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   1760700篇
  免费   43169篇
  国内免费   15154篇
电工技术   46421篇
技术理论   13篇
综合类   17935篇
化学工业   304264篇
金属工艺   75541篇
机械仪表   57581篇
建筑科学   61423篇
矿业工程   17316篇
能源动力   55322篇
轻工业   134756篇
水利工程   19567篇
石油天然气   48436篇
武器工业   1548篇
无线电   219594篇
一般工业技术   319304篇
冶金工业   206614篇
原子能技术   36476篇
自动化技术   196912篇
  2022年   16446篇
  2021年   23809篇
  2020年   18066篇
  2019年   19507篇
  2018年   24441篇
  2017年   25031篇
  2016年   28385篇
  2015年   24905篇
  2014年   37743篇
  2013年   98664篇
  2012年   49988篇
  2011年   65740篇
  2010年   56649篇
  2009年   63646篇
  2008年   58349篇
  2007年   55695篇
  2006年   55389篇
  2005年   50111篇
  2004年   48497篇
  2003年   47322篇
  2002年   45556篇
  2001年   42000篇
  2000年   40250篇
  1999年   40359篇
  1998年   58499篇
  1997年   48390篇
  1996年   41981篇
  1995年   35175篇
  1994年   32445篇
  1993年   31718篇
  1992年   27736篇
  1991年   24713篇
  1990年   24846篇
  1989年   23833篇
  1988年   22311篇
  1987年   20413篇
  1986年   19763篇
  1985年   23011篇
  1984年   22776篇
  1983年   20736篇
  1982年   19590篇
  1981年   19694篇
  1980年   18360篇
  1979年   18799篇
  1978年   18001篇
  1977年   18319篇
  1976年   20125篇
  1975年   16236篇
  1974年   15673篇
  1973年   15794篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
针对传统的电弧电路故障检测结果不准确的问题,设计用于电弧检测的SoC系统,并且在55nm工艺下进行流片验证。采用包含两种结构的模数转换器的片上电压源,设计了锁相环以及复位电路,精度最高可达8.67 bit。验证结果表明,本设计可提高电弧检测的准确性。  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