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261.
Peter Crabb 《The Australian geographer》2012,43(1):1-16
In spite of many proposals, Australia has no national freshwater research centre. Thus the passing in the Senate of Ralph Jacobi's private member's bill for an Institute of Freshwater Studies in 1982 was unusual. His driving force was the need to overcome State boundaries and for research to inform policy and management of water resources. It gained widespread support, and not just from the parliamentary Labor Party, but was strongly opposed by the Fraser government, State and federal water bureaucracies, and the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The election of 1983 prevented further discussion in parliament, but the proposal was part of the Labor Party platform taken to the election. An Interim Council set up to investigate whether or not such an institute should be established, but with narrow terms of reference very different from those in Jacobi's bill, sided with the large water bureaucracies and CSIRO, in spite of majority support for an institute. An institute was rejected and the government accepted the recommendation. Jacobi's proposal failed primarily because of a fear of independent advice by many in the bureaucracies, a potential loss of power and influence, and inter-governmental rivalries. The status quo remained; the bigger picture is still unseen. 相似文献
262.
A simulation program, which works seamlessly with GIS and simulates flows in coastal aquifers, is presented in the present paper. The model is based on the Galerkin finite element discretization scheme and it simulates both steady and transient freshwater and saltwater flow, assuming that the two fluids are separated by a sharp interface. The model has been verified in simple cases where analytical solutions exist. The simulation program works as a tool of the GIS program, which is the main database that stores and manages all the necessary data. The combined use of the simulation and the GIS program forms an integrated management tool offering a simpler way of simulating and studying saline intrusion in coastal aquifers. Application of the model to the Yermasogia aquifer illustrates the coupled use of modeling and GIS techniques for the examination of regional coastal aquifer systems.
Resumen Se ha desarrollado un modelo casi tridimensional de elementos finitos para simular el flujo de agua dulce y salada, tanto en régimen estacionario como en transitorio, en sistemas acuíferos costeros, bajo la hipótesis de separación por medio de una interfaz abrupta. Las ecuaciones del modelo han sido discretizadas mediante un esquema de Galerkin de discretización en elementos finitos. El modelo ha sido verificado en casos sencillos para los que existe solución analítica. Todos los datos necesarios se introducen y gestionan con un Sistema de Información Geográfica [SIG] por ordenador. El programa de simulación forma parte del programa de SIG, constituyendo una herramienta integrada de gestión para estudiar la intrusión salina en acuíferos costeros. La aplicación del modelo al acuífero de Yermasogia ilustra el uso acoplado de las técnicas de modelación y de SIG con el fin de examinar sistemas acuíferos costeros a escala regional.
Résumé Pour étudier un système aquifère côtier, nous avons développé un modèle aux éléments finis en quasi 3-D qui simule les écoulements deau douce et deau salée en régime aussi bien permanent que transitoire. Les équations qui les régissent sont discrétisées par un schéma de discrétisation de Garlekin aux éléments finis. Le modèle a été vérifié dans des cas simples où il existe des solutions analytiques. Toutes les données nécessaires sont introduites et gérées grâce à un logiciel de gestion de SIG. Le programme de simulation est utilisé comme un outil du logiciel de SIG, constituant ainsi un outil de gestion intégrée dont le but est de simuler et détudier lintrusion saline dans les aquifères côtiers. Lapplication du modèle à laquifère de Yermasogia illustre lutilisation couplée de la modélisation et des techniques de SIG pour létude des systèmes aquifères côtiers régionaux.相似文献
263.
264.
水既是战略物资又是生命的基础。水资源的安全关系到社会可持续的发展,关系到人类自身的生态系统的生存和发展,关系到国家的稳定、主权和安全。全球人口的增长、气候变暖、环境污染的加重、城市化进程的加快等都是影响水资源质和量的关键因素。全球水资源随着时间的推移日趋紧缺乃至危机;天然水分类表明,淡水资源是水资源最重要的成分。含有害成分的淡水资源是地方病的致病因素。中国水资源虽然不算少,但人口13亿,人均水资源量排在世界第128位,属于贫水国,并且水资源时空分布不平衡。面对中国淡水资源严重短缺问题,动员全民节水是现实可行的,但学习国外先进治水经验,加强水资源管理的国家级决策至为关键。 相似文献
265.
266.
Dr. Ernst Schegg 《Aquatic Sciences - Research Across Boundaries》1971,33(2):425-532
267.
Francisco Padilla Ana Méndez Rafael Fernández Pablo R. Vellando 《Environmental Geology》2008,55(1):215-226
This applied research deals with the numerical modelling and transient simulation of the joint surfacewater/groundwater flows
that characterize the freshwater/saltwater hydrology of the coastal alluvial valley of the Low Guadalhorce River, Malaga,
Spain. The MELEF model used was mainly adapted and calibrated for a simulation period of two hydrological years 1989/1990–1990/1991,
before the current channelling of the river, where floods and low precipitations have been recorded. The model calibration
process was performed with the aid of phreatic levels measured in numerous wells and piezometers, as well as recharges from
precipitation and irrigation on the alluvial surface, which was also assessed by the hydrologic model SSMA-2. The present
numerical approach can predict the forthcoming hydrology of the coastal alluvial of the Guadalhorce River after its final
channelling. 相似文献
268.
系统采集了位于青藏高原东北部的尕海湖淡水湖泊沉积物,对沉积物中正构烷烃及其氢同位素进行了分析,研究了沉积物中正构烷烃及其氢同位素组成,探讨了它们的来源。研究结果表明,尕海湖沉积物中正构烷烃分布反映了它们来自水生和陆生植物。尕海湖沉积正构烷烃氢同位素组成平均值为-221.9‰~-190.5‰。C_(21)~C_(33)奇碳数正构烷烃δD值明显地将样品划分为两种类型。类型Ⅰ样品的C_(21)~C_(33)奇碳数正构烷烃平均δD值明显地高于类型Ⅱ样品。类型Ⅰ沉积正构烷烃δD值分布特征反映了它们主要来自尕海湖水生植物;类型Ⅱ沉积物中正构烷烃δD值特征指示了它们主要来自研究区陆生草本植物。提出了具有δD值低、丰度高和CPI值低的中等链长正构烷烃起源于改造陆源草本植物的细菌。研究成果证实了沉积正构烷烃δD值可以作为指示有机质源的地球化学指标。 相似文献
269.
The Sundarbans is one of the productive mangrove wetland ecosystems in the Ganges-Brahmaputra delta in Bangladesh. The delta
is undergoing rapid ecological changes due to human activity. In the present study, surface water salinity data from 13 rivers
of the Sundarbans were collected in order to investigate the saline water intrusion in the mangrove wetlands. Results demonstrate
that saline water has penetrated the upstream area as river water salinity has increased significantly in 1976 compared to
the year 1968. The soil and river water salinity data also shows that it has crossed the water salinity threshold line in
most parts of the Sundarbans wetlands. These observations are due to the construction of Farakka Barrage in 1975, which reduced
the water discharge of the Ganges River from 3700 m3/s in 1962 to 364 m3/s in 2006. The shortage of freshwater discharge to the deltaic area is trailing active ecosystems function, especially in
the dry season in the south western region in Bangladesh. The objective of this study is to understand and analyze the present
degraded mangrove wetland ecosystems and their negative impacts. The findings of this study would contribute to the formulation
of the mangrove wetland ecosystems management plan in the Ganges delta of Bangladesh. 相似文献