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   1437108篇
  免费   30202篇
  国内免费   8595篇
电工技术   36390篇
技术理论   1篇
综合类   8530篇
化学工业   271457篇
金属工艺   64723篇
机械仪表   41105篇
建筑科学   46665篇
矿业工程   12296篇
能源动力   50936篇
轻工业   101968篇
水利工程   14654篇
石油天然气   39092篇
武器工业   445篇
无线电   196890篇
一般工业技术   270346篇
冶金工业   117850篇
原子能技术   34080篇
自动化技术   168477篇
  2021年   17063篇
  2020年   12929篇
  2019年   15432篇
  2018年   14800篇
  2017年   14118篇
  2016年   21182篇
  2015年   18537篇
  2014年   30283篇
  2013年   89275篇
  2012年   34661篇
  2011年   45318篇
  2010年   41999篇
  2009年   51049篇
  2008年   42769篇
  2007年   39203篇
  2006年   44016篇
  2005年   37916篇
  2004年   40127篇
  2003年   40235篇
  2002年   39616篇
  2001年   35722篇
  2000年   34616篇
  1999年   32924篇
  1998年   30463篇
  1997年   30702篇
  1996年   29914篇
  1995年   27662篇
  1994年   26375篇
  1993年   26196篇
  1992年   25494篇
  1991年   22325篇
  1990年   22759篇
  1989年   21815篇
  1988年   20231篇
  1987年   18618篇
  1986年   17880篇
  1985年   21247篇
  1984年   21831篇
  1983年   19811篇
  1982年   18949篇
  1981年   18988篇
  1980年   17563篇
  1979年   18181篇
  1978年   17434篇
  1977年   16535篇
  1976年   16373篇
  1975年   15759篇
  1974年   15305篇
  1973年   15362篇
  1972年   12847篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Ripe carambolas are hard to store and transport, while freeze-dried ones are easy to store. However, its long production time leads to higher costs. This study shows that high hydrostatic pressure (HHP) treatment could shorten the freeze-drying time of carambola slices. After HHP treatment (25–250 MPa), the drying time of the fresh sample can be shortened by 33.3–44.4% and the distribution of water and pigment in tissues is much uniform. With the increment of the pressure, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rate are increased. At 250 MPa, the total phenolic content (TPC) increased from 11.34 to 13.36 mg GAE g−1, and the total flavonoid content (TFC) of the control sample was increased from 10.77 to 12.73 mg RE g−1. Compared with the untreated sample, HHP treatment can enhance the flavour and shorten the freeze-drying time. This work guides the application of HHP technology for drying food processing.  相似文献   
22.
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   
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.
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   
28.
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   
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