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   477898篇
  免费   5215篇
  国内免费   1697篇
电工技术   8343篇
综合类   765篇
化学工业   73281篇
金属工艺   18694篇
机械仪表   14510篇
建筑科学   11097篇
矿业工程   2720篇
能源动力   11358篇
轻工业   43026篇
水利工程   5089篇
石油天然气   9818篇
武器工业   74篇
无线电   53347篇
一般工业技术   92754篇
冶金工业   89456篇
原子能技术   11874篇
自动化技术   38604篇
  2021年   3913篇
  2019年   3735篇
  2018年   6386篇
  2017年   6403篇
  2016年   6829篇
  2015年   4304篇
  2014年   7437篇
  2013年   20575篇
  2012年   12023篇
  2011年   16550篇
  2010年   12914篇
  2009年   14674篇
  2008年   15261篇
  2007年   15372篇
  2006年   13454篇
  2005年   12188篇
  2004年   11977篇
  2003年   11568篇
  2002年   11401篇
  2001年   11340篇
  2000年   10847篇
  1999年   11125篇
  1998年   26543篇
  1997年   18926篇
  1996年   14549篇
  1995年   11280篇
  1994年   9989篇
  1993年   9879篇
  1992年   7420篇
  1991年   6965篇
  1990年   7071篇
  1989年   6959篇
  1988年   6504篇
  1987年   5818篇
  1986年   5851篇
  1985年   6610篇
  1984年   6168篇
  1983年   5682篇
  1982年   5313篇
  1981年   5445篇
  1980年   5320篇
  1979年   5052篇
  1978年   5095篇
  1977年   5654篇
  1976年   7382篇
  1975年   4407篇
  1974年   4236篇
  1973年   4352篇
  1972年   3691篇
  1971年   3347篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
The capacitive idling converters derived from the Cuk, SEPIC, Zeta, and flyback topologies allow soft commutation of power switches without the need for additional circuitry, making it possible to increase the switching frequency while maintaining high efficiency  相似文献   
63.
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   
64.
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   
65.
66.
This research was supported under project No. 6.02.02/128-93 as part of the state scientific-technical program on future information technologies and systems by the Ukrainian State Committee, of Science and Technology.  相似文献   
67.
68.
69.
Carstensen and Rhodes1 have suggested that when, in stability programs, assays cannot be performed immediately after the protocol-designated storage time, then freezing them until such a time when assays can be performed would be a reasonable manner to retain the protocol schedule. They caution, however, that such a procedure may not be valid for dissolution data. The article to follow deals with real-time data showing that such a process is feasible for Nalidixic Acid tablets (and presumably for other tablets as well), and that, furthermore, the dissolution pattern would seem to be “frozen” as well.  相似文献   
70.
An extended logistic model with a varying asymptotic upper bound for long-range peak demand forecasting is described. The model has been applied to a typical fast growing system, the Saudi Consolidated Electric Company. The forecasts are compared with actual demands and with those obtained from classical forecasting methods. The model gave relatively accurate peak demand forecasts compared with other classical methods. The model with a single load observation is capable of producing several peak demand forecasts corresponding to different levels of maximum temperature and various levels of social activity. The forecasts produced by the model were also stable irrespective of the length of the ex-post simulation period  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