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   603篇
  免费   16篇
  2020年   10篇
  2019年   16篇
  2018年   18篇
  2017年   26篇
  2016年   22篇
  2015年   8篇
  2014年   14篇
  2013年   219篇
  2012年   9篇
  2011年   10篇
  2010年   5篇
  2009年   8篇
  2008年   12篇
  2007年   8篇
  2006年   11篇
  2005年   9篇
  2004年   9篇
  2003年   4篇
  2002年   4篇
  2001年   4篇
  2000年   4篇
  1999年   6篇
  1998年   5篇
  1997年   6篇
  1996年   4篇
  1995年   8篇
  1994年   5篇
  1993年   10篇
  1992年   5篇
  1991年   7篇
  1990年   10篇
  1989年   10篇
  1988年   3篇
  1987年   8篇
  1986年   7篇
  1985年   9篇
  1984年   7篇
  1983年   6篇
  1982年   6篇
  1981年   8篇
  1980年   8篇
  1979年   5篇
  1978年   5篇
  1977年   4篇
  1976年   10篇
  1975年   3篇
  1974年   4篇
  1973年   3篇
  1968年   2篇
  1959年   2篇
排序方式: 共有619条查询结果,搜索用时 46 毫秒
71.
The role of raw material quality in Oldowan technology has not been fully explored. There are numerous studies suggesting Oldowan hominins preferred certain types of stone for artifact manufacture. Previous studies of the artifact assemblage from the early Pliocene Oldowan locality of Kanjera South (South Rachuonyo District, Kenya) show that raw material selection and transport was an important aspect of Late Pliocene hominin adaptations. Yet the exact properties of stones that hominins were selecting remain enigmatic. Two potentially important features of artifact raw material are durability and fracture predictability. We investigate fracture predictability through mechanical tests of stone and investigations of the affect of stone properties on fracture patterns in archaeological collections. We investigate stone durability with actualistic studies of edge attrition combined with further mechanical tests of various lithologies. Oldowan hominins at Kanjera appear to have selected raw materials based on their durability. The ability for a stone to fracture consistently does not appear to be as important in hominin toolstone preference as previously assumed. Hominins that produced the assemblages at Kanjera South appear to have incorporated an extensive understanding of various attributes of raw material in the transport and production of stone artifacts. When combined with previous research on the transport patterns at Kanjera, the results of this study provide evidence for a more complex raw material acquisition strategy than has previously been suggested for Late Pliocene Oldowan hominins.  相似文献   
72.
Among peace researchers and practitioners, it is generally accepted that efforts to prevent violence can be instrumental in its mitigation. So, it was distressing to read the research findings of Meier, Bond, and Bond (2007) that mitigation was positively related to organized raids in the Horn of Africa where there is pastoralist–pastoralist and pastoralist–agriculturalist violence. This article seeks to build on their research. It uses a ‘de-trending’ approach for time-series analysis that is commonly used in economics and financial studies. It reports an opposite statistically significant finding. When the data used by Meier et al. are de-trended, violence associated with organized raids is negatively correlated with mitigation. This negative correlation is similar when data on mitigation and organized raids are de-trended with time as a predictor, on the one hand, and with seasonality over time as a predictor, on the other. Implications regarding the temporal dimension of peace research and practice are presented.  相似文献   
73.
ABSTRACT On a sample of U.S. urbanized areas in 2000, we test theoretical hypotheses of the effect of land‐use controls on the spatial size of urban areas. We find that minimum lot‐size zoning and maximum FAR restrictions expand the urban area, while maximum lot‐size zoning, urban growth boundaries, minimum square footage limits, maximum building permit restrictions, minimum person per room controls, and impact fees contract the urban area. All of these findings are consistent with theoretical predictions although the effect of urban growth boundaries and minimum square footage limits are not statistically significant.  相似文献   
74.
Despite rapid economic growth and massive inflows of aid, rural poverty in Mozambique is worsening. Agricultural production and productivity have not increased in the last decade. Use of chemical fertilizers and other modern technology is at a low level and decreasing. The present development model emphasizes that the role of government and donors is to provide human capital and infrastructure, while the private sector is responsible for economic development and ending poverty. The most recent national surveys confirm what is being seen elsewhere in Africa — that this non‐interventionist strategy does not raise agricultural productivity or reduce poverty. While 80 per cent of Mozambique's population is engaged in agriculture, this sector contributes only 20 per cent of GDP. This suggests that investments in agriculture are likely to generate pro‐poor growth, both to rural and urban dwellers. This policy failure is increasingly recognized, but donors and government have invested too much political capital in the current policy to change easily.  相似文献   
75.
Plant and particularly non-wood forest products have played an important role in the evolution of human cultures all over the world, as source of food but also of raw substances fulfilling material, spiritual, and medicinal requirements. Plant exudates and particularly dammar resins (Dipterocarpaceae family) were widely used in the past in Asia notably as waterproofing and caulking materials. This study focuses on the GC–MS chemical characterisation of freshly collected dammars and establishes new molecular parameters enabling discrimination between dammars and other types of plant resin, whatever their botanical origin. Such analyses provide clues for a precise identification (taxonomy, occurrence of other material in addition to the resin, alteration state) of unknown resinous material discovered in archaeological contexts. The value of our approach is illustrated by the taxonomic characterisation of two samples collected in jars from the Brunei wreck and a Chinese junk lost more than 40 km off the Sultanate of Brunei during the end of the fifteenth century or the early beginning of the sixteenth century.  相似文献   
76.
77.
This paper aims to characterise the varying magnitudes of landscape disturbance across the WWI battlefield of Verdun, France. Five study sites were surveyed to best reflect the varying degrees of disturbance under common similar environmental characteristics, e.g. bedrock, soil type and topographic position. Disturbance magnitude was determined by counting and measuring the dimensional attributes of craters in two 0.25 hectare plots at each of the five study sites. Additionally, a survey of microtopography was performed at each of the five study sites to record changes in elevation of damaged sites. The spatial character and variation in the magnitude of disturbance at the five disturbance study sites was linked to four variables: (1) location of armies in relation to the front; (2) stagnation of front lines; (3) topographic location of armies; and (4) geologic characteristics of the site.  相似文献   
78.
79.
Joseph Jacobs 《Folklore》2013,124(3):269-284
  相似文献   
80.
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