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   709091篇
  免费   9276篇
  国内免费   1989篇
电工技术   13426篇
综合类   683篇
化学工业   103403篇
金属工艺   29808篇
机械仪表   23019篇
建筑科学   16516篇
矿业工程   3373篇
能源动力   18191篇
轻工业   56585篇
水利工程   7207篇
石油天然气   12000篇
武器工业   43篇
无线电   82494篇
一般工业技术   139749篇
冶金工业   137275篇
原子能技术   13441篇
自动化技术   63143篇
  2021年   5699篇
  2020年   4138篇
  2019年   5413篇
  2018年   14863篇
  2017年   15057篇
  2016年   12593篇
  2015年   6877篇
  2014年   10992篇
  2013年   29754篇
  2012年   19191篇
  2011年   29877篇
  2010年   24721篇
  2009年   26321篇
  2008年   26707篇
  2007年   27943篇
  2006年   19176篇
  2005年   20157篇
  2004年   18480篇
  2003年   17896篇
  2002年   16387篇
  2001年   16196篇
  2000年   15201篇
  1999年   16197篇
  1998年   42365篇
  1997年   29401篇
  1996年   22643篇
  1995年   16908篇
  1994年   14693篇
  1993年   14412篇
  1992年   10233篇
  1991年   9731篇
  1990年   9496篇
  1989年   9158篇
  1988年   8474篇
  1987年   7372篇
  1986年   7279篇
  1985年   8215篇
  1984年   7577篇
  1983年   6704篇
  1982年   6275篇
  1981年   6479篇
  1980年   6048篇
  1979年   5856篇
  1978年   5631篇
  1977年   6836篇
  1976年   9016篇
  1975年   4884篇
  1974年   4603篇
  1973年   4655篇
  1972年   3843篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Electrospark treatment of OT4-1 titanium alloy was performed sequentially with a STIM-20N hard-alloy electrode (TiC–20% Ni) and carbon-containing material (graphite and carbon-based composite materials). Kinetics of the mass transfer of the hard-alloy electrode was studied. The cathode mass loss during the first minute of the treatment was established. The kinetics results were processed using the methods of mathematical statistics. The erosion resistance of the applied carbon-containing materials was determined. Phase composition and relief of the coatings formed were analyzed. It was found that the application of the carbon-containing material increases the content of refractory phases in the coatings. Increase in the time of the treatment using the carbon-containing materials decreases the roughness of the coatings.  相似文献   
132.
The patent literature concerning thermal spraying for biomedical applications is reviewed in this contribution. The patents were compiled from multiple databases search spanning the 2005-2018 period. For clarity and ease of reading, the results have been grouped into sections according to four individual material groups (apatites, titanium, oxide ceramics, other), with the secondary sorting criterion being related to the specific bioapplication areas (maxillofacial, orthopedic, methods). Lastly, the patents are grouped according to the selected thermal spray method within the individual subsections. In the paper, recent R&D trends in this field are further identified and briefly commented.  相似文献   
133.
Estimation of earth-fill dam height and dimension of spillway are strongly depend on accurate evaluation of dam overtopping reliability. Ideally, whole random and effective variables on overtopping should be considered for dam overtopping reliability assessment. However, taking into account all affecting random variables as well as overtopping reliability assessment using algorithms such as Monte Carlo (MC) could be excessively time consuming and impossible in some cases. In this study, new approach has been introduced as conditional reliability method and it has been tried to reduce the simulations time significantly by using combination of rainfall threshold theory, SUFI (Sequential Uncertainty Fitting) and MC methods. According two defined indexes, the obtain results shown, the relative error of new approach in computation of Jamishan dam overtopping reliability is less than 0.23%. Also, time saving in new method against to regular MC method is more than 87%. So, the new introduced method has more efficiency with acceptable accuracy for assessment of dam overtopping reliability. In addition, among hydrological and hydraulic uncertainties, hydrological uncertainties have more effect on overtopping reliability.  相似文献   
134.
135.
136.
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications.  相似文献   
137.
138.
139.
140.
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