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   19612篇
  免费   142篇
  国内免费   7篇
教育   14851篇
科学研究   1678篇
各国文化   161篇
体育   1017篇
综合类   3篇
文化理论   504篇
信息传播   1547篇
  2022年   49篇
  2021年   75篇
  2020年   150篇
  2019年   216篇
  2018年   2405篇
  2017年   2332篇
  2016年   1824篇
  2015年   323篇
  2014年   348篇
  2013年   1907篇
  2012年   437篇
  2011年   900篇
  2010年   1018篇
  2009年   598篇
  2008年   897篇
  2007年   1334篇
  2006年   274篇
  2005年   573篇
  2004年   588篇
  2003年   536篇
  2002年   288篇
  2001年   137篇
  2000年   136篇
  1999年   118篇
  1998年   111篇
  1997年   130篇
  1996年   121篇
  1995年   128篇
  1994年   119篇
  1993年   93篇
  1992年   111篇
  1991年   113篇
  1990年   101篇
  1989年   91篇
  1988年   84篇
  1987年   71篇
  1986年   66篇
  1985年   73篇
  1984年   62篇
  1983年   76篇
  1982年   74篇
  1981年   78篇
  1980年   83篇
  1979年   75篇
  1978年   54篇
  1977年   44篇
  1976年   53篇
  1975年   38篇
  1974年   34篇
  1973年   25篇
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
51.
52.
53.
Working Graphs     
  相似文献   
54.
An investigation has been undertaken at St Andrew’s church, Walpole St Andrew, Norfolk, to establish the underlying causes of the observed stone decay to the upper parts of the six stone piers. The stone decay was first recorded in the early 1930s. The salt-contaminated masonry within the church has been shown to undergo severe salt decay during the summer, with little damage occurring over the winter months. The south aisle piers have been shown to decay 2.5 times faster than the north aisle piers. Although crystallization–hydration cycles have been identified, the rate of decay is at its greatest when the cycling is relatively infrequent. This was not the expected trend. Furthermore, it has been shown that during extended periods where the ambient relative humidity is less than 75%, the rate of decay reaches a maximum. It is the length of this ‘drying’ period that apparently has the greatest influence on the rate of decay and could explain the significant difference in the rate of decay between the south and north aisle piers. The results have serious implications for passive conservation, where it is often recommended to lower the ambient relative humidity to well below the equilibrium relative humidity of the salt contaminant, to avoid crystallization–hydration cycles. Since, at the time of building, the church was situated on the coast, it is possible that the sodium chloride contamination occurred during the building process (1440–1520), particularly since the area was prone to sea-flooding at this time. Alternatively, the salt could have been applied as a treatment during the general restoration of 1897. Whatever the source of the salt, it seems likely that the ambient environment was changed by the insertion of a sealed floor in 1897, which could account for the onset of the salt decay.  相似文献   
55.
56.
57.
彻底简化IT     
如何实现"简化IT"的战略,这是困扰很多企业,尤其是CIO的一个重要问题。本文以日本新生银行的例子来诠释如何彻底简化IT。中世纪哲人William of Ock- ham说过,理论应该尽可能的简单。同样的原则适用于企业IT系统:它们按照尽可能少的标准  相似文献   
58.
At this critical point in its development as a burgeoning market economy ensconced within a socialist political system, China faces a dilemma in becoming a fully‐fledged player in the copyright arena. Over the past two decades, China has made great strides in creating a legal and governmental framework for the administration and enforcement of copyright. But its implementation has left much to be desired, owing partly to inadequate resources of money and personnel, partly to insufficiently harsh penalties for infringement, partly to cumbersome procedures required to bring action against infringers, and partly to a general cultural tolerance for practices that run contrary to cultivating a broad‐based respect for copyright. This article proposes that a balance of pressure and encouragement is likely to have the best chances of success in overcoming these problems and ensuring that China will become fully welcomed into the international publishing community.  相似文献   
59.
60.
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