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   2763篇
  免费   107篇
  国内免费   10篇
电工技术   35篇
综合类   7篇
化学工业   621篇
金属工艺   94篇
机械仪表   71篇
建筑科学   79篇
矿业工程   3篇
能源动力   195篇
轻工业   222篇
水利工程   22篇
石油天然气   8篇
无线电   269篇
一般工业技术   649篇
冶金工业   220篇
原子能技术   10篇
自动化技术   375篇
  2024年   12篇
  2023年   41篇
  2022年   85篇
  2021年   140篇
  2020年   91篇
  2019年   98篇
  2018年   124篇
  2017年   108篇
  2016年   87篇
  2015年   68篇
  2014年   108篇
  2013年   212篇
  2012年   133篇
  2011年   176篇
  2010年   108篇
  2009年   122篇
  2008年   90篇
  2007年   103篇
  2006年   62篇
  2005年   64篇
  2004年   50篇
  2003年   56篇
  2002年   45篇
  2001年   33篇
  2000年   32篇
  1999年   32篇
  1998年   35篇
  1997年   36篇
  1996年   38篇
  1995年   39篇
  1994年   33篇
  1993年   32篇
  1992年   36篇
  1991年   26篇
  1990年   14篇
  1989年   21篇
  1988年   24篇
  1987年   25篇
  1986年   18篇
  1985年   22篇
  1984年   29篇
  1983年   31篇
  1982年   29篇
  1981年   22篇
  1980年   17篇
  1979年   11篇
  1978年   10篇
  1976年   24篇
  1975年   6篇
  1971年   3篇
排序方式: 共有2880条查询结果,搜索用时 15 毫秒
101.
Protection of Metals and Physical Chemistry of Surfaces - Dense alumina coatings were fabricated over aluminum alloy via dip coating method using oxime-modified aluminum(III) isopropoxide as a...  相似文献   
102.
This paper presents a research study on a bridge site located along US highway 67 over SH 174 in Cleburne, Texas, where bridge approach slabs have experienced more than 0.4 m (17 in.) of settlement within a span of 16 years after construction. Many treatment methods attempted to mitigate this problem had proven to be ineffective. As part of novel rehabilitation works, the top of existing fill soil on the embankment was replaced with lightweight expanded polystyrene (EPS) geofoam blocks to alleviate the approach slab settlements. This paper describes initial design and construction details of the rehabilitation works performed on the embankment system along with a focus on the early performance details. Field monitoring studies were conducted for almost three years to study the bump/settlements under the EPS geofoam embankment system. Short term measured settlement data was analyzed with hyperbolic model to predict the long term settlements. Numerical finite element studies attempted in this study showed that settlements could be reasonably predicted by modeling these geofoam embankments. Based on the monitoring and modeling studies, the effectiveness of utilizing EPS geofoam as an embankment fill material was addressed to mitigate the differential settlements under a bridge approach slab.  相似文献   
103.
104.
105.
Singh  A. K.  Chandra  Devesh  Kattayat  Sandhya  Kumar  Shalendra  Alvi  P. A.  Rathi  Amit 《Semiconductors》2019,53(12):1584-1592
Semiconductors - Compositional variations in GaAs based ternary alloys have exhibited wide range alterations in electronic properties. In the present paper, first-principles study of...  相似文献   
106.
Wireless Personal Communications - In wireless communication channels, the signals arriving at the receiver may be of stochastic nature or be superpositioned due to non-uniform scattering and...  相似文献   
107.
Water Resources Management - Streamflow forecasting can offer valuable information for optimal management of water resources, flood mitigation, and drought warning. This research aims in evaluating...  相似文献   
108.
109.
A eutectic mixture of choline chloride and urea (commercially known as Reline) has been used as a medium from which CdS, CdSe, and ZnS thin films have been electrodeposited for the first time. Reline is a conductive room temperature ionic liquid (RTIL) with a wide electrochemical window, which is suitable for use as a medium for electrodeposition. The voltammetric behaviour of the Reline-Cd(II)-sulfur system has been investigated. Thin films of CdS deposited at constant potential were characterized by photocurrent and electrolyte electroabsorbance spectroscopies. Thin films of CdSe and ZnS have also been prepared, and their photocurrent excitation spectra have been measured.  相似文献   
110.
CuIn0.75Al0.25Se2 thin films prepared onto glass substrates at TS=573 K were single phase, nearly stoichiometric and polycrystalline with a strong (1 1 1) preferred orientation showing sphalerite structure. The results of X-ray diffraction and electron diffraction studies are compared, interpreted and correlated with micro-Raman spectra. The optical absorption studies indicated a direct band gap of 1.16 eV with high absorption coefficient (>104 cm?1) near the fundamental absorption edge.  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