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   41615篇
  免费   1619篇
  2020年   517篇
  2019年   814篇
  2018年   925篇
  2017年   1123篇
  2016年   1206篇
  2015年   922篇
  2014年   896篇
  2013年   14029篇
  2012年   1052篇
  2011年   1081篇
  2010年   1088篇
  2009年   1071篇
  2008年   1016篇
  2007年   949篇
  2006年   835篇
  2005年   587篇
  2004年   571篇
  2003年   533篇
  2002年   512篇
  2001年   511篇
  2000年   445篇
  1999年   514篇
  1998年   463篇
  1997年   421篇
  1996年   405篇
  1995年   408篇
  1994年   365篇
  1993年   411篇
  1992年   390篇
  1991年   298篇
  1990年   289篇
  1989年   307篇
  1988年   306篇
  1987年   325篇
  1986年   300篇
  1985年   415篇
  1984年   448篇
  1983年   455篇
  1982年   397篇
  1981年   385篇
  1980年   429篇
  1979年   415篇
  1978年   402篇
  1977年   423篇
  1976年   382篇
  1975年   382篇
  1974年   289篇
  1973年   264篇
  1972年   250篇
  1970年   224篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
983.
984.
After over a century of archaeological research in the American Southwest, questions focusing on population aggregation and abandonment continue to preoccupy much of Pueblo archaeology. This article presents a historical overview of the present range of explanatory approaches to these two processes, with a primary focus on population aggregation in those regions occupied by historic and prehistoric Pueblo peoples. We stress the necessarily complementary nature of most of these explanations of residential abandonment and aggregation. Case studies from the northern Southwest illustrate the continuous nature of these processes across time and space. We suggest that additional explanatory potential will be gained by the use of well-defined theoretical units to frame our current approaches. We extend the use of the local community concept as a theoretical unit of organization that, along with explicit archaeological correlates, should help advance our research into population aggregation and abandonment in this and other regions of the world.  相似文献   
985.
We review evidence from human biology—paleopathological and isotopic paleodietary studies on ancient Maya skeletons—to assess the validity of ecological models of the Classic Maya collapse, in which elevated disease and deteriorating diet are commonly assumed. To be upheld, the health arguments of ecological models require that the Maya disease burden (1) was greater than that for many other societies and (2) increased over the span of occupation. The dietary argument requires (1) consistent change in diet from Preclassic and Early Classic Periods to the Terminal Classic and (2) increasing social divergence in diet. A correlation between diet and disease is necessary to link these arguments. Neither pathology nor isotopic data consistently support these criteria. Instead, it appears that local environmental and political factors created diversity in both disease burden and diet. In view of the human biological data, we are skeptical of ecological models as generalized explanations for the abandonment of Classic Maya sites in the southern lowlands.  相似文献   
986.
This article reports on the excavations of a coastal site in Sharjah dating to the 5th millennium BC at which examples of painted cUbaid pottery, probably of Mesopotamian origin, were found.  相似文献   
987.
988.
Multiple sclerosis (MS) was first presented in a clinical setting in 1838. In this paper the presentation and treatment of a transient hemiparesis in a drummer in 1789 is discussed. This may have been an early case of MS and presents evidence against the theory that MS is an infectious disease beginning in the 19th century.  相似文献   
989.
990.
The concept of sustainability has become a significant consideration in planning in Europe and the US. At both the international and the national level, urban planners and policymakers have developed a package of policies designed to produce sustainable growth and development. In transport, this has been interpreted to mean that we need to increase accessibility while we reduce mobility by shifting trips from automobile to walking, bicycle or public transport modes. Using this criteria, the latest Dublin transport plan has been found to be only partially effective. Similar to many American transport plans, the DTI has opted for the infrastructure‐related sustainability policies and avoided the less popular economic disincentives.  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