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   137701篇
  免费   13003篇
  国内免费   7410篇
电工技术   9320篇
技术理论   6篇
综合类   10269篇
化学工业   21082篇
金属工艺   8759篇
机械仪表   9801篇
建筑科学   10972篇
矿业工程   5049篇
能源动力   3874篇
轻工业   11159篇
水利工程   3253篇
石油天然气   8534篇
武器工业   1396篇
无线电   14769篇
一般工业技术   14717篇
冶金工业   6252篇
原子能技术   1693篇
自动化技术   17209篇
  2024年   578篇
  2023年   2360篇
  2022年   4427篇
  2021年   6292篇
  2020年   4811篇
  2019年   3657篇
  2018年   3948篇
  2017年   4406篇
  2016年   4097篇
  2015年   5832篇
  2014年   7136篇
  2013年   8361篇
  2012年   9596篇
  2011年   10050篇
  2010年   9115篇
  2009年   8744篇
  2008年   8579篇
  2007年   8157篇
  2006年   8065篇
  2005年   6922篇
  2004年   4589篇
  2003年   3845篇
  2002年   3672篇
  2001年   3313篇
  2000年   3063篇
  1999年   2883篇
  1998年   2125篇
  1997年   1768篇
  1996年   1730篇
  1995年   1432篇
  1994年   1176篇
  1993年   765篇
  1992年   665篇
  1991年   450篇
  1990年   362篇
  1989年   312篇
  1988年   229篇
  1987年   151篇
  1986年   119篇
  1985年   69篇
  1984年   47篇
  1983年   42篇
  1982年   46篇
  1981年   39篇
  1980年   36篇
  1979年   27篇
  1965年   2篇
  1959年   10篇
  1957年   1篇
  1951年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
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   
8.
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   
9.
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   
10.
Multimedia Tools and Applications - Since Noar and Shamir introduced visual cryptography scheme (VCS), the cheating problem of VCS has absorbed much attention of scholars. The current researches on...  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