全文获取类型
| 收费全文 | 209篇 |
| 免费 | 5篇 |
| 国内免费 | 1篇 |
专业分类
| 测绘学 | 4篇 |
| 大气科学 | 17篇 |
| 地球物理 | 59篇 |
| 地质学 | 80篇 |
| 海洋学 | 21篇 |
| 天文学 | 6篇 |
| 综合类 | 1篇 |
| 自然地理 | 27篇 |
出版年
| 2023年 | 1篇 |
| 2021年 | 2篇 |
| 2020年 | 5篇 |
| 2019年 | 7篇 |
| 2018年 | 11篇 |
| 2017年 | 4篇 |
| 2016年 | 4篇 |
| 2015年 | 6篇 |
| 2014年 | 10篇 |
| 2013年 | 16篇 |
| 2012年 | 11篇 |
| 2011年 | 18篇 |
| 2010年 | 13篇 |
| 2009年 | 5篇 |
| 2008年 | 17篇 |
| 2007年 | 9篇 |
| 2006年 | 11篇 |
| 2005年 | 5篇 |
| 2004年 | 9篇 |
| 2003年 | 5篇 |
| 2002年 | 4篇 |
| 2001年 | 2篇 |
| 2000年 | 2篇 |
| 1999年 | 3篇 |
| 1998年 | 5篇 |
| 1997年 | 1篇 |
| 1996年 | 7篇 |
| 1995年 | 1篇 |
| 1994年 | 1篇 |
| 1993年 | 1篇 |
| 1992年 | 2篇 |
| 1991年 | 1篇 |
| 1990年 | 2篇 |
| 1987年 | 1篇 |
| 1986年 | 2篇 |
| 1984年 | 3篇 |
| 1982年 | 3篇 |
| 1975年 | 1篇 |
| 1968年 | 1篇 |
| 1967年 | 3篇 |
排序方式： 共有215条查询结果，搜索用时 31 毫秒
91.
Philippe E. Raison Claudiu C. Pavel Regis Jardin Emmanuelle Suard Richard G. Haire Karin Popa 《Physics and Chemistry of Minerals》2010,37(8):555-559
The thermal expansion of cubic pyrochlore Ce2Zr2O7 has been measured from room temperature to 898 K on polycrystalline material in conjunction with structural analyses using
neutron diffraction. This compound has a thermal expansion coefficient in line with the other comparable lanthanoide pyrochlore
oxides. The coefficient can be expressed as α(T) = 8.418 × 10−6 + 0.9861 × 10−9 × T. The structural refinements performed for each measured temperature showed a comparable linear evolution of the Ce–O/Zr–O
distances (within 0.57%). 相似文献
92.
Denise Christina Rüther Rune Mattingsdal Karin Andreassen Matthias Forwick Katrine Husum 《Quaternary Science Reviews》2011,30(19-20):2776-2792
A 280 km wide sediment wedge in outer Bjørnøyrenna (Bear Island Trough), south-western Barents Sea, has been investigated using 2D and 3D seismic data, sediment gravity cores, as well as regional swath and large scale bathymetry data. The bathymetry data indicate a division into an up to 35 m high frontal wedge with large depressions, and an upstream part characterized by mega scale glacial lineations (MSGL). From seismic sections increasing erosion is demonstrated for the upstream part, coinciding with the location of MSGL. Whether the latter are depositional features postdating an extensive erosional event or formed by erosion remains inconclusive. Based on the distinct morphology and internal structures, we infer that the system was deposited during a rapid readvance whereby the ice front pushed and bulldozed predominantly soft, diluted proglacial sediments. Analyses in the eastern part of the sediment system reveal the existence of imbricated thrust sheets in the frontal part of the wedge. This is suggested to imply upstream erosion of sedimentary rock and incorporation of thrusted blocks into the moraine, forming a composite ridge locally. We argue that observed large scale depressions are dead-ice features in the marine environment. It is envisioned that intense englacial thrusting may have developed into a decollement as the cold glacier snout got overrun by ice masses from the interior, thereby enabling the inclusion of slabs of ice in the push moraine mass. Radiocarbon dates indicate that the sediment wedge was deposited around 17,090 cal yrs BP (14,530 14C yrs BP) and that the ice front probably remained stable until 16,580 cal yrs BP (13,835 14C yrs BP). 相似文献
93.
Studies of lake sediments on Sejerø in southern Kattegat indicate a treeless arctic environment with the dwarf shrub Salix polaris, herbs and wetland mosses. The mean July temperature was around 8 to 10°C. An AMS radiocarbon age determination of a Salix twig yielded an age of around 36 000 14C yr BP, which is in accordance with previous conventional dating of bulk sediment samples. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
94.
95.
Karin Antonsson Heikki Seppä 《Boreas: An International Journal of Quaternary Research》2007,36(4):400-410
Inferred mean annual temperatures (Tann) from a radiocarbon-dated fossil pollen stratigraphy obtained from Lake Trehörningen, southwest Sweden, provide evidence of climate variability during the Holocene in the boreal-nemoral zone of Sweden. The record indicates low early Holocene temperatures, followed by a rising trend and maximum temperature values from about 7000 to 4000 cal. yr BP. During the later part of the Holocene until present day, a cooling trend is reflected in the temperature record. At about 8200 cal. yr BP, temperatures temporarily drop, and at 8000 cal. yr BP the rising temperature trend is recovered. Inferred mid-Holocene temperatures are about 2.5-3°C higher than at present, and also higher than other pollen-inferred mid-Holocene temperatures of 1.5-2.5°C further to the north and east in Scandinavia. The reconstructed long-term climate pattern in Trehörningen has an overall consistency with temperature reconstructions from Scandinavia, suggesting a regional climate link for the Holocene variability in Sweden. Holocene climate trends in Trehörningen also show a remarkably similar pattern with the classic work on postglacial climate change by Sernander (1893, Sernander 1909), Andersson (1909) and von Post (1924). 相似文献
96.
Sediment collections on a mainland fringing marsh, a lagoon marsh and a barrier island fringing marsh were conducted in conjunction with Geographic Information Systems (GIS) analysis of aerial photographs to relate changes in marsh area to sedimentary processes. The island marsh lost 7·2% of its area in 8 years by overwash. The lagoon marsh lost 10·6% of its area over 41 years by recession of marsh edges. The mainland marsh area increased by 8·2% over 50 years, primarily by upland encroachment. Surface sediment was collected monthly at the mainland and lagoon marshes for 1 year to identify changes in the mean grain size, organic content and mass of sediment deposited on sampling plates. Short-term variability in these characteristics obscured seasonal differences. Grain size and monthly sediment accumulation decreased towards the interior of both marshes, while the organic matter content increased. On the lagoon marsh, coarse sediment at creekside stations, as well as grain size contrasts between surface and subsurface sediment, are consistent with erosion evident in GIS analysis. On the mainland marsh, sediment does not vary as much with location or depth, and topography appears stable. Tidal currents appear to be competent to resuspend most particle sizes represented in surface sediment samples, including aggregates, except at the edge of the lagoon site. Decreasing rates of marsh edge change reflect moderation of oceanic processes, while the interior of both lagoon and mainland marshes remained stable throughout the study. Both lagoon marsh losses to recession and mainland marsh gains from upland reflect the submergence which this shoreline experiences. 相似文献
97.
Wave energy is a renewable source, which has so far not been exploited widely. Many of the various schemes in the past consist of large mechanical structures, often located near the sea surface. This article presents a range of systems with point absorbers on the surface and linear generators placed on the seabed, converting the wave motion into electrical power. Electrical power components are combined in different ways to obtain solutions suitable for various conditions. Different topologies for the electrical system transmitting power to the grid are discussed. Qualitative case studies are used to exemplify system options and connection schemes. 相似文献
98.
Karin M. Borenäs 《地球物理与天体物理流体动力学》2013,107(1-4):115-132
Abstract The stability of a rotating, stationary flow of zero potential vorticity in a slowly varying channel is examined using the method of multiple scales. This technique can be applied when the variations of the basic flow occur on a length scale which is much larger than the one associated with the perturbation. To lowest order the disturbance is described by a propagating part multiplied by a slowly changing amplitude. It is shown that when the phase speed of a disturbance approaches zero, the growth of the amplitude becomes unbounded. This happens when a perturbation superimposed upon a flow which is slightly sub/supercritical, or which alters from a super- to a subcritical state, propagates over a shoaling bottom. If, however, the change of the basic flow is from a sub- to a supercritical state, the phase speed is quite large and the amplitude of the perturbation will just show minor variations along the channel. The same holds true if the steady flow is only moderately affected by the changing topography. The problem has also been analyzed using wave-action formalism, and the outcome of this alternative approach to the stability problem proved to conform to the previously obtained results. Finally, an interpretation of the calculated growth rates is undertaken in terms of “convective” amplification and “absolute” instability. 相似文献
99.
ABSTRACTThis article analyses the nexus of technocracy–peacebuilding and its implications on water conflicts and hydropolitics. It is a conceptual exploration which advances an interdisciplinary approach by combining theories from two distinct research fields: peacebuilding and transboundary water management. It probes the argument that synergies between water management, development and peacebuilding frequently lead to technocratic and functional solutions. As empirical case illustration, the transboundary project, the Red Sea–Dead Sea Water Conveyance (RSDSWC) is analysed regarding its peacebuilding and peace promoting potential. Three concluding remarks are drawn from the conceptual and empirical analysis. First, strong emphasis on technocratic solutions is inclined to favour supply-oriented options rather than solutions based on ethics of sustainable development and rights-based distribution. Second, functional solutions to water conflicts downplay at times complex hydro-political and asymmetrical relations between adversaries. Third, wider trends of privatization in the water sector coincide with similar developments in the field of peacebuilding, where new transnational actors are gaining influence as “new peacemakers”, which are likely to have long-term consequences on power relations and the resolution of water conflict.
EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR not assigned 相似文献
100.
Adrian M. Hall Karin Ebert Clas Hättestrand 《Geografiska Annaler: Series A, Physical Geography》2013,95(1):33-49
We seek to quantify glacial erosion in a low relief shield landscape in northern Sweden. We use GIS analyses of digital elevation models and field mapping of glacial erosion indicators to explore the geomorphology of three granite areas with the same sets of landforms and of similar relative relief, but with different degrees of glacial streamlining. Area 1, the Parkajoki district, shows no streamlining and so is a type area for negligible glacial erosion. Parkajoki retains many delicate pre‐glacial features, including tors and saprolites with exposure histories of over 1 Myr. Area 2 shows the onset of significant glacial erosion, with the development of glacially streamlined bedrock hills. Area 3 shows extensive glacial streamlining and the development of hill forms such as large crag and tails and roches moutonnées. Preservation of old landforms is almost complete in Area 1, due to repeated covers of cold‐based, non‐erosive ice. In Area 2, streamlined hills appear but sheet joint patterns indicate that the lateral erosion of granite domes needed to form flanking cliffs and to give a streamlined appearance is only of the order of a few tens of metres. The inheritance of large‐scale, pre‐glacial landforms, notably structurally controlled bedrock hills and low relief palaeosurfaces, remains evident even in Area 3, the zone of maximum glacial erosion. Glacial erosion here has been concentrated in valleys, leading to the dissection and loss of area of palaeosurfaces. Semi‐quantitative estimates of glacial erosion on inselbergs and palaeosurfaces and in valleys provide mean totals for glacial erosion of 8 ± 8 m in Area 1 and 27 ± 11 m in Area 3. These estimates support previous views that glacial erosion depths and rates on shields can be low and that pre‐glacial landforms can survive long periods of glaciation, including episodes of wet‐based flow. 相似文献