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   572869篇
  免费   28326篇
  国内免费   15016篇
电工技术   23150篇
技术理论   34篇
综合类   21743篇
化学工业   91830篇
金属工艺   29645篇
机械仪表   27898篇
建筑科学   33136篇
矿业工程   11352篇
能源动力   15417篇
轻工业   44187篇
水利工程   7548篇
石油天然气   23673篇
武器工业   2563篇
无线电   66911篇
一般工业技术   82041篇
冶金工业   66661篇
原子能技术   7239篇
自动化技术   61183篇
  2023年   5776篇
  2022年   10058篇
  2021年   14761篇
  2020年   10918篇
  2019年   9900篇
  2018年   11615篇
  2017年   12821篇
  2016年   11609篇
  2015年   14773篇
  2014年   18915篇
  2013年   29398篇
  2012年   25642篇
  2011年   29628篇
  2010年   25385篇
  2009年   25041篇
  2008年   25167篇
  2007年   24741篇
  2006年   24950篇
  2005年   22266篇
  2004年   16742篇
  2003年   16228篇
  2002年   16484篇
  2001年   15296篇
  2000年   14096篇
  1999年   15812篇
  1998年   23788篇
  1997年   17766篇
  1996年   14782篇
  1995年   11531篇
  1994年   9932篇
  1993年   8535篇
  1992年   6345篇
  1991年   5669篇
  1990年   4824篇
  1989年   4480篇
  1988年   4245篇
  1987年   3454篇
  1986年   3259篇
  1985年   3695篇
  1984年   3245篇
  1983年   2876篇
  1982年   2685篇
  1981年   2662篇
  1980年   2509篇
  1979年   2301篇
  1978年   2237篇
  1977年   2808篇
  1976年   4171篇
  1975年   1899篇
  1974年   1795篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
The pipelined architecture and parallel organization of the AT&T Pixel Machine image computer are described and demonstrated with applications for the visualization of multidimensional fractals, particularly linear fractals and quaternion/ stacked Julia sets. Techniques for pushing the Pixel Machine to its peak abilities are described and apply to more recent parallel image computers as well.  相似文献   
182.
要提高曲线轮廓汉字的还原质量, 需要在字形还原时采用网格适配技术本文介绍了网格适配的基本原理, 并在分析汉字字形还原失真现象的基础上, 给出了我们自己设计并实现的适合于曲线轮廓汉字特点的二种网格适配方法, 即动态的补象素算法和曲线轮廓汉字的技术  相似文献   
183.
本文用计算机数字模拟方法研究了电活性分子多层Z型L-B膜修饰电极的循环伏安行为。计算了电极与修饰L-B膜分子第一层之间的电荷转移速度常数K_o,L-B膜分子层间的电荷转移速度常数k_i;对峰电位差△E_p及阳极峰面积Q的影响,以及在不同条件下各层分子的氧化态分数随扫描时间的变化。为研究和设计电活性分子修饰电极的实际体系提供了大量数据和信息。  相似文献   
184.
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   
185.
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   
186.
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   
187.
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   
188.
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   
189.
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   
190.
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   
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