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71.
72.
Anne-Marie Weijmans Michele Cappellari Roland Bacon P. T. de Zeeuw Eric Emsellem Jesús Falcón-Barroso Harald Kuntschner Richard M. McDermid Remco C. E. van den Bosch Glenn van de Ven † 《Monthly notices of the Royal Astronomical Society》2009,398(2):561-574
We use the integral-field spectrograph SAURON to measure the stellar line-of-sight velocity distribution and absorption line strengths out to four effective radii ( R e ) in the early-type galaxies NGC 3379 and 821. With our newly developed observing technique, we can now probe these faint regions in galaxies that were previously not accessible with traditional long-slit spectroscopy. We make optimal use of the large field-of-view and high throughput of the spectrograph: by adding the signal of all ∼1400 lenslets into one spectrum, we obtain sufficient signal-to-noise in a few hours of observing time to reliably measure the absorption line kinematics and line strengths out to large radius.
We find that the line strength gradients previously observed within 1 Re remain constant out to at least 4 R e , which puts constraints on the merger histories of these galaxies. The stellar halo populations are old and metal poor. By constructing orbit-based Schwarzschild dynamical models, we find that dark matter is necessary to explain the observed kinematics in NGC 3379 and 821, with 30–50 per cent of the total matter being dark within 4 R e . The radial anisotropy in our best-fitting halo models is less than in our models without halo, due to differences in orbital structure. The halo also has an effect on the Mg b – V esc relation: its slope is steeper when a dark matter halo is added to the model. 相似文献
We find that the line strength gradients previously observed within 1 R
73.
74.
Anne-Marie de Grosbois 《Environmental Geology》2007,52(6):1225-1230
75.
Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution 总被引:4,自引:6,他引:4
Barnier Bernard Gurvan Madec Thierry Penduff Jean-Marc Molines Anne-Marie Treguier Julien Le Sommer Aike Beckmann Arne Biastoch Claus Böning Joachim Dengg Corine Derval Edmée Durand Sergei Gulev Elizabeth Remy Claude Talandier Sébastien Theetten Mathew Maltrud Julie McClean Beverly De Cuevas 《Ocean Dynamics》2006,56(5-6):543-567
Series of sensitivity tests were performed with a z-coordinate, global eddy-permitting (1/4°) ocean/sea-ice model (the ORCA-R025 model configuration developed for the DRAKKAR project) to carefully evaluate the impact of recent state-of-the-art numerical schemes on model solutions. The combination of an energy–enstrophy conserving (EEN) scheme for momentum advection with a partial step (PS) representation of the bottom topography yields significant improvements in the mean circulation. Well known biases in the representation of western boundary currents, such as in the Atlantic the detachment of the Gulf Stream, the path of the North Atlantic Current, the location of the Confluence, and the strength of the Zapiola Eddy in the south Atlantic, are partly corrected. Similar improvements are found in the Pacific, Indian, and Southern Oceans, and characteristics of the mean flow are generally much closer to observations. Comparisons with other state-of-the-art models show that the ORCA-R025 configuration generally performs better at similar resolution. In addition, the model solution is often comparable to solutions obtained at 1/6 or 1/10° resolution in some aspects concerning mean flow patterns and distribution of eddy kinetic energy. Although the reasons for these improvements are not analyzed in detail in this paper, evidence is shown that the combination of EEN with PS reduces numerical noise near the bottom, which is likely to affect current–topography interactions in a systematic way. We conclude that significant corrections of the mean biases presently seen in general circulation model solutions at eddy-permitting resolution can still be expected from the development of numerical methods, which represent an alternative to increasing resolution. 相似文献
76.
Anne-Marie Lézine Jean-François Saliège Christian Robert Frédéric Wertz Marie-Louise Inizan 《Quaternary Research》1998,50(3):290-299
Paleoecology and paleohydrology of the Ramlat as-Sab'atayn (Southern Arabia) are reconstructed from a comparative study including sedimentology, mineralogy, stable isotope ratios of carbonates, and palynology of lacustrine sediments recovered from the al-Hawa depression. The section dates from 8700 to 7200 yr B.P. and records an early phase of flooding followed by distinct lacustrine development from 7800 to 7200 yr B.P., coeval with maximum activity of the Indian monsoon. Comparison of the pollen record with modern pollen deposition suggests that regional vegetation was then already of desert type and was related to strong seasonal trade winds. 相似文献
77.
A Compilation of Silicon and Thirty One Trace Elements Measured in the Natural River Water Reference Material SLRS-4 (NRC-CNRC) 总被引:1,自引:0,他引:1
Delphine Yeghicheyan Jean Carignan Michel Valladon Martine Bouhnik Le Coz Florence Le Cornec Maryse Castrec-Rouelle Michel Robert Luc Aquilina Emmanuel Aubry Carine Churlaud Aline Dia Samuel Deberdt Bernard Dupré Rémi Freydier Gérard Gruau Odile Hénin Anne-Marie de Kersabiec Joël Macé Luc Marin Nicole Morin Patrice Petitjean Elodie Serrat 《Geostandards and Geoanalytical Research》2001,25(2-3):465-474
The natural river water certified reference material SLRS-4 (NRC-CNRC, National Research Council-Conseil National de Recherches Canada) has been routinely analysed for major and trace elements by six French laboratories. Most measurements were made using inductively coupled plasma-mass spectrometry. For silicon and thirty one trace elements (rare earth elements, Ag, B, Br, Cs, Ga, Ge, Li, P, Pd, Rb, Se, Th, Ti, Tl, W, Y and Zr), no certified values are assigned by NRC-CNRC. We propose some compilation values and related uncertainties according to the results obtained by the different laboratories. 相似文献
78.
Anne-Marie Lzine 《Quaternary Research》1989,32(3)
Pollen and phytogeographic evidence provides a vegetational history of the Sahel for the period 0–18,000 yr B.P. The zonal vegetation fluctuated latitudinally and its most extreme positions occurred at 18,000 and 8500 yr B.P. The first involved a southward shift of the Sahelian wooded grassland to 10°N under the arid conditions of the last glacial maximum. The second change shows a rapid northward migration of humid vegetation: Guinean elements reach 16°N and Sahelo-Sudanian elements extend to the southern margin of the modern Sahara (21°N) when the Atlantic monsoon flux increased. In the middle Holocene the extensive spread of Sudanian elements into the modern Sahelian zone suggests the appearance of a markedly dry season. The modern Sahelian semiarid conditions appeared abruptly at 2000 yr B.P. 相似文献
79.
Around 8500 cal years BP, at the time of the maximum of the African Humid Period, lakes and wetlands expanded in the present-day Sahara while large paleodrainages were formed or re-actived, in response to an orbitally-induced increase in monsoon rainfall. It has been suggested that the direct consequence of this increase in rainfall was the northward displacement of the Sahara/Sahel boundary, thought to have reached 23°N in central and eastern Africa. Here, we show a more complex situation characterized by an increase in biodiversity as the desert accommodated more humid-adapted species from tropical forests and wooded grasslands: tropical plant species now found some 400 to 500 km to the south probably entered the desert as gallery-forest formations along rivers and lakes where they benefited from permanent fresh water. At the same time, Saharan trees and shrubs persisted, giving rise to a vegetation that has no analogue today. In this article, we present distribution maps of selected plant species to show both the amplitude of the vegetation change compared to the present and the composition of the past plant communities. We also estimate the migration rate of tropical plant taxa to their northernmost position in the Sahara. This study is based on the use of several data sets: a data set of the modern plant distribution in northern Africa and a data set of modern and fossil pollen sites (from the African Pollen Database, http://fpd.mediasfrance.org/ and http://medias.obs-mip.fr/apd/). 相似文献
80.
Vincent Famin Satoru Nakashima Anne-Marie Boullier Koichiro Fujimoto Tetsuro Hirono 《Earth and Planetary Science Letters》2008,265(3-4):487-497
Fourier transform infrared (FTIR) microanalysis of pseudotachylytes (i.e. friction-induced melts produced by seismic slip) from the Nojima fault (Japan) reveals that earthquakes almost instantaneously expel 99 wt.% of the wall rock CO2 content. Carbon is exsolved because it is supersaturated in the friction melts. By extrapolation to a crustal-scale fault rupture, large events such as the M7.2 Kobe earthquake (1995) may yield a total production of 1.8 to 3.4 × 103 tons CO2 within a few seconds. This extraordinary release of CO2 can cause a flash fluid pressure increase in the fault plane, and therefore enhance earthquake slip or trigger aftershocks; it may also explain the anomalous discharge of carbon monitored in nearby fault springs after large earthquakes. Because carbon saturation in silicate melts is pressure-dependent, FTIR can be used as a new tool to constrain the maximum depth of pseudotachylyte formation in exhumed faults. 相似文献