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   201423篇
  免费   2340篇
  国内免费   614篇
电工技术   3489篇
综合类   151篇
化学工业   29223篇
金属工艺   8076篇
机械仪表   6105篇
建筑科学   4876篇
矿业工程   1310篇
能源动力   5155篇
轻工业   17258篇
水利工程   2305篇
石油天然气   4040篇
武器工业   8篇
无线电   23277篇
一般工业技术   40268篇
冶金工业   37779篇
原子能技术   5101篇
自动化技术   15956篇
  2021年   1634篇
  2019年   1586篇
  2018年   2595篇
  2017年   2669篇
  2016年   2805篇
  2015年   1824篇
  2014年   3104篇
  2013年   8999篇
  2012年   5102篇
  2011年   7088篇
  2010年   5650篇
  2009年   6407篇
  2008年   6504篇
  2007年   6564篇
  2006年   5624篇
  2005年   5281篇
  2004年   5029篇
  2003年   4909篇
  2002年   4563篇
  2001年   4696篇
  2000年   4599篇
  1999年   4765篇
  1998年   11513篇
  1997年   8211篇
  1996年   6472篇
  1995年   4711篇
  1994年   4306篇
  1993年   4107篇
  1992年   3248篇
  1991年   3095篇
  1990年   2901篇
  1989年   2978篇
  1988年   2844篇
  1987年   2417篇
  1986年   2325篇
  1985年   2732篇
  1984年   2517篇
  1983年   2361篇
  1982年   2101篇
  1981年   2219篇
  1980年   2039篇
  1979年   2140篇
  1978年   2138篇
  1977年   2380篇
  1976年   3214篇
  1975年   1841篇
  1974年   1771篇
  1973年   1782篇
  1972年   1449篇
  1971年   1357篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
82.
This paper is devoted to presenting controllability and stabilizability issues associated to a class of nonsmooth dynamical systems, namely complementarity dynamical systems. The main existing results are summarized, and some possible research directions are provided. Convex analysis and complementarity problems are claimed to be the main analysis tools for control related studies. This paper mainly focuses on mechanical applications.  相似文献   
83.
The Metaflow architecture, a unified approach to maximizing the performance of superscalar microprocessors, is introduced. The Metaflow architecture exploits inherent instruction-level parallelism in conventional sequential programs by hardware means, without relying on optimizing compilers. It is based on a unified structure, the DRIS (deferred-scheduling, register-renaming instruction shelf), that manages out-of-order execution and most of the attendant problems. Coupling the DRIS with a speculative-execution mechanism that avoids conditional branch stalls results in performance limited only be inherent instruction-level parallelism and available execution resources. Although presented in the context of superscalar machines, the technique is equally applicable to a superpipelined implementation. Lightning, the first implementation of the Metaflow architecture, which executes the Sparc RISC instruction set is described  相似文献   
84.
85.
86.
87.
88.
Neural networks and blood cell identification   总被引:1,自引:0,他引:1  
The objective of this project is to propose a method of identifying cells found in human blood and to classify them based upon their morphological features using neural networks. The project focuses on three major blood cell types, namely, erythrocytes, leukocytes and platelets. The data are collected using peripheral blood smears from clinical patients. The image acquisition requires 100x magnification on all the blood smears, the preprocessing involves the use of median and edge enhance filters; the feature extraction is done by performing the wavelet transform on the images. Finally classification of the blood cell types is done using ALOPEX and Back Propagation trained neural networks. The efficacy of both networks is then compared by comparing their outputs and number of iterations required to reach the final result.  相似文献   
89.
Penetrating injuries of the eye are an important cause of unilateral visual loss. We studied a series of 82 cases of penetrating injuries treated here from 1987 through 1993. The injuries were caused by sharp objects in 66% and blunt trauma in 6%. The prognosis after a penetrating injury is greatly influenced by the nature of the injury and the extent of the initial drainage. Among factors associated with an unfavorable visual outcome were diminished preoperative visual acuity and scleral wounds with dense vitreous hemorrhage.  相似文献   
90.
A wideband wattmeter for measuring active power over a frequency range of dc to 500 kHz is described. The wattmeter is based on the three-voltmeter method in which three rms voltage measurements are used to calculate power. The wattmeter active power uncertainty is estimated to be within 0.03% from dc to 20 kHz and within 1.5% to 500 kHz  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