全文获取类型
收费全文 | 2463篇 |
免费 | 306篇 |
国内免费 | 248篇 |
专业分类
测绘学 | 406篇 |
大气科学 | 239篇 |
地球物理 | 532篇 |
地质学 | 526篇 |
海洋学 | 176篇 |
天文学 | 8篇 |
综合类 | 153篇 |
自然地理 | 977篇 |
出版年
2024年 | 9篇 |
2023年 | 25篇 |
2022年 | 97篇 |
2021年 | 143篇 |
2020年 | 145篇 |
2019年 | 140篇 |
2018年 | 121篇 |
2017年 | 107篇 |
2016年 | 115篇 |
2015年 | 124篇 |
2014年 | 143篇 |
2013年 | 192篇 |
2012年 | 125篇 |
2011年 | 131篇 |
2010年 | 120篇 |
2009年 | 128篇 |
2008年 | 120篇 |
2007年 | 131篇 |
2006年 | 137篇 |
2005年 | 121篇 |
2004年 | 110篇 |
2003年 | 97篇 |
2002年 | 88篇 |
2001年 | 59篇 |
2000年 | 48篇 |
1999年 | 36篇 |
1998年 | 41篇 |
1997年 | 31篇 |
1996年 | 29篇 |
1995年 | 17篇 |
1994年 | 23篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有3017条查询结果,搜索用时 31 毫秒
981.
翅碱蓬高光谱植被指数对土壤化学性质的响应 总被引:1,自引:0,他引:1
植被覆盖区土壤化学性质遥感监测一直是一个难点,往往只能通过生物地球化学的方法,利用上覆植被信息间接地反映。该研究通过野外采样分析的17个翅碱蓬(Suaeda salsa)光谱数据和其下土壤样品的理化分析配对数据,探讨土壤化学性质与翅碱蓬高光谱植被指数间的关系。结果表明:上覆翅碱蓬高光谱植被指数与土壤有机质、全氮、速效钾之间均无显著相关,高光谱植被指数(NDNI)可用于初步反映土壤全磷的含量变化,NDVI705可用于初步反映土壤pH值的变化,而高光谱植被指数(MSI)可以很好地反映土壤盐分含量的变化。在此基础上,建立了土壤全盐量与19个高光谱植被指数的偏最小二乘回归模型,这为翅碱蓬覆盖区域土壤盐渍化遥感监测提供了一种方法。 相似文献
982.
探讨了艾比湖生态系统的退化过程及其带来的影响,分析了艾比湖湿地、森林植被在维护艾比湖生态系统平衡方面的重要作用,提出了保湖和恢复森林植被同时并举的建议。 相似文献
983.
《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
984.
985.
A 405 cm long core was drilled in the Aparados da Serra National Park (Rio Grande do Sul, Brazil) at the end of 1999, and in all, 23 samples were taken for palynological investigation. The cores′ age is estimated at 27 000 a BP based on three radiocarbon dates taken from different depths of the core. Palynological methods were used to reconglacial conditions mainly influenced by the South Pole throughout several transition stages to today's humid warm climate, mainly being influenced by the Brazil stream. 相似文献
986.
Vegetation and soil properties and their associated changes through time and space affect the various stages of soil erosion. The island of Ishigaki in Okinawa Prefecture, Japan is of particular concern because of the propensity of the red‐soil‐dominated watersheds in the area to contribute substantial sediment discharge to adjacent coastal areas. This paper discusses the application of remote sensing techniques in the retrieval of vegetation and soil parameters necessary for the distributed soil‐loss modelling in small agricultural catchments and analyses the variation in erosional patterns and sediment distribution during rainfall events using numerical solutions of overland flow simulations and sediment continuity equations. To account for the spatial as well as temporal variability of selected parameters of the soil‐loss equations, a method is proposed to account for the variability of associated vegetation cover based on their spectral characteristics as captured by remotely sensed data. To allow for complete spatial integration, modelling the movement of sediment is accomplished under a loose‐coupled GIS computational framework. This study lends a theoretical support and empirical evidence to the role of vegetation as a potential agent for soil erosion control. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
987.
《The Professional geographer》1987,39(2):238-266
Book Reviewed in this article: Women, Work, and Ideology in the Third World . Haleh Afshar, ed. The Birth of the National Park Service. The Founding Years 1913–33 . Horace M. Albright Theatres of Accumulation: Studies in Asian and Latin American Urbanization . Warwick Armstrong and T.G. McGee. New Tools for Social Scientists, Advances and Applications in Research Methods . William D. Berry and Michael S. Lewis -Beck , eds . Uncertain Dimensions: Western Overseas Empires in the Twentieth Century . Raymond F. Betts. Geography of Sugar Cane . Helmut Blume. The Mines of Neptune: Minerals and Metals from the Sea . Elisabeth Mann Borgese. Geographical Dimensions of Energy . F.J. Calzonetti and B.D. Solomon, eds. Statistical Methods for Geographers . W. A. V. Clark and P. L. Hosking. In The Wake of Columbus, Islands and Controversy . John DeVorsey, Jr., and John Parker, eds. Housing, States and Localities . Peter Dickens, Simon Duncan, Mark Goodwin and Fred Gray. Physician Location and Specialty Choice . Richard L. Ernst and Donald E. Yett. Practical Ecology for Geography and Biology: Survey, Mapping, and Data Analysis . D.D. Gilbertson , M. Kent and F.B. Pyatt Large Scale Water Transfers: Emerging Environmental and Social Experiences . Genady N. Golubev and Asit K. Biswas, eds. The Nature of the Environment . Andrew Goudie. Planning for Population Change . W.T.S. Gould and R. Lawton. The Niger and its Neighbors: Environmental History and Hydrobiology. Human Use and Health Hazards of the Major West African Rivers . A.T. Grove, ed. Remote Sensing of Ice and Snow . Dorothy K. Hall and Jaroslav Martinec. Atlas of Antebellum Southern Agriculture . Sam Bowers Hilliard. Galilee Divided; The Israel-Lebanon Frontier, 1916-1984 . Frederic C. Hor . Plains Country Towns . John C. Hudson. Agricultural Geography: A Social and Economic Analysis . Brian W. Ilbery. Industry in the 1980s: Structural Change and Interdependence . U.N. Industrial Development Organization. Crabgrass Frontier: The Suburbanization of the United States . Kenneth T. Jackson. The Industrial Geography of Italy . Russell King. Studies in Linguistic Geography: The Dialects of English in Britain and Ireland . John M. Kirk, Stewart Sanderson, J.D.A. Widdowson, eds. Tourism: A Community Approach . Peter E. Murphy. Cities and Services: The Geography of Collective Consumption . Steven Pinch. An Historical Geography of Europe 1800–1914 . Norman J. G. Pounds. An Introduction to Human Ecology Research on Agricultural Systems in Southeast Asia . A. Terry Rambo and Percy E. Sajise, eds. Discovering Past Landscapes . Michael Reed, ed. Managing the Ocean: Resources, Research, Law . Jacques G. Richardson, ed. Carta fitosociologica de la transecta botanica de la Patagonia Austral . F.A. Roig , Juan Anchorema , Orlando Dollenz , A.M. Faggi and Eduardo Mandez Intermetropolitan Migration in Canada: Changing Determinants over Three Decades . R. Paul Shaw. Chinese Cities—The Growth of the Metropolis since 1949 . Victor F. Sit, ed. Urbanization in the World-Economy . Michael Timberlake, ed. The Al Business: Commercial Uses of Artificial Intelligence . Patrick H. Winston and Karen A. Prendergast, eds. 相似文献
988.
A model simulating the processes in responses of glacier and runoff to climatic change 总被引:1,自引:0,他引:1
This paper presents a dynamic glacier model that simulates the processes in response of Glacier No. 1 in headwaters of the
ürümqi River to various future climatic scenarios. The results indicate that the Glacier No. 1 will continue retreating if
current climatic conditions prevail, until it reaches an equilibrium state of 1600 m in length after 700 to 800 years. If
air temperature raise 1°C, the glacier would become a hanging glacier with a length of 300 m after 700 to 800 years. Due to
its retreat, cooling function of the glacier would be weakened, resulting in the air temperature in glaciated area higher
than that in ice-free areas. The results also indicate that the current glacier melt runoff is in higher value period in comparison
with the runoff in the equilibrium state under the current climatic condition. If the air temperature continues increasing,
however, the runoff would still increase to a new peak and then decrease rapidly.
The project supported by the National Natural Science Foundation of China. 相似文献
989.
GlObalwa-rmingisoneoftheseriousenvironmentproblemswhichattractattentionsofscientistsandgove~entsofvariouscountries.TheglobalatmOSpherecomponentschangebecauseofhtirnanactivitiesandthedevelopmentofindustry.Theincreaseofgreenhouseeffectleadstoglobalw~ng.Basedonthepredictionofgeneralcirculationmodel(GCM),bythemiddleofnextcentury,theconcentrationofopwillbedoubledandtheglobaltemperaturewillinCreasebyZt(Han,1993;She~,1983).WestudiedthelawofvegetationalterationunderthisconditioninnortheastChinain… 相似文献
990.
Discriminant functions link vegetation zones and surface pollen along the woodland–steppe ecotone in northern China. These links were utilised to reconstruct palaeovegetation using fossil pollen data from four lake sediment sites within the ecotone. Holocene movements of the vegetation zones were derived from the above results and were interpreted as the results of climatic, topographic and edaphic factors. This study shows that climatic change was the driving factor for ecotonal movement, but that the positions of vegetational zones were nevertheless controlled by topographical and edaphic conditions, and consequently boundaries between different vegetational zones responded individualistically. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献