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   938557篇
  免费   11306篇
  国内免费   4205篇
电工技术   21542篇
技术理论   3篇
综合类   6706篇
化学工业   142609篇
金属工艺   38392篇
机械仪表   31989篇
建筑科学   25476篇
矿业工程   7363篇
能源动力   25714篇
轻工业   73183篇
水利工程   11729篇
石油天然气   22578篇
武器工业   725篇
无线电   106117篇
一般工业技术   180710篇
冶金工业   154304篇
原子能技术   21045篇
自动化技术   83883篇
  2022年   7973篇
  2021年   11741篇
  2020年   9423篇
  2019年   10588篇
  2018年   15028篇
  2017年   15568篇
  2016年   16222篇
  2015年   12161篇
  2014年   18869篇
  2013年   44932篇
  2012年   28583篇
  2011年   37526篇
  2010年   30365篇
  2009年   33155篇
  2008年   33737篇
  2007年   32995篇
  2006年   29337篇
  2005年   26067篇
  2004年   23758篇
  2003年   23027篇
  2002年   22139篇
  2001年   21314篇
  2000年   20211篇
  1999年   20552篇
  1998年   47185篇
  1997年   33755篇
  1996年   26378篇
  1995年   20116篇
  1994年   17877篇
  1993年   17482篇
  1992年   13134篇
  1991年   12403篇
  1990年   12172篇
  1989年   11682篇
  1988年   11074篇
  1987年   9937篇
  1986年   9546篇
  1985年   10862篇
  1984年   9850篇
  1983年   9203篇
  1982年   8378篇
  1981年   8534篇
  1980年   7976篇
  1979年   8011篇
  1978年   7837篇
  1977年   8843篇
  1976年   11231篇
  1975年   6927篇
  1974年   6646篇
  1973年   6742篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
A candle filter was used to determine flow rate characteristics of filtering suspensions under axial vibrations. In this work, a generalised analysis of filtration under vibrating conditions was developed. The model required the use of experimental data interpretation. The analysis gives in a simplified form the complicated functional relationship between time, cumulative flow, vibration parameters and other process variables.Such a relationship can be used in the design of vibratory filters for predicting flow rate with time. These filters are useful in particle separation processes.  相似文献   
993.
994.
Translated from Atomnaya Énergiya, Vol. 66, No. 2, pp. 79–81, February, 1989.  相似文献   
995.
996.
This paper presents some improvements to the load flow solution in rectangular coordinates. First, in an attempt to use as linear a model as possible, both the nodal equations and the bus constraints are retained. The Newton-Raphson (NR) method is then applied to the enlarged set of equations, and written in terms of bus voltages and currents. This scheme, combined with a simple procedure to handle PV buses, leads to a computationally efficient algorithm, particularly advantageous in the presence of zero-injection buses. Experimental results are provided comparing the performance of the proposed approach with that of the conventional formulation  相似文献   
997.
Outage in digital microwave radio systems during multipath fading is highly correlated with the channel amplitude dispersion. This characteristic is exploited in a new digital microwave radio system measurement technique which yields dispersion signatures. These dispersion signatures can be readily applied to assess the effects of time varying channels on digital radio equipment. Thus, dispersion signatures can be used for in-service monitoring of equipment operation during actual fading. Routine maintenance assessment and laboratory evaluation of digital microwave radio equipment can also be readily carried out. The laboratory evaluation results can be used for system design both with and without diversity.  相似文献   
998.
999.
When sulphur dioxide inhibits the enzymic browning of catechol catalysed by mushroom tyrosinase, the main reaction product is 4-sulphocatechol. When assessed for its browning potential, this product appears to be unreactive and does not inhibit the enzyme.  相似文献   
1000.
Improving the efficiency of induction motors, which are the most energy consuming electric machines in the world, saves much energy. The efficiency can be increased by improving cooling performance as well as by using better materials or by improving electromagnetic performance with better design. This paper presents the relationship between the efficiency or the losses and the temperature of coils with experiments as well as simulations by changing parameters such as the load and the flow rate of cooling air. The losses and the efficiency are calculated from an equivalent circuit method as well as experiments. Coil temperatures variation affects much on the efficiency. The internal cooling method is better than that of external cooling for the coil temperature reduction. Several cooling methods are compared focusing on the fan efficiency and performance, from which the values of the efficiencies of the motors are expected. The fan efficiency as well as the fan performance should be considered for the optimum fan design to increase the total efficiency of a motor. The simulations are validated by the comparison with the experiments  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