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   1491篇
  免费   45篇
  国内免费   20篇
电工技术   15篇
综合类   99篇
化学工业   705篇
金属工艺   33篇
机械仪表   57篇
建筑科学   68篇
矿业工程   19篇
能源动力   38篇
轻工业   75篇
水利工程   6篇
石油天然气   30篇
武器工业   9篇
无线电   41篇
一般工业技术   67篇
冶金工业   64篇
原子能技术   10篇
自动化技术   220篇
  2024年   2篇
  2023年   13篇
  2022年   9篇
  2021年   27篇
  2020年   51篇
  2019年   82篇
  2018年   31篇
  2017年   16篇
  2016年   17篇
  2015年   42篇
  2014年   123篇
  2013年   108篇
  2012年   154篇
  2011年   174篇
  2010年   117篇
  2009年   65篇
  2008年   78篇
  2007年   75篇
  2006年   47篇
  2005年   40篇
  2004年   37篇
  2003年   34篇
  2002年   32篇
  2001年   27篇
  2000年   19篇
  1999年   17篇
  1998年   17篇
  1997年   8篇
  1996年   8篇
  1995年   13篇
  1994年   6篇
  1993年   6篇
  1992年   7篇
  1991年   5篇
  1990年   4篇
  1989年   2篇
  1988年   4篇
  1987年   3篇
  1985年   5篇
  1984年   3篇
  1983年   4篇
  1982年   4篇
  1981年   3篇
  1980年   5篇
  1979年   4篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1965年   1篇
排序方式: 共有1556条查询结果,搜索用时 622 毫秒
1.
Digital technology becomes more powerful, intelligent, pervasive and ubiquitous. Ethical aspects of this development have not yet drawn the appropriate attention of researchers and engineers. This paper presents an instrument that aims at measuring the individual ethical position with regard to the design and development of computer software. The development of the Epos tool was based on two data collections. The data of the first survey (n1 = 147 participants) were used to select items and to determine the factorial structure of the questionnaire. Results show that the Epos instrument reliably assesses peoples’ ethical opinion with respect to five central components: (1) regulation, (2) data privacy, (3) domain specific knowledge, (4) societal responsibility and (5) company responsibility. In the second survey, we determined the stability of the instruments factor structure by assessing a sample of n2?=?196 participants. A confirmatory factor analysis (CFA) supported the initial factor structure. Next steps and further implications are discussed regarding the final version of the questionnaire.  相似文献   
2.
物理化学课程创新教学模式是以学生学习为中心,吐故纳新,优化精选,以新颖或变化的教学方式进行教学。调查表明创新教学模式受到绝大多数学生的肯定和认可,有效地调动学生的积极性,提高了学生对物理化学的学习和探究兴趣,学生提问问题的广度和难度发生显著变化。该教学模式能够逐步提升学生的创新意识和创新能力。  相似文献   
3.
针对化学学科特点。使用ASP进行在线网络测试、自动阅卷、分析统计的方法。  相似文献   
4.
The Representative Interactive Flamelet (RIF) concept has been applied to numerically simulate the combustion processes and pollutant formation in the direct injection diesel engine. Due to the ability for interactively describing the transient behaviors of local flame structures with CFD solver, the RIF concept has the capabilities to predict the auto-ignition and subsequent flame propagation in the diesel engine combustion chamber as well as to effectively account for the detailed mechanisms of soot formation, NOX formation including thermal NO path, prompt and nitrous NOX formation, and reburning process. Special emphasis is given to the turbulent combustion model which properly accounts for vaporization effects on the mixture fraction fluctuations and the pdf model. The results of numerical modeling using the RIF concept are compared with experimental data and with numerical results of the commonly applied procedure which the low-temperature and high-temperature oxidation processes are represented by the Shell ignition model and the eddy dissipation model, respectively. Numerical results indicate that the RIF approach including the vaporization effect on turbulent spray combustion process successfully predicts the ignition delay time and location as well as the pollutant formation.  相似文献   
5.
Presents the citation, biography, and selected bibliography for Bruce E. Wampold, the 2007 recipient of the American Psychological Association's Award for Distinguished Professional Contributions to Applied Research. Also presented is an article based on the author's award address delivered at the APA's 115th annual meeting, held August 17-20, 2007, in San Francisco, California. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
7.
过去低渗油藏调剖,注入性和堵塞性很难统一,新研制的CHA无机凝胶体系是一种易注入、堵塞能力强的调剖剂,而且成胶时间在一定范围内可控。研究了配比、温度对CHA无机凝胶体系成胶时间的影响,成胶前的注入性,成胶后在高温高盐条件下的堵塞能力,得到了可应用于现场的CHA无机凝胶体系。该调剖剂在濮城油田沙三段和文卫结合部等高温、高盐低渗油藏应用后,取得了很好的效果。  相似文献   
8.
This paper describes the synthesis of cements, chemically and structurally related to Ca2SiO4. Silica was obtained from rice hull after heating at 600 °C. Calcium oxide and small amounts of barium chloride were mixed in order to obtain a final (Ca/Si) or (Ca+Ba)/Si ratio equal to 1.95, 1.90, and 1.80, which is lower than in the conventional cement. The solids were mixed and ultrasonically treated for 1 h with a water/solid ratio of about 20. After drying and grinding, the mixtures were heated up to 1100 °C. It was possible, in some cases, to obtain a cementitious material. These cements are structurally related to β-Ca2SiO4 and the lower (Ca+Ba)/Si ratio obtained was 1.95. The initial chemical compositions of these cements are: (Ca1.83+Ba0.12)SiO4 and (Ca1.79+Ba0.16)SiO4. A further lowering in the (Ca+Ba)/Si ratio changes the nature of the silicates.  相似文献   
9.
商业创新模式下的建筑设计服务   总被引:1,自引:0,他引:1  
购物中心作为一种现代的零售商业模式,从上世纪90年代进入中国后,已为一般民众厂为接受。文章首先简要地介绍了美国购物中心的开发历史和类型,尤其是近年来出现的生活方式中心的特点和发展趋势。对于购物中心在中国的开发、规划设计中经常遇到的一些内容,如融资方式,主力商店和专卖店等进行了讨论。最后对于建筑师在这新的商业模式下如何与设计团队一起提供专业服务方面根据自身的经验提出了自己的看法。  相似文献   
10.
The Steady radial distribution of chemical species in a wire‐to‐cylinder ozone generator filled with pure oxygen has been computed by applying four different plasma chemistry models of increasing complexity. The most complete model considers ten species (e, O2 +, O2 ?, O3 ?, O?, O2, O2(1Δg), O2(1g +), O and O3) and 79 reactions, including ionization by electron impact, electron attachment and detachment, electron-ion recombination, charge transfer, etc. The chemical model is coupled with the electrical model through Poisson's equation. The spatially averaged ozone density has been computed as a function of the current intensity and compared with the experimental values obtained by UV spectroscopy.  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