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   491078篇
  免费   50941篇
  国内免费   21445篇
电工技术   29579篇
技术理论   52篇
综合类   33595篇
化学工业   89084篇
金属工艺   26913篇
机械仪表   30161篇
建筑科学   38393篇
矿业工程   15037篇
能源动力   13449篇
轻工业   37174篇
水利工程   9453篇
石油天然气   29138篇
武器工业   4108篇
无线电   56383篇
一般工业技术   58970篇
冶金工业   23097篇
原子能技术   4953篇
自动化技术   63925篇
  2024年   1550篇
  2023年   6688篇
  2022年   12142篇
  2021年   18119篇
  2020年   14560篇
  2019年   13327篇
  2018年   15067篇
  2017年   16949篇
  2016年   16127篇
  2015年   21353篇
  2014年   26287篇
  2013年   31776篇
  2012年   32772篇
  2011年   35500篇
  2010年   32109篇
  2009年   30323篇
  2008年   29443篇
  2007年   27938篇
  2006年   27858篇
  2005年   24288篇
  2004年   16804篇
  2003年   14710篇
  2002年   13596篇
  2001年   12216篇
  2000年   12065篇
  1999年   11991篇
  1998年   8789篇
  1997年   7511篇
  1996年   7017篇
  1995年   5855篇
  1994年   4719篇
  1993年   3264篇
  1992年   2569篇
  1991年   1944篇
  1990年   1575篇
  1989年   1223篇
  1988年   1005篇
  1987年   609篇
  1986年   509篇
  1985年   303篇
  1984年   232篇
  1983年   164篇
  1982年   160篇
  1981年   106篇
  1980年   119篇
  1979年   50篇
  1978年   23篇
  1977年   25篇
  1976年   32篇
  1959年   16篇
排序方式: 共有10000条查询结果,搜索用时 187 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.
Xiao  Zhu  Chen  Yanxun  Jiang  Hongbo  Hu  Zhenzhen  Lui  John C. S.  Min  Geyong  Dustdar  Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of...  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