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   1644889篇
  免费   32723篇
  国内免费   9746篇
电工技术   37755篇
技术理论   6篇
综合类   10586篇
化学工业   284063篇
金属工艺   68673篇
机械仪表   48137篇
建筑科学   52716篇
矿业工程   13679篇
能源动力   52220篇
轻工业   126744篇
水利工程   17203篇
石油天然气   41722篇
武器工业   606篇
无线电   204117篇
一般工业技术   302814篇
冶金工业   211044篇
原子能技术   34691篇
自动化技术   180582篇
  2021年   18045篇
  2020年   13708篇
  2019年   16285篇
  2018年   17519篇
  2017年   17034篇
  2016年   23294篇
  2015年   19764篇
  2014年   31784篇
  2013年   91455篇
  2012年   41039篇
  2011年   54514篇
  2010年   46902篇
  2009年   54393篇
  2008年   50218篇
  2007年   47757篇
  2006年   49764篇
  2005年   43867篇
  2004年   45404篇
  2003年   45226篇
  2002年   44448篇
  2001年   41544篇
  2000年   39083篇
  1999年   38962篇
  1998年   60259篇
  1997年   48743篇
  1996年   42210篇
  1995年   35017篇
  1994年   32308篇
  1993年   31759篇
  1992年   27349篇
  1991年   24561篇
  1990年   24722篇
  1989年   23756篇
  1988年   22223篇
  1987年   20359篇
  1986年   19815篇
  1985年   23116篇
  1984年   22930篇
  1983年   20843篇
  1982年   19651篇
  1981年   19771篇
  1980年   18406篇
  1979年   18913篇
  1978年   18122篇
  1977年   18694篇
  1976年   21067篇
  1975年   16247篇
  1974年   15741篇
  1973年   15862篇
  1972年   13325篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
This study investigated the inhibitory effects of curcumin and piperine on fluorescent advanced glycation end products (fAGEs) formation in a bovine serum albumin (BSA)–fructose model. Model systems of BSA and fructose were prepared, and curcumin or piperine was added. fAGEs and BSA oxidation product (dityrosine, kynurenine and N'-formylkynurenine) contents were determined. The results showed that fAGEs content decreased with increasing concentration of curcumin and piperine (P < 0.05). Addition of curcumin and piperine at 160 µg mL−1 could inhibit fluorescent AGEs by 100% and 93% respectively. Dityrosine and N'-formylkynurenine contents decreased as curcumin and piperine concentration increased (P < 0.05). Furthermore, the result of principal component analysis indicated that curcumin and piperine markedly impeded BSA oxidation, resulting in a lower level of fAGEs in model systems. Therefore, adding curcumin and piperine may facilitate reduced fAGEs levels in BSA–fructose model.  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 - Endometriosis is a common gynecologic condition typically treated via laparoscopic surgery. Its visual versatility makes it hard to identify for non-specialized...  相似文献   
30.
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   
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