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   16664篇
  免费   244篇
  国内免费   54篇
教育   12325篇
科学研究   1158篇
各国文化   177篇
体育   1199篇
综合类   44篇
文化理论   78篇
信息传播   1981篇
  2021年   181篇
  2020年   232篇
  2019年   350篇
  2018年   494篇
  2017年   533篇
  2016年   490篇
  2015年   320篇
  2014年   452篇
  2013年   3342篇
  2012年   444篇
  2011年   459篇
  2010年   404篇
  2009年   391篇
  2008年   410篇
  2007年   388篇
  2006年   409篇
  2005年   356篇
  2004年   252篇
  2003年   245篇
  2002年   224篇
  2001年   364篇
  2000年   284篇
  1999年   247篇
  1998年   158篇
  1997年   154篇
  1996年   169篇
  1995年   142篇
  1994年   150篇
  1993年   135篇
  1992年   217篇
  1991年   209篇
  1990年   235篇
  1989年   213篇
  1988年   173篇
  1987年   184篇
  1986年   189篇
  1985年   175篇
  1984年   181篇
  1983年   168篇
  1982年   135篇
  1981年   137篇
  1980年   133篇
  1979年   190篇
  1978年   162篇
  1977年   114篇
  1976年   119篇
  1975年   112篇
  1974年   99篇
  1973年   105篇
  1971年   117篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
991.
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   
992.
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   
993.

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   
994.
995.
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   
996.
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   
997.
998.
To prepare a biosynthetic module in an infochemical communication project, we designed a silicon/glass microreactor with anti-adsorption polyelectrolyte multilayer coating and immobilized alcohol acetyl transferase (atf), one of the key biosynthetic enzymes of the pheromone of Spodoptera littoralis, on agarose beads inside. The system reproduces the last step of the biosynthesis in which the precursor diene alcohol (Z,E)-9,11-tetradecadienol is transformed into the major component (Z,E)-9,11-tetradecadienyl acetate. The scope of this study was to analyze and implement a multilayer, anti-adsorption coating based on layer-by-layer deposition of polyethylenimine/dextransulfate sodium salt (PEI/DSS). The multilayers were composed of two PEI with molecular weights 750 and 1.2 kDa at pH 9.2 or 6.0. Growth, morphology, and stability of the layers were analyzed by ellipsometry and atomic force microscopy (AFM). The anti-adsorption functionality of the multilayer inside the microreactor was validated. The activity of His(6)-(atf) was measured by gas chromatography coupled to mass spectrometer (GC-MS).  相似文献   
999.
Herein is described the fabrication and use of a plastic multilayer 3-channel microfluidic fixture. Multilayer devices were produced by laser machining of plastic polymethylmethacrylate and polyethyleneterapthalate laminates by ablation. The fixture consisted of an array of nine individually addressable gold or gold/ITO working electrodes, and a resistive platinum heating element. Laser machining of both the fluidic pathways in the plastic laminates, and the stencil masks used for thermal evaporation to form electrode regions on the plastic laminates, enabled rapid and inexpensive implementation of design changes. Electrochemiluminescence reactions in the fixture were achieved and monitored through ITO electrodes. Electroaddressable aryl diazonium chemistry was employed to selectively pattern gold electrodes for electrochemical multianalyte DNA detection from double stranded DNA (dsDNA) samples. Electrochemical detection of dsDNA was achieved by melting of dsDNA molecules in solution with the integrated heater, allowing detection of DNA sequences specific to breast and colorectal cancers with a non-specific binding control. Following detection, the array surface could be renewed via high temperature (95 °C) stripping using the integrated heating element. This versatile and simple method for prototyping devices shows potential for further development of highly integrated, multi-functional bioanalytical devices.  相似文献   
1000.
In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin. The carbon fibers underwent chemical modification in order to enable detection of hydrogen peroxide and ascorbic acid; electrochemical measurements were demonstrated using integrated electrode-hollow microneedle devices.  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