全文获取类型
收费全文 | 790篇 |
免费 | 30篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 16篇 |
大气科学 | 42篇 |
地球物理 | 209篇 |
地质学 | 314篇 |
海洋学 | 61篇 |
天文学 | 150篇 |
综合类 | 2篇 |
自然地理 | 31篇 |
出版年
2022年 | 5篇 |
2021年 | 17篇 |
2020年 | 13篇 |
2019年 | 21篇 |
2018年 | 27篇 |
2017年 | 35篇 |
2016年 | 35篇 |
2015年 | 22篇 |
2014年 | 36篇 |
2013年 | 41篇 |
2012年 | 33篇 |
2011年 | 51篇 |
2010年 | 35篇 |
2009年 | 47篇 |
2008年 | 40篇 |
2007年 | 37篇 |
2006年 | 39篇 |
2005年 | 25篇 |
2004年 | 27篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1976年 | 5篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1967年 | 2篇 |
1964年 | 2篇 |
1956年 | 2篇 |
1920年 | 2篇 |
排序方式: 共有825条查询结果,搜索用时 0 毫秒
221.
222.
Meteoroid impact has been shown to be a source of sodium, and most likely of other elements, on the Moon. The same process could be also relevant for Mercury. In this work we calculate the vapor and neutral Na production rates on Mercury due to the impacts of meteoroids in the radius range of 10−8-10−1 m. We limit our calculations to this size range, because meteoroids with radius larger than 10−1 m have not to be found important for the daily production of the exosphere. This work is based on a new dynamical model of the meteoroid flux at the heliocentric distance of Mercury, regarding objects in the size range 10−2-10−1 m. This size range, never investigated before, is not affected by nongravitational forces, such as the Poynting-Robertson effect, which is dominant for particles smaller than 10−2 m. In order to evaluate the release of neutral sodium atoms also for smaller meteoroids we have used the distribution reported by M.J. Cintala [1992. Impact-induced thermal effects in the lunar and mercurian regoliths. J. Geophys. Res. 97, 947-973] calculated for particle size range 10−8-10−3 m. We have extrapolated this distribution up to 10−2 m and we have based the impact calculations on a new surface composition assuming 90% plagioclase and 10% pyroxene. The results of our model are that (i) the total mass of vapor produced by the impact of meteoroids in the size range 10−8-10−1 m is 4.752×108 g per year, and (ii) the production rate of neutral sodium atoms is 1.5×1022 s−1. 相似文献
223.
Olivier Brivois Déborah Idier Jérôme Thiébot Bruno Castelle Gonéri Le Cozannet Daniel Calvete 《Comptes Rendus Geoscience》2012,344(5):277-287
Sandy barred beaches are often characterized by the presence of rhythmic patterns such as crescentic bars. In this article, a linear stability analysis (LSA) model is used to characterize the morphological behaviour of the double bar system of Truc Vert beach. Using a limited number of combinations of representative bathymetries, wave classes and water levels, the morphodynamic response of the system is analysed, focussing on the geometrical characteristics of 3D patterns generated with the model. These characteristics are described and then compared with available observations. The shapes and the wavelengths of the instabilities predicted by the model compare well with field observations. Thus, the use of the linear stability model, with representative hydrodynamic conditions and bathymetries of the considered site, allows a characterization of the global morphodynamic behaviour of a double-barred system. 相似文献
224.
Laurent Jolivet Fabien Trotet Patrick Monié Olivier Vidal Bruno Goffé Loïc Labrousse Philippe Agard Bad'r Ghorbal 《Tectonophysics》2010,480(1-4):133-148
Syn-orogenic detachments in accretionary wedges make the exhumation of high-pressure and low-temperature metamorphic rocks possible with little erosion. The velocity of exhumation within the subduction channel or the accretionary complex, and thus the shape of P–T paths, depend upon the kinematic boundary conditions. A component of slab retreat tends to open the channel and facilitates the exhumation. We document the effect of slab retreat on the shape of P–T paths using the example of the Phyllite–Quartzite Nappe that has been exhumed below the Cretan syn-orogenic detachment during the Miocene in Crete and the Peloponnese. Data show a clear tendency toward colder conditions at peak pressure and during exhumation where the intensity of slab retreat is larger. This spatial evolution of P–T gradient is accompanied with an evolution from a partly coaxial regime below the Peloponnese section of the detachment toward a clearly non-coaxial regime in Crete. 相似文献
225.
Law-Chune Stéphane Aouf Lotfi Dalphinet Alice Levier Bruno Drillet Yann Drevillon Marie 《Ocean Dynamics》2021,71(3):357-378
Ocean Dynamics - As part of the Copernicus Marine Service, WAVERYS is the multi-year wave reanalysis that provides global wave data with a fine grid resolution of 1/5°. This wave reanalysis... 相似文献
226.
Morphology and structure of a landslide complex in an active margin setting: The Waitawhiti complex, North Island, New Zealand 总被引:1,自引:0,他引:1
Aurlien Lacoste Lies Loncke Frank Chanier Julien Bailleul Bruno C. Vendeville Geoffroy Mahieux 《Geomorphology》2009,109(3-4):184-196
Multi-scale gravitational instabilities are widespread in the Coastal Ranges of the North Island of New Zealand. We document here a detailed analysis of the Waitawhiti landslide complex, located in the core of the Tawhero syncline, and investigate the potential landslides triggering factors in the area. Four contiguous large slides form the Waitawhiti complex. These slides involve fine-grained Miocene sandstones and massive fractured siltstones. Sliding occurs mostly along nearly horizontal strata. All slides are bounded laterally and/or distally by deep-incised valleys. Three gas seeps evidencing thermogenic gas release have been discovered in the vicinity of the slides. We propose that river incision, continuously removing distal buttresses, is the main destabilizing factor in the area. However, additional factors, such as tectonic activity and intense rainfall, cannot be excluded. We also propose that fluid overpressure, reducing the effective shear strength at the base of low-permeability layers, may have influenced the triggering of landslides in the Waitawhiti area. 相似文献
227.
Mario Mattia Marco Aloisi Giuseppe Di Grazia Salvatore Gambino Mimmo Palano Valentina Bruno 《Journal of Volcanology and Geothermal Research》2008
In this work, we report the results of an integrated approach using both seismological and geodetic data provided by the INGV-CT (Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania) Stromboli volcano monitoring systems, in order to improve the knowledge of its plumbing system. In particular, we investigated the relationships between the June 1999 seismic swarm, occurring in the area of Stromboli, and the possible activation of the NE–SW oriented volcano-tectonic structure. We analyzed this seismic swarm proposing new locations and a morphological analysis of the waveforms. This approach allowed us to demonstrate that there are relationships between the tectonic activity near Stromboli and the rising of magma. This evidence supports the hypothesis that during the 1999 swarm an intrusive process started from a crustal level where earthquakes were located (about 10–15 km b.s.l.). 相似文献
228.
Bruno Vallet Marc Pierrot-DeseillignyDidier Boldo Mathieu Brédif 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(5):732-742
We present a general framework to improve a vectorial building footprint database consisting of a set of 2D polygons. The aim of this improvement is to make the database more proper to subsequent 3D building reconstruction at a large scale. Each polygon is split into several simple polygons guided by a digital elevation model (DEM). We say that this segmentation is vectorial as we produce segmentations that intrinsically have simple polygonal shapes, instead of doing a raster segmentation of the DEM within the polygon then trying to simplify it in a vectorization step. The method is based on a Mumford and Shah like energy functional characterizing the quality of the segmentation. We simplify the problem by imposing that the segmentation edges have directions present in the input polygon over which the DEM is defined. We evaluate the validity of the proposed method on a very large dataset and discuss its pros and cons based on this evaluation. 相似文献
229.
Adrien Berchet Bruno Simon Anthony Beaudoin Pierre Lubin Germain Rousseaux Serge Huberson 《国际泥沙研究》2018,33(3):351-370
Tidal bores may appear in some estuaries when the tides quickly reach a high level. This phenomenon is rare but has a strong impact during its short duration: i.e. the river bed is significantly eroded and sediments are then transported. In this paper, the trajectories of suspended particles induced by this flow are numerically studied. Four undular bores with Froude numbers between 1.1 and 1.2 are studied. Despite similar Froude numbers, various initial flow conditions were selected to produce or not an inversion of the flow direction during the bore passage. The particle trajectories associated with each distinct flow configuration are presented and analyzed. These trajectories, estimated by solving the Maxey-Riley equation, appear to be very different even though the Froude numbers of flows are similar. These observations are important because the Froude number is often used to characterize a tidal bore as it describes well the free surface, however, it cannot describe the sediment transport. Finally, Chen's model of wave-current interactions is adapted to fit the cases studied and is applied to the four bores simulated. The results highlight that this latter model can reproduce the observed trajectories and dissociate their different components. From this model, it is shown that the inertial and Basset history effects can be neglected compared to the gravity and flow entrainment effects due to the viscous drag when one wants to determine the long-term trajectories of suspended particles. 相似文献
230.
Bruno Reynard 《Physics and Chemistry of Minerals》1991,18(1):19-25
New polarized infrared reflectance spectra of pure synthetic forsterite and natural Fo86-olivine have been recorded from 5000 to 100cm-1. Out of the 35 expected infrared active modes, 33 have been observed (8 B1u, 12 B2u, 13 B3u). The observed frequency shift from pure forsterite to Fo86-olivine is consistent with the higher mass of the substituted iron. The substitution of only 14% of iron also reduces the overal far-infrared reflectivity of olivine as compared to pure forsterite. Several discrepancies associated with previous studies of forsterite are explained by our investigation. We suggest that some of the previous investigations were complicated by polarization mixing. 相似文献