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101.
A linear model for neutral surface-layer flow over orography is presented. The Reynolds-Averaged Navier-Stokes and E– turbulence closure equations are expressed in a terrain-following coordinate system created from a simple analytical expression
in the Fourier domain. The perturbation equations are solved spectrally horizontally and by numerical integration vertically.
Non-dimensional solutions are stored in look-up tables for quick re-use. Model results are compared to measurements, as well
as other authors’ flow models in three test cases. The model is implemented and tested in two-dimensional space; the equations
for a full three-dimensional version are presented. 相似文献
102.
Pete Smith Gert-Jan Nabuurs Ivan A. Janssens Stefan Reis Gregg Marland Jean-François Soussana Torben R. Christensen Linda Heath Mike Apps Vlady Alexeyev Jingyun Fang Jean-Pierre Gattuso Juan Pablo Guerschman Yao Huang Esteban Jobbagy Daniel Murdiyarso Jian Ni Antonio Nobre Changhui Peng Adrian Walcroft Shao Qiang Wang Yude Pan Guang Sheng Zhou 《Climatic change》2008,88(3-4):209-249
Humans utilise about 40% of the earth’s net primary production (NPP) but the products of this NPP are often managed by different sectors, with timber and forest products managed by the forestry sector and food and fibre products from croplands and grasslands managed by the agricultural sector. Other significant anthropogenic impacts on the global carbon cycle include human utilization of fossil fuels and impacts on less intensively managed systems such as peatlands, wetlands and permafrost. A great deal of knowledge, expertise and data is available within each sector. We describe the contribution of sectoral carbon budgets to our understanding of the global carbon cycle. Whilst many sectors exhibit similarities for carbon budgeting, some key differences arise due to differences in goods and services provided, ecology, management practices used, land-management personnel responsible, policies affecting land management, data types and availability, and the drivers of change. We review the methods and data sources available for assessing sectoral carbon budgets, and describe some of key data limitations and uncertainties for each sector in different regions of the world. We identify the main gaps in our knowledge/data, show that coverage is better for the developed world for most sectors, and suggest how sectoral carbon budgets could be improved in the future. Research priorities include the development of shared protocols through site networks, a move to full carbon accounting within sectors, and the assessment of full greenhouse gas budgets. 相似文献
103.
Jean-Yves Boisson Lucien Bertrand Jean-François Heitz Yann Golvan 《Hydrogeology Journal》2001,9(1):108-123
In the context of a research and development program on waste disposal, an experimental site (Tournemire tunnel, Aveyron,
France) was selected by the French Institute for Nuclear Protection and Safety (IPSN) in order to undertake studies on potential
fluid flow at different scales of space and time within a 250-m-thick argillaceous formation. The argillite has a low natural
water content (~3–5%) and very low radii access porosity. Diffusion (tritiated water) coefficients (1×10–12 to 2×10–11 m2/s) and hydraulic conductivities derived from different types of laboratory tests (10–14 to 10–13 m/s) are characteristics of a very low-permeable rock. In situ hydraulic tests (including long-term hydraulic-head measurements)
were used to obtain values for hydraulic head and hydraulic conductivity at a scale of 1–10 m (10–13 to 10–11 m/s). Despite uncertainties on these data (due to a scale factor, presence of fissures, and possible artefacts due to hydro-chemo-mechanical
coupling), it is expected that fluid flow is essentially governed by diffusion processes. Identification of possible natural
flows at larger scales of time and space was investigated using natural isotopic tracers from interstitial fluids. Modelling,
based on the deuterium profile along the clay formation and assuming pure diffusion processes, provides estimations of possible
flow times. However, lack of knowledge concerning the past geological evolution of the site and the possible role of a fracture
network do not permit reduction of uncertainties on these estimations at this stage.
Electronic Publication 相似文献
104.
Jean-François Staszak 《GeoJournal》2004,60(4):353-364
The article advocates an articulation of cultural geography and art history, and in this perspective focuses on the analysis
of the primitivist movement and particularly on Gauguin's work and personal itinerary. Primitivism introduced artefacts of
‘primitive’ people into the history of Western art and signalled a change in the relationship between the West and the ‘Other’
and ‘Elsewhere’. This reversal of values has a major geographical dimension. Primitivism manifests the contradiction-rife
colonial ideology, but can also challenge colonization. Tourism, which is, in the case of Tahiti, directly linked to Gauguin
and to his myth, inherited a lot from primitivism, in terms of hopes and ambiguities. Conversely, primitivism casts light
on geographical features of these places, instituted as ‘Elsewheres‘ by the West, and visited, even transformed by painters,
colonizers and tourists.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
105.
106.
Jean-François Ghienne Max Deynoux Giänreto Manatschal Jean-Loup Rubino 《Comptes Rendus Geoscience》2003,335(15):1091-1100
In the Gargaf area, the stratigraphic architecture of the Late-Ordovician glacial drift results from successive glacial erosion events, with the location of the main glacial valleys partly controlled by inherited Panafrican structural trends, and by the existence of glacio-isostatically induced fault-related depocentres. Four laterally discontinuous, depositional units correspond to the filling of palaeovalleys. Each of the corresponding basal bounding surfaces was incised during a major ice front advance, reaching at least the northern Gargaf (>28°S). The bulk of the glacial record is made up of fluvial to shallow-marine sediments deposited in relatively distal glacial environments. Each unit, which recorded a glacial-interglacial climatic cycle, can be used for correlation throughout the Murzuq Basin and even at the scale of the North Gondwana platform. To cite this article: J.-F. Ghienne et al., C. R. Geoscience 335 (2003). 相似文献
107.
A parametric model of vertical eddy fluxes in the atmosphere 总被引:42,自引:2,他引:42
Jean-François Louis 《Boundary-Layer Meteorology》1979,17(2):187-202
A scheme for the representation of the vertical eddy fluxes of heat, momentum and water vapour in a forecast model is presented. An important feature of the scheme is the dependence of the diffusion coefficients on the static stability of the atmosphere. Two tests are presented, using the scheme in a one-dimensional model: the simulation of the diurnal cycle, and the transformation of a polar air mass moving over the warm sea. 相似文献
108.
Claude J. Allègre Michel Treuil Jean-François Minster Bernard Minster Francis Albarède 《Contributions to Mineralogy and Petrology》1977,60(1):57-75
This paper describes an extended application of the Rayleigh distillation law to trace element behavior in a fractional crystallization sequence. Using a trace element with a very low bulk partition coefficient as a reference (as suggested by Anderson and Greenland, 1969, and extended by Treuil and Varet, 1973), we can derive bulk partition coefficients for other elements and, in turn, the mineralogical composition of the cumulates. Trace elements with large D, such as Ni and Cr, further constrain the system, and we can deduce the initial composition of the magma. An example of this technique is shown for Terceira Island in the Azores.Contribution IPGNS no 229Now at Dept. of Geological Sciences, California Institute of Technology, Pasadena, California, USA 相似文献
109.
Jean-François Rubin 《Aquatic Sciences - Research Across Boundaries》1993,55(1):76-86
The growth rate of the Arctic charr,Salvelinus alpinus (L.), is exceptionally high in Lake Geneva; one of the highest every recorded. This can be explained by three factors: (1) the Arctic charr of Lake Geneva is the most southerly indigenous population in the world, (2) the trophic resources are important because of the eutrophication of the lake, (3) the fish density is low. 相似文献
110.
Mina Nassiry Claude Aubert Abdelkrim Mouzdahir Jean-François Rontani 《Organic Geochemistry》2009,40(1):38-50
In order to mimic the photodegradation of vitamin E during phytoplankton senescence and study the behaviour of the resulting photoproducts during cell lysis, vitamin E dispersed in seawater was irradiated with solar light in the presence of hematoporphyrin as sensitizer. Under these conditions, singlet oxygen-mediated photooxidation and free radical oxidation (autoxidation) acted simultaneously on the substrate, affording 4,8,12-trimethyltridecanal, 4,8,12-trimethyltridecanoic acid, 6,10,14-trimethylpentadecan-2-one, α-tocopherylquinone, 4,8,12,16-tetramethylheptadecan-4-olide, 2,3-epoxy-α-tocopherylquinone and 5,6-epoxy-α-tocopherylquinone as minor products. Different mechanisms were proposed to explain the formation of these different isoprenoids. The main products (85% of the degraded substrate) appeared to be previously described diastereoisomeric trimeric oxidation products of vitamin E, whose pyrolysis during gas chromatography–mass spectrometry (GC–MS) afforded 2,6,10,14-tetramethylpentadec-1-ene (prist-1-ene). On the basis of their greater ability to produce prist-1-ene during pyrolysis than intact vitamin E and their highly favoured production in phytoplanktonic cells, these trimers are proposed as likely sources of this isoprenoid alkene, previously identified in many pyrolysates from immature kerogens. 相似文献