一类具有良好特性的重要的特殊2-D系统,它在多方面均有重要的应用.本文在已有结果的基础上对具有可分性的2-D多输入多输出系统在再实现问题、渐近稳定性代数判据、状态观测器设计等方面进行了较为广泛的研究,得到了许多较好的结果.  相似文献   
59.
We consider a class of linear infinite-dimensional systems subject to boundary uncertainties, which are linear and time-invariant. Using a deterministic approach to the design of stabilizing feedback controls, uniform exponential stability of the zero state is achieved. Lyapunov techniques are combined with Datko or Ichikawa theory. Three illustrative examples are presented.  相似文献   
60.
Parallel to, and to some degree inreaction to French poststructuralisttheorization (as championed by Derrida,Foucault, and Lacan, among others) is a Frenchneo-structuralism built directly on theachievements of structuralism using electronicmeans. This paper examines some exemplaryapproaches to text analysis in thisneo-structuralist vein: SATOR's topoidictionary, the WinBrill POS tagger andFrançois Rastier's interpretativesemantics. I consider how a computer-assisted``Wissenschaft' accumulation of expertisecomplements the neo-structuralist approach.Ultimately, electronic critical studies will bedefined by their strategic position at theintersection of the two chief technologiesshaping our society: the new informationprocessing technology of computers and therepresentational techniques that haveaccumulated for centuries in texts.Understanding how these two informationmanagement paradigms complement each other is akey issue for the humanities, for computerscience, and vital to industry, even beyond thenarrow realm of the language industries. Thedirection of critical studies, a small planetlong orbiting in only rarefied academiccircles, will be radically altered by the sheersize of the economic stakes implied by a newkind of text, the industrial text, thetechnological heart of an information society.  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