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161.
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164.
Uncertainty and learning: implications for the trade-off between short-lived and long-lived greenhouse gases 总被引:1,自引:1,他引:0
The economic benefits of a multi-gas approach to climate change mitigation are clear. However, there is still a debate on how to make the trade-off between different greenhouse gases (GHGs). The trade-off debate has mainly centered on the use of Global Warming Potentials (GWPs), governing the trade-off under the Kyoto Protocol, with results showing that the cost-effective valuation of short-lived GHGs, like methane (CH4), should be lower than its current GWP value if the ultimate aim is to stabilize the anthropogenic temperature change. However, contrary to this, there have also been proposals that early mitigation mainly should be targeted on short-lived GHGs. In this paper we analyze the cost-effective trade-off between a short-lived GHG, CH4, and a long-lived GHG, carbon dioxide (CO2), when a temperature target is to be met, taking into consideration the current uncertainty of the climate sensitivity as well as the likelihood that this will be reduced in the future. The analysis is carried out using an integrated climate and economic model (MiMiC) and the results from this model are explored and explained using a simplified analytical economic model. The main finding is that the introduction of uncertainty and learning about the climate sensitivity increases the near-term cost-effective valuation of CH4 relative to CO2. The larger the uncertainty span, the higher the valuation of the short-lived gas. For an uncertainty span of ±1°C around an expected climate sensitivity of 3°C, CH4 is cost-effectively valued 6.8 times as high as CO2 in year 2005. This is almost twice as high as the valuation in a deterministic case, but still significantly lower than its GWP100 value. 相似文献
165.
Impact of Terrain Heterogeneity on Coherent Structure Properties: Numerical Approach 总被引:2,自引:2,他引:0
Clement Fesquet Sylvain Dupont Philippe Drobinski Thomas Dubos Christian Barthlott 《Boundary-Layer Meteorology》2009,133(1):71-92
A three-dimensional large-eddy simulation (LES) model, which includes the effects of plant–atmosphere interactions, is used
to study the effects of surface inhomogeneities on near-surface coherent structures over an open field and behind a forest
canopy. These simulated conditions are representative of two wind sectors of the Site Instrumental de Recherche par Télédétection
Atmosphérique (SIRTA) experimental site at the Institut Pierre Simon Laplace, Palaiseau, France. Coherent structure properties
deduced from wavelet transforms of the simulated near-surface vertical velocity time series are not modified by upstream terrain
heterogeneities, in agreement with site measurements. This feature is related to the nature of structures detected from the
vertical velocity time series. The turbulence close to the surface seems composed of both local coherent structures and large
coherent structures reflecting outer-layer properties, which depend on the overall surface heterogeneity or upstream heterogeneity.
It is argued that the streamwise velocity is representative of these large outer-layer structures that impinge onto the ground
through a top-down mechanism as identified through the space–time correlation of the wind velocity components. In contrast,
the vertical velocity is more representative of small structures resulting from the impingement of the large outer-layer structures.
These small structures represent locally-generated, active turbulence, which adjusts rapidly to local surface conditions,
and consequently they are only weakly dependent on upstream heterogeneities. 相似文献
166.
This work deals with the structure of the lunar Weak Stability Boundaries (WSB) in the framework of the restricted three and
four body problem. Geometry and properties of the escape trajectories have been studied by changing the spacecraft orbital
parameters around the Moon. Results obtained using the algorithm definition of the WSB have been compared with an analytical
approximation based on the value of the Jacobi constant. Planar and three-dimensional cases have been studied in both three
and four body models and the effects on the WSB structure, due to the presence of the gravitational force of the Sun and the
Moon orbital eccentricity, have been investigated. The study of the dynamical evolution of the spacecraft after lunar capture
allowed us to find regions of the WSB corresponding to stable and safe orbits, that is orbits that will not impact onto lunar
surface after capture. By using a bicircular four body model, then, it has been possible to study low-energy transfer trajectories
and results are given in terms of eccentricity, pericenter altitude and inclination of the capture orbit. Equatorial and polar
capture orbits have been compared and differences in terms of energy between these two kinds of orbits are shown. Finally,
the knowledge of the WSB geometry permitted us to modify the design of the low-energy capture trajectories in order to reach
stable capture, which allows orbit circularization using low-thrust propulsion systems. 相似文献
167.
Georges Ona-Nguema Guillaume Morin Yuheng Wang Farid Juillot Giuliana Aquilanti Christian Ruby François Guyot Gordon E. Brown Jr. 《Geochimica et cosmochimica acta》2009,73(5):1359-1446
X-ray Absorption Fine Structure (XAFS) spectroscopy was used in combination with high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), X-ray energy dispersive spectroscopy (XEDS), X-ray powder diffraction, and Mössbauer spectroscopy to obtain detailed information on arsenic and iron speciation in the products of anaerobic reduction of pure and As(V)- or As(III)-adsorbed lepidocrocite (γ-FeOOH) by Shewanella putrefaciens ATCC 12099. We found that this strain of S. putrefaciens is capable of using Fe(III) in lepidocrocite and As(V) in solution or adsorbed on lepidocrocite surfaces as electron acceptors. Bioreduction of lepidocrocite in the absence of arsenic resulted in the formation of hydroxycarbonate green rust 1 [FeII4FeIII2(OH)12CO3: GR1(CO3)], which completely converted into ferrous-carbonate hydroxide (FeII2(OH)2CO3: FCH) over nine months. This study thus provides the first evidence of bacterial reduction of stoichiometric GR1(CO3) into FCH. Bioreduction of As(III)-adsorbed lepidocrocite also led to the formation of GR1(CO3) prior to formation of FCH, but the presence of As(III) slows down this transformation, leading to the co-occurrence of both phases after 22-month of aging. At the end of this experiment, As(III) was found to be adsorbed on the surfaces of GR1(CO3) and FCH. After five months, bioreduction of As(V)-bearing lepidocrocite led directly to the formation of FCH in association with nanometer-sized particles of a minor As-rich Fe(OH)2 phase, with no evidence for green rust formation. In this five-month experiment, As(V) was fully converted to As(III), which was dominantly sorbed at the surface of the Fe(OH)2 nanoparticles as oligomers binding to the edges of Fe(OH)6 octahedra at the edges of the octahedral layers of Fe(OH)2. These multinuclear As(III) surface complexes are characterized by As-As pairs at a distance of 3.32 ± 0.02 Å and by As-Fe pairs at a distance of 3.50 ± 0.02 Å and represent a new type of As(III) surface complex. Chemical analyses show that the majority of As(III) produced in the experiments with As present is associated with iron-bearing hydroxycarbonate or hydroxide solids, reinforcing the idea that, at least under some circumstances, bacterial reduction can promote As(III) sequestration instead of mobilizing it into solution. 相似文献
168.
Naomi Murdoch Patrick Michel Derek C. Richardson Kerstin Nordstrom Christian R. Berardi Simon F. Green Wolfgang Losert 《Icarus》2012,219(1):321-335
Surfaces of planets and small bodies of our Solar System are often covered by a layer of granular material that can range from a fine regolith to a gravel-like structure of varying depths. Therefore, the dynamics of granular materials are involved in many events occurring during planetary and small-body evolution thus contributing to their geological properties.We demonstrate that the new adaptation of the parallel N-body hard-sphere code pkdgrav has the capability to model accurately the key features of the collective motion of bidisperse granular materials in a dense regime as a result of shaking. As a stringent test of the numerical code we investigate the complex collective ordering and motion of granular material by direct comparison with laboratory experiments. We demonstrate that, as experimentally observed, the scale of the collective motion increases with increasing small-particle additive concentration.We then extend our investigations to assess how self-gravity and external gravity affect collective motion. In our reduced-gravity simulations both the gravitational conditions and the frequency of the vibrations roughly match the conditions on asteroids subjected to seismic shaking, though real regolith is likely to be much more heterogeneous and less ordered than in our idealised simulations. We also show that collective motion can occur in a granular material under a wide range of inter-particle gravity conditions and in the absence of an external gravitational field. These investigations demonstrate the great interest of being able to simulate conditions that are to relevant planetary science yet unreachable by Earth-based laboratory experiments. 相似文献
169.
Christian Willmes Daniel Becker Sebastian Brocks Christoph Hütt Georg Bareth 《Transactions in GIS》2017,21(1):57-73
The development and application of an algorithm to compute Köppen‐Geiger climate classifications from the Coupled Model Intercomparison Project (CMIP) and Paleo Model Intercomparison Project (PMIP) climate model simulation data is described in this study. The classification algorithm was applied to data from the PMIP III paleoclimate experiments for the Last Glacial Maximum, 21k years before present (yBP), Mid‐Holocene (6k yBP) and the Pre‐Industrial (0k yBP, control run) time slices. To infer detailed classification maps, the simulation datasets were interpolated to a higher resolution. The classification method presented is based on the application of Open Source Software, and the implementation is described with attention to detail. The source code and the exact input data sets as well as the resulting data sets are provided to enable the application of the presented approach. 相似文献
170.
U.S. unconventional hydrocarbon production is a driver of economic growth, but mineral wealth ownership is poorly understood and shrouded in “local wealth” mythology that claims royalties from hydrocarbons mostly benefit people who live near sites of production. Mineral property tax appraisals, as proxies for mineral wealth from Live Oak County, a representative Eagle Ford Shale county in Texas, show that 96 percent of assessed mineral wealth concentrates among energy firms and individuals in Texas metropolitan regions; 1.95 percent of mineral wealth remains “local” to the production county, challenging local wealth myths. Deviating from nation-state scalar approaches, local and regional spatial studies of other energy regions might reveal similar wealth distributions, enabling generalizations about hydrocarbon production economic outcomes. 相似文献