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   1618855篇
  免费   33978篇
  国内免费   11085篇
电工技术   40024篇
技术理论   6篇
综合类   12486篇
化学工业   287912篇
金属工艺   70539篇
机械仪表   50221篇
建筑科学   54034篇
矿业工程   14895篇
能源动力   53050篇
轻工业   118109篇
水利工程   17175篇
石油天然气   44679篇
武器工业   939篇
无线电   207450篇
一般工业技术   297950篇
冶金工业   178044篇
原子能技术   35148篇
自动化技术   181257篇
  2022年   13216篇
  2021年   19664篇
  2020年   15058篇
  2019年   17169篇
  2018年   19724篇
  2017年   19585篇
  2016年   24758篇
  2015年   21420篇
  2014年   33421篇
  2013年   93353篇
  2012年   42124篇
  2011年   55597篇
  2010年   49028篇
  2009年   56991篇
  2008年   50636篇
  2007年   47777篇
  2006年   49847篇
  2005年   44391篇
  2004年   44490篇
  2003年   44328篇
  2002年   42973篇
  2001年   39779篇
  2000年   38098篇
  1999年   37795篇
  1998年   50820篇
  1997年   42858篇
  1996年   38196篇
  1995年   32732篇
  1994年   30398篇
  1993年   29870篇
  1992年   26769篇
  1991年   23750篇
  1990年   24014篇
  1989年   23019篇
  1988年   21461篇
  1987年   19647篇
  1986年   18980篇
  1985年   22235篇
  1984年   22381篇
  1983年   20289篇
  1982年   19274篇
  1981年   19405篇
  1980年   17973篇
  1979年   18458篇
  1978年   17706篇
  1977年   17467篇
  1976年   18393篇
  1975年   15974篇
  1974年   15464篇
  1973年   15574篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
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   
22.
In this work, the composition-dependent point defect types and formation energies of RE2Hf2O7 (RE = La, Ce, Pr, Nd, Pm, Sm, Eu and Gd) as well as the oxygen diffusion behavior are systematically investigated by first-principles calculations. The possible defect reactions and dominant defect complexes under stoichiometric and non-stoichiometric conditions are revealed. It is found that O Frenkel pairs are the predominant defect in stoichiometric pyrochlore hafnates. Hf-RE cation anti-site defects, accompanied by RE vacancies and/or oxygen interstitials, are stable in the non-stoichiometric case of HfO2 excess. On the other hand, RE-Hf anti-site defects together with oxygen vacancies and/or RE interstitials are preferable in the case of RE2O3 excess. The energy barriers for the migration along the VO48f - VO48f pathway of pyrochlore hafnates were calculated to be between 0.81 eV and 0.89 eV. Based on these results, a defect engineering strategy is proposed and the pyrochlore hafnates investigated here are predicted to exhibit potential oxygen ionic conductivity.  相似文献   
23.
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...  相似文献   
24.
25.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested...  相似文献   
26.
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell.  相似文献   
27.
Zhao  Ziyu  Lin  Haitao  Ma  Pibo 《Applied Composite Materials》2022,29(4):1675-1694
Applied Composite Materials - In this paper, the low-velocity impact deformation behavior of biaxial warp-knitted flexible composite was investigated. A simplified finite element model (FEM) of the...  相似文献   
28.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a...  相似文献   
29.
Multimedia Tools and Applications - In this work, a new fuzzy logic-based algorithm is proposed for the enhancement of low light color images. A generalization of a fuzzy set known as an...  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