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   3609篇
  免费   60篇
  国内免费   7篇
教育   2762篇
科学研究   294篇
各国文化   51篇
体育   250篇
综合类   12篇
文化理论   59篇
信息传播   248篇
  2023年   20篇
  2022年   40篇
  2021年   71篇
  2020年   107篇
  2019年   171篇
  2018年   225篇
  2017年   211篇
  2016年   175篇
  2015年   108篇
  2014年   144篇
  2013年   624篇
  2012年   140篇
  2011年   125篇
  2010年   132篇
  2009年   102篇
  2008年   93篇
  2007年   94篇
  2006年   88篇
  2005年   108篇
  2004年   104篇
  2003年   126篇
  2002年   93篇
  2001年   84篇
  2000年   53篇
  1999年   39篇
  1998年   22篇
  1997年   17篇
  1996年   19篇
  1995年   24篇
  1994年   14篇
  1993年   10篇
  1992年   11篇
  1991年   23篇
  1990年   14篇
  1989年   21篇
  1988年   9篇
  1987年   8篇
  1986年   11篇
  1985年   12篇
  1984年   7篇
  1982年   10篇
  1981年   13篇
  1980年   10篇
  1979年   9篇
  1978年   9篇
  1977年   10篇
  1974年   10篇
  1973年   8篇
  1966年   6篇
  1963年   6篇
排序方式: 共有3676条查询结果,搜索用时 15 毫秒
101.
102.
103.
Desalination is a relatively new intervention in the field of conservation of architectural heritage. Especially the desalination of immovable objects, such as masonry structures, is still a trial-error practice. In the field, different desalination materials and methods are used, sometimes with unsatisfactory results. Better understanding of the desalination process is needed in order to support the conservator with clear guidelines for choosing a suitable desalination material and method. The research presented in this paper constitutes the first step towards the development of a modular system of poultices, which can be adapted, i.e. fine-tuned to different types of substrates. Starting point is to make use of advection, i.e. the transport of salt ions with water flow. This transport mechanism is faster than diffusion and the application on immovable objects is relatively easy. In order to optimize salt extraction, a poultice working by advection should have smaller pores than the substrate. Starting from this principle the pore sizes of different desalination materials (sand, cellulose, kaolin and bentonite) mixed in different proportions, have been measured. Interesting results were obtained, showing that the desalination materials commonly used in the field are often not the most suitable ones. On the basis of the results, recipes for poultices, adapted to a specific substrate, can be formulated.  相似文献   
104.
In many Western science systems, funding structures increasingly stimulate academic research to contribute to practical applications, but at the same time the rise of bibliometric performance assessments have strengthened the pressure on academics to conduct excellent basic research that can be published in scholarly literature. We analyze the interplay between these two developments in a set of three case studies of fields of chemistry in the Netherlands. First, we describe how the conditions under which academic chemists work have changed since 1975. Second, we investigate whether practical applications have become a source of credibility for individual researchers. Indeed, this turns out to be the case in catalysis, where connecting with industrial applications helps in many steps of the credibility cycle. Practical applications yield much less credibility in environmental chemistry, where application-oriented research agendas help to acquire funding, but not to publish prestigious papers or to earn peer recognition. In biochemistry practical applications hardly help in gaining credibility, as this field is still strongly oriented at fundamental questions. The differences between the fields can be explained by the presence or absence of powerful upstream end-users, who can afford to invest in academic research with promising long term benefits.  相似文献   
105.
This article aims to open up the biographical black box of three experts working in the boundary zone between science, policy and public debate. A biographical-narrative approach is used to analyse the roles played by the virologists Albert Osterhaus, Roel Coutinho and Jaap Goudsmit in policy and public debate. These figures were among the few leading virologists visibly active in the Netherlands during the revival of infectious diseases in the 1980s. Osterhaus and Coutinho in particular are still the key figures today, as demonstrated during the outbreak of novel influenza A (H1N1). This article studies the various political and communicative challenges and dilemmas encountered by these three virologists, and discusses the way in which, strategically or not, they handled those challenges and dilemmas during the various stages of the field’s recent history. Important in this respect is their pursuit of a public role that is both effective and credible. We will conclude with a reflection on the H1N1 pandemic, and the historical and biographical ties between emerging governance arrangements and the experts involved in the development of such arrangements.  相似文献   
106.
107.
108.
Technological advancements in the workplace frequently have produced contradictory effects by facilitating accessibility and efficiency while increasing interruptions and unpredictability. We combine insights from organizational paradoxes and the job demands–resources model to construct a framework identifying positive and negative mechanisms in the relationship between communication technology use (CTU) and employee well-being, operationalized as work engagement and burnout. In this study of Dutch workers, we demonstrate that CTU increases well-being through positive pathways (accessibility and efficiency) and decreases well-being through negative pathways (interruptions and unpredictability). We highlight the importance of (1) investigating CTU resources and demands simultaneously to grasp the relationship between CTU and employee well-being, and (2) considering CTU's downsides to successfully implement new communication technologies and flexible work designs.  相似文献   
109.
110.
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