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   606422篇
  免费   9063篇
  国内免费   2089篇
电工技术   11456篇
综合类   681篇
化学工业   90278篇
金属工艺   23703篇
机械仪表   19046篇
建筑科学   13821篇
矿业工程   2939篇
能源动力   17020篇
轻工业   47002篇
水利工程   6039篇
石油天然气   10213篇
武器工业   39篇
无线电   74496篇
一般工业技术   121371篇
冶金工业   115355篇
原子能技术   12621篇
自动化技术   51494篇
  2022年   3790篇
  2021年   5927篇
  2020年   4537篇
  2019年   5512篇
  2018年   9404篇
  2017年   9337篇
  2016年   9961篇
  2015年   6589篇
  2014年   10643篇
  2013年   29508篇
  2012年   16654篇
  2011年   22230篇
  2010年   17853篇
  2009年   20053篇
  2008年   20840篇
  2007年   20499篇
  2006年   18117篇
  2005年   16160篇
  2004年   15269篇
  2003年   15285篇
  2002年   14344篇
  2001年   14474篇
  2000年   13520篇
  1999年   14309篇
  1998年   37165篇
  1997年   25680篇
  1996年   19792篇
  1995年   14736篇
  1994年   12991篇
  1993年   12899篇
  1992年   9186篇
  1991年   8768篇
  1990年   8641篇
  1989年   8177篇
  1988年   7855篇
  1987年   6818篇
  1986年   6639篇
  1985年   7397篇
  1984年   6761篇
  1983年   6281篇
  1982年   5761篇
  1981年   5799篇
  1980年   5474篇
  1979年   5210篇
  1978年   5033篇
  1977年   5953篇
  1976年   8129篇
  1975年   4322篇
  1974年   4114篇
  1973年   4160篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
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   
12.
Forschung im Ingenieurwesen - Das Arbeitsmittel in Wärmepumpen unterliegt einer Vielzahl von Anforderungen, welche für einen effizienten und sicheren Betrieb eingehalten werden...  相似文献   
13.
Wireless Personal Communications - Despite its various benefits, the Mobile Ad-hoc Network (MANET) has a number of obstacles due to its mobility, unstable topology, energy efficiency, and other...  相似文献   
14.
Telecommunication Systems - Energy saving in User Equipment (UE) is one of the important issues for limited sources of power in the device. It is critical for the UE to maximize its energy...  相似文献   
15.
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   
16.
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   
17.
Mobile Networks and Applications - Project MindCatcher is an art/research project which has the intention to explore the potential of interactive artistic environments for measuring and a better...  相似文献   
18.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the...  相似文献   
19.
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   
20.
A promising electrocatalyst containing variable percentage of V2O5–TiO2 mixed oxide in graphene oxide support was prepared by embedding the catalyst on Cu substrate through facile electroless Ni–Co–P plating for hydrogen evolution reaction. The solvothermal decomposition method was opted for tuning the crystalline characteristics of prepared material. The optimized mixed oxide was well characterized, active sites centres were identified and explained by X-ray diffraction, high resolution tunnelling electron microscopy, scanning electron microscopy coupled with energy dispersive X-ray and X-ray photon spectroscopy analysis. The structural and electronic characteristics of material was done by fourier transform infrared spectroscopy and the electrochemical behaviour of the prepared material was evaluated by using Tafel plot, electrochemical impedance analysis, linear sweep voltammetry, open circuit analysis and chronoamperometry measurements. The results show the enhanced catalytic activity of Ni–Co–P than pure Ni–P plate, due to synergic effect. Moreover, the prepared mixed oxide incorporated Ni–Co–P plate has a high activity towards HER with low over potential of 101 mV, low Tafel slope of 36 mVdec?1, high exchange current density of 9.90 × 10?2 Acm?2.  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