全文获取类型
收费全文 | 277篇 |
免费 | 19篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 7篇 |
2021年 | 3篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2018年 | 28篇 |
2017年 | 26篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 16篇 |
2013年 | 34篇 |
2012年 | 18篇 |
2011年 | 17篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 7篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有296条查询结果,搜索用时 15 毫秒
41.
Juan Pablo Galvis 《Development and change》2009,40(3):509-529
The modern project of rural development has been seen as one of increasing incorporation, control and rationalization of territory by the state. Evidence from the formulation of the Colombian land reform policy of 1961 gives more nuance to this general conceptualization. Those places where the state intervened through large‐scale resettlement programmes conceived within the framework of Cold War development are the same places where war and the drug economy — the most serious threats to the state itself — took root and grew. This article examines this contradiction. It interrogates the idea of modern development as a project that necessarily brings subjects and territories into the realm of state control. It also attempts to provide a counterweight to arguments about the territorialization of the war in Colombia being the outcome of state inaction and lack of development. 相似文献
42.
Gloria Cuenca-Bescós Lawrence G. Straus Manuel R. González Morales Juan C. García Pimienta 《Journal of archaeological science》2009
El Mirón is a large cave in the Cantabrian Cordillera of northern Spain that presents a long archaeostratigraphic sequence radiocarbon-dated by over 60 assays to between 41,000 and 2000 BP. The sediments, collected from four areas within the cave and sieved-washed with fine wire meshes, contain microvertebrate remains of fish, frogs, lizards, birds and mammals, of which the latter are most abundant. Preliminary taphonomic analysis suggests that the microvertebrates were naturally collected by owls and (less) small carnivores. Small mammal assemblages are useful for palaeoenvironmental reconstruction because they are linked to particular habitats and are sensitive to environmental changes. The small mammals from El Mirón are ideal for this because sample sizes are large, bone preservation is good, and the stratigraphic sequence is long. In this paper we reconstruct the late Quaternary environments in the Cantabrian region of Spain using small-mammal assemblages from El Mirón Cave. On the basis of the ecologic adaptations of this suite of fauna, the majority still extant, we have identified seven habitat types, which are plotted through time. The evolution of the small mammal assemblages at El Mirón reveals seven major climatic shifts that correspond closely to the climatic changes recognized in the Iberian Peninsula during the last 41 kyr. 相似文献
43.
古代建筑油饰彩绘传统工艺的科学化研究 总被引:2,自引:0,他引:2
为了获得传统建筑彩绘工艺过程中的相关科学信息,以传统彩绘工艺过程为基础,利用光学显微镜、电子扫描显微镜、红外光谱、紫外可见光谱、动态粘弹谱、冷冻干燥、化学发光、视频接触角等手段对相关物料在传统工艺操作下的相互作用进行了系统研究.研究主要集中在揭示用于地仗制作物料的功能及其原理.研究结果表明:传统工艺蕴涵着深刻的科学内涵.用于彩绘的地仗是一个典型的复合材料,这种复合材料优越的性能来自于各物质间显著的协同作用.每种物料在其中的作用均可以利用现代科学理念给予阐释.这些理念包括聚合反应、高分子薄膜的固化作用、应力分散、网络结构以及物料相容性等.这些研究结果不仅对传统工艺的理解具有重要的意义,而且对于传统彩绘修复乃至当今复合材料研究也具有重要价值. 相似文献
44.
Human body manipulation and secondary burials are widespread funerary practices in many areas of the world. The archaeology of the Pampas and North-Eastern Patagonia, Argentina, is no exception. In this paper, archaeological case studies from the lower basin of the Colorado River during the Final Late Holocene (ca. 1000–250 years BP) are presented and discussed. Secondary burials were recovered that indicated an intentional manipulation of bodies. Evidences of cut marks and the coloring of bone surfaces were recorded. The bundles were composed of individuals of both sexes and diverse age categories. The Pampean region and North-Eastern Patagonia witnessed significant hunter–gatherer population dynamics during the last 1000 years BP. Climatic, ecologic, demographic, and economic explanations have been proposed as the background to these changes. In this paper, it is argued that accompanying these factors, as part of a broader socio-cultural scenario, were significant social interaction networks and processes of social complementarity between groups. In this context, it is proposed that the complexity observed in relation to the handling of bodies is part of a worldview in which the body was seen as material culture – as a symbol – that played an important role for the community in group identity maintenance in a cultural context undergoing significant organizational changes. 相似文献
45.
The p‐regions problem involves the aggregation or clustering of n small areas into p spatially contiguous regions while optimizing some criteria. The main objective of this article is to explore possible avenues for formulating this problem as a mixed integer‐programming (MIP) problem. The critical issue in formulating this problem is to ensure that each region is a spatially contiguous cluster of small areas. We introduce three MIP models for solving the p regions problem. Each model minimizes the sum of dissimilarities between all pairs of areas within each region while guaranteeing contiguity. Three strategies designed to ensure contiguity are presented: (1) an adaptation of the Miller, Tucker, and Zemlin tour‐breaking constraints developed for the traveling salesman problem; (2) the use of ordered‐area assignment variables based upon an extension of an approach by Cova and Church for the geographical site design problem; and (3) the use of flow constraints based upon an extension of work by Shirabe. We test the efficacy of each formulation as well as specify a strategy to reduce overall problem size. 相似文献
46.
47.
Tarek Ben Hassen Juan‐Luis Klein Diane‐Gabrielle Tremblay 《The Canadian geographer》2011,55(4):439-456
This article analyzes the mechanisms through which metropolitan governance is established in Montreal's aeronautics sector, one of the most important and innovative industries in the region. The article also examines the role of lead firms, socio‐economic actors, and public agencies from a territorial point of view. It is established that on the one hand the existence of a small number of prime producers at the local level facilitates productive linkages among businesses through subcontracting, and on the other hand, the intensive participation of intermediate socio‐economic agencies and organizations ensures a metropolitan anchoring of the sector and creates a strong territorial identity among the players. 相似文献
48.
Ground-supported steel tanks experienced extensive damage in past earthquakes. The failure of tanks in earthquakes may cause severe environmental damage and economic losses. This study deals with the evaluation of the elastic buckling of above-ground steel tanks anchored to the foundation due to seismic shaking. The proposed nonlinear static procedure is based on the capacity spectrum method (CSM) utilized for the seismic evaluation of buildings. Different from the standard CSM, the results are not the base shear and the maximum displacement of a characteristic point of the structure but the minimum value of the horizontal peak ground acceleration (PGA) that produces buckling in the tank shell. Three detailed finite element models of tank-liquid systems with height to diameter ratios H/D of 0.40, 0.63, and 0.95 are used to verify the methodology. The 1997 UBC design spectrum and response spectra of records of the 1986 El Salvador and 1966 Parkfield earthquakes are used as seismic demand. The estimates of the PGA for the occurrence of first elastic buckling obtained with the proposed nonlinear static procedure were quite accurate compared with those calculated with more elaborate dynamic buckling studies. For all the cases considered, the proposed methodology yielded slightly smaller values of the critical PGA for the first elastic buckling compared to the dynamic buckling results. 相似文献
49.
This essay considers the ways in which the reception of Virgil's Georgics in eighteenth-century English verse may inform, enrich and complicate present-day readings of Virgil, focusing on questions raised by readers’ detection of wit or humorousness in Virgil and by the critical aim of discovering poetic unity in the Georgics. 相似文献
50.