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   14345篇
  免费   1419篇
  国内免费   1079篇
电工技术   1019篇
综合类   1955篇
化学工业   319篇
金属工艺   158篇
机械仪表   770篇
建筑科学   427篇
矿业工程   114篇
能源动力   294篇
轻工业   149篇
水利工程   186篇
石油天然气   183篇
武器工业   102篇
无线电   1341篇
一般工业技术   1396篇
冶金工业   139篇
原子能技术   51篇
自动化技术   8240篇
  2024年   48篇
  2023年   129篇
  2022年   193篇
  2021年   244篇
  2020年   337篇
  2019年   323篇
  2018年   246篇
  2017年   415篇
  2016年   442篇
  2015年   518篇
  2014年   661篇
  2013年   940篇
  2012年   879篇
  2011年   1026篇
  2010年   715篇
  2009年   961篇
  2008年   1019篇
  2007年   1094篇
  2006年   934篇
  2005年   781篇
  2004年   720篇
  2003年   641篇
  2002年   526篇
  2001年   456篇
  2000年   409篇
  1999年   317篇
  1998年   277篇
  1997年   265篇
  1996年   207篇
  1995年   164篇
  1994年   163篇
  1993年   111篇
  1992年   123篇
  1991年   79篇
  1990年   64篇
  1989年   61篇
  1988年   59篇
  1987年   34篇
  1986年   26篇
  1985年   37篇
  1984年   48篇
  1983年   28篇
  1982年   23篇
  1981年   20篇
  1980年   21篇
  1979年   19篇
  1978年   7篇
  1977年   11篇
  1976年   9篇
  1975年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
网带式连续烧结炉炉温及网带速度微机控制系统   总被引:1,自引:0,他引:1  
本文介绍一个基于STD总线的单片机网带式连续烧结炉炉温及网带速度控制系统,详细叙述了系统的硬件结构和控制算法。  相似文献   
72.
均匀设计在遗传算法中的应用研究   总被引:5,自引:1,他引:4  
通过分析均匀设计和遗传算法的内在关系,指出从某个角度上可以把均匀设计看作是遗传算法的一种特例,并针对遗传算法初始参数众多、难配置的问题,提出了利用均匀设计优化配置选择参数的方法,在一定程度上可以避免遗传算法参数配置的盲目性.仿真试验结果证明了该方法是合理、可行的。  相似文献   
73.
粒子群优化算法及其应用   总被引:20,自引:0,他引:20  
范娜  云庆夏 《信息技术》2006,30(1):53-56
粒子群优化(PSO)算法是一种新颖的演化算法,它属于一类随机全局优化技术,PSO算法通过粒子间的相互作用在复杂搜索空间中发现最优区域。PSO的优势在于简单而又功能强大。介绍了基本的PSO算法、研究现状及其应用,并讨论将来可能的研究内容。  相似文献   
74.
The search for good lineal, or depth-first, spanning trees is an important aspect in the implementation of a wide assortment of graph algorithms. We consider the complexity of findingoptimal lineal spanning trees under various notions of optimality. In particular, we show that several natural problems, such as constructing a shortest or a tallest lineal tree, are NP-hard. We also address the issue of polynomial-time, near-optimization strategies for these difficult problems, showing that efficient absolute approximation algorithms cannot exist unlessP = NP.This author's research was supported in part by the Sandia University Research Program and by the National Science Foundation under Grant M IP-8603879.This author's research was supported in part by the National Science Foundation under Grants ECS-8403859 and MIP-8603879.  相似文献   
75.
76.
We have designed a family of parallel data flow analysis algorithms for execution on distributed-memory MIMD machines, based on general-purpose, hybrid algorithms for data flow analysis [Marlowe and Ryder 1990]. We exploit a natural partitioning of the hybrid algorithms and explore a static mapping, dynamic scheduling strategy. Alternative mapping-scheduling choices and refinements of the flow graph condensation used are discussed. Our parallel hybrid algorithm family is illustrated on Reaching Definitions, although parallel algorithms also exist for many interprocedural (e.g., Aliasing) and intraprocedural (e.g., Available Expressions) problems [Marlowe 1989]. We have implemented the parallel hybrid algorithm for Reaching Definitions on an Intel iPSC/2. Our empirical results suggest the practicality of parallel hybrid algorithms.An earlier version of this paper was presented at Supercomputing '90.The research reported here was supported, in part, by the New Jersey Commission on Science and Technology and the CAIP Center's Industrial Members, by Siemens Research Corporation and by National Science Foundation grant CCR-8920078.  相似文献   
77.
Analogical planning provides a means of solving engineering problems where other machine learning methods fail. Unlike many machine learning paradigms, analogy does not require numerous previous examples or a rich domain theory. Instead, analogical planners adapt knowledge of solved problems in similar domains to the current problem. Unfortunately, the analogical planning task is an expensive one. While the process of forming correspondences between a known problem and a new problem is complex, the problem of selecting a base case for the analogy is virtually intractable.This paper addresses the issue of efficiently forming analogical plans. The Anagram planning system is described, which takes advantage of the massively parallel architecture of the Connection Machine to perform base selection and map formation. Anagram provides a tractable solution to analogical planning, with a complexity that is sublinear in the size of the plans.This paper describes the Anagram system and its parallel algorithms. The paper also presents theoretical analyses and empirical results of testing the system on a large database of plans from the domain of automatic programming.  相似文献   
78.
79.
In this paper, we consider a method (splitting) for calculating the auto- covariances of fractional integrated processes (ARFIMA) and generalized integrated processes (GARMA). The splitting method does not require any restriction on the autoregressive roots, and allows fast calculation of the autocovariances of these processes.  相似文献   
80.
In order to maximize systems average availability during a given period of time, it has recently been developed a non-periodic surveillance test optimization methodology based on genetic algorithms (GA). The fact of allowing non-periodic tests turns the solution space much more flexible and schedules can be better adjusted, providing gains in the overall system average availability, when compared to those obtained by an optimized periodic test scheme. This approach, however, turns the optimization problem more complex. Hence, the use of a powerful optimization technique, such as GA, is required.Considering that some particular features of certain systems can turn it advisable to introduce other specific constraints in the optimization problem, this work investigates the application of seasonal constraints for the set of the Emergency Diesel Generation of a typical four-loop pressurized water reactor in order to planning and optimizing its surveillance test policy. In this analysis, the growth of the blackout accident probability during summer, due to electrical power demand increases, was considered. Here, the used model penalizes surveillance test interventions when the blackout probability is higher.Results demonstrate the ability of the method in adapting the surveillance test policy to seasonal constraints. The knowledge acquired by the GA during the searching process has lead to test schedules that drastically minimize test interventions at periods of high blackout probability. It is compensated by more frequent redistributed tests through the periods of low blackout probability in order to improve on the overall average availability at the system level.  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