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   1653824篇
  免费   42631篇
  国内免费   15077篇
电工技术   45382篇
技术理论   13篇
综合类   17821篇
化学工业   297127篇
金属工艺   73000篇
机械仪表   52736篇
建筑科学   59041篇
矿业工程   16818篇
能源动力   54969篇
轻工业   121134篇
水利工程   18280篇
石油天然气   47538篇
武器工业   1539篇
无线电   215349篇
一般工业技术   300057篇
冶金工业   164277篇
原子能技术   35715篇
自动化技术   190736篇
  2022年   16315篇
  2021年   23608篇
  2020年   17898篇
  2019年   19334篇
  2018年   20857篇
  2017年   20952篇
  2016年   26588篇
  2015年   24554篇
  2014年   37570篇
  2013年   98129篇
  2012年   46656篇
  2011年   59237篇
  2010年   52505篇
  2009年   60401篇
  2008年   53404篇
  2007年   49827篇
  2006年   52848篇
  2005年   46345篇
  2004年   45812篇
  2003年   44980篇
  2002年   43714篇
  2001年   40094篇
  2000年   38622篇
  1999年   38099篇
  1998年   45739篇
  1997年   40525篇
  1996年   36997篇
  1995年   32284篇
  1994年   30092篇
  1993年   29365篇
  1992年   26916篇
  1991年   23799篇
  1990年   23899篇
  1989年   22965篇
  1988年   21269篇
  1987年   19477篇
  1986年   18822篇
  1985年   22087篇
  1984年   22284篇
  1983年   20231篇
  1982年   19252篇
  1981年   19324篇
  1980年   17966篇
  1979年   18465篇
  1978年   17671篇
  1977年   17384篇
  1976年   18074篇
  1975年   15936篇
  1974年   15439篇
  1973年   15530篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Food Science and Biotechnology - A rich source of nutrients, figs have a number of clinically validated benefits. This study aimed to evaluate the in vitro simulated gastrointestinal digestion, and...  相似文献   
22.
Polymer electrets have revealed great potential application in electromechanical devices because of the low weight, large quasi-piezoelectric sensitivity, and excellent flexibility. For an electret, a permanent and macroscopic electric field exists on the surface, principally led by a macroscopic electrostatic charge on the surface or a net orientation of polar groups inside the object. Here, progress in the development of polymer electrets is reviewed. After a brief retrospect of the research courses and those typical polymer electrets that are classified into fluorine polymer and nonfluorine polymer, we present a survey on the charging methods, including corona, soft X-ray, contact, thermal and monoenergetic particle beams. The latest representative applications (i.e., power harvesting, sensors, field effect transistors, and biomedicine) based on polymer electrets are also summarized. Finally, we complete this review with a discussion on perspectives and challenges in this field.  相似文献   
23.
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   
24.
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   
25.
26.
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   
27.
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   
28.
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   
29.
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   
30.
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   
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