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131.
Climatic change is expected to have serious impacts on the Pantanal, a large tropical wetland located in the Upper Paraguay River Basin, in the centre of South America, where a range of institutional responses are being developed to mitigate and adapt to climate change. In order to examine the institutional achievements and challenges for managing the region, a specific typology is initially introduced, which comprises a schematic gradient of institutional responses. An empirical analysis was conducted in Brazil, Bolivia and Paraguay, the three countries that share the Pantanal, which identified the hybrid basis of the policy framework under construction, in the sense that it actually combines elements of various institutional responses included in the proposed typology. Important factors that seem to undermine the efficacy of institutional responses in addressing climate change in the region are the strong influence of the agribusiness sector and the still relatively low importance of the Pantanal for national environmental policy-making. This essay makes a claim that the principles of climate justice should guiding policies and interventions as it they constitute the most appropriate strategy to address the inequality and unfairness related to climate change.  相似文献   
132.
Abstract

Traditional semi‐implicit formulations of nonhydrostatic compressible models may not be stable in the presence of steep terrain when pressure gradient terms are split and lagged in time. If all pressure gradient terms and the divergence are treated implicitly, the resulting wave equation for the pressure contains off‐diagonal cross‐derivative terms leading to a highly nonsymmetric linear system of equations. In this paper we present a more implicit formulation of the Mesoscale Compressible Community (MC2) model employing a Generalized Minimal Residual (GMRES) Krylov iterative solver and a more efficient semi‐Lagrangian advection scheme. Open boundaries now permit exact upwind interpolation and the ability to reproduce simulations to machine precision is illustrated for one‐way nesting at equivalent resolution. Numerical simulations of hydrostatic and nonhydrostatic mountain waves demonstrate the stability and accuracy of the new adiabatic kernel. The computational efficiency of the model is reported for 1D Jacobi and 3D Alternating Direction Implicit (ADI) line relaxation preconditioned implemented with a parallel data transposition strategy.  相似文献   
133.
The spectral global baroclinic primitive equation model described in Part I of this paper has been extensively tested. The model has been run daily from operational analyses for over a year. From this large sample of forecasts, verification statistics have been collected and compared with similar statistics collected from three competitive grid‐point models. The spectral model is also compared with the grid‐point models in a synoptic case study.

A second case study demonstrates the effect of horizontal resolution and physical effects on spectral model forecasts. The results of these experiments demonstrate that the spectral model is highly competitive with other models, in terms of both accuracy and computational efficiency. On 18 February 1976 the spectral model became the operational Canadian large‐scale forecast model.  相似文献   
134.
浙江舟山海岸带古木埋藏区铁的微生物成矿作用   总被引:1,自引:0,他引:1  
以浙江舟山海岸带铁矿石为研究对象, 通过对铁矿石及其周围环境背景样品的形态学显微观察、矿物学及地球化学分析, 结果显示渗漏水沉淀铁泥中存在大量形貌与Leptothrix ochracea和Gallionella ferruginea中性铁氧化菌极为相似的微生物鞘, 该微生物可促进Fe2+的氧化和Fe3+的快速沉淀, 并且细胞最终被完全矿化后将永久保存起来.与此相对应的是: 在铁矿石内部存在大量的似球形和丝杆状的针铁矿, 并且还保留了死亡的铁细菌外鞘, 这些特征揭示该铁矿石与微生物历史活动密切相关.将现代渗漏水铁泥中铁细菌的矿化作用和铁矿石中保留的微生物活动记录相对比, 为该环境下的铁矿石生物成矿作用及其成因机制提供了良好的佐证.铁矿石的形成与古木堆积密切相关, 古木埋藏腐烂过程产生的腐植酸加剧了基岩及其周围土壤中的铁淋滤进入到潮间带, 从而为铁矿石形成提供充足的铁来源.该研究有助于更好理解和认识地史时期腐植质及微生物在铁矿床形成中的作用.   相似文献   
135.
A Cretaceous amber deposit has recently been discovered in a quarry of Charente-Maritime (southwestern France), at Cadeuil. This paper presents the sedimentary and palaeoenvironmental settings of the uppermost Albian-lowermost Cenomanian series including the amber deposit. A preliminary analysis of the amber samples reveals diverse fossil arthropods (a few mites and at least 20 insect families within 9 orders), as well as numerous micro-organisms, mainly algae and mycelia. A myceloid colony of bacteria, a flagellate algae and four especially well preserved insects are illustrated (Diptera Dolichopodidae, Diptera Chironomidae, Hymenoptera Parasitica, and Heteroptera Tingidae). The abundance of the limnic micro-organisms is discussed in terms of bloom events. Their relative scarcity in almost all the amber pieces containing fossil arthropods is attributed to differences in the origin of resin: production along trunk and branches for amber with arthropods; production by aquatic roots for amber rich in algae. The absence of pollen and spores in amber is attributed to differences in the respective periods of resin and palynomorph production, which may be related to a seasonal climate during the Albian-Cenomanian transition in Western Europe.  相似文献   
136.
137.
Although fossil assemblages from the late Early Pleistocene are very rare in Britain, the site of Westbury Cave in Somerset, England, has the potential to address this gap. The mammal fossils recovered previously from the Siliceous Member in Westbury Cave, though few in number, have hinted at an age for the deposits that is as yet unparalleled in Britain. Here, we describe the first bona fide occurrence of Hippopotamus in the British Early Pleistocene, discovered during recent reinvestigation of the Siliceous Member. The hippo fossil indicates a refined biochronological age of ca. 1.5–1.07 Ma for the Siliceous Member and a palaeoclimate that was warm and humid, which accords well with previous palaeoenvironmental inferences. A synthesis of late Early Pleistocene hippo occurrences suggests that the Siliceous Member hippo may have been part of an early colonization of north-west Europe by these megaherbivores, possibly during MIS (Marine Oxygen Isotope Stage) 31. Alternatively, it evidences a currently cryptic northward migration during an even earlier temperate phase. In either case, the Siliceous Member is likely to represent a warm period that has not been recognized previously in the British Quaternary record.  相似文献   
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