全文获取类型
收费全文 | 94篇 |
免费 | 17篇 |
国内免费 | 19篇 |
专业分类
测绘学 | 11篇 |
大气科学 | 2篇 |
地球物理 | 26篇 |
地质学 | 49篇 |
海洋学 | 10篇 |
天文学 | 1篇 |
综合类 | 2篇 |
自然地理 | 29篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 4篇 |
2009年 | 11篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有130条查询结果,搜索用时 46 毫秒
31.
A series of micro-erosion-meter sites on different rock types and in differing wind regimes was established and re-read after four years on two sites in the Larsemann and Vestfold Hills. These two oases in Eastern Antarctica are subjected to both wind abrasion and salt wedging. The measurements displayed bimodal distributions, indicating that both abrasion and single-grain detachment could be observed. Surface lowering rates of 0·015 and 0·022 mm a?1 were demonstrated for the Larsemann and Vestfold Hills, respectively. 相似文献
32.
鄂尔多斯北部大牛地地区钻井施工中钻杆偏磨、耐磨环失效现象很普遍。通过对比分析研究,认为造成钻杆耐磨环失效的主要原因有:地层研磨性、钻杆的井下工况、耐磨材料选择与敷焊工艺的影响。 相似文献
33.
Drew Whitelegg 《Area》2002,34(2):128-138
This paper argues that intra –regional competition is as important as intra –regional in the shaping of an urban region. Recent concentration on urban promotion within the discipline places an emphasis on competition between cities that should be counterbalanced by stressing the degree of competition between cities and their suburban peripheries. Using the case of Atlanta, Georgia, and in particular its Vision 2020 initiative, the paper explores how regionalist approaches can easily unravel due to continued rivalries from individual constituents. Placing its theoretical grounding within David Harvey's notion of 'structural coherence', the paper argues that regional policies within a capitalist environment of uneven development tend towards only temporary solutions. 相似文献
34.
35.
基于ESDA的闽西发展不平衡格局动态分析 总被引:4,自引:2,他引:2
陈文成 《地理与地理信息科学》2010,26(2)
区域发展不平衡格局动态涉及空间、时间、属性多维信息,根据1999-2007年闽西区域经济面板数据,构建空间时态数据库。筛选20项指标构建县域经济综合评价指标体系,进行县域经济粒度闽西区域发展变权法三维评价。在此基础上,从县域经济综合角度,应用基于空间探索分析的全局空间相关分析、热点分析及相应的局域统计分析等方法,通过探测县域经济空间联系模式挖掘闽西发展不平衡格局图式与动态,并利用时空一体化模型逼近。 相似文献
36.
37.
Megagrooves are kilometre‐scale linear topographic lows carved in bedrock, separated by ridges, typically in areas of largely devoid of till. They have been reported from several areas covered by Pleistocene glaciations, such as Canadian Northwest (NW) Territories, Michigan and NW Scotland. Here we report two previously undocumented megagroove fields from Ungava, Canada, and northern England, and present new analyses of the megagrooves from NW Scotland. This paper seeks to determine the nature of the lithological and structural controls on the occurrence and formation of megagrooves. Analysis of both geomorphological and bedrock properties shows that megagrooves are generally:
- confined to well stratified or layered bedrock, such as (meta)sedimentary rocks with closely spaced joints, and tend not to occur on massive rocks such as gneiss or granite, or thick‐bedded sedimentary rocks;
- subparallel to palaeo‐ice flow and the strike of the strata; and tend not to occur where palaeo‐ice flow is at high angles to the strike of strata;
- produced by significant glacial erosion by sustained unidirectional ice flow.
38.
《The Professional geographer》1986,38(2):195-222
Book Reviewed in this article: The Vanishing Farmland Crisis, Critical Views of the Movement to Preserve Agricultural Land . John Baden Protecting Farmlands . Frederick R. Steiner and John E. Theilacker Ecological Effects of Fire in South African Ecosystems . Peter de V. Booysen and Neil M. Tainton Geography in China . Wu Chuanjun , Wang Nailiang , Lin Chao and Zhao Songqiao Resource Inventory and Baseline Study Methods for Developing Countries . Francis Conant , Peter Rogers , Marion Baumgardner , Cyrus Mc Kell , Raymond Dasmann, and Priscilla Reining Principles of Remote Sensing . Paul J. Curran Famine As A Geographical Phenomenon . Bruce Currey and Graeme Hugo The Suburban Squeeze: Land Conversion and Regulation in the San Francisco Bay Area . David E. Dowall Senses of Place . John Eyles Uneven Development and the Geographical Transfer of Value . D. K. Forbes and P. J. Rimmer Issues in Wilderness Management . Michael Frome Land-use and Prehistory in South-east Spain , The London Research Series in Geography 8. Antonio Gilman and John B. Thornes with Stephen Wise Regions in Question, Space, Development Theory and Regional Policy . Charles Gore The Colorado River: Instability and Basin Management . William L. Graf Hazardous Waste Sites: The Credibility Gap . Michael R. Greenberg and Richard F. Anderson Peasants, Subsistence Ecology, and Development in the Highlands of Papua New Guinea . Lawrence S. Grossman Silver Cities: The Photography of American Urbanization, 1839-1915 Peter B. Hales Silicon Landscapes . Peter Hall and Ann Markusen Remaking Ibieca: Rural Life in Aragon under Franco . Susan F. Harding The European Energy Challenge: East and West . George W. Hoffman The Global Climate . John T. Houghton The Urban Jobless in Eastern Africa . Abel G. M. Ishumi . The Tourist: Travel in Twentieth-Century North America . John A. Jakle City and Society: An Outline for Urban Geography . R. J. Johnston Residential Segregation, The State and Constitutional Conflict in American Urban Areas . R. J. Johnston Accessibility and Utilization: Geographical Perspectives on Health Care Delivery . Alun E. Joseph and David R. Phillips To the Heart of Asia: The Life of Sven Hedin . George Kish North American Culture , Vol 1. Ary J. Lamme III Past and Present in the Americas: A Compendium of Recent Studies . John Lynch Ethnicity in Contemporary America: A Geographical Appraisal . Jesse O. Mc Kee The Shell Countryside Book . Richard Muir and Eric Duffey 1990 Planning Conference Series. Proceedings of the National Geographic Areas Conference . Proceedings of the Regional Geographic Areas Conferences Wood, Brick, and Stone: The North American Settlement Landscape . Vol. 2: Barns and Farm Structures . Allen G. Noble Bangladesh: Biography of a Muslim Nation . Charles Peter O'donnell 相似文献
39.
The paper presents some numerical results of the problem on contact of stratified elastic half‐spaces possessing unevenness of their surface layers. The approach of the Jacobi polynomials is used to reduce the singular integral equation of the problem to a system of linear algebraic equations. On the basis of the system's solution the dependence of gaps' geometric characteristics on external load and friction is investigated for two types of initial boundary disturbances, namely a local symmetric recess and a periodic set of recesses at a flat boundary. Numerical results are presented in figures for a few elastic and geometric parameters of joint components. The analysis shows that elastic properties and geometric structure of a laminated half‐space have a significant influence on the shape of interface gaps and their location. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
40.
Physical controls on sand composition and relative durability of detrital minerals during ultra‐long distance littoral and aeolian transport (Namibia and southern Angola)
下载免费PDF全文
![点击此处可从《Sedimentology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Eduardo Garzanti Alberto Resentini Sergio Andò Giovanni Vezzoli Alcides Pereira Pieter Vermeesch 《Sedimentology》2015,62(4):971-996
Sediment in coastal Namibia to southern Angola is supplied dominantly from the Orange River with minor additional fluvial input and negligible modifications by chemical processes, which makes this a great test case for investigating physical controls on sand texture and composition. This study monitored textural, mineralogical and geochemical variability in beach and aeolian‐dune sands along a ca 1750 km stretch of the Atlantic coast of southern Africa by using an integrated set of techniques, including image analysis, laser granulometry, optical microscopy, Raman spectroscopy and bulk‐sediment geochemistry. These results contrast with previous reports that feldspars and volcanic detritus break down during transport, that sand grains are rounded rapidly in shallow‐marine environments, and that quartzose sands may be produced by physical processes. Mechanical wear is unable to modify the relative abundance of detrital components, including pyroxene and mafic volcanic rock fragments traditionally believed to be destroyed rapidly. The sole exceptions are poorly lithified or cleaved sedimentary/metasedimentary rock fragments, readily lost at the transition to the marine environment, and slow‐settling flaky micas, winnowed and deposited offshore. Coastal sediments tend to be depleted in relatively mobile amphibole, preferentially entrained offshore or re‐deposited in sheltered beaches, while less mobile garnet is retained onshore. No detrital mineral displays a significant increase in grain roundness after 300 to 350 km of longshore transport in high‐energy littoral environments from the Orange mouth to south of the Namib Erg, but all minerals get rapidly rounded after passing into the dunefield. Pyroxene and opaques get rounded faster than harder quartz and garnet, but sand mineralogy remains unchanged. Excepting strong transient selective‐entrainment effects, physical processes are unable to modify sand composition significantly. Selective mechanical breakdown can be largely neglected in quantitative provenance analysis of sand and sandstone even in the case of ultra‐long‐distance transport in high‐energy environments dominated by strong persistent winds and waves. 相似文献