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   1983篇
  免费   72篇
  2023年   12篇
  2021年   10篇
  2020年   23篇
  2019年   35篇
  2018年   61篇
  2017年   61篇
  2016年   74篇
  2015年   44篇
  2014年   39篇
  2013年   594篇
  2012年   66篇
  2011年   76篇
  2010年   61篇
  2009年   66篇
  2008年   49篇
  2007年   60篇
  2006年   51篇
  2005年   29篇
  2004年   18篇
  2003年   18篇
  2002年   19篇
  2001年   20篇
  2000年   18篇
  1999年   28篇
  1998年   12篇
  1997年   17篇
  1996年   18篇
  1995年   16篇
  1994年   11篇
  1993年   20篇
  1992年   16篇
  1991年   22篇
  1989年   10篇
  1988年   14篇
  1987年   18篇
  1986年   23篇
  1985年   18篇
  1984年   16篇
  1983年   20篇
  1982年   23篇
  1981年   19篇
  1980年   15篇
  1979年   16篇
  1978年   15篇
  1977年   14篇
  1976年   16篇
  1975年   15篇
  1973年   11篇
  1969年   11篇
  1967年   15篇
排序方式: 共有2055条查询结果,搜索用时 15 毫秒
11.
This paper proceeds in three steps. First, it gives more focus and rigor to the geographic reception of "postmodernism," through an investigation of the problem of representation as it has evolved from Kant through de Saussure and Wittgenstein to Derrida. Second, it arranges historical materialist encounters with the problem of representation along a spectrum of increasing seriousness leading from Palmer through Jameson to Adorno. Third, the various geographic responses to and avoidances of the key issues involved in postmodernism are read against the backdrop of possible seriousness opened up by the first two sections of the paper. The essay concludes by considering implications, for both social science and politics, not limited to questions about the possibility of disciplinary legitimacy.  相似文献   
12.
13.
14.
15.
16.
A number of investigations have been undertaken by the New South Wales Water Resources Commission to determine the regional and compound effects of large scale extractive industries on the stability of the Hunter River, New South Wales. Sedimentologic studies of bed material suggest that the Hunter River upstream of Denman has an armoured gravel bed that is immobile during regulated releases from Glenbawn Dam but is disrupted by moderate but less than bankfull flows. Annual bedloadyields have been computed by the bedload rating-flow duration technique for five river gauging stations. Approximate sand and gravel budgets for selected reaches of the Hunter River demonstrate that the present annual extraction rate from temporary sediment storages within the channel greatly exceeds the transport rate upstream of Denman and is approximately equal to the transport rate downstream of Denman. River degradation is imminent if extractive industries continue operating in the channel of the Hunter River  相似文献   
17.
18.
19.
20.
Biogeographers, ecologists, palaeontologists, and conservation managers often deal with checklists in which not all individuals have been identified to a species level, or the accuracy of species identification is questionable. Is it possible and credible to investigate species richness based on such checklists? Studies on macrofauna in the Far Eastern seas, eastern Arctic seas, and adjacent waters of the Pacific and Arctic Oceans suggest that in different habitats and for diverse taxa, species, and higher taxa richness strongly correlate with each other and increase with an expansion in the study area and sample size according to the species–area law. Such an increase is higher in the bottom zone than in the pelagic. Species and higher taxa richness also show a decrease from lower to higher latitudes, which is in line with the Humboldt–Wallace’s law. According to Willis’ law and self-similarity in the organisation of taxonomic levels, species richness can be assessed based on the genus, family, and order richness. In other words, supraspecies richness itself can tell us the same as species richness and therefore certain global patterns revealed at the species level may also be revealed at the supraspecies level. Such a concordance in general trends among richness parameters at different taxonomic levels in practice implies that species richness can be studied based on lists that lack species identifications or lists with doubtful species identification. We suggest bolder use of supraspecies richness in science and practice, discussing the disadvantages and advantages of this approach.  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