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Results of empirical research undertaken in New Zealand to determine public perceptions of natural character in the biophysical environment are presented and related to recent theoretical literature. The research comprised two distinct case studies using Q method and photographs, in which participants evaluated natural character in terms of their own landscape experiences by ranking the photographs in order of preference. The results confirm prevailing responses to nature recently specified in North American literature, and have some policy implications for environmental management in New Zealand. 相似文献
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KERR ANDREW C.; TARNEY JOHN; KEMPTON PAMELA D.; PRINGLE MALCOLM; NIVIA ALVARO 《Journal of Petrology》2004,45(9):1877-1906
The fault-bounded Bolívar Ultramafic Complex (BUC) onthe eastern fringes of the Western Cordillera of Colombia wastectonically accreted onto the western coast of South Americain the late Cretaceousearly Tertiary, along with pillowbasalts of the CaribbeanColombian Oceanic Plateau (CCOP).The complex consists of a lower sequence of ultramafic cumulates,successively overlain by layered and isotropic gabbroic rocks.The gabbros grade into, and are intruded by, mafic pegmatitesthat consist of large magnesiohornblende and plagioclase crystals.These pegmatites yield a weighted mean 40Ar39Ar step-heatingage of 90·5 ± 0·9 Ma and thus coincidewith the timing of peak CCOP volcanism. The chemistry of theBUC is not consistent with a subduction-related origin. However,the similarity in SrNdPbHf isotopes betweenthe CCOP and the BUC, in conjunction with their indistinguishableages, suggests that the BUC is an integral part of the plume-derivedCCOP. The parental magmas of the Bolívar complex wereprobably hydrous picrites that underwent 2030% crystallization.The residual magmas from this fractionation contained 相似文献
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Potential seasonal calibration for palaeoenvironmental reconstruction using skeletal microstructures and strontium measurements from the cold‐water coral Lophelia pertusa
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In this comment we argue that the premise on which the peat mound model developed by Armstrong (Earth Surface Process and Landforms, 1995, 20 , 473–477) is based, that hydraulic conductivity shows an exponential decline with depth in bog peats, is unsound. Empirical evidence in the literature for such an exponential decline is less sound than Armstrong suggests. In addition, Armstrong's suggestion that the hypothesis of Baird and Gaffney (Earth Surface Processes and Landforms, 1995, 20 , 561–566) supports an exponential decline is shown to be erroneous. 相似文献
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The anion compositions (SO24, HCO−3 and Cl−) of runoff from the Haut Glacier d'Arolla, Switzerland and Austre Brøggerbreen, Svalbard are compared to assess whether or not variations in water chemistry with discharge are consistent with current understanding of the subglacial drainage structure of warm- and polythermal-based glaciers. These glacial catchments have very different bedrocks and the subglacial drainage structures are also believed to be different, yet the range of anion concentrations show considerable overlap for SO2−4 and HCO−3. Concentrations of Cl− are higher at Austre Brøggerbreen because of the maritime location of the glacier. Correcting SO2−4 for the snowpack component reveals that the variation in non-snowpack SO2−4 with discharge and with HCO−3 is similar to that observed at the Haut Glacier d'Arolla. Hence, if we assume that the provenance of the non-snowpack SO2−4 is the same in both glacial drainage systems, a distributed drainage system also contributes to runoff at Austre Brøggerbreen. We have no independent means of testing the assumption at present. The lower concentrations of non-snowpack SO2−4 at Austre Brøggerbreen may suggest that a smaller proportion of runoff originates from a distributed drainage system than at the Haut Glacier d'Arolla. 相似文献
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A numerical model for porosity modification at a sandstone-mudstone boundary by quartz pressure dissolution and diffusive mass transfer 总被引:1,自引:0,他引:1
ANDREW M. MULLIS 《Sedimentology》1992,39(1):99-107
In many sandstones quartz cements significantly reduce porosity. The origin of these cements is often unclear. This paper investigates a possible mechanism for the generation of silica for quartz cement by pressure dissolution in interbedded mudstones. Theoretical models of quartz pressure dissolution, including the effects of silica precipitation kinetics, show that the concentration of dissolved silica in the pore fluids of a compacting sediment increases with decreasing grain size and silica precipitation constant. Quartz precipitation is strongly inhibited by the presence of small amounts of clay within a sediment, suggesting that siltstones and quartz-rich mudstones which are undergoing pressure dissolution may act as a source of dissolved silica for export to nearby, coarser sediments. A computational model for the diagenetic modification of a sandstone-mudstone interface due to pressure dissolution is described. Both sandstone and mudstone layers are assumed to be actively compacting by pressure dissolution, and mass transport by molecular diffusion is considered. As quartz precipitation in the mudstone layer is relatively slow compared to that in the sandstone, significant amounts of dissolved silica become available in the mudstone, and may be exported into the adjacent sandstone. In the absence of pore-fluid advection, this may result in the formation of extensive secondary quartz within the sandstone, close to the interface. The volume of silica exported from the mudstone is limited by the length scale over which diffusion through the mudstone is effective. This is typically 3–5 m. The volume of silica available therefore suggests that extensive porosity modification within the adjacent sandstone can only occur close to the mudstone. Thus it is possible that thin sandstones could become cemented by slow diffusive transfer of silica, but that in thicker sandstones the silica may become dispersed by pore-fluid advection. 相似文献