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   11241篇
  免费   334篇
  国内免费   8篇
电工技术   110篇
综合类   13篇
化学工业   2131篇
金属工艺   152篇
机械仪表   222篇
建筑科学   633篇
矿业工程   31篇
能源动力   269篇
轻工业   868篇
水利工程   82篇
石油天然气   28篇
武器工业   1篇
无线电   769篇
一般工业技术   1977篇
冶金工业   2537篇
原子能技术   145篇
自动化技术   1615篇
  2022年   117篇
  2021年   160篇
  2020年   125篇
  2019年   149篇
  2018年   194篇
  2017年   191篇
  2016年   212篇
  2015年   180篇
  2014年   263篇
  2013年   694篇
  2012年   435篇
  2011年   576篇
  2010年   412篇
  2009年   447篇
  2008年   484篇
  2007年   518篇
  2006年   494篇
  2005年   420篇
  2004年   350篇
  2003年   344篇
  2002年   286篇
  2001年   220篇
  2000年   224篇
  1999年   234篇
  1998年   354篇
  1997年   262篇
  1996年   244篇
  1995年   224篇
  1994年   184篇
  1993年   173篇
  1992年   153篇
  1991年   115篇
  1990年   113篇
  1989年   136篇
  1988年   147篇
  1987年   125篇
  1986年   123篇
  1985年   139篇
  1984年   128篇
  1983年   127篇
  1982年   90篇
  1981年   117篇
  1980年   81篇
  1979年   79篇
  1978年   90篇
  1977年   88篇
  1976年   99篇
  1975年   57篇
  1973年   56篇
  1972年   55篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry  相似文献   
2.
A series of studies of top European and other firms has revealed patterns of design management associated with commercial success. Firms that invest resources and professional expertise in product and industrial design in traditional and new industries have been commercially more successful than firms that pay less attention to these aspects of design. As an industry matures there is a shift in emphasis from design associated with technological innovation, to designs supporting technical improvements, and then to supporting user needs, fashion and product variants. These issues are illustrated through the history of the evolution of the bicycle.  相似文献   
3.
Two classes of glial cells are found in the embryonic Drosophila CNS, midline glial cells and lateral glial cells. Midline glial development is triggered by EGF-receptor signalling, whereas lateral glial development is controlled by the gcm gene. Subsequent glial cell differentiation depends partly on the pointed gene. Here we describe a novel component required for all CNS glia development. The tramtrack gene encodes two zinc-finger proteins, one of which, ttkp69, is expressed in all non-neuronal CNS cells. We show that ttkp69 is downstream of gcm and can repress neuronal differentiation. Double mutant analysis and coexpression experiments indicate that glial cell differentiation may depend on a dual process, requiring the activation of glial differentiation by pointed and the concomitant repression of neuronal development by tramtrack.  相似文献   
4.
Reviews the book, Constructing the subject: Historical origins of psychological research by Kurt Danziger (1990). Kurt Danziger's Constructing the Subject: Historical Origins of Psychological Research is a book of singular importance because it provides such a penetrating analysis, and does so in a manner that is cause for considerable reflection. In brief, Danziger provides a history lesson that not only situates the names and the projects of experimental psychology in the first part of this century, but also aims to clarify the project of knowledge generation both past and present. Indeed, shades of Quine, Kuhn, and Hesse permeate this book in a way that demands psychologists examine their own investigative practices and logics of justification. Through Wundt, through Galton, through Ebbinghaus and others, Danziger illuminates the development of experimental psychology along with the historical and philosophical vicissitudes that have given rise to numerous psychological knowledge claims. If it is true that we must understand our history in order to understand our present, then Danziger's book should be required reading in all research laboratories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
5.
6.
7.
8.
This paper discusses the testing accomplished to determine the radio frequency (RF) susceptibility of a typical electroencephalograph (EEG) and to determine the effectiveness of lead X-ray shielding as an RF shield. New data are presented on threshold field strengths and frequencies which just begin to cause interference on a typical EEG brain scan. Results are combined with data from other studies to show that a typical EEG machine would be immune to the RF environment expected in the vicinity of most hospitals. Therefore, expensive RF shielding in a hospital EEG suite is usually not required. Finally, an inexpensive shielding system utilizing X-ray shielding which was developed by the U.S. Veterans Administration is presented.  相似文献   
9.
A fast full-band device simulator for wurtzite and zincblende GaN using a Cellular Monte Carlo (CMC) approach is reported for wurtzite and zincblende GaN. The full-phonon dispersion relationship including anisotropic polar-optical phonon scattering is taken into account for the wurtzite GaN calculation. In the bulk simulation, the CMC model is about 30–100 times faster than the conventional Ensemble Monte Carlo model at high electric field region. This CMC model is applied to the simulator of MESFET devices, and the calculation speed is significantly improved.  相似文献   
10.
A physically based hysteresis theory incorporating a domain size that depends on the Weiss effective field explains the observed ranges of reversible and irreversible magnetization in the initial-magnetization curve and exterior loop of ferromagnetic materials. The theory applies to materials exhibiting both normal and wasp-waisted exterior loops and agrees well with measured data. It also provides close linkages between magnetization at the quantum scale, domain properties at the mesoscopic scale, and measurements at the macroscopic scale.  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