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   228篇
  免费   14篇
  2020年   2篇
  2019年   9篇
  2018年   12篇
  2017年   11篇
  2016年   10篇
  2015年   7篇
  2014年   11篇
  2013年   68篇
  2012年   6篇
  2011年   4篇
  2010年   8篇
  2009年   6篇
  2008年   7篇
  2007年   6篇
  2006年   5篇
  2005年   5篇
  2004年   4篇
  2003年   6篇
  2002年   2篇
  2001年   5篇
  2000年   3篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   2篇
  1991年   3篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   5篇
  1982年   3篇
  1981年   1篇
  1980年   2篇
  1979年   3篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1974年   1篇
  1972年   1篇
  1971年   1篇
  1953年   1篇
  1952年   1篇
排序方式: 共有242条查询结果,搜索用时 15 毫秒
31.
This is the story of the building of a replica Viking craft. Being only 22 ft (6.7 m) long and having 4 ft 6 in (1.37 m) beam, the Gokstad faering does not conform to our usual image of a Viking boat. However, the smaller craft shows all the construction details found in the larger ships. A close examination can help us to see some of the principles the Vikings applied to their boatbuilding.  相似文献   
32.
Although the dietary importance of barnacles is recognized in Europe and elsewhere around the world, indigenous use of barnacles on the Pacific coast of North America has not been well-documented. On the Northwest Coast, most shell middens located along estuaries are dominated by clams (such as Saxidomus, Protothaca, etc.), while those on the outer coast are dominated by mussels (Mytilus californianus). At Kit’n’Kaboodle Cave in southeast Alaska, the acorn barnacle Semibalanus cariosus is unusually abundant over a 3500-year period, but is replaced by mussels over time. These results are placed within a larger geographic context to more closely examine patterns of barnacle use by First Nations of the Pacific Northwest.  相似文献   
33.
34.
35.
The remains of Henry V's flagship, the Grace Dieu, currently lie buried within the inter-tidal sediments of the River Hamble (S. England). Previous archaeological investigations have been hindered by difficult excavation conditions resulting in a poor understanding of the dimensions, shape and degradation state of the hull's deeper structure. This study therefore aimed to image, characterize and reconstruct the buried remains of this vessel using a high-resolution 3D acoustic sub-bottom Chirp system with RTK-GPS positioning capability. The accurate navigation and high-resolution data that were acquired enabled the construction of a full 3D image of the site that not only identified the remains of the wooden hull, but also features buried within it. In addition, the degradation state of these buried wooden remains were investigated by calculating reflection coefficients while a hypothetical larger reconstruction of the Grace Dieu's hull was achieved, through the use of the ShipShape ship design software package.  相似文献   
36.
Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is applied to the study of four samples of opaque glass of Late Bronze Age date. The technique is uniquely capable of identifying compositional heterogeneity at a sub-micron resolution within the crystalline opacifiers dispersed through homogeneous glass matrices. It is shown that this provides crucial information on the possible raw ingredients of the opacifying inclusions used, and has the potential for highlighting regional variations in the production technology involved in creating different colours of opaque glass.  相似文献   
37.
Research on the neurobiology and pharmacotherapy of attention-deficit/hyperactivity disorder (ADHD) has grown exponentially since 1980. A reasonable question is whether this research has improved our understanding and treatment of ADHD. This article describes relevant developments that took place roughly between 1900 and 1970. During this time, the efficacy of stimulant therapy for the disorder was established and the symptoms of ADHD were linked to many possible nervous system disorders including in the brain-stem, reticular formation, diencephalon, basal ganglia, frontal lobes, and cortex. In 1970, the catecholamine hypothesis of ADHD was proposed. It is concluded that early theories about the neurobiologic basis of ADHD anticipated core ideas of modern theory.  相似文献   
38.
Trace element compositions of 25 shards of Chinese Late Ming export blue-and-white porcelain from Zhangzhou and Jingdezhen kilns are analysed by Inductively Coupled Plasma Mass Spectrometry. Principle components analysis and REE distribution curves are used to establish method for provenance unknown Chinese export blue-and-white porcelain which may have originated from Zhangzhou or Jingdezhen kilns. By matching the REE distribution curves of Zhangzhou kiln samples and parent rocks of the possible clay sources used to make Zhangzhou blue-and-white, and comparing it with previous results of geological, geochemical and archaeological researches, the clay used for producing Zhangzhou export blue-and-white has been identified as having been collected from the weathered shells of a nearby potassium feldspar miarolitic granite outcrop.  相似文献   
39.
Gibson, Martha L. Conflict Amid Consensus in American Trade Policy. Washington, DC: Georgetown University Press, 2000. Pp. 213. $55.00 hardbound; $17.95 softbound.

Henehan, Marie T. Foreign Policy and Congress: An International Relations Perspective. Ann Arbor, MI: University of Michigan Press, 2000. Pp. 248. $49.50 hardbound.

Brands, H.W. The Foreign Policies of Lyndon Johnson: Beyond Vietnam. College Station, TX: Texas A&M Press, 1999. Pp. 194. $29 95 hardbound.

McNamara, Robert S., James G. Blight, and Robert K. Brigham, with Thomas J. Biersteker and Herbert Y. Schandler. Argument Without End: In Search of Answers to the Vietnam Tragedy. New York, NY: Public Affairs, 1999. Pp. 512. $27.50 hardbound; $17.00 softbound.  相似文献   
40.
Abstract

This study presents the methodology and results of a core-periphery GIS model of the historical growth and spread of Islam in China based on a dataset of 1,774 mosques. These sites were organized into data subsets according to their founding dates during five major dynastic periods in Chinese history: Tang/Song, Yuan, Ming, Qing, and Republican. Core areas were identified and mapped based on where mosques clustered during each period. North China was the paramount core region in all periods. Not until the late Qing and Republican periods did the Northwest and Yunnan compare with North China, while coastal China never developed into a core area.  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