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   456530篇
  免费   36732篇
  国内免费   20155篇
电工技术   27050篇
技术理论   52篇
综合类   32834篇
化学工业   75080篇
金属工艺   26428篇
机械仪表   29630篇
建筑科学   36137篇
矿业工程   14866篇
能源动力   12420篇
轻工业   31342篇
水利工程   8694篇
石油天然气   29756篇
武器工业   3690篇
无线电   49435篇
一般工业技术   49771篇
冶金工业   22920篇
原子能技术   4664篇
自动化技术   58648篇
  2024年   1496篇
  2023年   6559篇
  2022年   11766篇
  2021年   17381篇
  2020年   13170篇
  2019年   10632篇
  2018年   12250篇
  2017年   13841篇
  2016年   12678篇
  2015年   17683篇
  2014年   22370篇
  2013年   26830篇
  2012年   29559篇
  2011年   32462篇
  2010年   28733篇
  2009年   27276篇
  2008年   26841篇
  2007年   25685篇
  2006年   26108篇
  2005年   22923篇
  2004年   15475篇
  2003年   13851篇
  2002年   13006篇
  2001年   11567篇
  2000年   11304篇
  1999年   12018篇
  1998年   9241篇
  1997年   7823篇
  1996年   7411篇
  1995年   6127篇
  1994年   4948篇
  1993年   3353篇
  1992年   2692篇
  1991年   1989篇
  1990年   1576篇
  1989年   1287篇
  1988年   1031篇
  1987年   638篇
  1986年   499篇
  1985年   311篇
  1984年   227篇
  1983年   172篇
  1982年   162篇
  1981年   98篇
  1980年   118篇
  1979年   61篇
  1978年   20篇
  1977年   25篇
  1976年   35篇
  1973年   14篇
排序方式: 共有10000条查询结果,搜索用时 101 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