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121.
Benthic exchange of nutrients in Galveston Bay, Texas 总被引:4,自引:0,他引:4
Kent W. Warnken Gary A. Gill Peter H. Santschi Lawrence L. Griffin 《Estuaries and Coasts》2000,23(5):647-661
Nutrient regeneration rates were determined at three sites increasing in distance from the Trinity River, the main freshwater
input source, to Galveston Bay, Texas, from 1994 through 1996. Diffusive fluxes generally agreed in direction with directly
measured benthic fluxes but underestimated the exchange of nutrients across the sediment-water interface. While the fluxes
of ammonium and phosphate were directed from the sediment into the overlying waters, the fluxes of silicate and chloride changed
in both magnitude and direction in response to changing Trinity River flow conditions. Oxygen fluxes showed benthic production
during both summer 1995 and winter 1996, while light-dark deployments showed production-consumption, respectively. Benthic
inputs of nutrients were higher at either the middle or outer Trinity Bay regions, most likely due to a higher quality and
quantity of the autochthonous organic matter deposited. This feature is consistent with and gives evidence for previously
observed non-conservative mixing behaviors reported for nutrients in this region of Galveston Bay. Calculated turnover times,
between 7 to 135 d for phosphate, 4 to 56 d for silicate, and 0.3 to 10 d for ammonium were significantly shorter than the
average Trinity Bay water residence time of 1.5 yr for the period September 1995 through October 1996. During periods of decreased
Trinity River flow and increased residence times, benthic inputs of ammonium and phosphate were 1 to 2 orders of magnitude
greater than Trinity River inputs and were the dominant input source of these nutrients to Trinity Bay. The sediments, a sink
for silicate when overlying water column concentrations of silicate were elevated, became a source of silicate to the overlying
waters of Trinity Bay under reduced flow, high salinity conditions. 相似文献
122.
D. A. Naylor G. R. Davis B. G. Gom T. A. Clark M. J. Griffin 《Monthly notices of the Royal Astronomical Society》2000,315(3):622-628
The submillimetre atmospheric transmission spectrum above Mauna Kea has been measured at a resolution of 0.005 cm−1 (150 MHz) with a Fourier transform spectrometer at the James Clerk Maxwell Telescope, using the Sun as a source. Column abundances of O2 , H2 O and O3 determined from these spectra are found to be in excellent agreement with independent measurements. The derived column abundances have been used as inputs to the atmospheric spectral modelling program fascod . The synthetic transmission spectrum is found to be in excellent agreement with the measured spectrum, and provides a template for submillimetre observations from the JCMT. 相似文献
123.
Ancient mantle lithosphere beneath the Khanka massif in the Russian Far East: in situ Re–Os evidence
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Kuo‐Lung Wang Vladimir Prikhodko Suzanne Y. O'Reilly William L. Griffin Norman J. Pearson Victor Kovach Yoshiyuki Iizuka Yu‐Hsian Chien 《地学学报》2015,27(4):277-284
The Os‐isotope compositions of sulphides in mantle xenoliths hosted by Late Miocene alkali basalts from the Sviyaginsky volcano, Russian Far East, reveal the presence of Archaean–Proterozoic subcontinental lithospheric mantle beneath the Khanka massif. Their TMA and TRD model ages reveal similar peaks at 1.1 and 0.8 Ga suggesting later thermotectonic events in the subcontinental lithospheric mantle, whereas TRD model ages range back to 2.8 ± 0.5 (2σ) Ga. The events recognized in the subcontinental lithospheric mantle are consistent with those recorded in the crust of the Khanka massif. The sulphide Os‐isotope data show that the subcontinental lithospheric mantle beneath the Khanka massif had formed at least by the Mesoproterozoic, and was subsequently metasomatized by juvenile crustal‐growth events related to the evolution of the Altaids. The Khanka massif is further proposed to have tectonic affinity to the Siberia Craton and should originate from it accordingly. 相似文献
124.
Relative role and extent of marine and groundwater inundation on a dune‐dominated barrier island under sea‐level rise scenarios
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Climate change and sea‐level rise will have severe impacts on coastal water resources around the world. However, whereas the influence of marine inundation is well documented in the literature, the impact of groundwater inundation on coastal communities is not well known. Here, core analysis, groundwater monitoring, and ground penetrating radar are utilized to assess the groundwater regime of the surficial aquifer on Bogue Banks Barrier Island (USA). Then, geospatial techniques are used to assess the relative roles and extents of groundwater and marine inundation on the dune‐dominated barrier island under sea‐level rise scenarios of 0.2, 0.5, and 1.0 m above current conditions by 2100. Additionally, the effects of rising water tables on onsite wastewater treatment systems (OWTS) are modelled using the projected sea‐level rise scenarios. The results indicate that the surficial aquifer comprising fine to medium sands responds quickly to precipitation. Water‐level measurements reveal varying thicknesses of the vadose zone (>3 to 0 m) and several groundwater mounds with radial flow patterns. Results from projected sea‐level rise scenarios suggest that owing to aquifer properties and morphology of the island, groundwater inundation may occur at the same rate as marine inundation. Furthermore, the area inundated by groundwater may be as significant as that affected by marine inundation. The results also show that the proportion of land in the study area where OWTS may be perpetually compromised by rising water tables under worst case scenarios may range from ~43 to ~54% over an 86‐year‐period. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
125.
In this paper, the authors analyze a wide range of recreational management strategies for their impacts on red snapper yield, economic surplus and the fish stock. Simulating a wide range of policies, the authors find Data Envelopment Analysis (DEA) inspired policy efficiency frontiers that lead to finding those management strategies that offer the greatest level of economic surplus for any biological target, looking at both the east and west Gulf of Mexico fisheries. Red snapper has been declared overfished since 1988 and the 2005 SEDAR 7 stock assessment declared red snapper were overfished and undergoing overfishing. In November 2009, the update of the assessment declared that overfishing was no longer occurring but that the red snapper stocks needed to be rebuilt. In this analysis, it was found that red snapper are neither overfished or undergoing overfishing. The main difference between the present model and the SEDAR 7 model is that the latest model uses a higher mortality rate for juveniles and a density dependent model. The authors also suggest that the east and west should be managed as separate units. 相似文献
126.
Peter R. Oke David A. Griffin 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):574-591
During the Austral summer of 2006-07 a series of extreme oceanic events occurred in the Tasman Sea. Following a series of strong wind-driven upwelling events, an intense cold-core eddy developed off Sydney, Australia. A data-assimilating, eddy-resolving ocean model is used to create a three-dimensional time-varying reanalysis of these events. The reanalysis indicates that the cold anomalies associated with the upwellings were in excess of −5 °C near the coast, where sea level decreased by as much as 0.2 m. The reanalysed three-dimensional structure of the cold-core eddy shows the eddy "leaning" to the west-north-west, in towards the continental shelf. The diameter of the eddy is about 100 km and the sea-level anomaly at the eddy centre peaks at around −1 m, with an associated sub-surface temperature anomaly in excess of −8 °C at 200 m depth, corresponding to an upward isotherm excursion of 600 m. The circulation around the cyclonic eddy is ageostrophic, with upwelling in the southern sector of the eddy (where flow is onshore and climbing the continental slope) and downwelling in the northern sector (where flow is descending off the slope). Three-dimensional trajectories of water parcels around the eddy involve 50-100-m vertical excursions. Based on the reanalysed circulation and composite satellite images of Chlorophyll-a, we hypothesise that the circulation around the eddy led to significant nutrient enrichment in the euphotic zone around the perimeter of the eddy. 相似文献
127.
128.
R. Griffin 《Journal of Astrophysics and Astronomy》1988,9(4):193-203
HD 88021/2 (ADS 7662) is a very close visual binary. The accepted visual orbit, which is of very high eccentricity and graded
“reliable”, led to the expectation of a periastron passage in 1981, when there should have been a large difference in radial
velocity between the components. No such event took place, and there is little indication that it is likely to occur in the
near future. A new interpretation of the visual orbital data leads to an orbit of a different character from those hitherto
proposed. A decision between the competing orbits should be possible within a very few years. Meanwhile, the method of spectral
subtraction developed in Paper 1 has enabled us to separate the spectra of the two components and to show that their spectral
types are K0 III and A2m. 相似文献
129.
130.
R. F. Griffin 《Journal of Astrophysics and Astronomy》1990,11(4):491-505
A comprehensive survey of bright composite-spectrum binaries in the northern sky has provided so many radial-velocity data
that orbits can now be determined for many objects whose orbits were hitherto unknown or else insecure or actually erroneous.
Elements are given for the orbits of 30 such objects, thereby more than doubling the number of composite-spectrum binaries
with known orbits 相似文献