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   569篇
  免费   35篇
  国内免费   1篇
电工技术   2篇
综合类   1篇
化学工业   138篇
金属工艺   3篇
机械仪表   6篇
建筑科学   49篇
矿业工程   1篇
能源动力   17篇
轻工业   55篇
水利工程   17篇
无线电   54篇
一般工业技术   106篇
冶金工业   25篇
原子能技术   4篇
自动化技术   127篇
  2024年   2篇
  2023年   13篇
  2022年   11篇
  2021年   31篇
  2020年   11篇
  2019年   14篇
  2018年   26篇
  2017年   34篇
  2016年   18篇
  2015年   18篇
  2014年   26篇
  2013年   38篇
  2012年   35篇
  2011年   53篇
  2010年   32篇
  2009年   37篇
  2008年   39篇
  2007年   31篇
  2006年   36篇
  2005年   20篇
  2004年   14篇
  2003年   12篇
  2002年   15篇
  2001年   10篇
  2000年   8篇
  1999年   4篇
  1998年   4篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   4篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1981年   1篇
排序方式: 共有605条查询结果,搜索用时 15 毫秒
51.
Local and Global Interactions in an Evolutionary Resource Game   总被引:2,自引:0,他引:2  
Conditions for the emergence of cooperation in a spatial common-pool resource game are studied. This combines in a unique way local and global interactions. A fixed number of harvesters are located on a spatial grid. Harvesters choose among three strategies: defection, cooperation, and enforcement. Individual payoffs are affected by both global factors, namely, aggregate harvest and resource stock level, and local factors, such as the imposition of sanctions on neighbors by enforcers. The evolution of strategies in the population is driven by social learning through imitation, based on local interaction or locally available information. Numerous types of equilibria exist in these settings. An important new finding is that clusters of cooperators and enforcers can survive among large groups of defectors. We discuss how the results contrast with the non-spatial, but otherwise similar, game of Sethi and Somanathan (American Economic Review 86(4):766–789, 1996).   相似文献   
52.
This study examined the effect of using a group awareness tool on online collaboration. Furthermore, we examined whether the effect of using a group awareness tool on online collaboration is mediated by group awareness (i.e., students’ awareness of their group members’ levels of participation). To answer these questions, we determined how often and how long 107 secondary education students used the Participation-tool (PT), a group awareness tool designed to visualize group members’ relative contribution to the online collaborative process. Our analyses show that duration of PT use (how long students displayed the tool on their screens) significantly predicted group members’ participation in the online dialogue, their participation when writing collaborative texts, equality of participation within the group, and coordination and regulation of activities in the relational space (i.e., discussing the collaboration process with group members). No effect of using the PT on group performance was found. Mediation analyses showed that the effect of using the PT is only partially mediated by group awareness: an indirect effect of using the PT, via enhanced awareness of participation, on student participation during chat discussions and the collaborative writing process was found.  相似文献   
53.
In recent years, the number of organizations making digital information available has increased dramatically. This evolution has encouraged the development of various approaches to represent complex digital objects. Approaches that are of specific relevance to the digital library and archiving community include the Metadata Encoding and Transmission Standard (METS), the Content Packaging XML Binding of the Instructional Management System (IMS) project, and the Sharable Content Object Reference Model (SCORM). The MPEG-21 Digital Item Declaration MPEG-21 DID) is yet another packaging approach that, so far, has received little attention in the digital library community. The primary goal of this article is to offer a method to compare these packaging approaches in the context of the needs of the digital library community and the rising digital preservation programs. The contribution of this paper is the definition of an integrated reference framework, based on both the ISO OAIS Reference Model and a set of additional significant properties that affect the quality, usability, encoding, and behavior of complex digital objects. This article also gives a brief insight into MPEG-21 DID and examines its potential relevance by showing the results obtained from applying the proposed reference framework. Published online: 8 April 2005  相似文献   
54.
Network and service management has established itself as a research field in the general area of computer networks. However, up to now, no appropriate organization of the field has been carried out in terms of a comprehensive list of terms and topics. In this paper, we introduce a taxonomy for network and service management. With such a taxonomy, it is possible to better understand the landscape of research as well as to reason about possible future challenges and opportunities. As such, in addition to the taxonomy itself, we also present an initial analysis of the field’s past, present, and future, based on the records of papers submitted and accepted in major conferences in the area, as well as a site survey performed through a questionnaire answered by experts from both industry and academia.  相似文献   
55.
This study examined the effects of the shared space (SS) on students’ behaviors in a computer-supported collaborative learning (CSCL) environment. The SS visualizes discussion and agreement during online discussions. It was hypothesized the SS would increase the media richness of the CSCL-environment, would stimulate critical and exploratory group-norms, would lead to more positive perceptions of online collaboration, and would have an impact on students’ collaborative activities. In total, 59 students working in 20 groups had access to the SS visualization, while 58 students working in 20 groups did not. The results show that students with access to the SS visualization: (a) perceived higher media richness; (b) had a more exploratory group-norm perception; (b) perceived more positive group behavior; (c) perceived their group’s task strategies to be more effective; (d) engaged in different collaborative activities and (e) performed better on one part of the group task. These results demonstrate the potential benefits of visualizing agreement and discussion during CSCL.  相似文献   
56.
We conducted a quantitative meta-analysis of previous research on the technology acceptance model (TAM) in an attempt to make well-grounded statements on the role of subjective norm. Furthermore, we compared TAM results by taking into account moderating effects of one individual-related factor (type of respondents), one technology-related factor (type of technology), and one contingent factor (culture). Results indicated a significant influence of subjective norm on perceived usefulness and behavioral intention to use. Moderating effects were found for all three factors. The findings yielded managerial implications for both intra-company and market-based settings.  相似文献   
57.
The aim of this large-scale study was to understand the technology acceptation of learning management systems (LMS) by secondary school teachers and to investigate the instructional use of LMS, distinguishing between informational use and communicational use. The predictive model further includes: perceived usefulness, perceived ease of use, subjective norm, personal innovativeness in the domain of information technology, experience and internal ICT support at school level. Data were collected from 505 Flemish secondary school teachers. After performing satisfactory reliability and validity checks, the study was able to support all relationships among the 9 variables. Informational use was found to be a precursor for communicational use, perceived ease of use of the LMS is the strongest predictor in LMS-acceptation. Internal ICT support has a direct effect on the informational use of the LMS and on subjective norm. Implications stress that secondary school managers in education should take into account the importance of a teachers’ efforts and performance perceptions and the direct and indirect impact of internal ICT support on LMS adoption.  相似文献   
58.
We show counterexamples exist to confluence modulo hypercollapsing subterms, fair normalisation, and the normal form property in orthogonal infinitary higher-order rewriting with non-fully-extended rules. This sets these systems apart from both fully-extended and finite systems, where no such counterexamples are possible.  相似文献   
59.
Network and service management is an established research field within the general area of computer networks. A few years ago, an initial taxonomy, organizing a comprehensive list of terms and topics, was established through interviews with experts from both industry and academia. This taxonomy has since been used to better partition standardization efforts, identify classes of managed objects and improve the assignment of reviewers to papers submitted in the field. Because the field of network and service management is rapidly evolving, a biyearly update of the taxonomy was proposed. In this paper, a large-scale questionnaire is presented which was answered by experts in the field, evaluating the relevance of each individual topic for the next five years. Missing topics, which are likely to become relevant over the next few years, are identified as well. Furthermore, an analysis is performed of the records of papers submitted to major conferences in the area. Based on the obtained results, an updated version of the taxonomy is proposed.  相似文献   
60.
Video games are often regarded as promising teaching and learning tools for the 21st century. One of the main arguments is that video games are appealing to contemporary students. However, there are indications that video game acceptance cannot be taken for granted. In this study, a path model to examine and predict student acceptance of video games is proposed, and empirically tested by involving 858 secondary school students. The results show that students’ preference for using video games in the classroom is affected directly by a number of factors: the perceptions of students regarding the usefulness, ease of use, learning opportunities, and personal experience with video games in general. Gender effects are found as well, but appear to be mediated by experience and ease of use.  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