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   8086篇
  免费   124篇
  国内免费   1篇
电工技术   140篇
综合类   4篇
化学工业   904篇
金属工艺   109篇
机械仪表   146篇
建筑科学   180篇
矿业工程   33篇
能源动力   108篇
轻工业   707篇
水利工程   42篇
石油天然气   22篇
无线电   807篇
一般工业技术   1008篇
冶金工业   3164篇
原子能技术   109篇
自动化技术   728篇
  2021年   55篇
  2020年   38篇
  2019年   47篇
  2018年   53篇
  2017年   61篇
  2016年   80篇
  2015年   62篇
  2014年   89篇
  2013年   197篇
  2012年   169篇
  2011年   241篇
  2010年   205篇
  2009年   218篇
  2008年   232篇
  2007年   244篇
  2006年   205篇
  2005年   206篇
  2004年   189篇
  2003年   168篇
  2002年   144篇
  2001年   148篇
  2000年   166篇
  1999年   209篇
  1998年   743篇
  1997年   459篇
  1996年   375篇
  1995年   235篇
  1994年   216篇
  1993年   265篇
  1992年   151篇
  1991年   145篇
  1990年   141篇
  1989年   160篇
  1988年   143篇
  1987年   116篇
  1986年   138篇
  1985年   124篇
  1984年   89篇
  1983年   89篇
  1982年   81篇
  1981年   67篇
  1980年   67篇
  1979年   78篇
  1978年   81篇
  1977年   112篇
  1976年   178篇
  1975年   60篇
  1974年   56篇
  1973年   54篇
  1972年   37篇
排序方式: 共有8211条查询结果,搜索用时 31 毫秒
21.
Although continuing care is strongly related to positive treatment outcomes for substance use disorder (SUD), participation rates are low and few effective interventions are available. In a randomized clinical trial with 150 participants (97% men), 75 graduates of a residential Veterans Affairs Medical Center SUD program who received an aftercare contract, attendance prompts, and reinforcers (CPR) were compared to 75 graduates who received standard treatment (STX). Among CPR participants, 55% completed at least 3 months of aftercare, compared to 36% in STX. Similarly, CPR participants remained in treatment longer than those in STX (5.5 vs. 4.4 months). Additionally, CPR participants were more likely to be abstinent compared to STX (57% vs. 37%) after 1 year. The CPR intervention offers a practical means to improve adherence among individuals in SUD treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
22.
23.
Using an enhanced multiple output domino logic (EMODL) implementation of a carry lookahead adder (CLA), sums of several consecutive bits can be built in one nFET tree with a single carry-in. Based on this result, a new sparse carry chain architecture is proposed for the CLA adder. We demonstrate the design approach using a 32-b adder, and show that only four carries are sufficient for generating all sums, with a consequent reduction in the number of stage delays. Using a 1.2-μm CMOS technology, we verify our simulation procedures by fabrication and measurement of a 2.7 ns critical path  相似文献   
24.
Replacement of the pyridinium ring of 6,11-ethanobenzo[b]quinolizinium cations with thiazolium (4a and 4b) and N-methylimidazolium (4c and 4d) resulted in equipotent compounds in the [3H]TCP binding assay. The corresponding N-methyl-1,2,4-triazolium analogs were less potent in this assay. The thiazolium derivative 4b, with a Ki = 2.9 nM, is being evaluated as a possible neuroprotective N-methyl-D-aspartic acid (NMDA) antagonist.  相似文献   
25.
The centerline velocity profiles obtained from the solution of the two- and three-dimensional representations of the lid driven cavity flow problem are compared for different Reynolds numbers. Two configurations were used in this study: a unit cavity and a cavity with an aspect ratio of 2. The Reynolds numbers ranged from 100 to 5000 for all of the configurations studied. A new method of extending the Jacobi collocation technique called spectral difference is developed in this paper together with a unique computational grid. In addition, an iterative method for solving the pressure problem is also developed. This new numerical method allowed the calculation of three-dimensional Navier-Stokes equations to be performed in computers with very modest computational capabilities such as workstations.  相似文献   
26.
27.
The object-oriented approach to integrating knowledge data, and models is examined. Under the object-oriented paradigm, everything is an object, which is itself an encapsulation of data and methods to manipulate and access the data within the object. Thus knowledge, data, and models can be defined as special kinds of objects. Active knowledge/data language (KDL), a functional object-oriented database system is considered, covering the active-KDL-type system and functions, and query-driven simulation  相似文献   
28.
29.
30.
Measurements made in an untuned resonator by Fourier Transform Spectroscopy of atmospheric aerosols are explained by a pumped phonon model due to Fröhlich.  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