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   30篇
  免费   1篇
  2022年   1篇
  2020年   1篇
  2019年   3篇
  2018年   2篇
  2017年   6篇
  2016年   2篇
  2015年   1篇
  2013年   2篇
  2012年   1篇
  2011年   1篇
  2010年   3篇
  2009年   1篇
  2005年   1篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1993年   1篇
排序方式: 共有31条查询结果,搜索用时 15 毫秒
1.
ABSTRACT. Real variable analysis has een used to great benefit in a variety of classical problems in location theory. In this paper we explore basic complex variable techniques in one formulation of the obnoxious location problem. A general definition of center points is first given and used to formulate several alternate versions of the obnoxious location problem. A logarithmic transformation is then used to demonstrate some equivalences between these families of distinct location problems (defined via center points). A prototype logarithmic potential function which results from this formulation is then investigated, and it is demonstrated that the extremal solutions with this objective reside on the boundary of its domain of definition. An application using zero- and one-dimensional centers is discussed, and a generalization to the spatial obnoxious problem is also briefly examined. We define a zero-dimensional center as a critical point of the logarithmic potential function, and it is shown that these centers are equivalent to the solutions of the Complex Moment Problem.  相似文献   
2.
ABSTRACT

This article aims to shed light on Quebec’s role in cross-border security governance. It exposes the challenges Quebec is facing in this area and what cross-border activities fall within its jurisdiction. The supported hypothesis in this article is that security is subjected to an increasing politicization from the Quebec government in a post-9/11 context, which contributes to the edification of an embryonic “multilevel governance.” If this politicization was noticeable in political statements and international agreements, it seems that it was more driven by conjectural imperatives than a real desire to make Quebec a leader in transnational security. Therefore, there were no diplomatic and financial commitments to make security part of the Gérin-Lajoie doctrine and develop a similar paradiplomacy as in other fields. However, on different technical and bureaucratic levels, transgovernmental relations between certain Quebec governmental organizations, including police corps, and their American counterparts were created. Consequently, they contributed to make continental action more effective, at least in a certain measure.  相似文献   
3.
The Rabat-Témara region of the Moroccan Atlantic coast reveals a succession of Quaternary palaeobeaches. This coastal area is dotted with numerous prehistoric caves. The study of the Upper Pleistocene coastal landscape associated with these caves is of paramount importance in the knowledge of human population subsistence. During the Upper Pleistocene, the ocean level changes drastically influenced the coastal geomorphology as well as the fauna assemblages. The chrono-lithostratographical analysis of the coastal sedimentary formations allows the distinction of three sequences rich in marine fauna. These sequences date from MIS 11 to MIS 5. The identification of malacofauna species from these deposits revealed 39 species, along with Bryozoans, Crustaceans, and Echinoids. These assemblages show a constant fauna cortege highlighted by the dominance of the amphi-Atlantic species Stramonita haemastoma. This species shows an increase in the number of specimens in the uppermost part of marine deposits, probably in relation with a climate warming in the MIS 5. This fauna of both intertidal rocky substrates and sandy substratum indicates environmental conditions close to the present-day Rabat-Témara coastline. As in other coastal locations of Africa from MIS 5, the Middle Stone Age Homo sapiens population benefitted from a littoral environment rich in coastal resources. Comparison between thanatocenoses and archaeological records allows us to identify both species available for Middle Stone Age population and those preferred for human use.  相似文献   
4.
5.
In this article, the authors assess some of the major trends within anglophonic feminist historical geography appearing in the decade since Rose & Ogborn called for the development of an explicitly feminist approach to the subfield. In examining the 'geography' of feminist historical geographies, three main categories of scholarship are evident: a 'new' historical geography of North America, portions of which are informed by feminist theories and methods; a British school of feminist historical geography with a focus on the discipline of geography, geographical knowledges and colonialism/imperialism; and feminist historical geography interventions in cultural politics of space and place. A diversity of feminist methods and epistemologies appears across the literature. In an attempt to avoid a reading of these trends as better or worse approximations of historical 'progress', the authors conceptualize them as emplaced within a number of specific social and spatial contexts. Most recent work is concerned with the production of gender differences as they are worked through economic, political, cultural and sexual differences in the creation of past geographies. The continued need simply to write women into historical narratives and geographies, however, is also evident. The work of feminist historical geography questions and challenges geography's masculinist historical record.  相似文献   
6.
7.
The manipulation of fire is a technological act. The identification of the archaeological signatures of the controlled use of fire has important implications not only for the estimations of the origins and functions of the first fireplaces but also for our understanding of prehistoric technological development and resource use. At Riwi (Kimberley region, Western Australia), excavations over two field seasons have revealed a discontinuous occupation sequence over the past 45 ka, showing numerous, different combustion features interspersed within the deposit. Anthracological and micromorphological investigations at Riwi Cave indicate that the combustion features at the site can be categorised into three types: flat combustion features (type A), dug combustion features (type B) and thick accumulations of mixed combustion residues (type C). These provide evidence for two kinds of combustion practice: (i) fires lit directly on the ground and most likely not re-used and (ii) ground ovens, the latter appearing some 10,000 years after the first evidence for occupation of the site. A comparison of the wood species identified within these combustion features with those from equivalent scattered context levels, enables an exploration of the potential factors influencing wood selection and fire use through time at the site. A detailed understanding of the relationship between wood charcoal remains and archaeological context yields significant information on changes to environmental context and site occupation patterns over time.  相似文献   
8.
9.
ABSTRACT

Seventeen years before the first excavation at the archaeological site of Lapita (New Caledonia) in 1952, two men of the cloth met and exchanged artefacts, notes and ideas to produce some of the earliest analyses of what later became known as Lapita pottery. Otto Meyer (1877–1937), a Sacred Heart Missionary stationed on Watom Island, described chance finds of ‘prehistoric pottery’ in 1909, following these with more systematic excavations. Patrick O’Reilly (1900–88), a Marist Father associated with the Musée de l’Homme in Paris, drew on Meyer’s work, his own extensive bibliographical knowledge and his observations during a one-year mission in the region in 1934–5 to present part of the collection in France, laying the ground for further theories. The publication, interpretation and curation of the Meyer/O’Reilly collection represents an exemplary journey through the history of Pacific archaeology and the emergence of the Lapita paradigm. We consider the context of Meyer’s encounter with O’Reilly, the ideas both men advanced in analysing the collection and the site, and how these resonated during the development of Pacific and Lapita archaeology throughout the first half of the 20th century.  相似文献   
10.
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