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   1595152篇
  免费   28066篇
  国内免费   7014篇
电工技术   34733篇
综合类   6472篇
化学工业   269723篇
金属工艺   65663篇
机械仪表   45287篇
建筑科学   47467篇
矿业工程   11613篇
能源动力   50548篇
轻工业   122053篇
水利工程   16217篇
石油天然气   37820篇
武器工业   155篇
无线电   199339篇
一般工业技术   298552篇
冶金工业   216913篇
原子能技术   34326篇
自动化技术   173351篇
  2021年   15579篇
  2020年   12082篇
  2019年   14871篇
  2018年   17807篇
  2017年   17211篇
  2016年   22482篇
  2015年   17695篇
  2014年   28924篇
  2013年   88461篇
  2012年   38124篇
  2011年   52187篇
  2010年   44743篇
  2009年   52494篇
  2008年   48193篇
  2007年   45749篇
  2006年   46657篇
  2005年   41819篇
  2004年   43627篇
  2003年   43238篇
  2002年   41995篇
  2001年   39459篇
  2000年   37516篇
  1999年   37657篇
  1998年   62375篇
  1997年   49623篇
  1996年   42074篇
  1995年   34698篇
  1994年   31913篇
  1993年   31888篇
  1992年   27044篇
  1991年   24285篇
  1990年   24540篇
  1989年   23603篇
  1988年   21600篇
  1987年   19844篇
  1986年   19306篇
  1985年   22637篇
  1984年   22394篇
  1983年   20322篇
  1982年   19293篇
  1981年   19486篇
  1980年   18095篇
  1979年   18503篇
  1978年   17815篇
  1977年   18331篇
  1976年   20535篇
  1975年   15957篇
  1974年   15445篇
  1973年   15558篇
  1972年   13104篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
21.
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   
22.
23.
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   
24.
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   
25.
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   
26.
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   
27.
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   
28.
Forschung im Ingenieurwesen - Das Arbeitsmittel in Wärmepumpen unterliegt einer Vielzahl von Anforderungen, welche für einen effizienten und sicheren Betrieb eingehalten werden...  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