全文获取类型
收费全文 | 268篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 24篇 |
地球物理 | 60篇 |
地质学 | 125篇 |
海洋学 | 35篇 |
天文学 | 21篇 |
自然地理 | 18篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 18篇 |
2013年 | 20篇 |
2012年 | 10篇 |
2011年 | 9篇 |
2010年 | 16篇 |
2009年 | 10篇 |
2008年 | 27篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有285条查询结果,搜索用时 15 毫秒
121.
Markus J. Schwab Petra Werner Peter Dulski Edward McGee Norbert R. Nowaczyk Sébastien Bertrand Suzanne A.G. Leroy 《Quaternary Science Reviews》2009,28(11-12):991-1005
Lake Sapanca is located on a strand of the Northern Anatolian Fault Zone (NAFZ, Turkey), where a series of strong earthquakes (Ms >6.0) have occurred over the past hundred years. Identifying prehistoric earthquakes in and around Lake Sapanca is key to a better understanding of plate movements along the NAFZ. This study contributes to the development of palaeolimnological tools to identify past earthquakes in Lake Sapanca. To this end several promising proxies were investigated, specifically lithology, magnetic susceptibility, grain size (thin-section and laser analysis), geochemistry, pollen concentration, diatom assemblages, 137Cs and 210Pb. Sedimentological indicators provided evidence for reworked, turbidite-like or homogeneous facies (event layers) in several short cores (<45 cm). Other indicators of sediment input and the historical chronicles available for the area suggest that three of these event layers likely originated from the AD 1957, 1967 and 1999 earthquakes. Recent changes in sediment deposition and nutrient levels have also been identified, but are probably not related to earthquakes. This study demonstrates that a combination of indicators can be used to recognize earthquake-related event layers in cores that encompass a longer period of time. 相似文献
122.
Lucie Mathieu Paul Byrne Damien Guillaume Benjamin van Wyk de Vries Bertrand Moine 《Journal of Volcanology and Geothermal Research》2011,199(3-4):206-215
The Kerguelen Archipelago is part of an oceanic plateau with a complex history. Little work has been done on the tectonics of the onshore areas, even though the extensive outcrop renders the islands especially good for structural work. We present the results of three field campaigns and remote sensing analysis carried out in the main Kerguelen Island, around Val Travers valley and Mt Ross volcano (Central Plateau) and in the Rallier du Baty peninsula (SW part of the archipelago). We have mapped faults, fracture sets, and the location and geometry of intrusive bodies. We found that the plateau basalt lavas that make up most of the area are densely fractured, crossed by many veins, dykes and some small faults. This work provides a general framework for the structure of Kerguelen Archipelago that is dominated by 110°-striking faults and veins, dyke swarms and an alignment of recent central volcanoes, which have formed in N-S to NNW-SSE directed extensional stress field. The other structures are fractures, veins and dykes which strike 130–150°, 000° and 030–050°. They are likely related to transform faults of the Indian oceanic crust and to faults of the north Kerguelen Plateau (offshore basement of the archipelago). These buried structures were likely re-activated by a low magnitude stress field. 相似文献
123.
In order to protect infrastructures against rockfalls, civil-engineered mitigation measures are widely used. Flexible metallic fences are particularly well suited to stop the propagation of blocks of rock whose kinetic energy can reach 5000?kJ before impact. This paper focuses on the design of highly flexible rockfall fences under the new European guideline ETAG027. The experimental testing and the numerical modeling using the discrete element method (DEM) of a new metallic rockfall fence are presented. Several scales of study were considered; the mesh, the net and the entire structure. The calibration of the DEM models is described and a parametrical study is proposed. The latter aims to underline the type of information that can be obtained from numerical simulations of such a system to enhance its design. 相似文献
124.
This study examines the hydrodynamics of the Roman harbor of Portus during the Trajanic period (second century A.D.). We have evaluated the impact of the north‐eastern channel on water circulation and sediment resuspension within the harbor in relation to the problem of sediment infilling. We used a 2D numerical model to compute the distribution of the depth‐averaged current velocity, bed shear stress, and kinetic energy induced by each of the four prevailing local winds. First, the results confirm the persistent conditions for sediment infilling over the entire western harbor basin, even when the north‐eastern channel is operational; these conditions being present for 61.3% (40.3%) of the summer period and up to 68% (44.2%) of the winter period in the south‐western harbor basin. Second, the results show that favorable conditions for navigation occur in the central basin, leading to the landing installations, under the S 180°, SE 135°, and NE 22° winds when the north‐eastern channel is operational; these conditions being present for 21% of the summer period and 51.3% of the winter period. Inversely, the access to the landing installations with both channels operating remains affected by sediment infilling, for 40.3% of the summer period and 16.7% of the winter period. 相似文献
125.
Grégoire Messager Bertrand Nivière Pierre Lacan Yves Hervouët Jean-Paul Xavier 《International Journal of Earth Sciences》2014,103(3):929-951
We present here a record of Plio-Pleistocene deformations above the flexural front of the southern Central Andes of Argentina. We combine a seismic profile with structural and geomorphological observations to show that thin-skinned extension located on top of the crustal front flexure is coeval with thin-skinned shortening at the toe of the topographic bulge. The seismic line shows that a flat zone with no internal deformation separates the stretched and shortened domains. Such features are usually interpreted as the result of strike-slip faulting along basement faults, or tangential longitudinal strain folding in the soft sedimentary cover above crustal bending. We propose an alternative linking extension at the apex of the crustal anticline, to basal contraction by the downslope translation of a rigid thin nappe of sediments (30 × 30 km2 in area) above evaporites at a depth of 700–900 m. The size of such a process is unusually large onshore (630–810 km3) but mimics the gravity gliding observed in deltas and passive margins. Since this process disconnects zones with a shallow stress field from deeper crustal levels, it could allow extension above a compressive deformation front and should not be interpreted merely as a record of the crustal stress regime. Large-scale gravity gliding of the cover down the slope of a structural high could also explain some of the extension observed in mountain hinterlands. 相似文献
126.
A tomographic imagery segmentation methodology for three-phase geomaterials based on simultaneous region growing 总被引:2,自引:2,他引:0
Mir Amid Hashemi Ghonwa Khaddour Bertrand François Thierry J. Massart Simon Salager 《Acta Geotechnica》2014,9(5):831-846
X-ray computed tomography is a powerful non-destructive technique used in many domains to obtain the three-dimensional representation of objects, starting from the reconstitution of two-dimensional images of radiographic scanning. This technique is now able to analyze objects within a few micron resolutions. Consequently, X-ray microcomputed tomography opens perspectives for the analysis of the fabric of multiphase geomaterials such as soils, concretes, rocks and ceramics. To be able to characterize the spatial distribution of the different phases in such complex and disordered materials, automated phase recognition has to be implemented through image segmentation. A crucial difficulty in segmenting images lies in the presence of noise in the obtained tomographic representation, making it difficult to assign a specific phase to each voxel of the image. In the present study, simultaneous region growing is used to reconstitute the three-dimensional segmented image of granular materials. First, based on a set of expected phases in the image, regions where specific phases are sure to be present are identified, leaving uncertain regions of the image unidentified. Subsequently, the identified regions are grown until growing phases meet each other with vanishing unidentified regions. The method requires a limited number of manual parameters that are easily determined. The developed method is illustrated based on three applications on granular materials, comparing the phase volume fractions obtained by segmentation with macroscopic data. It is demonstrated that the algorithm rapidly converges and fills the image after a few iterations. 相似文献
127.
Jean-Baptiste Charlier Catherine Bertrand Stéphane Binet Jacques Mudry Nicolas Bouillier 《Hydrogeology Journal》2010,18(8):1963-1969
Continuous measurements of natural fluorescence of dissolved organic matter (DOM) in groundwater have been used to characterize infiltration through an unstable fractured hillslope at the event time scale. Within the gneissic Valabres rockfall area in the southern French Alps, two sites, in the unstable massif and in the collapse area, were continuously monitored for electrical conductivity and for DOM natural fluorescence using a field fluorometer, and analyzed weekly for hydrochemical data. Two main results were found. From a methodological point of view, DOM natural fluorescence was a relevant tracer of fast infiltration in fissured media, knowing that continuous measurements improved the study of infiltration processes at the event time scale. From a hydrogeological point of view, the unstable fractured massif showed delayed dilution phenomena and the collapse areas showed fast and slow infiltration by piston-type flows via more or less open fractures. Consequently, from this conceptual model one may suppose that, unlike the collapse zones, the fractured hillslope threatening the valley is not submitted to strong pore-water pressure variations. 相似文献
128.
129.
Stephane Binet Herve Jomard Thomas Lebourg Yves Guglielmi Emmanuel Tric Catherine Bertrand Jacques Mudry 《水文研究》2007,21(25):3463-3472
Artificial and natural tracer tests combined with high accurate electronic distancemeter measurements are conducted on a small landslide with a well known slip surface geometry. Outflow yields and chemical contents are monitored for all the experiment duration and they analyzed to estimate the slip surface hydraulic parameters. The main result is that the slip surface acts as a drain for groundwater flows that evacuates interstitial pressures in the slope and brings the sliding mass to be more stable one. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
130.
Loic Piret Sebastien Bertrand Jon Hawkings Malin E. Kylander Fernando Torrejón Benjamin Amann Jemma Wadham 《地球表面变化过程与地形》2021,46(1):239-251
Proglacial lakes are effective sediment traps but their impact on the reliability of downstream sediment records to reconstruct glacier variability remains unclear. Here, we investigate the sedimentary signature of the recent recession of Steffen Glacier (Chilean Patagonia, 47°S) in downstream fjord sediments, with a focus on identifying the trapping (decreased downstream sediment yield) and filtering (removal of coarse particles) effectiveness of a growing intermediate proglacial lake. Four sediment cores were collected along a 14 km longitudinal transect in Steffen Fjord and the sediment physical and chemical properties were compared with aerial imagery at high temporal resolution. The caesium-137 (137Cs) chronology of the most distal core and sediment trap data suggest that sediment accumulation in the fjord remained relatively stable through time, despite the accelerating glacier recession and the growth of Steffen proglacial lake. This is in contrast with many studies that indicate a decrease in sediment yield during proglacial lake expansion. It implies that the increase in sediment export due to accelerating meltwater production may be balanced by the sediment trapping effect of the growing proglacial lake. The fjord sediments show a slight fining upward accompanied by a marked decrease in flood-induced grain-size peaks, most likely due to the increasing filtering and dampening effect of the expanding proglacial lake. Our findings show that the filtering effect of the proglacial lake reached a threshold in 1985, when the lake attained an area of 2.02 km2. The additional 5 km of glacier recession during the following 32 years did not have any significant impact on downstream sedimentation. This study confirms that proglacial lakes act as sediment traps but it indicates that (1) the trapping effect can be outpaced by accelerating glacier recession and (2) the filtering effect becomes stable once the lake attains a certain critical size. © 2020 John Wiley & Sons, Ltd. 相似文献