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   1538935篇
  免费   29437篇
  国内免费   7197篇
电工技术   34916篇
综合类   6588篇
化学工业   276978篇
金属工艺   66038篇
机械仪表   45286篇
建筑科学   46706篇
矿业工程   11498篇
能源动力   51864篇
轻工业   115046篇
水利工程   15321篇
石油天然气   37827篇
武器工业   169篇
无线电   201644篇
一般工业技术   289822篇
冶金工业   169191篇
原子能技术   34499篇
自动化技术   172176篇
  2021年   16734篇
  2020年   12679篇
  2019年   15536篇
  2018年   17052篇
  2017年   16357篇
  2016年   22673篇
  2015年   18341篇
  2014年   30267篇
  2013年   89947篇
  2012年   37820篇
  2011年   50981篇
  2010年   44770篇
  2009年   53128篇
  2008年   46635篇
  2007年   43337篇
  2006年   45876篇
  2005年   40397篇
  2004年   42325篇
  2003年   42116篇
  2002年   41227篇
  2001年   38025篇
  2000年   36372篇
  1999年   35505篇
  1998年   47286篇
  1997年   40277篇
  1996年   36270篇
  1995年   31251篇
  1994年   29170篇
  1993年   28994篇
  1992年   26210篇
  1991年   23332篇
  1990年   23764篇
  1989年   22812篇
  1988年   21169篇
  1987年   19474篇
  1986年   18820篇
  1985年   22142篇
  1984年   22308篇
  1983年   20282篇
  1982年   19284篇
  1981年   19383篇
  1980年   18018篇
  1979年   18518篇
  1978年   17779篇
  1977年   17583篇
  1976年   18616篇
  1975年   16015篇
  1974年   15522篇
  1973年   15623篇
  1972年   13077篇
排序方式: 共有10000条查询结果,搜索用时 156 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.
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   
23.
24.
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   
25.
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   
26.
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   
27.
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   
28.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  相似文献   
29.

We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.

  相似文献   
30.
Engineering new glass compositions have experienced a sturdy tendency to move forward from (educated) trial-and-error to data- and simulation-driven strategies. In this work, we developed a computer program that combines data-driven predictive models (in this case, neural networks) with a genetic algorithm to design glass compositions with desired combinations of properties. First, we induced predictive models for the glass transition temperature (Tg) using a dataset of 45,302 compositions with 39 different chemical elements, and for the refractive index (nd) using a dataset of 41,225 compositions with 38 different chemical elements. Then, we searched for relevant glass compositions using a genetic algorithm informed by a design trend of glasses having high nd (1.7 or more) and low Tg (500 °C or less). Two candidate compositions suggested by the combined algorithms were selected and produced in the laboratory. These compositions are significantly different from those in the datasets used to induce the predictive models, showing that the used method is indeed capable of exploration. Both glasses met the constraints of the work, which supports the proposed framework. Therefore, this new tool can be immediately used for accelerating the design of new glasses. These results are a stepping stone in the pathway of machine learning-guided design of novel glasses.  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