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   1537289篇
  免费   31939篇
  国内免费   9491篇
电工技术   37857篇
技术理论   3篇
综合类   10413篇
化学工业   278710篇
金属工艺   66965篇
机械仪表   45852篇
建筑科学   50090篇
矿业工程   13241篇
能源动力   51726篇
轻工业   113934篇
水利工程   15898篇
石油天然气   41217篇
武器工业   713篇
无线电   201742篇
一般工业技术   287370篇
冶金工业   153242篇
原子能技术   34452篇
自动化技术   175294篇
  2021年   17839篇
  2020年   13660篇
  2019年   16024篇
  2018年   17056篇
  2017年   16612篇
  2016年   22628篇
  2015年   19477篇
  2014年   31466篇
  2013年   90708篇
  2012年   38323篇
  2011年   50831篇
  2010年   45357篇
  2009年   53521篇
  2008年   47090篇
  2007年   43851篇
  2006年   47221篇
  2005年   41326篇
  2004年   42764篇
  2003年   42577篇
  2002年   41655篇
  2001年   38298篇
  2000年   36641篇
  1999年   35741篇
  1998年   42118篇
  1997年   37834篇
  1996年   34785篇
  1995年   30709篇
  1994年   28781篇
  1993年   28367篇
  1992年   26485篇
  1991年   23407篇
  1990年   23647篇
  1989年   22619篇
  1988年   21100篇
  1987年   19409篇
  1986年   18774篇
  1985年   22043篇
  1984年   22319篇
  1983年   20285篇
  1982年   19228篇
  1981年   19292篇
  1980年   17866篇
  1979年   18485篇
  1978年   17702篇
  1977年   17190篇
  1976年   17747篇
  1975年   15965篇
  1974年   15538篇
  1973年   15589篇
  1972年   13040篇
排序方式: 共有10000条查询结果,搜索用时 14 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.
Ceramic microparticles have great potentials in various fields such as materials engineering, biotechnology, microelectromechanical systems, etc. Morphology of the microparticle performs an important role on their application. To date, it remains difficult to find an effective and controllable way for fabricating nonspherical ceramic microparticles with 3D features. This work demonstrates a method that combines UV light lithography and single emulsion opaque-droplet-templated microfluidic molding to prepare the crescent-shaped ceramic microparticles. By tailoring the intensity of UV light and flow rate of fluid, the shapes of microparticles are accordingly tuned. Therefore, varieties of crescent-shaped microparticles and their variations have been fabricated. After sintering, the crescent-shaped alumina ceramic microparticles were obtained. Benefitting from the light absorption and scattering behavior of most ceramic nanoparticles, this system can serve as a general platform to produce crescent-shaped microparticles made from different materials, and hold great potentials for applications in microrobotics, structural materials in MEMS, and biotechnology.  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.
29.
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   
30.

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   
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