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   506725篇
  免费   35132篇
  国内免费   19031篇
电工技术   26091篇
技术理论   50篇
综合类   32117篇
化学工业   81376篇
金属工艺   29526篇
机械仪表   30880篇
建筑科学   36234篇
矿业工程   14741篇
能源动力   12901篇
轻工业   31725篇
水利工程   9275篇
石油天然气   29013篇
武器工业   3475篇
无线电   54991篇
一般工业技术   61945篇
冶金工业   24255篇
原子能技术   4575篇
自动化技术   77718篇
  2024年   1340篇
  2023年   6267篇
  2022年   10891篇
  2021年   16380篇
  2020年   12491篇
  2019年   10131篇
  2018年   24205篇
  2017年   24899篇
  2016年   20862篇
  2015年   17329篇
  2014年   21322篇
  2013年   25467篇
  2012年   30579篇
  2011年   39120篇
  2010年   34339篇
  2009年   30451篇
  2008年   31172篇
  2007年   31154篇
  2006年   24644篇
  2005年   22695篇
  2004年   15514篇
  2003年   14167篇
  2002年   12717篇
  2001年   11022篇
  2000年   10931篇
  1999年   11666篇
  1998年   8964篇
  1997年   7611篇
  1996年   7269篇
  1995年   5965篇
  1994年   4818篇
  1993年   3237篇
  1992年   2622篇
  1991年   1936篇
  1990年   1511篇
  1989年   1236篇
  1988年   1010篇
  1987年   614篇
  1986年   484篇
  1985年   299篇
  1984年   224篇
  1983年   170篇
  1982年   159篇
  1981年   93篇
  1980年   112篇
  1979年   58篇
  1968年   46篇
  1965年   46篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
1.
Feng  Wenran  Li  Zhen  Chen  Yingying  Chen  Jinyang  Lang  Haoze  Wan  Jianghong  Gao  Yan  Dong  Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in...  相似文献   
2.
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   
3.
Tang  Haina  Zhao  Xiangpeng  Ren  Yongmao 《Wireless Networks》2022,28(3):1197-1202
Wireless Networks - Geolocation is important for many emerging applications such as disaster management and recommendation system. In this paper, we propose a multilayer recognition model (MRM) to...  相似文献   
4.
5.
6.
7.
8.
The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP.  相似文献   
9.
Ripe carambolas are hard to store and transport, while freeze-dried ones are easy to store. However, its long production time leads to higher costs. This study shows that high hydrostatic pressure (HHP) treatment could shorten the freeze-drying time of carambola slices. After HHP treatment (25–250 MPa), the drying time of the fresh sample can be shortened by 33.3–44.4% and the distribution of water and pigment in tissues is much uniform. With the increment of the pressure, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rate are increased. At 250 MPa, the total phenolic content (TPC) increased from 11.34 to 13.36 mg GAE g−1, and the total flavonoid content (TFC) of the control sample was increased from 10.77 to 12.73 mg RE g−1. Compared with the untreated sample, HHP treatment can enhance the flavour and shorten the freeze-drying time. This work guides the application of HHP technology for drying food processing.  相似文献   
10.
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   
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