全文获取类型
收费全文 | 87篇 |
免费 | 0篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 2篇 |
地球物理 | 13篇 |
地质学 | 51篇 |
海洋学 | 7篇 |
天文学 | 3篇 |
自然地理 | 9篇 |
出版年
2018年 | 2篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 14篇 |
2008年 | 5篇 |
2007年 | 11篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有87条查询结果,搜索用时 0 毫秒
31.
32.
Anne-Marie de Grosbois 《Environmental Geology》2007,52(7):1449-1454
33.
34.
35.
Anne-Marie de Grosbois 《Environmental Geology》2007,52(5):1011-1017
36.
37.
Pollen analyses off Senegal: Evolution of the coastal palaeoenvironment during the last deglaciation
Pollen and dinoflagellate cysts from marine sediments in core A180-48 (15°19′N, 18°06′W; 2450 m water depth; 530 cm length) are used to reconstruct palaeoenvironmental conditions of nearshore tropical west Africa during the last deglaciation. High concentrations and influxes of pollen and dinoflagellate cysts between 11 000 and 10 000 yr BP are interpreted as reflecting an increase in continental trade-wind circulation and related coastal upwelling at 15°N latitude. The sea-surface temperature difference between glacial and interglacial times was not as strong as previously suggested. Together with local (fresh) ground-water input, this smaller temperature difference may explain the persistence of the Rhizophora mangrove and Guinean gallery forests near the shore until their massive extension during the early Holocene humid maximum around 9500 yr BP. Pollen data from the core are compared with data from Rosilda N110-Z, from the continental shelf at the same latitude. 相似文献
38.
Heather Haynes Anne-Marie Ockelford Elisa Vignaga William M. Holmes 《Acta Geophysica》2012,60(6):1589-1606
The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (?? g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion. 相似文献
39.
Anne-Marie Weijmans Davor Krajnovi Glenn van de Ven † Tom A. Oosterloo Raffaella Morganti P. T. de Zeeuw 《Monthly notices of the Royal Astronomical Society》2008,383(4):1343-1358
We present H i observations of the elliptical galaxy NGC 2974, obtained with the Very Large Array. These observations reveal that the previously detected H i disc in this galaxy is in fact a ring. By studying the harmonic expansion of the velocity field along the ring, we constrain the elongation of the halo and find that the underlying gravitational potential is consistent with an axisymmetric shape.
We construct mass models of NGC 2974 by combining the H i rotation curve with the central kinematics of the ionized gas, obtained with the integral-field spectrograph SAURON. We introduce a new way of correcting the observed velocities of the ionized gas for asymmetric drift, and hereby disentangle the random motions of the gas caused by gravitational interaction from those caused by turbulence. To reproduce the observed flat rotation curve of the H i gas, we need to include a dark halo in our mass models. A pseudo-isothermal sphere provides the best model to fit our data, but we also tested an NFW halo and modified Newtonian dynamics, which fit the data marginally worse.
The mass-to-light ratio M / L I increases in NGC 2974 from 4.3 M⊙ /L⊙ , I at one effective radius to 8.5 M⊙ /L⊙ , I at 5 R e . This increase of M / L already suggests the presence of dark matter: we find that within 5 R e at least 55 per cent of the total mass is dark. 相似文献
We construct mass models of NGC 2974 by combining the H i rotation curve with the central kinematics of the ionized gas, obtained with the integral-field spectrograph SAURON. We introduce a new way of correcting the observed velocities of the ionized gas for asymmetric drift, and hereby disentangle the random motions of the gas caused by gravitational interaction from those caused by turbulence. To reproduce the observed flat rotation curve of the H i gas, we need to include a dark halo in our mass models. A pseudo-isothermal sphere provides the best model to fit our data, but we also tested an NFW halo and modified Newtonian dynamics, which fit the data marginally worse.
The mass-to-light ratio M / L
40.
Anne-Marie Aucour Pierre Faure Bernard Gomez Yann Hautevelle Raymond Michels Frédéric Thévenard 《Organic Geochemistry》2009,40(7):784-794
The chemical composition of Cretaceous leaf remains showing exceptionally well preserved cuticles was investigated using pyrolysis gas chromatography–mass spectrometry (Py-GC–MS) and thermally assisted hydrolysis methylation (THM)-GC–MS. Samples of Coniferales (Frenelopsis) and Ginkgoales (Nehvizdya penalveri) leaf remains were collected from freshwater and coastal marine depositional environments. Material for pyrolysis included (i) untreated leaves and cuticles obtained after extraction from mineral rock matrix and bleaching, (ii) kerogen fraction from both materials, (iii) non-hydrolysable fraction from kerogen. The THM-GC–MS data from untreated leaves and bleached cuticles show that the fossil cuticle geopolymer essentially released aliphatic components upon thermal treatment, with a dominance of fatty acids (FAs) and n-alkanes/n-alkenes. The FAs are essentially resistant to bleaching and remain after solvent extraction. They occur mainly as short chain compounds ranging from C6 to C16 and with maximum abundance at C8–C9. The n-alkanes/n-alkenes from kerogen and the non-hydrolysable residue occur mainly as short chain compounds in the range C10–C16, with the highest abundance at C9–C12. The THM-GC–MS pyrograms of the fossil cuticles differ from those of cutan from fresh living plants. They support the preservation model via polymerization of monomers derived from cutin or from unsaturated cell FAs. 相似文献