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   51659篇
  免费   2603篇
  国内免费   204篇
电工技术   758篇
综合类   141篇
化学工业   10933篇
金属工艺   2214篇
机械仪表   3326篇
建筑科学   1167篇
矿业工程   33篇
能源动力   2231篇
轻工业   4055篇
水利工程   279篇
石油天然气   133篇
武器工业   4篇
无线电   8076篇
一般工业技术   11019篇
冶金工业   4151篇
原子能技术   668篇
自动化技术   5278篇
  2024年   51篇
  2023年   590篇
  2022年   892篇
  2021年   1534篇
  2020年   1107篇
  2019年   1216篇
  2018年   1479篇
  2017年   1455篇
  2016年   1791篇
  2015年   1339篇
  2014年   2157篇
  2013年   3134篇
  2012年   3351篇
  2011年   3999篇
  2010年   2911篇
  2009年   3020篇
  2008年   2910篇
  2007年   2256篇
  2006年   2126篇
  2005年   1779篇
  2004年   1641篇
  2003年   1602篇
  2002年   1426篇
  2001年   1222篇
  2000年   1055篇
  1999年   972篇
  1998年   1654篇
  1997年   1057篇
  1996年   859篇
  1995年   601篇
  1994年   479篇
  1993年   435篇
  1992年   305篇
  1991年   288篇
  1990年   274篇
  1989年   258篇
  1988年   213篇
  1987年   177篇
  1986年   126篇
  1985年   122篇
  1984年   99篇
  1983年   66篇
  1982年   43篇
  1981年   45篇
  1980年   36篇
  1979年   33篇
  1978年   32篇
  1977年   46篇
  1976年   75篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Complementary electroplating combined with electrophoresis enhanced the field emission characteristics of emitters by improving the adhesions between CNT emitters and substrate. The emitting current of the CNT emitters prepared by our combined method increased nine times higher than that of CNT emitters prepared by electrophoresis only, since electroplating improved the adhesion of CNT emitters. During the life-time measurement for 10 h, the emitting current of CNT emitters fabricated by electrophoresis only was drastically decreased to 13% of the initial current, while that prepared by the combination of electrophoresis and successive electroplating decreased to 64% of the initial current. We suggest that our method is a promising approach for the efficient fabrication of reliable CNT emitters.  相似文献   
93.
This paper explains the manufacturing process of a composite train carbody with a sandwich composite structure for bodyshell and a stainless steel structure for the under frame. In addition, the structural behavior and safety of the composite carbody of the Korean tilting train was investigated by the static load tests. From the test results, the stiffness of the composite carbody met the specified design. In the aspect of strength, the maximum stress of the composite bodyshell was of 12.2% of strength of CF1263 carbon/epoxy.  相似文献   
94.
汽车负载突降保护的重要性 今天,汽车中并联在供电线路上的许多电子控制器和设备与三、四十年前生产的汽车有了很大的不同。那时汽车中的唯一的电子设备就是汽车收音机。  相似文献   
95.
This paper reports an alternative method for the growth of GaN epitaxial layer on (0001) Al2O3 substrate by hot-wall vapor phase epitaxy technique. Tris (N,N-dimethyldithiocarbamato)-gallium (III), Ga(mDTC)3 was introduced as a precursor material for the seed layer formation in the growth of GaN. Optimal growth conditions with seed layers formed by the Ga(mDTC)3 concentration of 0.047 mol/L were identified: Growth temperature was found to be 850 °C, and optimal distance between the reactant outlet and substrate was determined to be 12.5 cm. Characterization results showed that this growth method produce high-crystallinity GaN epitaxial layers at a relatively lower growth temperature compared to the existing growth techniques and simplify the growth process.  相似文献   
96.
GeoFilter: Geometric Selection of Mesh Filter Parameters   总被引:1,自引:0,他引:1  
  相似文献   
97.
98.
99.
100.
The purpose of this study was to analyze the symbolization of colors as cultural codes, based on costume colors. In order to study the significance of colors in cultural changes, we carried out a quantitative analysis and interpreted it from the perspective of cultural semiotics. The range of this study was focused on Korean costume colors, over diverse diachronic stages of Korean culture. For this study 1535 color samples were collected, measured with a spectrophotometer, and analyzed quantitatively according their diachronic stages of origin. As a result, red, blue, and yellow were found to be the most frequently used colors during the Chosun Dynasty, a period based on Confucianism. These colors acted as cultural codes with cultural significance. During the Modern times pink, light blue, and black increased in frequency and represented the reception of western culture, the changing sex role of women in society, and utilitarianism. In these days, neutral colors and grayish tones of all colors are the most significant colors of high frequency. The use of such colors is closely related to industrialization, mechanization, functionalism, and the changes of women's sex roles in the societies. They are used as cultural codes, especially to emphasize a rational and masculine image rather than a feminine image. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 71–79, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20290  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