全文获取类型
收费全文 | 718篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 29篇 |
大气科学 | 65篇 |
地球物理 | 181篇 |
地质学 | 268篇 |
海洋学 | 64篇 |
天文学 | 98篇 |
综合类 | 5篇 |
自然地理 | 24篇 |
出版年
2023年 | 3篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 27篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 31篇 |
2012年 | 30篇 |
2011年 | 43篇 |
2010年 | 26篇 |
2009年 | 40篇 |
2008年 | 37篇 |
2007年 | 25篇 |
2006年 | 27篇 |
2005年 | 28篇 |
2004年 | 32篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 15篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1969年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有734条查询结果,搜索用时 62 毫秒
231.
Javier Sanchez Hans-Jürgen Götze Michael Schmitz 《International Journal of Earth Sciences》2011,100(7):1697-1712
A 3-D structural model of the Caribbean-South American plate boundary was constructed by gravity modeling. The model was constrained
by four wide-angle seismic refraction sections, Moho depth estimations from receiver functions, and additionally seismological
hypocenters, surface geology, and geodynamic information. Density values were calculated from empirical velocity-density functions,
and mineralogical-chemical composition considering specific P/T conditions. We tested different structural models for Western
and Eastern Venezuela. In the final model, the fit of the measured and modeled gravity fields for a long Caribbean slab in
Western Venezuela was better than the fit obtained for a short one. This interpretation is consistent with the constraining
data. The slab is interpreted to extend further to the south beneath Northern Colombia and culminates in the area of the seismic
cluster of the Bucaramanga nest. The modeling estimates a slab dip angle under Maracaibo and Mérida Andes of 15°, which increases
to 32° below 100 km depth. The dip direction of approx. N150°E ± 5 increases lightly eastward. In Eastern Venezuela, considering
its short wavelength, lineaments analyzed from gravity data (by curvature methods and Euler deconvolution) seem to be related
to shallow structures and density contrast in the Serranía del Interior and not from a deep detached slab beneath the continental
crust. It is deduced from modeling results that this slab configuration has a very small influence on the gravity field. The
slab was modeled according to the subduction-transform propagation model with purely westward subduction and a slab break
off along a vertical dip-slip tear through the lithosphere. 相似文献
232.
Henry A. Ruhl Michel AndréLaura Beranzoli M. Namik Ça?atayAna Colaço Mathilde CannatJuanjo J. Dañobeitia Paolo FavaliLouis Géli Michael GilloolyJens Greinert Per O.J. HallRobert Huber Johannes KarstensenRichard S. Lampitt Kate E. LarkinVasilios Lykousis Jürgen MienertJ. Miguel Miranda Roland PersonImants G. Priede Ingrid PuillatLaurenz Thomsen Christoph Waldmann 《Progress in Oceanography》2011,91(1):1-33
Society’s needs for a network of in situ ocean observing systems cross many areas of earth and marine science. Here we review the science themes that benefit from data supplied from ocean observatories. Understanding from existing studies is fragmented to the extent that it lacks the coherent long-term monitoring needed to address questions at the scales essential to understand climate change and improve geo-hazard early warning. Data sets from the deep sea are particularly rare with long-term data available from only a few locations worldwide. These science areas have impacts on societal health and well-being and our awareness of ocean function in a shifting climate.Substantial efforts are underway to realise a network of open-ocean observatories around European Seas that will operate over multiple decades. Some systems are already collecting high-resolution data from surface, water column, seafloor, and sub-seafloor sensors linked to shore by satellite or cable connection in real or near-real time, along with samples and other data collected in a delayed mode. We expect that such observatories will contribute to answering major ocean science questions including: How can monitoring of factors such as seismic activity, pore fluid chemistry and pressure, and gas hydrate stability improve seismic, slope failure, and tsunami warning? What aspects of physical oceanography, biogeochemical cycling, and ecosystems will be most sensitive to climatic and anthropogenic change? What are natural versus anthropogenic changes? Most fundamentally, how are marine processes that occur at differing scales related?The development of ocean observatories provides a substantial opportunity for ocean science to evolve in Europe. Here we also describe some basic attributes of network design. Observatory networks provide the means to coordinate and integrate the collection of standardised data capable of bridging measurement scales across a dispersed area in European Seas adding needed certainty to estimates of future oceanic conditions. Observatory data can be analysed along with other data such as those from satellites, drifting floats, autonomous underwater vehicles, model analysis, and the known distribution and abundances of marine fauna in order to address some of the questions posed above. Standardised methods for information management are also becoming established to ensure better accessibility and traceability of these data sets and ultimately to increase their use for societal benefit. The connection of ocean observatory effort into larger frameworks including the Global Earth Observation System of Systems (GEOSS) and the Global Monitoring of Environment and Security (GMES) is integral to its success. It is in a greater integrated framework that the full potential of the component systems will be realised. 相似文献
233.
234.
A reversible method is presented to transform waterlogged sediment cores into dry and stable specimens which can go on exhibition or into permanent storage, needing no special precautions. Wet sediment core segments are bath-impregnated with polyethylene glycol of molecular weight 3,350 (PEG 3,350) dissolved in water. The samples are then subjected to a freeze-drying process, during which the PEG forms a stabilising and bonding porous network structure in the capillary system of the sediment. Standard sediment cores at least 1 m long become strong enough to stand upright. Sediment types ranging from muddy deep-sea sediments to very coarse littoral Halimeda sand were successfully stabilised. For standard cores of 10-cm diameters split length-wise, impregnation times vary from 2 weeks for coarse sand to 6–10 weeks for more compacted sediments. With regard to the stability of the samples and the visual clarity of detail, best results were obtained by impregnation with 25 to 60% solutions of PEG 3,350, coarse sediments needing more PEG than finer ones. Colour changes are systematic – the processed samples are lighter in appearance and the contrasts are enhanced, but there is no serious shift in colour tones. The PEG can easily be re-dissolved and washed out of the sediments. Display specimens can thus be made available for research again. 相似文献
235.
236.
237.
238.
239.
240.