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   462729篇
  免费   38034篇
  国内免费   20598篇
电工技术   27882篇
技术理论   51篇
综合类   33117篇
化学工业   76473篇
金属工艺   27077篇
机械仪表   30398篇
建筑科学   36802篇
矿业工程   15333篇
能源动力   12936篇
轻工业   30726篇
水利工程   8872篇
石油天然气   29984篇
武器工业   3779篇
无线电   50459篇
一般工业技术   50603篇
冶金工业   22967篇
原子能技术   4671篇
自动化技术   59231篇
  2024年   1546篇
  2023年   6728篇
  2022年   12839篇
  2021年   17973篇
  2020年   13548篇
  2019年   10950篇
  2018年   12553篇
  2017年   14185篇
  2016年   12958篇
  2015年   18118篇
  2014年   22764篇
  2013年   27294篇
  2012年   29938篇
  2011年   32781篇
  2010年   28908篇
  2009年   27375篇
  2008年   26831篇
  2007年   25649篇
  2006年   26148篇
  2005年   22873篇
  2004年   15548篇
  2003年   14276篇
  2002年   13641篇
  2001年   12217篇
  2000年   11510篇
  1999年   12156篇
  1998年   9233篇
  1997年   7852篇
  1996年   7481篇
  1995年   6137篇
  1994年   4952篇
  1993年   3358篇
  1992年   2700篇
  1991年   1990篇
  1990年   1566篇
  1989年   1272篇
  1988年   1033篇
  1987年   631篇
  1986年   510篇
  1985年   315篇
  1984年   235篇
  1983年   180篇
  1982年   165篇
  1981年   104篇
  1980年   118篇
  1979年   66篇
  1978年   18篇
  1977年   23篇
  1976年   28篇
  1959年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 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