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   243620篇
  免费   2948篇
  国内免费   1243篇
电工技术   4859篇
综合类   264篇
化学工业   35424篇
金属工艺   10861篇
机械仪表   7066篇
建筑科学   6239篇
矿业工程   481篇
能源动力   6273篇
轻工业   24149篇
水利工程   1836篇
石油天然气   1335篇
武器工业   3篇
无线电   31062篇
一般工业技术   44914篇
冶金工业   50128篇
原子能技术   3860篇
自动化技术   19057篇
  2021年   1567篇
  2019年   1423篇
  2018年   2322篇
  2017年   2223篇
  2016年   2444篇
  2015年   1907篇
  2014年   3160篇
  2013年   10795篇
  2012年   5454篇
  2011年   7794篇
  2010年   6288篇
  2009年   6967篇
  2008年   7563篇
  2007年   7662篇
  2006年   7033篇
  2005年   6523篇
  2004年   6248篇
  2003年   6269篇
  2002年   6242篇
  2001年   6377篇
  2000年   5807篇
  1999年   6423篇
  1998年   16568篇
  1997年   11604篇
  1996年   8952篇
  1995年   6693篇
  1994年   5910篇
  1993年   5730篇
  1992年   4052篇
  1991年   3995篇
  1990年   3582篇
  1989年   3506篇
  1988年   3442篇
  1987年   2907篇
  1986年   2843篇
  1985年   3414篇
  1984年   3053篇
  1983年   2746篇
  1982年   2550篇
  1981年   2568篇
  1980年   2434篇
  1979年   2274篇
  1978年   2239篇
  1977年   2810篇
  1976年   4173篇
  1975年   1900篇
  1974年   1797篇
  1973年   1786篇
  1972年   1460篇
  1971年   1317篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
A constant-time algorithm for labeling the connected components of an N×N image on a reconfigurable network of N3 processors is presented. The main contribution of the algorithm is a novel constant-time technique for determining the minimum-labeled PE in each component. The number of processors used by the algorithm can be reduced to N/sup 2+(1/d/), for any 1⩽d⩽log N, if O(d) time is allowed  相似文献   
122.
Multicast communication, in which the same message is delivered from a source node to an arbitrary number of destination nodes, is being increasingly demanded in parallel computing. System supported multicast services can potentially offer improved performance, increased functionality, and simplified programming, and may in turn be used to support various higher-level operations for data movement and global process control. This paper presents efficient algorithms to implement multicast communication in wormhole-routed direct networks, in the absence of hardware multicast support, by exploiting the properties of the switching technology. Minimum-time multicast algorithms are presented for n-dimensional meshes and hypercubes that use deterministic, dimension-ordered routing of unicast messages. Both algorithms can deliver a multicast message to m-1 destinations in [log 2 m] message passing steps, while avoiding contention among the constituent unicast messages. Performance results of implementations on a 64-node nCUBE-2 hypercube and a 168-node Symult 2010 2-D mesh are given  相似文献   
123.
We have developed a problem-solving framework, called ConClass, that is capable of classifying continuous real-time problems dynamically and concurrently on a distributed system. ConClass provides an efficient development environment for describing and decomposing a classification problem and synthesizing solutions. In ConClass, decomposed concurrent subproblems specified by the application developer effectively correspond to the actual distributed hardware elements. This scheme is useful for designing and implementing efficient distributed processing, making it easier to anticipate and evaluate system behavior. The ConClass system provides an object replication feature that prevents any particular object from being overloaded. In order to deal with an indeterminate amount of problem data, ConClass dynamically creates object networks that justify hypothesized solutions, and thus achieves a dynamic load distribution. A number of efficient execution mechanisms that manage a variety of asynchronous aspects of distributed processing have been implemented without using schedulers or synchronization schemes that are liable to develop bottlenecks. We have confirmed the efficiency of parallel distributed processing and load balancing of ConClass with an experimental application  相似文献   
124.
What is the implication for business when information technology (IT) changes in the workplace without a commensurate change in the composition of business programs educating tomorrow's employees? A survey of MBA graduates forms the basis of this article on the IT skills needed in the marketplace.  相似文献   
125.
This paper is a reply to Laviolette and Seaman's critical discussion of fuzzy set theory. Rather than questioning the interest of the Bayesian approach to uncertainty, some reasons why Bayesian find the idea of a fuzzy set not palatable are laid bare. Some links between fuzzy sets and probability that Laviolette and Seaman seem not to be aware of are pointed out. These links suggest that, contrary to the claim sometimes found in the literature, probability theory is not a special case of fuzzy set theory. The major objection to Laviolette and Seaman is that they found their critique on as very limited view of fuzzy sets, including debatable papers, while they fail to account for significant works pertaining to axiomatic derivation of fuzzy set connectives, possibility theory, fuzzy random variables, among others  相似文献   
126.
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   
127.
Growth hormone (GH) has recently been shown to affect polymorphonuclear neutrophil granulocyte (PMN) function and to be secreted by mononuclear cells, indicating that the hormone may be active in an immunophysiologic network, acting as an endo- or paracrine priming agent. The purpose of the present study was to evaluate the chemotactic responsiveness of canine peripheral PMN in a dog with acromegaly, caused by spontaneous, progesterone-induced hypersecretion of GH and, secondary to this, a seven-fold increase in insulin-like growth factor I (IGF-I). The chemotactic responsiveness towards zymosan-activated serum (ZAS) and leukotriene B4 (LTB4) was evaluated at a time when the dog suffered from acromegaly and again 57 days after corrective surgery (ovariohysterectomy). The experiments showed that PMN from the patient exhibited enhanced chemotactic migration that appeared to be associated with the hypersomatotropic condition as judged from the reversibility of the phenomenon. The glucose intolerance and elevated serum alkaline phosphatase that were observed in the acromegalic dog were also shown to be reversible following surgery.  相似文献   
128.
129.
130.
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