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   203134篇
  免费   15729篇
  国内免费   188篇
电工技术   3250篇
综合类   117篇
化学工业   42528篇
金属工艺   9742篇
机械仪表   6361篇
建筑科学   4620篇
矿业工程   1889篇
能源动力   3475篇
轻工业   15503篇
水利工程   2996篇
石油天然气   8724篇
武器工业   12篇
无线电   21095篇
一般工业技术   49183篇
冶金工业   28325篇
原子能技术   6933篇
自动化技术   14298篇
  2020年   2603篇
  2019年   4679篇
  2018年   5980篇
  2017年   6418篇
  2016年   7130篇
  2015年   5524篇
  2014年   6703篇
  2013年   11123篇
  2012年   6895篇
  2011年   7629篇
  2010年   6946篇
  2009年   7319篇
  2008年   6898篇
  2007年   6649篇
  2006年   5706篇
  2005年   5124篇
  2004年   4914篇
  2003年   4757篇
  2002年   4621篇
  2001年   4513篇
  2000年   4378篇
  1999年   3638篇
  1998年   7046篇
  1997年   5168篇
  1996年   3712篇
  1995年   2908篇
  1994年   2592篇
  1993年   2712篇
  1992年   2248篇
  1991年   2300篇
  1990年   2407篇
  1989年   2303篇
  1988年   2303篇
  1987年   2173篇
  1986年   2244篇
  1985年   2285篇
  1984年   2199篇
  1983年   2122篇
  1982年   1965篇
  1981年   2182篇
  1980年   2050篇
  1979年   2250篇
  1978年   2429篇
  1977年   2424篇
  1976年   3083篇
  1975年   2239篇
  1974年   2296篇
  1973年   2333篇
  1972年   2152篇
  1971年   1902篇
排序方式: 共有10000条查询结果,搜索用时 548 毫秒
1.
Grachev  A. I. 《Semiconductors》2022,56(2):67-70
Semiconductors - In this work, we discuss for the first time the principle of rotation in the constant electric field of a conducting particle with participation of the Lorentz force, which ensures...  相似文献   
2.
Journal of Communications Technology and Electronics - A quantitative comparison of the spectral characteristics of the human visual system and matrix photodetectors is carried out. Criteria for a...  相似文献   
3.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
4.
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...  相似文献   
5.
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of...  相似文献   
6.
Automation and Remote Control - A linear-quadratic positional differential game of three persons is considered. Coefficient criteria are established under which there is no Nash equilibrium...  相似文献   
7.
Recent advances in three‐dimensional (3D) printing have enabled the fabrication of interesting structures which are not achievable using traditional fabrication approaches. The 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks, which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through a facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions with a chitosan polymer matrix are achieved. Consequently, the mechanical properties of the 3D printed composites improve when nanogrooved carbon microtubes are used, compared to untreated microtubes. We show that by carefully controlling the coagulation bath, extrusion pressure, printing distance and printed line distance, we can 3D print composite lattices which are composed of well‐defined and separated printed lines. The conductive composite 3D structures with highly customised design presented in this work provide a suitable platform for applications ranging from soft robotics to smart tissue engineering scaffolds. © 2019 Society of Chemical Industry  相似文献   
8.
Russian Engineering Research - Digital tools for managing improvements in automobile production are developed. An operative tool provides warnings regarding the operational quality of the vehicles...  相似文献   
9.
Theoretical Foundations of Chemical Engineering - Using gas–liquid chromatography, the activity coefficients upon the infinite dilution of the components of the reaction mixture for obtaining...  相似文献   
10.
Ceria-based solid solutions are important materials for high- and medium-temperature electrochemical applications. However, the stabilities of both binary and ternary ceria-based solid solutions are insufficient at elevated temperatures, which limits their application as solid electrolytes or SOFC cathodes. Data on the high-temperature stability of ceria-based ceramics are unavailable in the literature. In the present study, we report a thermodynamic stability investigation of Y2O3-CeO2 and Y2O3-ZrO2-CeO2 solid solutions. The thermal prehistories of binary and ternary systems were investigated using STA, XRD, and ESCA techniques. The vaporization processes were investigated in the temperature range of 1577–2227°С via the Knudsen effusion mass spectrometry technique. Using data on the component activity in solid-phase thermodynamic properties of Y2O3-CeO2 solid solutions, which is represented as the Gibbs energy, the excess Gibbs energy was calculated as a function of the ceria mol. %. It was shown that the reduction of Ce4+ to Ce3+ in Y2O3-CeO2 and Y2O3-ZrO2-CeO2 solid solutions corresponds to less-negative Gibbs energy compared to ZrO2-CeO2 solid solutions.  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