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   3713篇
  免费   156篇
  国内免费   2篇
电工技术   41篇
综合类   14篇
化学工业   1129篇
金属工艺   78篇
机械仪表   50篇
建筑科学   193篇
矿业工程   7篇
能源动力   61篇
轻工业   365篇
水利工程   4篇
石油天然气   4篇
无线电   205篇
一般工业技术   729篇
冶金工业   451篇
原子能技术   38篇
自动化技术   502篇
  2023年   41篇
  2022年   59篇
  2021年   80篇
  2020年   46篇
  2019年   69篇
  2018年   53篇
  2017年   60篇
  2016年   97篇
  2015年   92篇
  2014年   118篇
  2013年   190篇
  2012年   182篇
  2011年   224篇
  2010年   170篇
  2009年   180篇
  2008年   187篇
  2007年   171篇
  2006年   144篇
  2005年   136篇
  2004年   108篇
  2003年   81篇
  2002年   78篇
  2001年   67篇
  2000年   69篇
  1999年   85篇
  1998年   123篇
  1997年   84篇
  1996年   60篇
  1995年   69篇
  1994年   56篇
  1993年   50篇
  1992年   48篇
  1991年   50篇
  1990年   30篇
  1989年   35篇
  1988年   40篇
  1987年   34篇
  1986年   28篇
  1985年   30篇
  1984年   35篇
  1983年   18篇
  1982年   19篇
  1981年   26篇
  1980年   19篇
  1979年   24篇
  1978年   21篇
  1977年   21篇
  1976年   37篇
  1975年   25篇
  1974年   20篇
排序方式: 共有3871条查询结果,搜索用时 15 毫秒
21.
22.
23.
Several states have designed and implemented innovative programs for Medicaid beneficiaries that carve-out the provision of mental health from general health care. This paper describes several such programs and outlines the choices states face in designing these services. Major decisions include the selection of a public or private agency, how that agency is chosen, reimbursement schemes, eligibility criteria, and benefits to be covered. While carve-out programs have yielded initial savings, more research is needed on their effect on quality of care and general health care costs.  相似文献   
24.
A double-blind clinical study was performed to evaluate prednisolone as treatment for idiopathic feline lower urinary tract disease. No differences in response were observed in prednisolone- and placebo-treated cats.  相似文献   
25.
The multi-class binomial failure rate model   总被引:1,自引:0,他引:1  
The impact of common cause failure (CCF) on PSA results for NPPs is in sharp contrast with the limited quality which can be achieved in their assessment. This is due to the dearth of observations and cannot be remedied in the short run. Therefore, the methods employed for calculating failure rates should be devised such as to make the best use of the few available observations on CCF. The Multi-Class Binomial Failure Rate (MCBFR) Model presented here achieves this by assigning observed failures to different classes according to their technical characteristics and applying the BFR formalism to each of these. The results are determined by a superposition of BFR type expressions for each class, each of them with its own coupling factor. The model hence integrates additional technical information on CCFs and leads to a better quality of results whenever this information is available. This is demonstrated by evaluating CCFs observed for combined impulse pilot valves in German NPPs.  相似文献   
26.
The reduction of nitric oxide with ammonia on an unsupported iron oxide catalyst has been studied in a continuous-flow recycle reactor using simulated flue gas. The responses of the employed reactor system to step and pulse inputs of tracer indicate that the system could be regarded as a continuous stirred tank reactor (CSTR). Preliminary tests were carried out to determine the effect of temperature and particle size on the measured reaction rates. Additional experiments were performed in order to study the influence of oxygen and water concentration on these rates. A gas chromatographic system has been developed to analyze the gas components NO, N2O, NO2, NH3, H2O, O2, CO2 and N2. In addition, the concentrations of NO and NO2 were measured with a nondisperse infrared (NDUV/NDIR) analyzer.  相似文献   
27.
28.
29.
In case of findings of authorized genetically modified (gm) plant ingredients below the 0.9 per cent threshold, exceptions from labelling requirements according to regulation (EC) No. 1829/2003 can only be made, “provided that this presence is adventitious or technically unavoidable”. The authors describe factors that should be considered regarding contaminations by gm plant ingredients as technically unavoidable or not. A practical approach for interpretation, taking into account quality control measures and documentation as well as present findings in comparable products is proposed. Received: February 23, 2007  相似文献   
30.
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