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191.
Groundwater nitrate pollution in the recharge zone of a regional Quaternary flow system (Wielkopolska region, Poland) 总被引:2,自引:0,他引:2
Krzysztof Dragon 《Environmental Earth Sciences》2013,68(7):2099-2109
The present study examines the behaviour of nitrate in the recharge zone of a regional Quaternary flow system. The presence of contaminated groundwater with high nitrate content in the shallow part of the flow system was documented. Tritium analyses confirmed that these contaminants can migrate downward. A high downward gradient exists in the study area, extending into the regions of groundwater extraction. In the unconfined part of the flow system, which is the most vulnerable to pollution, a high concentration of nitrate was found to occur at great depth. However, denitrification processes limit nitrate migration. As a result, in the deeper parts of the flow system in regions under confined conditions, an absence of nitrate was observed, and a higher sulphate concentration and total hardness were evident. The denitrification was also confirmed by the existence of a high gaseous N2 concentration. It was documented that denitrification occurs in both the confined and unconfined parts of the flow system, but the potential for denitrification is higher in the confined parts (leading to the disappearance of nitrate in deep aquifers). Autotrophic denitrification supported by sulphide compounds was indicated as the dominant denitrification process. 相似文献
192.
Ladislav Bnesz Josef Hromada Janusz Kozlowski Krzysztof Sobczyk Maciej Pawlikowski 《Geoarchaeology》1995,10(4):237-255
The site of Moravany-Žakovska in western Slovakia is situated in a loessic terrain and is dated to the end of the Late Glacial Maximum. This article shows the importance of analyzing the 0.01-0.1 mm fraction to interpret the sedimentological environment and a number of measured anthropogenic indices, such as burnt quartz grains, charcoal, radiolarite chips, microflakes, and microfragments of bone. Analysis of the profile of the site through time reveals the relationship between occupational levels and phases of slope wash that occurred during wetter climatic episodes; these are separated by phases of aeolian sedimentation. At the same time, analysis of anthropogenic indices in this size fraction permitted the identification of occupational levels, including those not recorded by macrofinds. Analysis of anthropogenic indices in horizontal exposures enabled the identification of latent settlement structures such as hearths, areas of radiolarite processing, zones where mineral dyes were prepared, and other structures not recorded by macrofinds. 相似文献
193.
Conventional cross-section balancing techniques based on layer length measuring can be applied only for foreland structures. To analyse complicated hinterland structure with numerous small-scale folds, this balancing technique requires the reliable and detailed tracing of the morphology of any layer throughout the cross-section, which is unattainable. We present a special kinematic method of balancing cross sections based “on the geometry of the folded domain” which enables the structural restoration of hinterland regions. We apply the method to restore the detailed structural section along the Shilbilisaj River, having a length of 26 km. We divided this section into 40–60 so-called “domains” each including 2–7 folds. Our method uses the fold's morphology to determine the strain ellipsoid, which describes the deformation of each domain and is used to restore its pre-folded state. By combining the pre-folded states of the domains, we reconstruct the entire profile, and calculate shortening values as K = L0/L1 (initial to final length). The overall shortening value for the profile is 4.49, incrementally varying along the section from 3.79 to 5.53. The comparable results of two independently performed reconstructions emphasize the reliability of the applied balancing method. 相似文献