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   112000篇
  免费   9651篇
  国内免费   4947篇
电工技术   6412篇
技术理论   6篇
综合类   7399篇
化学工业   18825篇
金属工艺   6746篇
机械仪表   7662篇
建筑科学   9111篇
矿业工程   3768篇
能源动力   3251篇
轻工业   7766篇
水利工程   1926篇
石油天然气   7919篇
武器工业   893篇
无线电   12071篇
一般工业技术   12878篇
冶金工业   5425篇
原子能技术   1234篇
自动化技术   13306篇
  2024年   485篇
  2023年   2011篇
  2022年   3544篇
  2021年   4749篇
  2020年   3750篇
  2019年   3009篇
  2018年   3267篇
  2017年   3697篇
  2016年   3371篇
  2015年   4607篇
  2014年   5606篇
  2013年   6644篇
  2012年   7161篇
  2011年   7696篇
  2010年   6661篇
  2009年   6396篇
  2008年   6206篇
  2007年   5877篇
  2006年   6206篇
  2005年   5459篇
  2004年   3502篇
  2003年   3175篇
  2002年   3070篇
  2001年   2756篇
  2000年   2634篇
  1999年   2866篇
  1998年   2249篇
  1997年   1872篇
  1996年   1822篇
  1995年   1505篇
  1994年   1245篇
  1993年   792篇
  1992年   686篇
  1991年   482篇
  1990年   379篇
  1989年   324篇
  1988年   241篇
  1987年   152篇
  1986年   128篇
  1985年   73篇
  1984年   53篇
  1983年   45篇
  1982年   45篇
  1981年   32篇
  1980年   32篇
  1979年   20篇
  1978年   2篇
  1977年   2篇
  1974年   4篇
  1959年   3篇
排序方式: 共有10000条查询结果,搜索用时 31 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.
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   
3.
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   
4.
In this work, the composition-dependent point defect types and formation energies of RE2Hf2O7 (RE = La, Ce, Pr, Nd, Pm, Sm, Eu and Gd) as well as the oxygen diffusion behavior are systematically investigated by first-principles calculations. The possible defect reactions and dominant defect complexes under stoichiometric and non-stoichiometric conditions are revealed. It is found that O Frenkel pairs are the predominant defect in stoichiometric pyrochlore hafnates. Hf-RE cation anti-site defects, accompanied by RE vacancies and/or oxygen interstitials, are stable in the non-stoichiometric case of HfO2 excess. On the other hand, RE-Hf anti-site defects together with oxygen vacancies and/or RE interstitials are preferable in the case of RE2O3 excess. The energy barriers for the migration along the VO48f - VO48f pathway of pyrochlore hafnates were calculated to be between 0.81 eV and 0.89 eV. Based on these results, a defect engineering strategy is proposed and the pyrochlore hafnates investigated here are predicted to exhibit potential oxygen ionic conductivity.  相似文献   
5.
Zhao  Ziyu  Lin  Haitao  Ma  Pibo 《Applied Composite Materials》2022,29(4):1675-1694
Applied Composite Materials - In this paper, the low-velocity impact deformation behavior of biaxial warp-knitted flexible composite was investigated. A simplified finite element model (FEM) of the...  相似文献   
6.
7.
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex...  相似文献   
8.
Zhang  Nan  Zhao  Man  Liu  Guangfa  Wang  Jiaoyang  Chen  Yunzhi  Zhang  Zhengjian 《Journal of Materials Science》2022,57(19):8687-8700
Journal of Materials Science - A green modification method for effectively enhancing toughness of PLA was established. Herein, alkaline lignin (LG) was firstly alkylated with dodecane, and then...  相似文献   
9.
Wang  Chen  Bao  Chun-Hui  Wu  Wan-Yu  Hsu  Chia-Hsun  Zhao  Ming-Jie  Zhang  Xiao-Ying  Lien  Shui-Yang  Zhu  Wen-Zhang 《Journal of Materials Science》2022,57(26):12341-12355
Journal of Materials Science - Molybdenum oxide (MoOx) films had been grown by using plasma-enhanced atomic layer deposition (PEALD) with Mo(CO)6 precursor and O2 plasma reactant in a substrate...  相似文献   
10.
Sun  Junli  Wang  Huaibin  Li  Yang  Zhao  Min 《Journal of Porous Materials》2021,28(3):889-894
Journal of Porous Materials - Co3O4 has been widely investigated as a promising candidate anode material for lithium-ion batteries. We report on the porous Co3O4 column synthesized via a simple...  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