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   1475149篇
  免费   32943篇
  国内免费   10634篇
电工技术   38684篇
技术理论   3篇
综合类   11930篇
化学工业   275792篇
金属工艺   66774篇
机械仪表   43905篇
建筑科学   49862篇
矿业工程   13443篇
能源动力   52100篇
轻工业   105052篇
水利工程   15364篇
石油天然气   41602篇
武器工业   889篇
无线电   200985篇
一般工业技术   274306篇
冶金工业   119675篇
原子能技术   34478篇
自动化技术   173882篇
  2021年   18335篇
  2020年   14025篇
  2019年   16279篇
  2018年   15726篇
  2017年   15237篇
  2016年   22107篇
  2015年   19983篇
  2014年   32304篇
  2013年   91569篇
  2012年   37318篇
  2011年   48325篇
  2010年   44862篇
  2009年   53569篇
  2008年   45346篇
  2007年   41689篇
  2006年   46365篇
  2005年   39881篇
  2004年   41632篇
  2003年   41497篇
  2002年   40974篇
  2001年   36902篇
  2000年   35508篇
  1999年   33828篇
  1998年   31237篇
  1997年   31347篇
  1996年   30495篇
  1995年   28138篇
  1994年   26751篇
  1993年   26421篇
  1992年   25707篇
  1991年   22441篇
  1990年   22864篇
  1989年   21888篇
  1988年   20271篇
  1987年   18643篇
  1986年   17912篇
  1985年   21253篇
  1984年   21854篇
  1983年   19823篇
  1982年   18959篇
  1981年   19011篇
  1980年   17567篇
  1979年   18187篇
  1978年   17433篇
  1977年   16533篇
  1976年   16377篇
  1975年   15758篇
  1974年   15304篇
  1973年   15362篇
  1972年   12846篇
排序方式: 共有10000条查询结果,搜索用时 15 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