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   10953篇
  免费   489篇
  2020年   153篇
  2019年   250篇
  2018年   318篇
  2017年   304篇
  2016年   361篇
  2015年   249篇
  2014年   237篇
  2013年   3109篇
  2012年   324篇
  2011年   338篇
  2010年   345篇
  2009年   331篇
  2008年   263篇
  2007年   291篇
  2006年   250篇
  2005年   149篇
  2004年   137篇
  2003年   140篇
  2002年   160篇
  2001年   198篇
  2000年   148篇
  1999年   169篇
  1998年   146篇
  1997年   120篇
  1996年   133篇
  1995年   105篇
  1994年   101篇
  1993年   109篇
  1992年   105篇
  1991年   89篇
  1990年   77篇
  1989年   90篇
  1988年   84篇
  1987年   105篇
  1986年   91篇
  1985年   106篇
  1984年   120篇
  1983年   123篇
  1982年   93篇
  1981年   106篇
  1980年   114篇
  1979年   103篇
  1978年   90篇
  1977年   110篇
  1976年   87篇
  1975年   97篇
  1974年   61篇
  1973年   56篇
  1972年   63篇
  1971年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
This paper is concerned with the products of a number of Neolithic quarries in highland Britain. It investigates the claim that the scale of axe distribution was partly the result of social factors which resulted in these artefacts gaining an added value in areas remote from their sources. One case study considers the sequence of production in Cumbria, in relation to the tensile strength of the rock quarried in different parts of the region. It shows that these considerations had only a limited influence over the choice of stone source and the scale on which it was worked. A second study compares the tensile strength of the main raw materials used for making non-flint axes with the extent to which these sources were actually exploited. Again there is only a limited relationship between the two, suggesting that social factors may indeed have been important.  相似文献   
72.
Global social, political, and economic change during the past quarter-century has been profound, particularly in major areas with languages different from those usually employed by Canadian geographers. Surveys by the author suggest that senior Canadian geography graduate students, however, are inadequately prepared to assimilate primary world sources of information, including the relevant research literatures (except those published in this country's two official languages), and that few geography departments any longer require competence in more than one language at any level of study. Nevertheless, geographers and their students could benefit in many ways from foreign language expertise. Suggestions are made whereby geography departments could reinforce their existing rigorous training programs with foreign linguistic and area competence.  相似文献   
73.
74.
75.
76.
77.
78.
ABSTRACT. The premise of this paper is that one can discover much about the location determinants of high-technology industry by examining the location (migration) decision of workers with high-technology occupations. A model of the high-technology worker migration decision is developed that permits estimation of worker response to both personal and area characteristics, the latter chosen to mirror location factors often cited by high-technology firms as important for both the attraction and retention of their specialized work force. Logit estimates of this model between 1975 and 1980 are presented. The paper is concluded with a discussion of policy implications.  相似文献   
79.
Digital analysis of Landsat data is applied to up-dating land cover maps for the Goondiwindi district of southern, inland Queensland. The imagery was paired with climax cover maps obtained from land systems reports with analysis conducted separately for each of three climax cover types (open forest, woodland and open woodland). Computer classification using this approach produced readily interpreted and reliable results. This work demonstrates that Landsat can be used in conjunction with existing, land systems derived maps to produce data that combine the advantages of two approaches to environmental survey, the former being based on current land cover/land use and the latter on the original environment and its land use potential.  相似文献   
80.
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