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   2034篇
  免费   223篇
  国内免费   202篇
电工技术   15篇
技术理论   1篇
综合类   291篇
化学工业   16篇
金属工艺   2篇
机械仪表   30篇
建筑科学   364篇
矿业工程   3篇
能源动力   7篇
轻工业   45篇
水利工程   3篇
石油天然气   2篇
无线电   149篇
一般工业技术   100篇
冶金工业   363篇
自动化技术   1068篇
  2024年   6篇
  2023年   39篇
  2022年   56篇
  2021年   61篇
  2020年   61篇
  2019年   48篇
  2018年   61篇
  2017年   75篇
  2016年   67篇
  2015年   87篇
  2014年   119篇
  2013年   122篇
  2012年   131篇
  2011年   160篇
  2010年   163篇
  2009年   163篇
  2008年   146篇
  2007年   164篇
  2006年   159篇
  2005年   133篇
  2004年   93篇
  2003年   87篇
  2002年   63篇
  2001年   40篇
  2000年   30篇
  1999年   17篇
  1998年   17篇
  1997年   17篇
  1996年   13篇
  1995年   6篇
  1994年   8篇
  1993年   2篇
  1992年   8篇
  1991年   2篇
  1990年   2篇
  1989年   4篇
  1988年   2篇
  1986年   6篇
  1983年   2篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   3篇
  1972年   1篇
  1968年   1篇
  1963年   1篇
  1960年   1篇
  1959年   1篇
  1954年   2篇
排序方式: 共有2459条查询结果,搜索用时 15 毫秒
51.
本文通过系统的介绍普雷斯顿·斯科特·科恩从早期实验性质的到现今中国一系列的建筑设计实践,探究其新颖的设计手法并从中总结出一般规律,并希望以此重新审视设计的方法与过程以及所要解决的问题。  相似文献   
52.
This paper provides a critical analysis of Mobile Learning projects published before the end of 2007. The review uses a Mobile Learning framework to evaluate and categorize 102 Mobile Learning projects, and to briefly introduce exemplary projects for each category. All projects were analysed with the criteria: context, tools, control, communication, subject and objective. Although a significant number of projects have ventured to incorporate the physical context into the learning experience, few projects include a socializing context. Tool support ranges from pure content delivery to content construction by the learners. Although few projects explicitly discuss the Mobile Learning control issues, one can find all approaches from pure teacher control to learner control. Despite the fact that mobile phones initially started as a communication device, communication and collaboration play a surprisingly small role in Mobile Learning projects. Most Mobile Learning projects support novices, although one might argue that the largest potential is supporting advanced learners. All results show the design space and reveal gaps in Mobile Learning research.  相似文献   
53.
After a brief history of the Committee on International Relations of the American Psychological Association, 3 points are made about international psychological research that matters. First, it matters when the definition of the research problem area and the findings can potentially be reflected in policy change, in the practice of educators or psychologists, or in the mindsets of a new generation of researchers. Person-centered analysis of adolescents’ social and political attitudes has this potential and can complement variable-centered analysis. A cluster analysis of the IEA Civic Education Study’s data in 5 Western European and 5 Eastern European countries illustrates this. The following 5 clusters of adolescents were identified: those supportive of social justice but not participative, those active in conventional politics and the community, those indifferent, those disaffected, and a problematic cluster of alienated adolescents. Second, research that matters is situated in a cultural context. It is proposed that publications using data from any single country be required to include information about the cultural context in which the research was conducted. Finally, it matters that attention be given to the dynamics of the collaborative international research process, not only to research results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
54.
[Correction Notice: An erratum for this article was reported in Vol 35(2) of Journal of Experimental Psychology: Animal Behavior Processes (see record 2009-05154-003). The URL provided for the supplemental material was incomplete. The complete URL is http://dx.doi.org/10.1037/a0012497.supp] Pigeons' pecks produced grain under progressive ratio (PR) schedules, whose response requirements increased systematically within sessions. Experiment 1 compared arithmetic (AP) and geometric (GP) progressions. Response rates increased as a function of the component ratio requirement, then decreased linearly (AP) or asymptotically (GP). Experiment 2 found the linear decrease in AP rates to be relatively independent of step size. Experiment 3 showed pausing to be controlled by the prior component length, which predicted the differences between PR and regressive ratio schedules found in Experiment 4. When the longest component ratios were signaled by different key colors, rates at moderate ratios increased, demonstrating control by forthcoming context. Models for response rate and pause duration based on Bizo and Killeen (1997) described performance on AP schedules; GP schedules required an additional parameter representing the contextual reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
56.
Although people often have to learn from environments with scarce and highly selective outcome feedback, the question of how nonfeedback trials are represented in memory and affect later performance has received little attention in models of learning and decision making. In this article, the authors use the generalized context model (Nosofsky, 1986) as a vehicle to test contrasting hypotheses about the coding of nonfeedback trials. Data across 3 experiments with selective decision-contingent and selective outcome-contingent feedback provide support for the hypothesis of constructivist coding (Elwin, Juslin, Olsson, & Enkvist, 2007), according to which the outcomes on nonfeedback trials are coded with the most likely outcome, as inferred by the individual. The relation to sampling-based approaches to judgment, and the adaptive significance of constructivist coding, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
57.
The purpose of this study is to design a structural model explaining how users could utilize Facebook for educational purposes. In order to shed light on the educational usage of Facebook, in constructing the model, the relationship between users' Facebook adoption processes and their educational use of Facebook were included indirectly while the relationship between users' purposes in using Facebook and the educational usage of Facebook was included directly. In this study, data is collected from Facebook users with an online survey developed by the researchers. The study group consists of 606 Facebook users whose answers were examined by using a structural equation model. The analyses of the 11 observed and 3 latent variables provided by the model showed that 50% of educational usage of Facebook could be explained by user purposes along with the adoption processes of Facebook. It was also found that Facebook adoption processes could explain 86% of all user purposes. Finally, while Facebook adoption processes explained 45% of its educational usage, it could explain 50% of variance in educational usage of Facebook when the user purposes were added into the analyses.  相似文献   
58.
在网关GPRS(通用无线分组业务)支持节点(GGSN)项目与服务GPRS支持节点(SGSN)项的集成测试中发现了GGSN相关协议的一处流程交互的定义的缺陷,该缺陷导致在异常的流程处理中大量垃圾上下文的生成,并使得GGSN与SGSN两侧信息产生较大的不一致,这些不一致的信息将在较长时间影响系统的后续运行并产生运行错误.本文分析了此流程缺陷产生的原因并对相应流程提出一种改进的方法.实验环境下的测试结果表明,对协议做这样的改进可以完全解决这一问题并保证工程实现的高效性.  相似文献   
59.
杨超 《山西建筑》2009,35(4):32-34
研究了南京市金陵中学本部校园的背景及现状,通过对南京金陵中学本部校园改造规划设计的分析,提出了基于文脉整合的校园更新策略,指出全面深入地理解校园历史,创造性地诠释校园文化必将成为任何规划设计的原点。  相似文献   
60.
Incremental Dynamics   总被引:1,自引:0,他引:1  
A new system of dynamic logic is introduced and motivated, witha novel approach to variable binding for incremental interpretation. Thesystem is shown to be equivalent to first order logic and complete.The new logic combines the dynamic binding idea from DynamicPredicate Logic with De Bruijn style variable free indexing. Quantifiersbind the next available variable register; the indexing mechanismguarantees that active registers are never overwritten by newquantifiers actions. Apart from its interest in its own right, theresulting system has certain advantages over Dynamic Predicate Logic orDiscourse Representation Theory. It comes with a more well behaved(i.e., transitive) consequence relation, it gives a more explicitaccount of how anaphoric context grows as text gets processed, and ityields new insight into the dynamics of anaphoric linking in reasoning.Incremental dynamics also points to a new way of handling contextdynamically in Montague grammar.  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