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   568篇
  免费   42篇
  2023年   10篇
  2022年   2篇
  2021年   3篇
  2020年   17篇
  2019年   33篇
  2018年   37篇
  2017年   49篇
  2016年   42篇
  2015年   24篇
  2014年   20篇
  2013年   124篇
  2012年   27篇
  2011年   40篇
  2010年   32篇
  2009年   26篇
  2008年   16篇
  2007年   10篇
  2006年   16篇
  2005年   8篇
  2004年   9篇
  2003年   6篇
  2002年   14篇
  2001年   6篇
  2000年   5篇
  1999年   9篇
  1998年   2篇
  1997年   4篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1985年   1篇
  1972年   2篇
  1971年   1篇
排序方式: 共有610条查询结果,搜索用时 15 毫秒
531.
The small mineral-binding bone protein, osteocalcin, has been applied in a number of studies on ancient bone due to predictions of its long-term stability. However, the intact protein has not been shown to survive in ancient bone devoid of DNA, which is a much more phylogenetically informative biomolecule. In this investigation, the survival of osteocalcin is directly compared to the amplification of mtDNA in a set of 34 archaeological samples from four sites throughout Europe. We also present unpublished osteocalcin sequences of seven mammalian species in addition to the 19 published sequences to highlight phylogenetic limitations of this protein. The results indicate that the intact osteocalcin molecule survives less in archaeological samples than mtDNA and is more subject to the temperature of the archaeological site. Amino acid analyses show the persistence of the dominant protein collagen in samples that failed both osteocalcin and mtDNA analyses. The implications these findings present for biomolecular species identification in archaeological and palaeontological material are that, although proteins do survive beyond ancient DNA, osteocalcin does not appear to be the most ideal target.  相似文献   
532.
533.
534.
535.
The study of precontact anthropogenic mounded features—earthen mounds, shell heaps, and shell rings—in the American Southeast is stymied by the spotty distribution of systematic surveys across the region. Many extant, yet unidentified, archaeological mound features continue to evade detection due to the heavily forested canopies that occupy large areas of the region, making pedestrian surveys difficult and preventing aerial observation. Object-based image analysis (OBIA) is a tool for analyzing light and radar (lidar) data and offers an inexpensive opportunity to address this challenge. Using publicly available lidar data from Beaufort County, South Carolina, and an OBIA approach that incorporates morphometric classification and statistical template matching, we systematically identify over 160 previously undetected mound features. This result improves our overall knowledge of settlement patterns by providing systematic knowledge about past landscapes.  相似文献   
536.
The onset of the long eighth century demanded that churchmen develop new visions for their place in the changing social and political landscapes of Anglo‐Saxon England. The Anonymous Life of Saint Cuthbert (699–705) and Bede's Life of Saint Cuthbert (c.721) responded to these changes by offering two such visions. Each author made systematic divergences from his exemplars, articulated with a finesse often mistaken for emulation. Nevertheless, each of these texts offered a distinct vision for the church, giving particular attention to the role of monasticism in the changing circumstances of the long eighth century.  相似文献   
537.
538.
This paper summarises research on obsidian findings across the region of Island Southeast Asia (ISEA), from the first reporting of obsidian on Sumatra as a result of cave excavations in the early 1900s through to the latest published discoveries in 2009. These results are the background for the first region-wide research project focussing on obsidian characterisation and its role in prehistoric inter-island exchange. It is commonly held that distribution of obsidian in ISEA was only localised and inter-island transportation limited. The review, however, suggests that this hypothesis derives from an incomplete knowledge of obsidian distribution in the region rather than typifying prehistoric social patterns. Obsidian sourcing has been carried out only intermittently in ISEA since the 1970s and has generally been focussed only at the single site level, thus explaining this very partial understanding.  相似文献   
539.
Matthew G. Hannah 《对极》2011,43(4):1034-1055
Abstract: The terms biopower and biopolitics have been deployed in widely varying ways in recent critical political analyses. This essay seeks to rescue from the welter of its deployments a general understanding of biopower potentially useful to left political projects. First, recent iterations of the concept of biopower are surveyed. In the main body of the paper, a series of interventions in recent critical debates are used to trace out a critical re‐mapping of the concept of “life” that names the ends of biopower. Biopolitically relevant life is reconsidered in terms of its proper geographical scope, its gender, racial and ethnic specificities, its distinguishing vital qualities, and its relation to temporality (particularly the future). Through this exercise the notion of biopower is redefined so as to provide potential “docking points” for Marxist, feminist and green discourses, and conceptual resources for left struggles against global injustice.  相似文献   
540.
Instrumental neutron activation analysis (INAA) was used to characterize the chemical composition of chert from a primary source in western North Dakota. Known as Sentinel Butte, this source is part of the Eocene-age White River Group (WRG), a widespread geological formation on the central and northern Plains. INAA results demonstrate that it is chemically distinct from other known chert-bearing WRG. Further, analysis of three bifaces from the nearby Beach Clovis cache site demonstrates that they are made of chert from Sentinel Butte, and most likely the other 55 White River Group Silicate (WRGS) bifaces in the cache are as well. Although Clovis caches typically are dominated by materials transported hundreds of kilometers, it is argued that the advance manufacture and caching of bifaces even a short distance from a source may be a highly effective tactic to reduce gearing up time and hence search costs associated with the pursuit of mobile game at the close of the Pleistocene.  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