全文获取类型
收费全文 | 481篇 |
免费 | 17篇 |
出版年
2023年 | 3篇 |
2020年 | 5篇 |
2019年 | 17篇 |
2018年 | 14篇 |
2017年 | 18篇 |
2016年 | 28篇 |
2015年 | 19篇 |
2014年 | 10篇 |
2013年 | 124篇 |
2012年 | 15篇 |
2011年 | 16篇 |
2010年 | 13篇 |
2009年 | 9篇 |
2008年 | 17篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有498条查询结果,搜索用时 31 毫秒
31.
New ages for the post-Howiesons Poort,late and final Middle Stone Age at Sibudu,South Africa 总被引:1,自引:0,他引:1
Zenobia Jacobs Ann G. Wintle Geoffrey A.T. Duller Richard G. Roberts Lyn Wadley 《Journal of archaeological science》2008
Optically stimulated luminescence (OSL) measurements are reported for single grains of quartz from deposits within Sibudu rock shelter. Such measurements enable rejection of unrepresentative grains and application of the finite mixture and central age models to obtain the most reliable age estimates. Three types of single-grain equivalent dose (De) distributions were observed: one sample represented a single dose population, three samples indicated mixing between Iron Age (IA) and Middle Stone Age (MSA) deposits, and 10 samples (in addition to the three mixed samples) showed scattered distributions. The latter type resulted from differences in the beta dose received by individual grains. For these samples, the beta doses were modelled and adjusted accordingly. Ages for the 14 samples collected from MSA deposits post-dating the Howiesons Poort (HP) resulted in three age clusters, which are stratigraphically consistent with the three informally named cultural phases at Sibudu: namely, the post-HP, late MSA and final MSA. Weighted mean ages of 58.5 ± 1.4 ka, 47.7 ± 1.4 ka and 38.6 ± 1.9 ka were calculated for these phases, respectively. The three phases were separated by two occupational hiatuses with durations of 10.8 ± 1.3 ka and 9.1 ± 3.6 ka. We hypothesise that the punctuated presence of humans at Sibudu was determined by large-scale fluctuations in climate during oxygen isotope stage (OIS) 3, which resulted in alternating wet and dry periods. Phases of occupation correspond to wet periods when fresh water was available in the Tongati River, whereas intervals of site abandonment correspond to dry periods when people were forced to migrate in search of a reliable source of fresh water. Where people migrated to, remains unresolved. 相似文献
32.
Bitumen, found in abundance in Mesoamerica’s southern Gulf Coast region in natural seeps and in many archeological contexts, is an important economic resource and exchange item that has received little consideration in Mesoamerica. Analyses of archeological, ethnoarcheological, and experimental data provide insights on the organization of bitumen processing activities, and the end product (archeological bitumen), which the Olmec (1200–400 BC) used in the production of many items. Archeological data are derived from investigations at El Remolino and Paso los Ortices— two Early Formative period levee sites in the San Lorenzo Olmec region. Our findings suggest that among the Olmec, bitumen processing was organized as a specialized activity, involving multiple production stages, but not necessarily elite involvement or control. 相似文献
33.
Patricia M. Lambert 《Journal of Archaeological Research》2002,10(3):207-241
This article reviews recent archaeological research on warfare in prestate societies of native North America. This survey comprises six regions: Arctic/Subarctic, Northwest Coast, California, Southwest/Great Basin, Great Plains, and Eastern Woodlands. Two lines of evidence, defensive settlement behavior and injuries in human skeletal remains, figure prominently in archaeological reconstructions of violence and warfare in these regions. Burning of sites and settlements also has been important for identifying the consequences of war and investigating more subtle aspects of strategy and directionality. Weaponry and iconography have to date provided important but more limited insights. Although considerable disparities exist between regions in the archaeological evidence for intra- and intergroup violence, all regions show a marked increase after A.D. 1000. These findings suggest that larger forces may have been responsible for escalating violence throughout North America at this time. 相似文献
34.
Tanzania Maasai began large‐scale urban labour migration in the mid‐1990s, impelled by livestock losses from disease, drought and land alienation. Although they were readily hired in cities as night watchmen and security guards, many urban citizens expressed condescending views of the migrants, typifying them as ‘unmodern’, and as curious young warriors who were lazy, naive, drunk and dirty. Interviews with about 200 Maasai proved these discursive characterizations to be largely incorrect. Although the State has tried over the last century to ‘develop’ and settle semi‐nomadic pastoralists, the Maasai image is widely used as part of an instrumentalist agenda, to advertise items from telephones to tourism. Lacking political or social capital, the migrants manipulate and reinforce Maasai identity by continuing to wear traditional garments (illkarash), and by engaging in practices that emphasize their difference from the ‘WaSwahili’, bolster cohesion and solidarity among themselves, and increase their chances of urban employment. 相似文献
35.
36.
37.
38.
This paper examines changes in the location of ore-based steel-makingcapacity in the U.S. over the period 1974 to 1991 using data on each of the 45 ore-based mills that were in operation in 1974. We find that the geographic ddistributions of demand and of competition from minimills and imports were important in determining where capacity reductions occurred and which plants were closed. Technology in use at the plant also affected capacity adjustment. However, we find that regional variation in prices of raw materials were notimportant factors in determining where steel-making capacity was reduced. 相似文献
39.
40.
The Persian Gulf: Iran's Role. By Rouhollah K. Ramazani. Charlottesville, Va.: University Press of Virginia, 1972. 157 pp. $7.50.
Patrick J. Hurley and American Foreign Policy. By Russell D. Buhite. Ithaca, N.Y.: Cornell University Press, 1973. 342 pp. $14.50. 相似文献