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   18141篇
  免费   268篇
  国内免费   54篇
教育   13357篇
科学研究   1235篇
各国文化   193篇
体育   1463篇
综合类   44篇
文化理论   115篇
信息传播   2056篇
  2022年   121篇
  2021年   227篇
  2020年   308篇
  2019年   485篇
  2018年   647篇
  2017年   680篇
  2016年   634篇
  2015年   409篇
  2014年   544篇
  2013年   3679篇
  2012年   504篇
  2011年   505篇
  2010年   435篇
  2009年   419篇
  2008年   435篇
  2007年   411篇
  2006年   428篇
  2005年   371篇
  2004年   262篇
  2003年   259篇
  2002年   231篇
  2001年   374篇
  2000年   297篇
  1999年   250篇
  1998年   163篇
  1997年   161篇
  1996年   177篇
  1995年   150篇
  1994年   161篇
  1993年   141篇
  1992年   216篇
  1991年   208篇
  1990年   240篇
  1989年   217篇
  1988年   174篇
  1987年   184篇
  1986年   188篇
  1985年   178篇
  1984年   179篇
  1983年   168篇
  1982年   134篇
  1981年   137篇
  1980年   132篇
  1979年   194篇
  1978年   161篇
  1977年   102篇
  1976年   113篇
  1975年   101篇
  1973年   98篇
  1971年   101篇
排序方式: 共有10000条查询结果,搜索用时 734 毫秒
961.
Many user-centred studies of electronic information resources include a think-aloud element – where users are asked to verbalise their thoughts, interface actions and sometimes their feelings whilst using these resources to help them complete one or more information tasks. These studies are usually conducted with the purpose of identifying usability issues related to the resource(s) used or understanding aspects of users’ information behaviour. However, few of these studies present detailed accounts of how their think-aloud data was collected and analysed or provide detailed reflection on methodological decisions made. In this article, we discuss and reflect on the methodology used when planning and conducting a think-aloud study of lawyers’ interactive information behaviour. Our discussion is framed by Blandford et al.’s PRET A Rapporter (‘ready to report’) framework – a framework that can be used to plan, conduct and describe user-centred studies of electronic information resource use from an information work perspective.  相似文献   
962.
This paper is aimed to investigate the operating characteristics of a static synchronous compensator (STATCOM) integrated with superconducting magnetic energy storage (SMES) for high power applications in the transmission network level. The STATCOM controller topology comprises multi-level multi-pulse neutral-point clamped-type (NPC) voltage source inverters (VSIs) using the harmonics cancellation technique, and incorporates a SMES coil. An innovative two-quadrant multi-level dc-dc converter is proposed to effectively interface the STATCOM with the superconducting coil using a buck-boost topology with neutral point voltage control capabilities; thus enabling to simultaneously control both active and reactive power exchange with the high voltage power system. A detailed analysis of major system variables is presented, including analytical results and digital simulations using the MATLAB/Simulink environment. Moreover, a three-level control scheme is designed, including a full decoupled current control strategy in the d-q reference frame with a novel controller to prevent the STATCOM dc bus capacitors voltage drift/imbalance and an enhanced power system frequency controller.  相似文献   
963.
Many services can be self-provided. An individual user or a user firm can, for example, choose to do its own accounting - choose to self-provide that service - instead of hiring an accounting firm to provide it. Since users can ‘serve themselves’ in many cases, it is reasonable to suspect that they can also innovate with respect to the services they self-provide - possibly without the assistance of service providers.In this paper, we conduct the first quantitative exploration of the importance of services innovation by users, focusing on the field of commercial and retail banking services. We find that 55% of today's computerized commercial banking services were first developed and implemented by non-bank firms for their own use, and 44% of today's computerized retail banking services were first developed and implemented by individual service users rather than by commercial financial service providers. Manual precursors to these services - manual procedures that carried out functions similar to computerized services in our sample - were almost always developed by users as self-services.Our empirical findings differ significantly from prevalent producer-centered views of service development. We speculate that the patterns we have observed in banking with respect to the major role of users in service development will prove to be quite general. If so, this will be an important matter: on the order of 75% of GDP in advanced economies today is derived from services. We discuss the implications of our findings for research and practice in service development.  相似文献   
964.
Software must evolve in order to adapt to new demands and scenarios. In the case of packaged software that can be customized, this evolution implies the maintenance of both out-of-the-box and customized functionality alike. New user interface technologies provide a way to interact with applications that software vendors are forced to incorporate in order to meet new user and market requirements. Packaged software vendors are facing software evolution processes in order to attract more customers and conserve the existing ones. This case analysis describes the evolution of packaged software, Meta4 PeopleNet, towards the addiction of Rich Internet Applications features to a Human and Intellectual Capital Management tool. The findings and lessons learned presented in this case study provide useful insights for packaged software vendors facing software product evolution.  相似文献   
965.
Information technology allows national and local governments to satisfy the needs of citizens in a cost effective way. Unfortunately, citizens still tend to prefer traditional, more costly channels, such as the front desk, phone and mail. Through pilot projects government agencies attempt to influence this behavior of citizens, directing them towards the online channel. With this paper we provide insight into the possibility to influence citizens’ behavior in the complex landscape of multi-channel service provision. The paper systematically compares five pilot projects using a framework that is based on organizational and marketing literature. The results show that socio-psychological factors are crucial in multi-channel management, much more than the technology itself. We conclude that citizens can be directed towards the online channel. However, not all projects are successful. Economic and legal instruments tend to sort more direct effects than communication or service instruments. Moreover, organizational factors such as bureaucracy often hinder eventual success. Choosing a smart and relatively small scope and strong project manager may help to evoke success in directing citizen online behavior.  相似文献   
966.

Objective:

The objective of this study was to validate an assessment instrument for MEDLINE search strategies at an academic medical center.

Method:

Two approaches were used to investigate if the search assessment tool could capture performance differences in search strategy construction. First, data from an evaluation of MEDLINE searches from a pediatric resident''s longitudinal assessment were investigated. Second, a cross-section of search strategies from residents in one incoming class was compared with strategies of residents graduating a year later. MEDLINE search strategies formulated by faculty who had been identified as having search expertise were used as a gold standard comparison. Participants were presented with a clinical scenario and asked to identify the search question and conduct a MEDLINE search. Two librarians rated the blinded search strategies.

Results:

Search strategy scores were significantly higher for residents who received training than the comparison group with no training. There was no significant difference in search strategy scores between senior residents who received training and faculty experts.

Conclusion:

The results provide evidence for the validity of the instrument to evaluate MEDLINE search strategies. This assessment tool can measure improvements in information-seeking skills and provide data to fulfill Accreditation Council for Graduate Medical Education competencies.

Highlights

  • The University of Michigan MEDLINE Search Assessment tool can be used to assess search skills in residency education.
  • Five elements were identified as critical elements in the development of an effective MEDLINE search strategy: inclusion of all search concepts, appropriate use of Medical Subject Headings, appropriate use of search limits, successful combination of all concepts, and search efficiency.

Implications

  • This validated assessment tool can serve as an effective means to measure improvements in residents'' information-seeking skills and provide data to fulfill Accreditation Council for Graduate Medical Education competencies.
  相似文献   
967.
968.
旨在探索一种新的采购管理模式,帮助企业降低采购成本,提高采购效率。通过构建以EVA为指导的采购流程,重点讨论与采购人员、供应商相关的核心环节,提出了完善采购人员管理体系、健全供应商管理机制等方面的策略,以实现“采购使企业增值”的目的。  相似文献   
969.
吕婧 《科技与管理》2011,13(2):128-130
我国高校的行政化管理模式由来已久,随着现代高等教育体制与教学制度的不断完善,高校行政化收到了越来越多的非议,并逐步演变成为教育体制改革的焦点。通过对高校“行政化”弊端的分析,认真反思如何使高效发展走出“行政化”制约,如何归还高校办学的独立自主权利。由此可见,废除高校行政级别、剥离教育部对高校的管理和评价权、排除行政干预对学术活动带来影响等呼声日益高涨,逐步演变成为“去行政化”改革的重要手段。  相似文献   
970.
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