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Ryan Plummer Danuta de Grosbois Derek Armitage Rob C. de Loë 《Global Environmental Change》2013,23(4):749-763
Assessing vulnerability related to water is a global concern and especially important to populations experiencing multiple exposures and sensitivities. Approaches are required that span social and physical concerns, and that bridge multiple types and forms of knowledge. This research investigates the water vulnerability of three First Nation communities in Ontario, Canada. A collaborative process was used to build an integrative understanding of water vulnerability, develop an associated instrument, and undertake the community scale assessments. Results from the assessment provided communities with a comprehensive overview of water vulnerability, and pointed to gaps in knowledge and specific areas where attention was needed. Conducting assessments at a community scale following the methodology employed in this research responds to the need for integration and context sensitivity when engaging in water vulnerability assessments and introduces innovations to existing assessment tools. A holistic approach to water vulnerability assessment provided decision-makers with the context-specific details and empirical insights they require to prioritize issues and allocate resources. 相似文献
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The lithic record from the Solent River and its tributaries is re‐examined in the light of recent interpretations about the changing demography of Britain during the Lower and early Middle Palaeolithic. Existing models of the terrace stratigraphies in the Solent and its tributary areas are reviewed and the corresponding archaeological record (specifically handaxes) for each terrace is assessed to provide models for the relative changes in human occupation through time. The Bournemouth area is studied in detail to examine the effects of quarrying and urbanisation on collection history and on the biases it introduces to the record. In addition, the effects of reworking of artefacts from higher into lower terraces are assessed, and shown to be a significant problem. Although there is very little absolute dating available for the Solent area, a cautious interpretation of the results from these analyses would suggest a pre‐Marine Isotope Stage (MIS) 12 date for the first appearance of humans, a peak in population between MIS 12 and 10, and a decline in population during MIS 9 and 8. Owing to poor contextual data and small sample sizes, it is not clear when Levallois technology was introduced. This record is compared and contrasted to that from the Thames Valley. It is suggested that changes in the palaeogeography of Britain, in particular land connections to the continent, might have contributed to differences in the archaeological records from the Solent and Thames regions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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We describe additions made to a multi‐size sediment routing model enabling it to simulate width adjustment simultaneously alongside bed aggradation/incision and fining/coarsening. The model is intended for use in single thread gravel‐bed rivers over annual to decadal timescales and for reach lengths of 1–10 km. It uses a split‐channel approach with separate calculations of flow and sediment transport in the left and right sides of the channel. Bank erosion is treated as a function of excess shear stress with bank accretion occurring when shear stress falls below a second, low, threshold. A curvature function redistributes shear stress to either side of the channel. We illustrate the model through applications to a 5·6‐km reach of the upper River Wharfe in northern England. The sediment routing component with default parameter values gives excellent agreement with field data on downstream fining and down‐reach reduction in bedload flux, and the width‐adjustment components with approximate calibration to match maximum observed rates of bank shifting give plausible patterns of local change. The approach may be useful for exploring interactions between sediment delivery, river management and channel change in upland settings. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Zhiyuan Ge Rob L. Gawthorpe Atle Rotevatn Leo Zijerveld Christopher A.-L. Jackson Ayodeji Oluboyo 《Basin Research》2020,32(5):875-893
Salt tectonics is an important part of the geological evolution of many continental margins, yet the four-dimensional evolution of the minibasins, the fundamental building block of these and many other salt basins, remains poorly understood. Using high-quality 3D seismic data from the Lower Congo Basin, offshore Angola we document the long-term (>70 Myr) dynamics of minibasin subsidence. We show that, during the Albian, a broadly tabular layer of carbonate was deposited prior to substantial salt flow, diapirism, and minibasin formation. We identify four subsequent stages of salt-tectonics and related minibasin evolution: (i) thin-skinned extension (Cenomanian to Coniacian) driven by basinward tilting of the salt layer, resulting in the formation of low-displacement normal faults and related salt rollers. During this stage, local salt welding led to the along-strike migration of fault-bound depocentres; (ii) salt welding below the eastern part of the minibasin (Santonian to Paleocene), causing a westward shift in depocentre location; (iii) welding below the minibasin centre (Eocene to Oligocene), resulting in the formation of a turtle and an abrupt shift of depocentres towards the flanks of the bounding salt walls; and (iv) an eastward shift in depocentre location due to regional tilting, contraction, and diapir squeezing (Miocene to Holocene). Our study shows that salt welding and subsequent contraction are key controls on minibasin geometry, subsidence and stratigraphic patterns. In particular, we show how salt welding is a protracted process, spanning > 70 Myr of the salt-tectonic history of this, and likely other salt-rich basins. The progressive migration of minibasin depocentres, and the associated stratigraphic architecture, record weld dynamics. Our study has implications for the tectono-stratigraphic evolution of minibasins. 相似文献
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Rob Sternberg Egon Lass Eric Marion Kaushik Katari Matthew Holbrook 《Geoarchaeology》1999,14(5):415-439
As part of a program to investigate archaeomagnetic secular variation in Israel and implications for archaeomagnetic dating, we have identified “anomalous” results that have yielded information about site formation processes. Stereonets, vector demagnetization diagrams, and sample location maps are most useful in examining stability of magnetization and consistency of archaeomagnetic directions with each other and with what would be expected from normal secular variation. A collection of examples is presented, including: strong and hard remanence due to vitrification, unstable magnetization due to lightning strikes, superimposed thermal magnetizations, chemical remagnetization, magnetization of a hearth fragment before falling, magnetization of a hot brick after falling, and mechanical deformation of an archaeomagnetic feature. © 1999 John Wiley & Sons, Inc. 相似文献
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