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51.
52.
F. Nguyen G. Van Rompaey H. Teerlynck M. Van Camp D. Jongmans T. Camelbeeck 《Journal of Seismology》2004,8(1):41-56
To provide quantitative information on site effects in the northern part of Belgium, forty-seven H/V microtremor measurements were performed with 5 second seismometers over an area of about 15.000 km2. Most of the results show a northward regular increase of the fundamental period in agreement with the augmentation of the Mesozoic and Cainozoic soft sedimentsthickness from a few meters 40 km south of Brussels to 900 m at the Netherlands-Belgium border. The measured resonance frequency values wereconsistent with theoretical computations performed at different sites onthe basis of existing information and shallow seismic experiments. At oneparticular site (Uccle) where borehole data were available, microtremor measurements using an array of four seismological stations with differentapertures allowed to obtain the low frequency part of the Rayleigh wave dispersion curve, extending the range covered by the analysis of surfacewaves artificially generated. The Vs profile derived from the surface waveinversion corroborates the 1 Hz natural frequency of the site. Comparison of these results with the macroseismic information concerning the MS = 5.0 1938 earthquake which occurred 50 km west of Brussels,confirmed the hypothesis that the geological structure of the Brabant massifis likely to control damage distribution during such an earthquake. Comparisonbetween the intensity map of the 1938 earthquake and the resonance period ofsediments obtained by our microtremor study shows a clear relation betweenthe two parameters. During the 1938 earthquake, site effects played a prominent role due to the dimension of the source whose corner frequency wasabout 1 Hz. 相似文献
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About 70% of its land area as mountains and plateaus,China is the largest mountain countryin the world.Thanks to its vast territory (9.6 million km2),outstanding relief and varied climates,China boasts extremely plenty of ecosystems and landscapes.From south to north,it traverses almostall the temporal zones from tropical rainforest in the southernmost to frigid-temperate needle-leavedforest in the northernmost; from east to west,it sees a gradual transition fro humid forest landscape toextremely arid desert landscape; vertical change of landscapes is most striking owing to the existenceof many high mountains (above 6000-7000 m,e.g.,the Himalayas,the Kunlun,the Tianshan,theHengduan,etc.) and plateaus,especially the immense Tibetan Plateau (averagely 4500 m above sealevel).All of this give rise to the richness and diversity of ecosystems and landscape in China.Some ofthe ecosystems are endemic to China,e.g.,alpine desert and alpine steppe in the Tibetan Plateau.As aresult,China bears a great responsibility in the protection of global ecosystems and landscape. 相似文献
55.
Green''''s functions for uniformly distributed loads acting on an inclined line in a poroelastic layered site 总被引:4,自引:0,他引:4
Based on one type of practical Biot's equation and the dynamic-stiffness matrices of a poroelastic soil layer and half-space, Green's functions were derived for uniformly distributed loads acting on an inclined line in a poroelastic layered site. This analysis overcomes significant problems in wave scattering due to local soil conditions and dynamic soil-structure interaction. The Green's functions can be reduced to the case of an elastic layered site developed by Wolf in 1985. Parametric studies are then carried out through two example problems. 相似文献
56.
Thorsten Wagener Hoshin V. Gupta 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(6):378-387
Methods for the identification of models for hydrological forecasting have to consider the specific nature of these models
and the uncertainties present in the modeling process. Current approaches fail to fully incorporate these two aspects. In
this paper we review the nature of hydrological models and the consequences of this nature for the task of model identification.
We then continue to discuss the history (“The need for more POWER‘’), the current state (“Learning from other fields”) and
the future (“Towards a general framework”) of model identification. The discussion closes with a list of desirable features
for an identification framework under uncertainty and open research questions in need of answers before such a framework can
be implemented. 相似文献
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Sustaining the human ecological benefits of surface water requires carefully planned strategies for reducing the cumulative
risks posed by diverse human activities. Municipal governments in Aksaray City play a key role in developing solutions to
surface water management and protection problems. The responsibility to provide drinking water and sewage works, regulate
the use of private land, and protect public health provides the mandate and authority to take action. A large part of Aksaray
City uses Mamasın dam water as its primary source for drinking water. Several point sources of contamination may result from
direct wastewater discharges from Melendiz and Karasu rivers, which recharge the Mamasın dam watershed. Relevant studies were
carried out for monitoring the eutrophication process, which usually occurs in the static water mass of the Mamasın dam lake.
This process may be caused by the continual increase in nutrients and decrease of O2 levels, causing anaerobic conditions. Stimulated algae growth in these water bodies consequently reduces water quality. Hydrochemical
parameters were evaluated to estimate the types of pollution sources, the level of pollution, and its environmental impacts
on the Mamasın dam drinking water reservoir. 相似文献
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60.
Reflecting internal catchment hydrological processes in hydrological models is important for accurate predictions of the impact of climate and land-use change on water resources. Characterizing these processes is however difficult and expensive due to their dynamic nature and spatio-temporal variability. Hydropedology is a relatively new discipline focusing on the synergistic integration of hydrology, soil physics and pedology. Hydropedological interpretations of soils and soil distribution can be used to characterize key hydrological processes, especially in areas with no or limited hydrometric measurements. Here we applied a hydropedological approach to reflect flowpaths through detailed routing in SWAT+ for a 157 ha catchment (Weatherley) in South Africa. We compared the hydropedological approach and a standard (no routing) approach against measured streamflow (two weirs) and soil water contents (13 locations). The catchment was treated as ‘ungauged’ and the model was not calibrated against hydrometric measurements in order to determine the direct contribution of hydropedology on modelling efficiency. Streamflow was predicted well without calibration (NSE > 0.8; R2 > 0.82) for both approaches at both weirs. The standard approach yielded slightly better streamflow predictions. The hydropedological approach resulted in considerable improvements in the simulation of soil water contents (R2 increased from 0.40 to 0.49 and PBIAS decreased from 40% to 20%). The routing capacity of SWAT+ as employed in the hydropedological approach reduced the underestimation of wetland water regimes drastically and resulted in a more accurate representation of the dominant hydrological processes in this catchment. We concluded that hydropedology can be a valuable source of ‘soft data’ to reflect internal catchment structure and processes and, potentially, for realistic calibrations in other studies, especially those conducted in areas with limited hydrometric measurements. 相似文献