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   217243篇
  免费   3301篇
  国内免费   1081篇
电工技术   4172篇
技术理论   1篇
综合类   859篇
化学工业   33728篇
金属工艺   10805篇
机械仪表   7760篇
建筑科学   4750篇
矿业工程   2566篇
能源动力   4930篇
轻工业   13555篇
水利工程   3111篇
石油天然气   8576篇
武器工业   114篇
无线电   22738篇
一般工业技术   46538篇
冶金工业   35002篇
原子能技术   6744篇
自动化技术   15676篇
  2021年   2535篇
  2020年   1940篇
  2019年   2356篇
  2018年   4032篇
  2017年   4078篇
  2016年   4333篇
  2015年   2671篇
  2014年   4329篇
  2013年   9362篇
  2012年   6434篇
  2011年   7953篇
  2010年   6524篇
  2009年   7158篇
  2008年   7209篇
  2007年   7094篇
  2006年   6221篇
  2005年   5619篇
  2004年   4991篇
  2003年   4851篇
  2002年   4664篇
  2001年   4728篇
  2000年   4447篇
  1999年   4484篇
  1998年   10417篇
  1997年   7392篇
  1996年   5687篇
  1995年   4288篇
  1994年   3727篇
  1993年   3917篇
  1992年   3057篇
  1991年   3051篇
  1990年   2942篇
  1989年   2886篇
  1988年   2886篇
  1987年   2528篇
  1986年   2588篇
  1985年   2855篇
  1984年   2691篇
  1983年   2559篇
  1982年   2308篇
  1981年   2269篇
  1980年   2347篇
  1979年   2359篇
  1978年   2383篇
  1977年   2487篇
  1976年   2876篇
  1975年   2188篇
  1974年   2068篇
  1973年   2166篇
  1972年   1940篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
4.
Mangiferin (MGF) is a phenolic compound isolated from mango, but its poor solubility significantly limits its use. In this study, MGF was embedded into the inner aqueous phase of W1/O/W2 emulsions. Firstly, the dissolution method of MGF was determined. MGF remained stable in solution with pH 13 at 30 min, and its solubility reached 10 mg mL−1. When the pH of MGF solutions was adjusted from pH 13 to pH 6, MGF did not immediately crystallise, providing sufficient time to construct the MGF-loaded W1/O/W2 emulsions. Subsequently, the MGF-loaded W1/O/W2 emulsions were constructed using polyglycerol polyricinoleate (PGPR) and calcium caseinate (CAS). The formation and stability of the W1/O/W2 emulsions were investigated. The MGF-loaded W1/O/W2 emulsions stabilised with 1% PGPR and 1% – 3% CAS exhibited a low viscosity, limited loading capacity, and poor stability. Conversely, the MGF-loaded W1/O/W2 emulsions stabilised by 3%PGPR–3%CAS exhibited optimal loading capacity (encapsulation efficiency = 95.31% and loading efficiency = 0.91%) and stability, which was attributed to the fact that high viscosity and gel state retarded the migration of inner aqueous phase. These results indicated that the W1/O/W2 emulsions stabilised by PGPR and CAS may be a potential alternative for encapsulating mangiferin.  相似文献   
5.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a...  相似文献   
6.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  相似文献   
7.
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...  相似文献   
8.
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of...  相似文献   
9.
Recent advancements in isolation and stacking of layered van der Waals materials have created an unprecedented paradigm for demonstrating varieties of 2D quantum materials. Rationally designed van der Waals heterostructures composed of monolayer transition-metal dichalcogenides (TMDs) and few-layer hBN show several unique optoelectronic features driven by correlations. However, entangled superradiant excitonic species in such systems have not been observed before. In this report, it is demonstrated that strong suppression of phonon population at low temperature results in a formation of a coherent excitonic-dipoles ensemble in the heterostructure, and the collective oscillation of those dipoles stimulates a robust phase synchronized ultra-narrow band superradiant emission even at extremely low pumping intensity. Such emitters are in high demand for a multitude of applications, including fundamental research on many-body correlations and other state-of-the-art technologies. This timely demonstration paves the way for further exploration of ultralow-threshold quantum-emitting devices with unmatched design freedom and spectral tunability.  相似文献   
10.
Automation and Remote Control - A linear-quadratic positional differential game of three persons is considered. Coefficient criteria are established under which there is no Nash equilibrium...  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