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   260375篇
  免费   3787篇
  国内免费   898篇
电工技术   4973篇
综合类   260篇
化学工业   37915篇
金属工艺   9734篇
机械仪表   7821篇
建筑科学   6322篇
矿业工程   917篇
能源动力   7571篇
轻工业   22624篇
水利工程   2297篇
石油天然气   3292篇
武器工业   15篇
无线电   34804篇
一般工业技术   51244篇
冶金工业   49367篇
原子能技术   5135篇
自动化技术   20769篇
  2022年   1483篇
  2021年   2558篇
  2020年   1843篇
  2019年   2247篇
  2018年   3636篇
  2017年   3689篇
  2016年   3753篇
  2015年   2463篇
  2014年   4296篇
  2013年   12097篇
  2012年   6715篇
  2011年   9136篇
  2010年   7294篇
  2009年   8312篇
  2008年   8759篇
  2007年   8606篇
  2006年   7633篇
  2005年   6671篇
  2004年   6471篇
  2003年   6780篇
  2002年   6270篇
  2001年   6698篇
  2000年   6100篇
  1999年   6500篇
  1998年   16720篇
  1997年   11591篇
  1996年   8934篇
  1995年   6691篇
  1994年   5965篇
  1993年   5912篇
  1992年   4167篇
  1991年   4049篇
  1990年   3892篇
  1989年   3668篇
  1988年   3592篇
  1987年   3032篇
  1986年   2961篇
  1985年   3223篇
  1984年   2935篇
  1983年   2832篇
  1982年   2643篇
  1981年   2549篇
  1980年   2470篇
  1979年   2313篇
  1978年   2113篇
  1977年   2613篇
  1976年   3591篇
  1975年   1773篇
  1974年   1736篇
  1973年   1672篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast...  相似文献   
4.
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks.  相似文献   
5.
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   
6.
Wireless Personal Communications - Despite its various benefits, the Mobile Ad-hoc Network (MANET) has a number of obstacles due to its mobility, unstable topology, energy efficiency, and other...  相似文献   
7.
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...  相似文献   
8.
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of...  相似文献   
9.
Mobile Networks and Applications - Project MindCatcher is an art/research project which has the intention to explore the potential of interactive artistic environments for measuring and a better...  相似文献   
10.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the...  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