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   379351篇
  免费   30717篇
  国内免费   16665篇
电工技术   22534篇
技术理论   47篇
综合类   27141篇
化学工业   63465篇
金属工艺   21924篇
机械仪表   24147篇
建筑科学   30053篇
矿业工程   12225篇
能源动力   10342篇
轻工业   25728篇
水利工程   7190篇
石油天然气   24244篇
武器工业   2996篇
无线电   41495篇
一般工业技术   41823篇
冶金工业   19061篇
原子能技术   3966篇
自动化技术   48352篇
  2024年   1272篇
  2023年   5596篇
  2022年   10431篇
  2021年   14702篇
  2020年   10960篇
  2019年   8930篇
  2018年   10347篇
  2017年   11590篇
  2016年   10622篇
  2015年   14631篇
  2014年   18593篇
  2013年   22293篇
  2012年   24398篇
  2011年   27014篇
  2010年   23970篇
  2009年   22677篇
  2008年   22163篇
  2007年   21132篇
  2006年   21433篇
  2005年   18851篇
  2004年   12755篇
  2003年   11430篇
  2002年   10643篇
  2001年   9472篇
  2000年   9365篇
  1999年   9972篇
  1998年   7580篇
  1997年   6502篇
  1996年   6169篇
  1995年   5071篇
  1994年   4111篇
  1993年   2785篇
  1992年   2185篇
  1991年   1649篇
  1990年   1291篇
  1989年   1056篇
  1988年   871篇
  1987年   525篇
  1986年   407篇
  1985年   261篇
  1984年   204篇
  1983年   151篇
  1982年   137篇
  1981年   81篇
  1980年   105篇
  1979年   57篇
  1977年   31篇
  1976年   30篇
  1962年   44篇
  1961年   39篇
排序方式: 共有10000条查询结果,搜索用时 234 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.
4.
5.
6.
7.
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   
8.
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   
9.
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   
10.
Neural Processing Letters - The boundedness and the global Mittag-Leffler synchronization (GMLS) of fractional-order inertial Cohen–Grossberg neural networks (CGNNS) with time delays are...  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