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   16698篇
  免费   591篇
  国内免费   25篇
电工技术   225篇
综合类   13篇
化学工业   3918篇
金属工艺   300篇
机械仪表   394篇
建筑科学   740篇
矿业工程   103篇
能源动力   450篇
轻工业   1543篇
水利工程   161篇
石油天然气   185篇
武器工业   1篇
无线电   1038篇
一般工业技术   2537篇
冶金工业   3575篇
原子能技术   162篇
自动化技术   1969篇
  2022年   238篇
  2021年   334篇
  2020年   248篇
  2019年   273篇
  2018年   322篇
  2017年   335篇
  2016年   356篇
  2015年   284篇
  2014年   357篇
  2013年   1043篇
  2012年   638篇
  2011年   804篇
  2010年   556篇
  2009年   575篇
  2008年   685篇
  2007年   646篇
  2006年   624篇
  2005年   520篇
  2004年   421篇
  2003年   407篇
  2002年   428篇
  2001年   278篇
  2000年   262篇
  1999年   285篇
  1998年   315篇
  1997年   298篇
  1996年   293篇
  1995年   285篇
  1994年   270篇
  1993年   313篇
  1992年   252篇
  1991年   198篇
  1990年   211篇
  1989年   225篇
  1988年   173篇
  1987年   218篇
  1986年   213篇
  1985年   253篇
  1984年   227篇
  1983年   203篇
  1982年   182篇
  1981年   194篇
  1980年   163篇
  1979年   179篇
  1978年   183篇
  1977年   141篇
  1976年   154篇
  1975年   173篇
  1974年   134篇
  1973年   132篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Amphetamine and cocaine dependence present significant public health concerns, yet no broadly effective pharmacotherapy for stimulant dependence has been developed. Two human laboratory studies are reviewed that tested the ability of aripiprazole, a novel antipsychotic with partial agonist activity at D2 dopamine receptors, to alter the behavioral effects of stimulants using d-amphetamine as a model agent. In each of these experiments, volunteers learned to discriminate 15 mg d-amphetamine (i.e., ≥80% drug-appropriate responding over 4 consecutive sessions). The effects of a range of doses of d-amphetamine (0, 2.5, 5, 10, and 15 mg) were then tested alone and following pretreatment with aripiprazole (20 mg in Experiment 1; 10 mg in Experiment 2). In Experiment 1, aripiprazole (20 mg) attenuated the discriminative stimulus and many of the subject-rated effects of amphetamine. Aripiprazole alone produced performance decrements. To determine whether a lower dose of aripiprazole would also attenuate the behavioral effects of d-amphetamine without impairing performance, Experiment 2 was conducted. Aripiprazole (10 mg) failed to alter the discriminative-stimulus effects but attenuated some of the subject-rated effects of d-amphetamine. This dose of aripiprazole did not impair performance. The results of these experiments indicate that aripiprazole may have clinical utility in treating stimulant dependence. Future human laboratory research should better model the clinical use of aripiprazole by examining the effects of chronic aripiprazole combined with either methamphetamine or cocaine in dependent individuals. A large-scale clinical trial is also needed to evaluate the efficacy of aripiprazole for the treatment of stimulant dependence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry  相似文献   
8.
Scanning acoustic microscopy of SCS-6 silicon carbide fiber reveals large radial variations in acoustic reflectivity associated with the chemical composition and microstructure of a given fiber region. Rayleigh wave fringe patterns observed in each of five subregions are used to calculate the average Young modulus of that subregion. The Young modulus is found to increase monotonically from 40 GPa in the carbon core to a value of 413 GPa in the stoichiometric SiC region. The effective Young modulus of the fiber as a whole is estimated from the moduli of the individual regions and it is compared with mechanical measurements reported in the literature.  相似文献   
9.
Effective systems development techniques attract a lot of attention, but little has been done to effectively address systems maintenance. This article describes an effective, proven approach to resurrecting existing systems and Increasing their useful life, using a system that employs both software tools and a rigorous methodology.  相似文献   
10.
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