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   293312篇
  免费   6567篇
  国内免费   2717篇
电工技术   7422篇
技术理论   2篇
综合类   2675篇
化学工业   44530篇
金属工艺   16757篇
机械仪表   13668篇
建筑科学   8720篇
矿业工程   2893篇
能源动力   6589篇
轻工业   20277篇
水利工程   3432篇
石油天然气   6956篇
武器工业   339篇
无线电   32174篇
一般工业技术   58362篇
冶金工业   41331篇
原子能技术   5771篇
自动化技术   30698篇
  2022年   2061篇
  2021年   3446篇
  2020年   2424篇
  2019年   2666篇
  2018年   12087篇
  2017年   12767篇
  2016年   8344篇
  2015年   3961篇
  2014年   5038篇
  2013年   10490篇
  2012年   9901篇
  2011年   17863篇
  2010年   15536篇
  2009年   15079篇
  2008年   14895篇
  2007年   16549篇
  2006年   7356篇
  2005年   10128篇
  2004年   7812篇
  2003年   6981篇
  2002年   5887篇
  2001年   5161篇
  2000年   4997篇
  1999年   5047篇
  1998年   11201篇
  1997年   8087篇
  1996年   6280篇
  1995年   4807篇
  1994年   4047篇
  1993年   3854篇
  1992年   2844篇
  1991年   2757篇
  1990年   2584篇
  1989年   2584篇
  1988年   2481篇
  1987年   2209篇
  1986年   2120篇
  1985年   2416篇
  1984年   2216篇
  1983年   2046篇
  1982年   1907篇
  1981年   1966篇
  1980年   1819篇
  1979年   1833篇
  1978年   1790篇
  1977年   2115篇
  1976年   2705篇
  1975年   1567篇
  1974年   1555篇
  1973年   1620篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Zhao  Jiandong  Lei  Wei  Li  Zijian  Zhao  Dongfeng  Han  Mingmin  Hou  Xiaoqing 《Multimedia Tools and Applications》2022,81(4):4753-4780
Multimedia Tools and Applications - The crowding in bus is an important factor affecting passenger satisfaction and bus dispatching level. However, how to use video images to detect crowding...  相似文献   
2.
3.
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   
4.
5.
6.
7.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical...  相似文献   
8.
Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection.  相似文献   
9.
Journal of Communications Technology and Electronics - A new design of wavelets based on the convolution of a compactly supported function with a rectangular pulse is proposed and theoretically...  相似文献   
10.
Journal of Communications Technology and Electronics - A statistical study of the effectiveness of the non-threshold search procedure for a noise-like phase-shift keyed signal by the delay time is...  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