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   8060篇
  免费   114篇
  国内免费   2篇
电工技术   140篇
综合类   5篇
化学工业   880篇
金属工艺   112篇
机械仪表   156篇
建筑科学   167篇
矿业工程   32篇
能源动力   110篇
轻工业   704篇
水利工程   42篇
石油天然气   23篇
无线电   813篇
一般工业技术   1019篇
冶金工业   3139篇
原子能技术   113篇
自动化技术   721篇
  2021年   51篇
  2019年   49篇
  2018年   53篇
  2017年   59篇
  2016年   78篇
  2015年   53篇
  2014年   84篇
  2013年   192篇
  2012年   173篇
  2011年   235篇
  2010年   202篇
  2009年   210篇
  2008年   232篇
  2007年   235篇
  2006年   206篇
  2005年   213篇
  2004年   187篇
  2003年   168篇
  2002年   145篇
  2001年   148篇
  2000年   166篇
  1999年   208篇
  1998年   747篇
  1997年   458篇
  1996年   377篇
  1995年   236篇
  1994年   219篇
  1993年   265篇
  1992年   152篇
  1991年   148篇
  1990年   142篇
  1989年   158篇
  1988年   145篇
  1987年   116篇
  1986年   140篇
  1985年   122篇
  1984年   91篇
  1983年   90篇
  1982年   88篇
  1981年   66篇
  1980年   68篇
  1979年   79篇
  1978年   79篇
  1977年   110篇
  1976年   178篇
  1975年   58篇
  1974年   56篇
  1973年   53篇
  1972年   37篇
  1971年   36篇
排序方式: 共有8176条查询结果,搜索用时 15 毫秒
101.
102.
This article estimates workplace injury costs in the U.S. These costs have been studied in less detail than most injury costs. Our methods, which mostly use regularly published data, produce order-of-magnitude estimates. Overall, workplace injuries cost the U.S. an estimated $140 billion annually. This estimate includes $17 billion in medical and emergency services, $60 billion in lost productivity, $5 billion in insurance costs, and $62 billion in lost quality of life. One sixth of the societal costs result from the 3% of workplace injuries in motor vehicle crashes. Motor vehicle costs per injury are almost 6 times the workplace injury average.  相似文献   
103.
Web Sights     
Miller  P. 《Spectrum, IEEE》1998,35(2):81-81
  相似文献   
104.
105.
Consideration is given to the control problem in a linear stochastic differential system where constant noise intensities in equations of state and observation are prescribed only accurate within the membership of some known sets. For control optimization, an integral root-mean-square performance criterion is used. The problem is solved by the transition to a dual one, which makes it possible to prove the existence of a saddle point of the criterion and obtain an explicit expression for the minimax control operator as functions of the solution to the dual problem. To solve the latter, an iteration algorithm is proposed; the convergence of the algorithm is proved and investigated by a model example.  相似文献   
106.
Examined the effects of counselor note-taking behavior on participants' impressions of a counselor during a career counseling session. A total of 140 participants (70 men and 70 women) rated 1 of 2 videotapes designed to credibly simulate a real career counseling interview. Note-taking was the independent variable. Results of this study suggest that whether a counselor is observed in a note-taking or non-note-taking condition has no significant effect on perceived counselor expertness, attractiveness, or trustworthiness. However, there was a significantly greater willingness of the participants to see the counselor who refrained from note-taking. Results offer tentative suggestions for those counselors who choose to take notes during a career counseling session. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
107.
The present study is based on the hypothesis that patients with recurrent attacks of aphonia differ from those with non-recurring attacks of aphonia in their anxiety levels, social assertiveness and stress-coping strategies. A comparison was made between 21 women with recurring aphonia and 19 women with non-recurring aphonia with respect to these three factors. Seventeen healthy women served as volunteers. Compared to patients with non-recurring aphonias, patients with recurring aphonias exhibited a significantly higher level of anxiety and significantly more respect for social norms and codes of propriety. Their coping was also characterized by a higher escape tendency. Patients with recurring aphonias also reported a significantly higher number of problems in their private lives within the preceding 5-year period. In therapy patients should be encouraged to reflect upon a possible rigidity toward social norms and better understand fears regarding conflicts in personal relationships.  相似文献   
108.
Five wavelength multiplexed pulse streams are generated in an integrated 16×1 laser modulator array by sinusoidally driving five of the potential 16 electroabsorption modulators. At a repetition rate of 2.5 GHz, near transform-limited pulses spaced in wavelength over 7.6 nm are observed. Pseudorandom coding of one channel is achieved by applying an electrical RZ data signal to the modulator  相似文献   
109.
110.
Endocrine disorders in critically ill infants and children can be the manifestation of an existing but previously unrecognized condition, or hormonal derangements precipitated by deleterious effects on endocrine function of a critical illness or its prescribed therapy. To achieve successful resolution of these crises, a general understanding of various endocrine dysfunctions, clinical symptomatology, diagnosis, and medical and nursing management is essential.  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