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   5282篇
  免费   22篇
电工技术   14篇
化学工业   181篇
金属工艺   16篇
机械仪表   33篇
建筑科学   33篇
矿业工程   2篇
能源动力   12篇
轻工业   43篇
水利工程   11篇
无线电   146篇
一般工业技术   163篇
冶金工业   4544篇
原子能技术   10篇
自动化技术   96篇
  2021年   9篇
  2019年   7篇
  2018年   9篇
  2017年   9篇
  2016年   9篇
  2015年   7篇
  2014年   14篇
  2013年   37篇
  2012年   30篇
  2011年   43篇
  2010年   27篇
  2009年   29篇
  2008年   39篇
  2007年   32篇
  2006年   31篇
  2005年   23篇
  2004年   22篇
  2003年   23篇
  2002年   16篇
  2001年   15篇
  2000年   14篇
  1999年   151篇
  1998年   1366篇
  1997年   765篇
  1996年   499篇
  1995年   294篇
  1994年   214篇
  1993年   290篇
  1992年   61篇
  1991年   80篇
  1990年   67篇
  1989年   91篇
  1988年   82篇
  1987年   85篇
  1986年   55篇
  1985年   70篇
  1984年   28篇
  1983年   28篇
  1982年   35篇
  1981年   44篇
  1980年   38篇
  1979年   22篇
  1978年   15篇
  1977年   129篇
  1976年   245篇
  1975年   13篇
  1974年   14篇
  1973年   9篇
  1972年   9篇
  1966年   11篇
排序方式: 共有5304条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
Despite the growing awareness of wife abuse as a serious social problem of epidemic proportions, to date no systematic research has been conducted to delineate on an empirical basis distinct patterns of abuse within this heterogeneous population. The present study has as its goal the identification of differential patterns of wife abuse, each having a unique etiological profile with attendant implications for intervention. Toward this end a multivariate quantitative taxonomic procedure was employed to delineate 5 homogeneous subgroups of women (N?=?119; 17–58 yrs) abused by their partners. Subsequent analyses revealed these 5 subtypes to differ significantly in frequency and severity of abuse, usual precipitants, typical responses of the woman and her assailant, history of violence in the family of origin, and disposition following brief residence at a shelter for battered women. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
996.
Rates of microbial biodegradation of components of South Louisiana crude oil were determined by computer analysis of data obtained from computerized mass spectrometry. Total residue of the oil decreased exponentially with time, with maximum decrease noted at logarithmic phase, whereas asphaltenes and resins increased at the logarithmic phase of growth. Saturates decreased continuously during growth. Microbial degradation of components of crude oil was concluded to be a dynamic process.  相似文献   
997.
998.
Snyder  W.E. 《Computer》1981,14(8):7-9
Only a few years ago, even the simplest image processing operations strained state-of-the-art computers to their limits. 128 x 128 arrays took a lot of memory, and even the most trivial operations required enormous amounts of time. Then, with faster computers and cheaper memory, the technology finally began to catch up. Today, image operations are still time consuming, but it is no longer unthinkable to process 512 x 512 images. Now, imaging sensors are becoming an increasingly important part of closed-loop controllers in robotics, missile guidance, the automatic tracking of moving objects, and other intelligent systems. However, these applications require real-time processing of image sequences, and once again, the demands of image processing are pushing the available technology to its limits.  相似文献   
999.
Physical training is associated with a reduction of intrinsic sinoatrial activity; the present study examined the role of the parasympathetic nervous system in this reduction. Six groups of rats were studied for 10 weeks: inactive control; treadmill exercised; parasympathetic receptor blockade with atropine; exercise plus atropine; parasympathetic receptor stimulation with carbachol; and exercise plus carbachol. In vivo ISF (cardiac frequency 20 min after injection of propranolol and atropine) was measured at 3-week intervals. At the end of 10 weeks the right atrium was excised, in vitro measurements were made of ISF, and chronotropic dose-response curves to acetylcholine and norepinephrine were established. In vivo, ISF was reduced with time, the greatest reduction being found in the exercise plus atropine group; the treadmill-exercised and the atropine-treated groups also had a greater reduction than the control group. In vitro, no differences were observed in acetylcholine responses. The maximum norepinephrine chronotropic response was reduced in the treadmill-exercised and the exercise plus atropine groups. The maximum norepinephrine-induced frequency correlated with the in vitro ISF (r = 0.75). Thus, ISF was reduced with training, but this effect was independent of parasympathetic activity. The properties of the sinoatrial node which set ISF also influenced the maximum norepinephrine response.  相似文献   
1000.
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