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   448527篇
  免费   6225篇
  国内免费   1444篇
电工技术   8323篇
综合类   684篇
化学工业   65608篇
金属工艺   17445篇
机械仪表   13880篇
建筑科学   10906篇
矿业工程   2386篇
能源动力   11116篇
轻工业   39877篇
水利工程   4672篇
石油天然气   7475篇
武器工业   84篇
无线电   54032篇
一般工业技术   87141篇
冶金工业   83536篇
原子能技术   9497篇
自动化技术   39534篇
  2021年   3898篇
  2020年   2920篇
  2019年   3702篇
  2018年   6311篇
  2017年   6372篇
  2016年   6727篇
  2015年   4497篇
  2014年   7321篇
  2013年   20298篇
  2012年   11783篇
  2011年   15723篇
  2010年   12606篇
  2009年   14015篇
  2008年   14897篇
  2007年   14860篇
  2006年   13008篇
  2005年   11937篇
  2004年   11354篇
  2003年   11104篇
  2002年   10411篇
  2001年   10476篇
  2000年   10106篇
  1999年   10400篇
  1998年   25251篇
  1997年   17991篇
  1996年   14091篇
  1995年   10669篇
  1994年   9556篇
  1993年   9309篇
  1992年   7227篇
  1991年   6808篇
  1990年   6484篇
  1989年   6327篇
  1988年   6053篇
  1987年   5325篇
  1986年   5118篇
  1985年   6063篇
  1984年   5635篇
  1983年   5153篇
  1982年   4723篇
  1981年   4961篇
  1980年   4578篇
  1979年   4538篇
  1978年   4336篇
  1977年   5128篇
  1976年   6721篇
  1975年   3928篇
  1974年   3873篇
  1973年   3918篇
  1972年   3091篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
51.
52.
53.
54.
Uses a Markov process to model a real-time expert system architecture characterized by message passing and event-driven scheduling. The model is applied to the performance evaluation of rule grouping for real-time expert systems running on this architecture. An optimizing algorithm based on Kernighan-Lin heuristic graph partitioning for the real-time architecture is developed and a demonstration system based on the model and algorithm has been developed and tested on a portion of the advanced GPS receiver (AGR) and manned manoeuvring unit (MMU) knowledge bases  相似文献   
55.
Implementing a neural network on a digital or mixed analog and digital chip yields the quantization of the synaptic weights dynamics. This paper addresses this topic in the case of Kohonen's self-organizing maps. We first study qualitatively how the quantization affects the convergence and the properties, and deduce from this analysis the way to choose the parameters of the network (adaptation gain and neighborhood). We show that a spatially decreasing neighborhood function is far more preferable than the usually rectangular neighborhood function, because of the weight quantization. Based on these results, an analog nonlinear network, integrated in a standard CMOS technology, and implementing this spatially decreasing neighborhood function is then presented. It can be used in a mixed analog and digital circuit implementation.  相似文献   
56.
We present the design of E-kernel, an embedding kernel on the Victor V256 message-passing partitionable multiprocessor, developed for the support of program mapping and network reconfiguration. E-kernel supports the embedding of a new network topology onto Victor's 2D mesh and also the embedding of a task graph onto the 2D mesh network or the reconfigured network. In the current implementation, the reconfigured network can be a line or an even-size ring, and the task graphs meshes or tori of a variety of dimensions and shapes or graphs with similar topologies. For application programs having these task graph topologies and that are designed according to the communication model of E-kernel, they can be run without any change on partitions connected by the 2D mesh, line, or ring. Further, E-kernel attempts the communication optimization of these programs on the different networks automatically, thus making both the network topology and the communication optimization attempt completely transparent to the application programs. Many of the embeddings used in E-kernel are optimal or asymptotically optimal (with respect to minimum dilation cost). The implementation of E-kernel translated some of the many theoretical results in graph embeddings into practical tools for program mapping and network reconfiguration in a parallel system. E-kernel is functional on Victor V256. Measurements of E-kernel's performance on V256 are also included  相似文献   
57.
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 95–112, March–April, 1994.  相似文献   
58.
59.
60.
The electrochemical and corrosion behaviour of a nickel base super alloy (C-263) has been investigated in the deaerated binary and ternary solution mixture of concentrated phosphoric acid, acetic acid, sulphuric acid, nitric acid or water using potentiostatic technique at 35°C. The possibilities of electropolishing of this alloy in these solution mixtures have been also explored. The alloy showed distinct active, passive and transpassive behaviour in the experimental solutions. The alloy remained active and turned passive in the negative potential region. Transpassive dissolution of the alloy is observed and electropolishing is achieved in this region. The best electropolishing is obtained in 50% H3PO4 + 40% CH3COOH + 10% H2SO4. Higher content of water in the electrolytic solution is not useful for electropolishing of the alloy The experimental results also suggest that a current plateau in the transpassive potential region is not a sufficient condition to achieve electropolishing.  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