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   5961篇
  免费   270篇
  2023年   36篇
  2020年   111篇
  2019年   100篇
  2018年   191篇
  2017年   216篇
  2016年   205篇
  2015年   145篇
  2014年   106篇
  2013年   1630篇
  2012年   131篇
  2011年   145篇
  2010年   149篇
  2009年   151篇
  2008年   152篇
  2007年   113篇
  2006年   111篇
  2005年   86篇
  2004年   71篇
  2003年   74篇
  2002年   78篇
  2001年   73篇
  2000年   78篇
  1999年   90篇
  1998年   78篇
  1997年   56篇
  1996年   64篇
  1995年   61篇
  1994年   58篇
  1993年   69篇
  1992年   62篇
  1991年   43篇
  1990年   41篇
  1989年   62篇
  1988年   51篇
  1987年   60篇
  1986年   58篇
  1985年   77篇
  1984年   96篇
  1983年   83篇
  1982年   68篇
  1981年   75篇
  1980年   77篇
  1979年   71篇
  1978年   71篇
  1977年   57篇
  1976年   75篇
  1975年   77篇
  1974年   49篇
  1973年   39篇
  1972年   36篇
排序方式: 共有6231条查询结果,搜索用时 15 毫秒
891.
892.
893.
The elevation and age of surveyed shorelines in St Jonsfjorden, western Spitsbergen, provide a chronology for Late Weichselian deglaciation and a proxy for former ice thickness. Support is provided for previous reports of two sets of shorelines on NW Spitsbergen, the oldest (at 60 m in St Jonsfjorden) dating to a pre‐late Weichselian glaciation and the youngest documenting postglacial rebound. The remarkable survival of the older shorelines suggests that a large area of NW Spitsbergen was either covered by protective, cold‐based ice or was subject to only local glaciation during the late Weichselian even though glacier ice extended to the shelf edge in the Isfjorden Trough. A marine limit of 46 m at the mouth of St Jonsfjorden is compatible with the regional late Weichselian marine limit (LWML) dated to ~13 ka BP. A partial relative sea level curve and equidistant shoreline diagram are produced for St Jonsfjorden and used in conjunction with relative sea level curves based on data from previous studies to produce an isobase map for 9 ka BP. The curves indicate that western sites were subject to initial slow emergence followed by rapid emergence between 10 ka and 8.2 ka BP, trends characteristic of areas affected by a full glacial sea or at least subject to early break up of a thin or discontinuous glacier ice cover. A step in the 9 ka BP shoreline long profile over the western end of the peninsula separating Isfjorden and van Mijenfjorden suggests that Holocene neotectonics may have produced anomalously high rebound rates in that area.  相似文献   
894.
During the late‐Midlandian (25–13 14C ka BP), the last Irish Ice Sheet was thicker in the Western Mourne Mountains than previously argued. Geomorphological and sedimento‐logical analysis shows that regional ice from the Irish Ice Sheet spilled over the mountains, reaching a major limit 5 km along Pigeon Rock Valley. These findings differ from the previous view that a local valley glacier occupied the valley during this period. The pattern of deglaciation was reconstructed using glacial and periglacial evidence. A complex topographic environment in the upper reaches of the valley suggests that regional ice stagnated as it wasted away. During the Nahanagan Stadial (Younger Dryas, ca. 11–10 ka 14C BP) an arcuate ridge was formed on the western flank of the valley. Calculations suggest that the Equilibrium Line Altitude, influenced by topographic conditions favourable for snow accumulation, was approximately between 1736 m and 1386 m lower during the Nahanagan Stadial than at present.  相似文献   
895.
In 2003, three proposals were being mediated through the planning system in the peri‐urban environment of St Andrews, Fife: a large housing development, a rail link, and a Green Belt. Using questionnaires and semi‐structured interviews with key stakeholders, we investigate the ways in which diverse conceptions of ‘the environment’ shaped public reactions to these proposals, and evaluate the fit between these and the respondents’ stated environmental perceptions. 98% of local residents surveyed describe themselves as ‘concerned about the environment’. However, large majorities conceive of the environment as a local rather than a global phenomenon, and regard it primarily in terms of personal benefits (such as landscape aesthetics or traffic considerations). By exploring the environmental perceptions in the light of the planning proposals, the study supports the contention that the ‘local environment’ is a socially constructed phenomenon which can be fashioned and re‐fashioned according to local perceptions of threats and opportunities.  相似文献   
896.
897.
898.
899.
900.
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