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   123篇
  免费   2篇
  2023年   1篇
  2020年   4篇
  2019年   3篇
  2018年   1篇
  2017年   4篇
  2016年   2篇
  2015年   1篇
  2014年   5篇
  2013年   16篇
  2012年   3篇
  2011年   11篇
  2010年   4篇
  2009年   9篇
  2008年   6篇
  2007年   7篇
  2006年   5篇
  2005年   3篇
  2004年   1篇
  2003年   3篇
  2002年   5篇
  2001年   2篇
  2000年   3篇
  1999年   2篇
  1998年   2篇
  1996年   2篇
  1993年   2篇
  1992年   1篇
  1990年   2篇
  1989年   4篇
  1988年   2篇
  1987年   2篇
  1986年   4篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
排序方式: 共有125条查询结果,搜索用时 15 毫秒
71.
This article examines the merging of security and development agendas in primary commodity sectors, focusing on the case of peace‐building reforms in Sierra Leone's diamond sector. Reformers frequently assume that reforming the diamond sector through industrializing alluvial diamond mining will reduce threats to security and development, thereby contributing to peace building. Our findings, however, suggest that the industrialization of alluvial diamond mining that has taken place in Sierra Leone has not reduced threats to security and development, as it has entailed human rights abuses and impoverishment of local communities without consolidating state fiscal revenues and trust in local authorities. This suggests alternative strategies for resource‐related peace‐building initiatives, which we consider at the end of the article: the decriminalization of informal economic activities; the prioritization of local livelihoods and development needs over central government fiscal priorities and foreign direct investment; and better integration between local economies and industrial resource exploitation.  相似文献   
72.
Long voyages required serious logistics. Onboard meat supplies were analysed from animal remains found in shipwrecks. Here we present a bibliographical synthesis of results obtained from the study of 33 published shipwrecks in order to assess the importance of the presence of animals aboard and to underline questions still unanswered. © 2011 The Author  相似文献   
73.
The Chauvet-Pont d'Arc and Deux-Ouvertures caves, located along the Ardèche River (France), contain abundant remains of the extinct cave bear (Ursus spelaeus). Because they also display a variety of Palaeolithic anthropogenic evidences, such as the earliest charcoal drawings recorded to date (Chauvet-Pont d'Arc), and delicate engravings (Deux-Ouvertures), they offer the opportunity of studying the interaction between animals and human beings during a key period for Pleistocene species extinctions. We characterized cave bear specimens from these two sites by radiocarbon dating, stable isotopes, and mitochondrial DNA analysis. In Chauvet-Pont d'Arc, we obtained radiocarbon ages that ranged between 29,000 and 37,300 years before present (BP). The Deux-Ouvertures cave bear specimens clustered to the bottom of this time frame, returning radiocarbon ages of 27,440–30,220 years BP. Cave bear nitrogen isotope values were all compatible with a vegetarian diet. Mitochondrial DNA analysis, carried out on a highly variable domain of the control region, evidenced only two cave bear haplotypes, including a new haplotype, and a common one which largely predominated. We detected both haplotypes in Chauvet-Pont d'Arc, but only recorded the predominant one in the Deux-Ouvertures Cave. Our data put forward the surprising observation that cave bears inhabited Ardèche over a short period of time, from about 37,000 to 27,400 years BP. They were notably present during the first (Aurignacian) phase of human intrusions in Chauvet-Pont d'Arc, 30,000–32,000 years BP. This points to the possible competition for cave sites, presumably on a seasonal scale considering the cave bear habit for hibernation. During this time period, the small number of haplotypes is at variance with the extensive genetic diversity reported elsewhere for much more ancient specimens.  相似文献   
74.
Abstract: This article contributes to emerging research on the social construction of carbon markets by focusing on the mobilisation of desire amongst carbon market actors, and on the routinisation of financial practices within such markets. We examine specifically the markets that have emerged around the Clean Development Mechanism. First, we look at the stories market actors tell each other in advertising and at Carbon Expo. Second, we look at the routinisation of carbon finance through the borrowing of ideas and tools from traditional financial markets. We suggest that the former animates the markets while the latter enables the markets to become “normalised” for financiers. We also suggest that the two aspects however also work in tension with each other, and that the character of this tension is one way of understanding the distinctiveness of carbon markets.  相似文献   
75.
76.
77.
Vladimir Fock was a Soviet theoretical physicist who, from the 1930s, worked to prove that modern physics was compatible with the Marxist philosophy of dialectical materialism. In 1957, he went to Copenhagen, and a dispute over the interpretation of quantum mechanics began with Niels Bohr. Fock later claimed that he had found points of convergence with his Danish colleague, most of them concerning issues of wording and recognition of the reality of the world independently of our mind. It led to a specific narrative among historians of physics on Fock and his interpretation of quantum mechanics: The Soviet physicist is often described as a member of the Copenhagen school that contributed to the rapprochement of the Soviet philosophy of physics with the ideas of complementarity in stripping away the positivism in its formulation. Our contribution aims to show that this ideological dimension was only one aspect of reality. Returning to the foundations of Fock's epistemology of physics, we argue that he relied on the principles of antireductionism and scientific realism to develop an interpretation of the theory that sought to overcome Bohr's approach and that the differences between the two men cannot be reduced to mere questions of formulation.  相似文献   
78.
For several decades, a growing number of protohistoric sites in Auvergne (Massif Central, France)—mostly excavated through preventive archaeology—have been subject to the collection of archaeobotanical analysis. This study presents the archaeobotanical results from ten La Tène sites dating from the last five centuries before the Roman conquest. In addition to providing an inventory of taxa, this paper concerns crops and crop cultivation methods. These results are interpreted in a wider context, dealing with crop husbandry, arable farming, storage and consumption practices. The sites are located in the Limagne plain within a 50-km radius around the city of Clermont-Ferrand. A total of 23,579 carpological remains were identified from 163 sediment samples totalizing a volume of 1096 l. Comparable to other sites in Gaul, the spectrum of cereals and pulses is restricted. Spelt (Triticum spelta), einkorn (Triticum monococcum) and foxtail millet (Setaria italica) are disappearing or becoming rare. A better control of agricultural techniques and increased yields is supposed during the ca. five centuries of the La Tène period. Mixed cultivation is hereby replaced by the sowing of monocrops. At the beginning of this period, farming systems are dominated by a polyculture of cereals and pulses. They become more specialized during the last two centuries before the Roman conquest; diversity of cereals and pulses is decreased.  相似文献   
79.
This paper reports the results of a study into the effectiveness of core sampling for discovering Palaeolithic and Mesolithic hunter-gatherer sites in the Netherlands and northwestern Belgium. Earlier work established optimal sampling strategies for use in archaeological heritage management survey in the Netherlands. However, the statistical model used for this was based on a limited amount of data on the distribution of lithic artefacts in Palaeolithic and Mesolithic sites. For the current study we have analyzed the distribution of artefacts in a selected number of excavated sites, and estimated discovery probabilities of these sites through simulation. The simulation results indicate that discovery probabilities are lower than expected due to the effect of clustering of finds. Furthermore, the density of flints in Palaeolithic and Mesolithic sites is generally lower than the estimates that were used for setting up the optimal sampling strategies, and a substantial number of sites is very small. This means that, in order to discover Palaeolithic and Mesolithic sites with sufficient reliability, we will have to apply more intensive survey strategies than have been recommended up to now.  相似文献   
80.
Recent studies on urban poverty in Canadian cities suggest a growing spatial concentration of poor populations within metropolitan regions. This article assesses trends in the intra‐urban distribution of the poor population from 1986 to 2006 in eight of Canada's largest cities. We consider five well‐known dimensions of segregation, as identified by Massey and Denton (1988) , in order to examine changes in the spatial distribution of poor populations within metropolitan areas: evenness, exposure, concentration, clustering, and centralization. These indices were calculated for low‐income populations at the census tract level using data from five Canadian censuses. Although each metropolitan area has distinctive characteristics, we were able to identify some general trends. The results suggest that, in 2006 compared to 1986, low‐income populations lived in more spatially concentrated areas, which were, at the same time, socioeconomically more homogeneous and more dispersed throughout the metropolitan area. In addition, we observed that over the last twenty years areas of poverty have been located, for the most part, in neighbourhoods adjacent to downtown cores. Nevertheless, we found that poverty has mostly increased in suburban areas located outside inner‐city neighbourhoods. Growing socioeconomic homogeneity and dispersion of low income areas in metropolitan areas reveal new spatial patterns of urban poverty distribution. These findings should be cause for concern as social isolation in the most disadvantaged neighbourhoods could affect the life chances and opportunities for the residents of those areas.  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