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   323527篇
  免费   3374篇
  国内免费   920篇
电工技术   6446篇
综合类   274篇
化学工业   45166篇
金属工艺   15809篇
机械仪表   12979篇
建筑科学   7403篇
矿业工程   1611篇
能源动力   7884篇
轻工业   22236篇
水利工程   3231篇
石油天然气   4603篇
武器工业   15篇
无线电   40897篇
一般工业技术   68296篇
冶金工业   53971篇
原子能技术   6094篇
自动化技术   30906篇
  2022年   1470篇
  2021年   2202篇
  2020年   1584篇
  2019年   1943篇
  2018年   11326篇
  2017年   11941篇
  2016年   7971篇
  2015年   2748篇
  2014年   4072篇
  2013年   11597篇
  2012年   8783篇
  2011年   16613篇
  2010年   14557篇
  2009年   14484篇
  2008年   14651篇
  2007年   16588篇
  2006年   7446篇
  2005年   10026篇
  2004年   8196篇
  2003年   8092篇
  2002年   6653篇
  2001年   6582篇
  2000年   6110篇
  1999年   6419篇
  1998年   16493篇
  1997年   11420篇
  1996年   8812篇
  1995年   6623篇
  1994年   5941篇
  1993年   5874篇
  1992年   4153篇
  1991年   4048篇
  1990年   3860篇
  1989年   3651篇
  1988年   3573篇
  1987年   3026篇
  1986年   2949篇
  1985年   3213篇
  1984年   2933篇
  1983年   2837篇
  1982年   2639篇
  1981年   2556篇
  1980年   2468篇
  1979年   2312篇
  1978年   2116篇
  1977年   2609篇
  1976年   3565篇
  1975年   1770篇
  1974年   1731篇
  1973年   1666篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
94.
95.
Powder Metallurgy and Metal Ceramics - The mechanisms of phase interactions in granular media were studied to elaborate the results obtained previously at the Nekrasov Iron and Steel Institute of...  相似文献   
96.
Neural Computing and Applications - The identification of water stress is a major challenge for timely and effective irrigation to ensure global food security and sustainable agriculture. Several...  相似文献   
97.
The data on the use of solar photovoltaic plants (PVPs) for providing a reliable and guaranteed power supply to telecommunication systems and cellular communication systems in the conditions prevalent in Uzbekistan are given. The research-based structures developed by OOO MIR SOLAR and the selection of PVP elements ensuring their reliable operation are described. The main influencing factors are discussed, and the use of effective combinations of different types of panels (from monocrystalline and polycrystalline silicon) and a specially developed controller are considered.  相似文献   
98.
Alkyd resins are generally used in the production of printing inks. All industries look for alternative raw materials in the production of ink with the growing inclination toward using natural products. Resins forming the vehicle of the ink to be obtained from natural resources will provide benefits for the environment, nature, and living creatures. The aim of the study was to promote the use of natural resin in the ink system. Natural Pinus pinaster resin was added into vegetable and mineral oil-based solvents in pure form with alkyd resin in different amounts and ink varnishes of different combinations were prepared. Then, printing inks were produced from these varnishes in pure and hybrid form. Following the assessment of the rheological properties of the inks prepared, printing tests were conducted to assess the printing quality parameters. Ideal mixing ratios of the natural resins in the ink were determined for printability. The environmental importance and advantages of the use of natural resins were discussed. Recommendations were given in line with the results to encourage widespread use of natural resins in near future.  相似文献   
99.
This work presents simulation of microstructure evolution in the nugget zone (NZ) of a AZ31-Mg-alloy friction stir weld. The process parameters (tool geometrical characteristics, rotational speed, travel speed, applied load) have been correlated with the resulting microstructural features in the NZ of the weld (grain size and population) with the aid of the MICRESS software, which provides the ability to simulate both nucleation and grain growth during dynamic recrystallization phenomena evolving in the NZ during the weld thermal cycle. The input parameters of the developed model include the tool geometry, the welding conditions as well as the recrystallization energy, the grain boundary mobility and specific material properties. NZ microstructure obtained by simulation shows good agreement with experimental measurements for both grain population and size.  相似文献   
100.
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