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   7029篇
  免费   278篇
  国内免费   17篇
电工技术   84篇
综合类   8篇
化学工业   1582篇
金属工艺   110篇
机械仪表   152篇
建筑科学   341篇
矿业工程   9篇
能源动力   242篇
轻工业   594篇
水利工程   62篇
石油天然气   29篇
武器工业   2篇
无线电   659篇
一般工业技术   1172篇
冶金工业   1071篇
原子能技术   38篇
自动化技术   1169篇
  2023年   68篇
  2022年   108篇
  2021年   180篇
  2020年   124篇
  2019年   128篇
  2018年   178篇
  2017年   160篇
  2016年   193篇
  2015年   164篇
  2014年   225篇
  2013年   414篇
  2012年   372篇
  2011年   440篇
  2010年   335篇
  2009年   384篇
  2008年   367篇
  2007年   381篇
  2006年   271篇
  2005年   264篇
  2004年   208篇
  2003年   200篇
  2002年   163篇
  2001年   121篇
  2000年   120篇
  1999年   112篇
  1998年   157篇
  1997年   144篇
  1996年   106篇
  1995年   119篇
  1994年   102篇
  1993年   83篇
  1992年   71篇
  1991年   36篇
  1990年   50篇
  1989年   68篇
  1988年   58篇
  1987年   45篇
  1986年   54篇
  1985年   66篇
  1984年   48篇
  1983年   63篇
  1982年   40篇
  1981年   41篇
  1980年   43篇
  1979年   30篇
  1978年   29篇
  1977年   28篇
  1976年   32篇
  1975年   32篇
  1974年   28篇
排序方式: 共有7324条查询结果,搜索用时 0 毫秒
1.
ABSTRACT

The concept of digital game-based learning (DGBL) evolves rapidly together with technological enhancements of virtual reality (VR) and smart phones. However, the mental workload (MWL) that VR-training applications demand and motivational qualities originating from user experience (UX) should be identified in order to create effective and enjoyable training/learning challenges that fit with individual users’ capabilities. This study examined the effects of reality-based interaction (RBI) and VR on measures of student motivation and MWL, in a mental arithmetic game for secondary school pupils. In a randomised controlled trial with sixty school children, a mental arithmetic game was tested with three different interaction and two different presentation methods – VR RBI, VR head-mounted-display tapping and tablet flick-gesture. Results found a significant effect of RBI on MWL but no differences in enjoyment of training were found between VR-experience and tablet training-experience. In fact, adding the gaming-context to the mental arithmetic task created an enjoyable, motivating experience regardless of presentation or interaction-style.  相似文献   
2.
Industries in the US continue to lose ground in international competition. If IS is to help change that trend, it will have to become more creative. Creativity improvement programs are being introduced in other areas of the company— now is the time for IS organizations to follow suit.  相似文献   
3.
A clear understanding of the concept and consequences of diversity in science and technology is a key issue for Europe, when considering the current debate on cohesion Put forward within the Single European Act. According to Article 130B of the Single Act, all European policies, including technological policies must contribute to the achievement of a greater cohesion throughout the EC. The European market is generally presented as mainly a patchwork of national or even regional characteristics, with compartmentalized niches, and specific regulations. But does cohesion mean decreasing disparities between regions, which in such case signifies a passive policy of reallocation of resources within the EC, at the risk of generating uniformity? Or, does cohesion mean integration of all innovative and creative efforts, which implies a more complex policy of stimulation, under the condition to maintain a certain diversity? Must the governments systematically reduce diversity, or on the contrary must they enlarge diversity? How can they distinguish between negative and positive aspects of diversity? How do they operate a trade off between economies of scale and economies of diversity? To try to answer these political issues and to set up a coherent industrial policy at the EC level, a careful analysis of the sources of diversity, of the mechanisms that generate or reduce diversity, of the ways to valorize diversity are discussed in this paper  相似文献   
4.
Due to several inherent advantages, plasma processing technology may become a very useful tool in the production of new materials. An increasing research effort based on experimental as well as theoretical investigations has been invested in this area for the synthesis of advanced materials. In describing the thermal-plasma processing technique, this article employs examples from research at the Plasma Processing Laboratory at the University of Idaho.  相似文献   
5.
The main objective of the present work is to modify the traditional mapping method for the simulation of distributive mixing of multiphase flows in geometries involving moving parts such as, internal mixers or twin-screw extruders without a limitation on their geometrical periodicity. The periodicity condition, limits the results of traditional mapping method to tracking mapping mesh between specific discrete time intervals or distances for that geometry is repeated, hence, result is only for fixed orientation of rotors. Imaginary domain method is introduced to track mapping mesh from one state to the next free of geometrical periodicity limitations. In this work the method is introduced and its applicability and accuracy is discussed in details. A two-dimensional (2D) simulation of mixing of two Newtonian fluids with different viscosities in an intermeshing internal mixer is used as a test case study. In this example the key issues of ability to predict mixing state in details for all orientations of rotors is presented. To reduce diffusion errors of mapping method in the boundaries of the rotors, mapping mesh refinement technique that relies upon one single reference mesh is also presented.  相似文献   
6.
By contrast to design meetings, design evaluation meetings (DEMs) have generally been considered as situations in which, according to DEM methodologies, design activities are quite marginal. In a study of DEMs in software development, i.e. in technical review meetings following a particular review methodology, we showed: (i) the occurrence of design activities as part of an argumentation process; (ii) the relative importance of cognitive synchronisation as a prerequisite for evaluation; (iii) the important role played in evaluation by argumentation that makes explicit the underlying design rationale (DR). On the basis of our results, we discuss the potential for using DR methodologies in this kind of meetings.  相似文献   
7.
8.
Evaluated the effects of performance feedback on levels of treatment integrity in school-based behavioral consultation. Three teachers employed in a residential treatment community were responsible for treatment implementation. Treatment integrity was defined as the percentage of 2-min intervals during which contingent teacher reinforcement for student on-task behavior was directly observed. Teacher and child behavior were monitored across baseline, traditional consultation, and consultation with performance feedback conditions in a multiple baseline design. Following a Problem Identification Interview and Problem Analysis Interview (J. R. Bergan, 1977), mean levels of treatment integrity for the 3 teachers ranged from 9% to 37%. The addition of a performance feedback package increased treatment integrity for all 3 teachers to levels ranging from 60% to 83%. The findings contribute to a growing literature supporting the need for direct assessment of treatment integrity in school-based consultation research and practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Wooden sticks used to suspend feces obtained for surveillance cultures were found to be the source of Rhizopus microsporus var. rhizopodiformis causing a pseudo-outbreak among 17 immunocompromised patients cared for in three different wards. Nonsterile wooden products should therefore not be used for collecting, handling, and processing specimens for microbiological examination.  相似文献   
10.
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