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261.
Physical properties of alluvial environments typically feature a high degree of anisotropy and are characterized by dynamic interactions between the surface and the subsurface. Hydrogeological models are often calibrated under the assumptions of isotropic hydraulic conductivity fields and steady-state conditions. We aim at understanding how these simplifications affect predictions of the water table using physically based models and advanced calibration and uncertainty analysis approaches based on singular value decomposition and Bayesian analysis. Specifically, we present an analysis of the information content provided by steady-state hydraulic data compared to transient data with respect to the estimation of aquifer and riverbed hydraulic properties. We show that assuming isotropy or fixed anisotropy may generate biases both in the estimation of aquifer and riverbed parameters as well as in the predictive uncertainty of the water table. We further demonstrate that the information content provided by steady-state hydraulic heads is insufficient to jointly estimate the aquifer anisotropy together with the aquifer and riverbed hydraulic conductivities and that transient data can help to reduce the predictive uncertainty to a greater extent. The outcomes of the synthetic analysis are applied to the calibration of a dynamic and anisotropic alluvial aquifer in Switzerland (The Rhône River). The results of the synthetic and real world modeling and calibration exercises documented herein provide insight on future data acquisition as well as modeling and calibration strategies for these environments. They also provide an incentive for evaluation and estimation of commonly made simplifying assumptions in order to prevent underestimation of the predictive uncertainty. 相似文献
262.
Guillaume Dodet Bruno Castelle Gerd Masselink Timothy Scott Mark Davidson France Floc'h Derek Jackson Serge Suanez 《地球表面变化过程与地形》2019,44(1):393-401
The storm sequence of the 2013–14 winter left many beaches along the Atlantic coast of Europe in their most eroded state for decades. Understanding how beaches recover from such extreme events is essential for coastal managers, especially in light of potential regional increases in storminess due to climate change. Here we analyse a unique dataset of decadal beach morphological changes along the west coast of Europe to investigate the post-2013–14 winter recovery. We show that the recovery signature is site specific and multi-annual, with one studied beach fully recovered after 2 years, and the others only partially recovered after 4 years. During the recovery phase, winter waves primarily control the timescales of beach recovery, as energetic winter conditions stall the recovery process whereas moderate winter conditions accelerate it. This inter-annual variability is well correlated with climate indices. On exposed beaches, an equilibrium model showed significant skill in reproducing the post-storm recovery and thus can be used to investigate the recovery process in more detail. © 2018 John Wiley & Sons, Ltd. 相似文献
263.
Hubert Gagné Patrick Lajeunesse Guillaume St-Onge Andrée Bolduc 《Geo-Marine Letters》2009,29(3):191-200
Multibeam sonar data, acoustic sub-bottom profiles and box cores were used to study the activity of submarine canyons and
fans near the city of Les Escoumins, on the North Shore of the Lower St. Lawrence Estuary (Eastern Canada). The multibeam
data were used to generate a high-resolution digital terrain model that reveals the presence of a large number of canyons
and fans along the northern slopes of the Laurentian Channel. This paper focuses on two of the larger canyons, and their associated
submarine fans. The sub-bottom profiles on the fans reveal high-amplitude reflections at the sediment/water interface and
near the seafloor surface, indicating the occurrence of layers of coarse material. A turbidite was observed in a box core
sampled in one of the fans, confirming the nature of the coarse layer. Geophysical and sedimentological data indicate that
the canyons and fans play an important role in transferring coastal sandy sediments to the deeper marine environments by longshore
drift-initiated turbidity flows, and thereby contribute to the negative sediment budget along the coast. The morphology of
the canyons indicates that they were produced by a combination of erosive turbidity flows and retrogressive failures. The
two box cores sampled on the fans reveal a recent (~last 60 years) quasi-exponential increase in sand content near the surface
of the cores, possibly reflecting recent deforestation and/or increased coastal erosion. 相似文献
264.
Impact of model simplifications on soil erosion predictions: application of the GLUE methodology to a distributed event‐based model at the hillslope scale
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In this paper, we analyse how the performance and calibration of a distributed event‐based soil erosion model at the hillslope scale is affected by different simplifications on the parameterizations used to compute the production of suspended sediment by rainfall and runoff. Six modelling scenarios of different complexity are used to evaluate the temporal variability of the sedimentograph at the outlet of a 60 m long cultivated hillslope. The six scenarios are calibrated within the generalized likelihood uncertainty estimation framework in order to account for parameter uncertainty, and their performance is evaluated against experimental data registered during five storm events. The Nash–Sutcliffe efficiency, percent bias and coverage performance ratios show that the sedimentary response of the hillslope in terms of mass flux of eroded soil can be efficiently captured by a model structure including only two soil erodibility parameters, which control the rainfall and runoff production of suspended sediment. Increasing the number of parameters makes the calibration process more complex without increasing in a noticeable manner the predictive capability of the model. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
265.
Bassetto Sabrina Cancès Clément Enchéry Guillaume Tran Quang-Huy 《Computational Geosciences》2022,26(5):1297-1322
Computational Geosciences - We propose several numerical approaches building on upstream mobility two-point flux approximation finite volumes to solve Richards’ equation in domains made of... 相似文献
266.
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268.
The 1D version of the Model for Applications at Regional Scale is used to parameterize the effects of sea surface waves in
2D in a horizontally homogeneous offshore zone of the Iroise sea. Here we present the first simulation of the Iroise sea including
sea surface waves forcing, and more generally, the first study of a boundary layer including the Hasselmann force with a tidal
wave. We use a single equation turbulence closure based on a non-local diagnosis for energetic and dissipation length scales.
The turbulent energy flux at the surface due to whitecaps and the Hasselmann force induced by Stokes drift are assessed using
the whole sea surface waves spectrum given by the Wave Watch Third generation model. The ability of the parameterization to
reproduce surface currents over a period of 1 year (2007) is tested with high frequency radar using spectral and time-frequency
analysis. One problem with 1D modelling, corresponding to overestimation of current oscillating at inertial frequency is illustrated
by comparing 1D and 3D simulations. We found an overall improvement by including the Hasselmann force mainly within the bandwidth
of less than one cycle per day to one cycle per day for surface currents. Turbulence is induced by whitecaps decaying rapidly
below the ocean surface but the mixed layer below 40 m is deeper due to waves breaking on the sea surface. 相似文献
269.
Guillaume Morard Denis Andrault Nicolas Guignot Julien Siebert Gaston Garbarino Daniele Antonangeli 《Physics and Chemistry of Minerals》2011,38(10):767-776
High pressure melting behavior of three Fe-alloys containing 5 wt% Ni and (1) 10 wt% Si, (2) 15 wt% Si or (3) 12 wt% S was
investigated up to megabar pressures by in situ X-ray diffraction and laser-heated diamond anvil cell techniques. We observe
a decrease in melting temperature with increasing Si content over the entire investigated pressure range. This trend is used
to discuss the melting curve of pure Fe. Moreover, our measurements of eutectic melting in the Fe–Fe3S system show a change in slope around 50 GPa concomitant with the fcc–hcp phase transition in pure solid iron. Extrapolations
of our melting curve up to the core–mantle boundary pressure yield values of 3,600–3,750 K for the freezing temperature of
plausible outer core compositions. 相似文献
270.
Guillaume Pierre 《Geodinamica Acta》2013,26(1):45-54
RésuméLa question de la capture de la Meuse lorraine est abordée par le biais de l’étude des sables tertiaires qui jalonnent les plateaux de l’Ardenne méridionale. Toujours polygéniques, ces sables ont une histoire plus ou moins longue qui débute à l’Éocène où l’altération poussée du socle produit un épais manteau sableux. Certains gisements in situ fossilisés sont restés quasiment intacts (Régniowez) tandis que d’autres (Doisches) portent la marque de remaniements successifs (marins et/ou continentaux) qui se suivent jusqu’au Miocène sans que leur filiation avec le matériau d’origine, attestée par la nature de leurs barylites, ne se perde. Comme les sables fluviatiles miocènes (in fine) du plateau ardennais ne portent pas la signature minéralogique d’une Meuse lorraine, à l’inverse de la Traînée mosane (datée du Miocène moyen), la capture se trouve à la fois confirmée et datée. L’ancien réseau de la Meuse lorraine, quant à lui, n’a pu se mettre en place qu’après l’Oligocène, époque à laquelle un glacis incliné de l’Ardenne vers le Bassin parisien fonctionnait encore. © 2000 Éditions scientifiques et médicales Elsevier SAS 相似文献