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   38篇
  免费   2篇
  国内免费   1篇
地球物理   9篇
地质学   23篇
海洋学   2篇
自然地理   7篇
  2018年   2篇
  2017年   2篇
  2016年   1篇
  2015年   1篇
  2014年   3篇
  2012年   2篇
  2011年   1篇
  2010年   1篇
  2009年   8篇
  2008年   3篇
  2007年   5篇
  2005年   1篇
  2004年   4篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  1998年   1篇
  1997年   1篇
排序方式: 共有41条查询结果,搜索用时 15 毫秒
11.
This article aims to make a contribution to current debates in the literature on food access by describing a mixed-methods approach to study the access to food in one rural community in Cuba. Each of the forty households in our study was asked to complete a detailed food diary in which they indicated what they ate and where they acquired each of the ingredients that they used for a full week. Although in Cuba the state plays a central role in organizing the distribution of food items, this method revealed a much more complex web of rural food access. By addressing alternative networks of food access and informal social relations, we aim to show how the use of food diaries, in combination with qualitative data from interviews and participant observation, can provide detailed insights in the complex processes and networks of food access.  相似文献   
12.
Transmogrifying Regions   总被引:1,自引:1,他引:0  
《The Journal of geography》2012,111(5):226-227
Abstract

Teacher Education Models in Geography: An International Comparison by William Marsden, ed. Kalamazoo, Ml: Commission on Geographical Education, 1984. v and 155 pp., figs., tables, and refs. NP

Principles of Thematic Map Design by D.B. Dent Reading, MA: Addison-Wesley, 1984. xv and 398 pp., figs., tables, photos, maps, refs., and index. $29.95 cloth.

Health Care in Developing Countries by Wilbert M. Gesler Resource Publication in Geography, edited by C.G. Knight. Washington, DC: Association of American Geographers, 1984.88 pp., figs., graphs, tables, maps, and biblio. $5.00 paper.

Cotton Fields No More: Southern Agriculture 1865–1980 by Gilbert C. Fite Lexington: University Press of Kentucky, 1984. xiv and 273 pp., tables, photos, app., refs., and index. $28.00 cloth; $10.00 paper.

Population: Patterns, Dynamics, and Prospects by James Newman and Gordon Matzke Englewood Cliffs, NJ: Prentice-Hall, 1984. xi and 306 pp., figs., graphs, tables, maps, biblio., and index. $27.95 cloth.  相似文献   
13.
The aim of this work is to evaluate the changes in groundwater chemistry in an alluvial aquifer in the Moa area. Surface and ground water, metallurgical waste and various geological material samples were collected in order to evaluate groundwater composition. The results show that the alluvial aquifer is polluted with SO42-, Mg2+and heavy metals. According to its major components in the alluvial aquifer, two types of groundwater are identified: magnesi-bicarbonated and sulphate-magnesic. Maximum SO42– and Mg2+ contents are more than 1000 mg/L, and are four times higher than the acceptable levels for human consumption of water. The high values of Cr(VI), Ni(II), Mn(II) Fe(total), SO42– and Mg2+ in alluvial aquifers are due to polluted recharge from metallurgical waste from the tailing dam. This recharge is favoured by the preferential flow due to desiccation cracks in metallurgical waste. Geochemical modelling showed that potentially toxic heavy metals might exist largely in the forms of MSO42– and M2+ in pore water of SAL metallurgical waste. All samples were supersaturated in goethite and hematite. Results from batch testing indicate that the heavy metals have two origins: natural, due to the existing ultramaphic rocks and laterites, and anthropogenic, by metallurgical waste rich in sulphate and (oxy)hydroxide minerals. These results highlight the need to locate and evaluate a new water source to supply the population of the city of Moa.  相似文献   
14.
The Palaeogene volcanic arc successions of the Sierra Maestra, southeastern Cuba, were intruded by calc-alkaline, low- to medium-K tonalites and trondhjemites during the final stages of subduction and subsequent collision of the Caribbean oceanic plate with the North American continental plate. U-Pb SHRIMP zircon dating of five granitoids yielded 206Pb/238U emplacement ages between 60.5±2.2 and 48.3±0.5 Ma. The granitoids are the result of subduction-related magmatism and have geochemical characteristics similar to those of magmas from intra-oceanic island-arcs such as the Izu Bonin-Mariana arc and the New Britain island arc, Lesser Antilles. Major and trace element patterns suggest evolution of these rocks from a single magmatic source. Geochemical features characterize these rocks as typical subduction-related granitoids as found worldwide in intra-oceanic arcs, and they probably formed through fractional crystallization of mantle-derived low- to medium-K basalt.  相似文献   
15.
In this study, we address the late Miocene to Recent tectonic evolution of the North Caribbean (Oriente) Transform Wrench Corridor in the southern Sierra Maestra mountain range, SE Cuba. The region has been affected by historical earthquakes and shows many features of brittle deformation in late Miocene to Pleistocene reef and other shallow water deposits as well as in pre-Neogene, late Cretaceous to Eocene basement rocks. These late Miocene to Quaternary rocks are faulted, fractured, and contain calcite- and karst-filled extension gashes. Type and orientation of the principal normal palaeostress vary along strike in accordance with observations of large-scale submarine structures at the south-eastern Cuban margin. Initial N–S extension is correlated with a transtensional regime associated with the fault, later reactivated by sinistral and/or dextral shear, mainly along E–W-oriented strike-slip faults. Sinistral shear predominated and recorded similar kinematics as historical earthquakes in the Santiago region. We correlate palaeostress changes with the kinematic evolution along the boundary between the North American and Caribbean plates. Three different tectonic regimes were distinguished for the Oriente transform wrench corridor (OTWC): compression from late Eocene–Oligocene, transtension from late Oligocene to Miocene (?) (D1), and transpression from Pliocene to Present (D2–D4), when this fault became a transform system. Furthermore, present-day structures vary along strike of the Oriente transform wrench corridor (OTWC) on the south-eastern Cuban coast, with dominantly transpressional/compressional and strike-slip structures in the east and transtension in the west. The focal mechanisms of historical earthquakes are in agreement with the dominant ENE–WSW transpressional structures found on land.  相似文献   
16.
The seismicity of Cuba is briefly presented together with a few fundamental neotectonic elements of the adjacent Caribbean region. The Cuban seismicity catalogue has been extended back to 1528 and it shows that the largest earthquakes occurred in 1766 and 1852 (I = IX MSK). Two types of seismicity (intraplate and interplate) can be distinguished in Cuba. Western and Eastern Seismotectonic Units correspond to intraplate type and the Southeastern Seismotectonic Unit to interplate type. Western Cuba is characterized by a low frequency of earthquake occurrence. Distribution of epicenters is not regular and the most important events mainly concentrate along two regional active fault system (Nortecubana and Surcubana). Due to the lack of seismic stations in this region, the characterization of seismicity is frequently done on the grounds of historical data available from 1693. The main seismogenic source for Cuba is the Bartlett-Cayman fault system, but inland there are other active structures. Some issues about historical and present day Cuban seismological research are also showed.  相似文献   
17.
This article examines the social spaces of self‐employment in Havana, Cuba, to uncover the deeply conflicting and contradictory values that comprise the dialectics of state–society relations. These spaces and the many actors who traverse them provide important insight into the complexity surrounding contemporary Cuba. Through detailed research into one form of self‐employment, paladares (small in‐home restaurants), this article examines how paladares have come to reflect the struggle for society and state to mediate the multitude of external and internal pressures amongst the current geopolitical climate. Using interviews conducted during several visits in 1999 and 2000, we demonstrate that paladares do not necessarily represent a capitalist transition. Rather, they embody the struggle to mediate contradictory spaces through the assertion of the self in the discourse of change.  相似文献   
18.
Seismic attenuation of coda waves in the eastern region of Cuba   总被引:1,自引:0,他引:1  
Cuba's seismic attenuation had never been studied in detail. In this paper we present the results of the research on the seismic attenuation of Cuba's eastern zone based upon the information collected by the seismological Cuban network from 1998 to 2003. 581 earthquakes were selected from the Cuban catalogue to make this study. All of them, recorded by at least three seismic stations, had their epicenters located in the eastern Cuban region (19.3–22 N, 79–73 W), epicentral distances between 15 km and 213 km, their coda duration magnitudes ranging from 2 and 4.1 and their focal depths reaching up to 30 km. The seismic wave attenuation was studied using coda waves. The single scattering method proposed by Sato in 1977 was applied, the attenuation and frequency dependency for different paths and the correlation of the results with the geotectonics of the region are presented in this paper.The mean Qc value calculated was Qc = (64 ± 2)f0.84 ± 0.01. The relatively low Q0 and the high frequency dependency agree with the values of a region characterized by a high tectonic activity. The Qc values of seven subregions of eastern Cuba were calculated and correlated with the geology and tectonics of the area.  相似文献   
19.
Currently there is a strong interest in Cuba in improving the performance of the fisheries sector with respect to social, biological, and economic outcomes. Many important fishery resources appear to be overexploited, and previous fishery regulations have had mixed success in restoring fishery stocks. The current fishing pressure could also have adverse impacts on other valuable ecosystem services that support economic activities such as dive tourism and recreational fishing. A new State policy to expand cooperative enterprises to non-agricultural sectors provides an opportunity for fishery cooperatives to be created for the first time since the early years of the Cuban Revolution. This paper explores the potential ecological, social, and economic benefits of adopting fishery cooperatives as a co-management scheme for Cuba's marine fisheries. It concludes that well-designed fishery cooperatives can offer substantial benefits to the management of the fishery sector. Based on an analysis of the relative success of fishing cooperatives worldwide, guidelines are provided for the design of fishery cooperatives in Cuba.  相似文献   
20.
A late Albian ammonite assemblage from the Provincial Formation of Villa Clara Province, Cuba is described. The Provincial Formation is a lithostratigraphic unit of Albian-Cenomanian age extensively exposed in central Cuba and formed within a part of the Caribbean Tethys that was volcanic during the Cretaceous. The formation is mainly composed of calcareous, terrigenous marine, and volcano-sedimentary deposits characterized by a series of micritic limestones intercalated with marls, sandstones, calcareous conglomerates, ash, and tuffaceous material. A rich assemblage of ammonites recovered from the calcareous biomicrites and marls is of late Albian (Stoliczkaia dispar Zone, Mortoniceras rostratum Subzone) age. The ammonite fauna shows a strong Tethyan affinity, and only a single hoplitid ammonite species was recorded. Although scarce, the first Cuban report of this and other boreal ammonite species now allows precise correlations to be made between Cuba and Albian sediments elsewhere in the world.  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