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   50篇
  免费   3篇
  2020年   1篇
  2019年   3篇
  2018年   4篇
  2017年   4篇
  2016年   3篇
  2015年   3篇
  2013年   12篇
  2012年   5篇
  2011年   2篇
  2010年   1篇
  2009年   4篇
  2008年   2篇
  2007年   1篇
  2006年   2篇
  1999年   1篇
  1997年   2篇
  1991年   1篇
  1965年   1篇
  1963年   1篇
排序方式: 共有53条查询结果,搜索用时 15 毫秒
21.
22.
Roc de Marsal has yielded numerous remains of Mousterian occupations, including lithics, fauna and combustion features. It was made famous by the discovery of the skeleton of a Neanderthal child. Given the need to date the sequence, TL and OSL were applied on heated flints and quartz, and OSL on unheated quartz. Chronological results combined with palaeoenvironmental data – faunal remains and micromorphological features in the sediments from the cave, pollen proxies and faunal remains from the region – allowed us to place climate variations in southwest France on a numerical time scale. Denticulate Mousterian occupations were dated to the middle of MIS 4 (65–70 ka) and Quina layers either to the very end of MIS 4 or to MIS 3. Interestingly, a faunal pattern showing a mix of red deer, roe deer and reindeer was found to have occurred during MIS 4, which was shown to be consistent with data from other similar sites in southwest France.  相似文献   
23.
24.
Flooding and flood control long have been topics of concern for geographers and historians of North America, from Gilbert White's foundational work to attempts to understand the recent disaster in New Orleans. This paper considers the problem of flood control along the Assiniboine River in the province of Manitoba, Canada. The first section addresses the local landscape and the larger context, explaining changes in the relevant human and physical geography. The second section examines efforts to mitigate flooding, focusing on how the risk of inundation was shifted in location (not eliminated altogether) and compounded through time (not progressively resolved). The third focuses on a further source of complexity: the contested character of government jurisdiction. This final section also addresses major mid twentieth century changes in mitigation efforts: in the light of flooding on an unprecedented scale, governments became more open to compromise and more willing to undertake substantial projects. Gilbert White asserted that while floods are natural occurrences, flood damages are the responsibility of humanity. The question of responsibility might seem relatively clear in relation to flood mitigation, given that dykes are human constructions. The history of flood mitigation along the Assiniboine would suggest, however, that assigning responsibility for the failures and successes of flood mitigation is not so straightforward.  相似文献   
25.
Despite the enormous potential of anadromous fish, foragers do not mass extract and store salmonids until very late in the archaeological record of California. Acorns, by contrast, were intensively used quite early in the record. Salmon are traditionally viewed as a low cost, high ranking resource, and acorns as a high cost, low ranking resource. The question thus arises: why were salmon not used and stored en masse much earlier? We offer a solution using a simple foraging model that distinguishes resources on their storage as well as overall cost, making it possible to calculate the risk of resource caching, which appears to have delayed intensive salmon procurement in California.  相似文献   
26.
27.
This research is an examination of the role of organized interests in international climate change policy formation. Systematic survey results are used to demonstrate that organized interests actually engage in the same activities in both the international and domestic arenas. This research demonstrates that the climate change negotiations can be characterized as both a policy subsystem and an international regime. It is further argued that these two concepts are in fact highly analogous, thereby facilitating new cross-discipline research opportunities. The research is based on a web survey of organized interests accredited by the United Nations Framework Convention on Climate Change (UNFCCC), and on interviews and field research at the 8th Conference of the Parties of the UNFCCC in New Delhi, India.  相似文献   
28.
Archaeologists strive to document the process of excavation and discovery as completely as possible. Over the past several decades archaeologists have incorporated a growing number of computerized techniques for documenting archaeological finds. Scanning is one such technique. There are a number of technologies that now allow archaeologists to scan structures, excavation surfaces and in situ artifacts to create high-resolution, 3D data sets. We report here on a trial application of one of these, a structured-light scanner, to create 3D representations of excavated surfaces and associated artifacts at two Middle Paleolithic sites in southwest France. In each instance, surfaces of approximately 2.5 m2 were scanned in approximately 1 day. The resulting data sets are very good representations of the originals in terms of colors and spatial details, and as such provided an important piece of archaeological documentation. To use this equipment successfully in the field, however, required solving a number of logistical issues, and the amount of time required to learn to use this equipment was significant. Once these issues are addressed, this technology is appropriate for documenting extraordinary, unique finds where time and costs are offset by the importance of good documentation.  相似文献   
29.
30.
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