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   212941篇
  免费   24173篇
  国内免费   6275篇
电工技术   9654篇
技术理论   9篇
综合类   8958篇
化学工业   44781篇
金属工艺   10638篇
机械仪表   11154篇
建筑科学   11888篇
矿业工程   4006篇
能源动力   4913篇
轻工业   16615篇
水利工程   3547篇
石油天然气   9766篇
武器工业   1055篇
无线电   25146篇
一般工业技术   38540篇
冶金工业   12534篇
原子能技术   4895篇
自动化技术   25290篇
  2024年   735篇
  2023年   2446篇
  2022年   4906篇
  2021年   6727篇
  2020年   6139篇
  2019年   7070篇
  2018年   8185篇
  2017年   8932篇
  2016年   8981篇
  2015年   9525篇
  2014年   11225篇
  2013年   14190篇
  2012年   12563篇
  2011年   13094篇
  2010年   11655篇
  2009年   11429篇
  2008年   10839篇
  2007年   10117篇
  2006年   9297篇
  2005年   7923篇
  2004年   6331篇
  2003年   6258篇
  2002年   6277篇
  2001年   5657篇
  2000年   4955篇
  1999年   3904篇
  1998年   3002篇
  1997年   2461篇
  1996年   2153篇
  1995年   1868篇
  1994年   1624篇
  1993年   1352篇
  1992年   1291篇
  1991年   1148篇
  1990年   1149篇
  1989年   1066篇
  1988年   964篇
  1987年   899篇
  1986年   813篇
  1985年   747篇
  1984年   752篇
  1981年   698篇
  1979年   755篇
  1978年   800篇
  1977年   767篇
  1976年   804篇
  1975年   729篇
  1974年   730篇
  1973年   733篇
  1972年   710篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
941.
An upgraded system for controlling pneumatic transportation of glass batch materials produced by the Stromizmeritel' JSC is considered. Comparative analysis of various schemes of control over the process of filling the pneumatic-cell pump with material is provided.  相似文献   
942.
A testing technique developed for determining the acceptance levels of different inspected zones of a wheel pair is considered. It has been shown that the acceptance levels are individual for different inspected zones and are set on the basis of the statistical data obtained during the tests of wheel pairs containing flaws detected beforehand. A test record sheet containing coordinates of flaws and comments on their hazard is issued during automated acoustic-emission testing of the wheel pairs of a freight-car carriage.  相似文献   
943.
944.
通过质量检测、煤的岩相分析和20kg试验焦炉炼焦试验,对澳大利亚两种进口焦煤诺维茨煤和峰景煤的煤质和结焦特性进行了研究,两种进口焦煤低灰、低硫,为单一煤层煤,煤质稳定,配煤炼焦有利于焦炭质量稳定。峰景煤和国内柳湾煤的结焦性能相当,诺维茨煤的结焦性能与国内恒山煤和祁县煤的结焦性能接近。  相似文献   
945.
Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 1, pp. 51–53, January–February, 1992.  相似文献   
946.
The results are presented of experimental examination of the effect of the grain size on the spoliation of copper. Levels of the loading pressure, corresponding to various stages of spollation, were determined for two initial states characterized by a mean grain size of 0.29 and 1.62 mm. The results show that for the material with the smaller grain these levels are approximately 0.2 GPa higher than for the material with the larger grain size.Translated from Problemy Prochnosti, No. 2, pp. 73–75, February, 1996.  相似文献   
947.
A method of calculating the response of sensitive elements based on wave delay devices is described using as an example a gauge for measuring the diameter of holes in metal objects. The efficiency of a sensitive element consisting a cylindrical helix with a longitudinally conducting shield is demonstrated. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 46–50, September, 1996.  相似文献   
948.
The application of a combination of join and semi-join operations to minimize the amount of data transmission required for distributed query processing is discussed. Specifically, two important concepts that occur with the use of join operations as reducers in query processing, namely, gainful semi-joins and pure joint attributes, are used. Some semi-joint, though not profitable themselves, may benefit the execution of subsequent join operations as reducers. Such a semi-join is termed a gainful semi-join. In addition, join attributes that are not part of the output attributes are referred to as pure join attributes. They exploit the usefulness of gainful semi-joins and use the removability of pure join attributes to reduce the amount of data transmission required for query processing. Heuristic searches are developed to determine a sequence of join and semi-join reducers for query processing. Results indicate the importance of the approach to combining joins and semi-joins for distributed query processing  相似文献   
949.
The potential associated with quantum well (QW) structures is usually assumed to be a step function; this implies a compositional abruptness at each interface. But abrupt interfaces do not occur in practice, especially if one of the atoms segregates during growth. This leads to asymmetries in the QW potentials which could radically affect device performance.  相似文献   
950.
As a science and as a special activity concerned with measurements, the science of metrology pursues a classical, orthodox purpose, mainly involving the measurement of physical quantities. The term “measurement” is now applied also to social, economic, medical, and other disciplines, including cybernetics and problems of management and control. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 17–20, July, 1996.  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