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   1053篇
  免费   45篇
  2023年   8篇
  2020年   13篇
  2019年   35篇
  2018年   34篇
  2017年   58篇
  2016年   52篇
  2015年   21篇
  2014年   35篇
  2013年   322篇
  2012年   34篇
  2011年   35篇
  2010年   31篇
  2009年   25篇
  2008年   36篇
  2007年   21篇
  2006年   16篇
  2005年   9篇
  2004年   18篇
  2003年   18篇
  2002年   14篇
  2001年   21篇
  2000年   16篇
  1999年   13篇
  1998年   7篇
  1997年   9篇
  1996年   8篇
  1995年   9篇
  1994年   6篇
  1993年   12篇
  1992年   9篇
  1991年   10篇
  1990年   5篇
  1988年   6篇
  1987年   7篇
  1986年   6篇
  1985年   11篇
  1984年   9篇
  1983年   10篇
  1982年   14篇
  1981年   8篇
  1980年   5篇
  1979年   3篇
  1978年   9篇
  1977年   4篇
  1976年   9篇
  1975年   5篇
  1974年   3篇
  1973年   5篇
  1972年   7篇
  1970年   3篇
排序方式: 共有1098条查询结果,搜索用时 15 毫秒
31.
An examination of the surface deposit of an Etruscan cup said to have been dug up in Cheshire suggests instead that it had been buried in Italy and brought to England in recent times. The method described here might usefully be employed to assess the provenance of buried artefacts.  相似文献   
32.
ABSTRACT. Average monthly price data from twelve hinterland markets and the Houston port price for wheat are studied in a cointegration framework using the Engle-Granger "two-step" procedure and Johansen's maximum likelihood procedure. Out-of-sample forecasts from an error correction model are compared to those from a vector autoregression fit to levels and a univariate autoregression fit to first differences. This comparison suggests that modeling these (cointegrated) data as a levels vector autoregression, rather than as an error-correction process, results in significantly higher error bias, but lower error variance, at long horizons.  相似文献   
33.
The chronology of the period is briefly considered in the light of the dendrochronological results which have appeared in recent years. Patterns of settlement history in different parts of the area are then examined, and it is suggested that in some of them the late fourth millennium was a period of population decline which was not reversed until the Early Bronze Age, 1000 years later. Detailed information about specific local occupation patterns is provided by recent work on the circum-Alpine lake villages. Changes in cultural patterns during the period, especially the appearance of the Corded Ware, are discussed and explanations of them reviewed. It is argued that changing patterns of gender relations were a major feature of the period, linked to processes which eventually led to the development of small-scale chiefdoms. The development of copper and bronze metallurgy and its connection to these processes are discussed.  相似文献   
34.
35.
36.
Many timber finds lack some or all of the outer, sapwood rings formed in the years just before felling. In order to estimate felling date once the outermost remaining ring has been dated, it is necessary to estimate the number of sapwood rings originally present. Methods doing this for oak are reviewed in the light of an intensive study of living trees at one site and an extensive study of 175 samples from living trees in North Wales and northwest England. Some methods reported in the literature are found to be invalid. A method reported by Hollstein (1965) is most reliable, with modifications for known variations in sapwood number with position in the tree. At present the best available estimate is that a value of 30 sapwood rings be used (95% confidence limits: 19–50).  相似文献   
37.
Allen V. Kneese and F. Lee Brown, The Southwest Under Stress .
Richard A. Berk, et al., Water Shortage .  相似文献   
38.
39.
"Accommodation of a multi-ethnic population within the territory of a single state has been recognized as a world-wide problem. Within such a society language maintenance is frequently the avenue through which cultural groups seek to preserve their identity. This paper describes and evaluates the Canadian experience of language planning by concentrating on the bilingual district, the key spatial instrument in the federal Official Languages Act. The paper argues for a cautious and spatially varied application of the 1969 Act and seeks to suggest ways in which a geolinguistic analysis may further our understanding of plurilingual societies."  相似文献   
40.
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