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481.
Groundwater flow and solute transport at the Mourquong saline-water disposal basin, Murray Basin, southeastern Australia 总被引:5,自引:0,他引:5
Craig T. Simmons Kumar A. Narayan Juliette A. Woods Andrew L. Herczeg 《Hydrogeology Journal》2002,10(2):278-295
Saline groundwater and drainage effluent from irrigation are commonly stored in some 200 natural and artificial saline-water
disposal basins throughout the Murray-Darling Basin of Australia. Their impact on underlying aquifers and the River Murray,
one of Australia's major water supplies, is of serious concern. In one such scheme, saline groundwater is pumped into Lake
Mourquong, a natural groundwater discharge complex. The disposal basin is hydrodynamically restricted by low-permeability
lacustrine clays, but there are vulnerable areas in the southeast where the clay is apparently missing. The extent of vertical
and lateral leakage of basin brines and the processes controlling their migration are examined using (1) analyses of chloride
and stable isotopes of water (2H/1H and 18O/16O) to infer mixing between regional groundwater and lake water, and (2) the variable-density groundwater flow and solute-transport
code SUTRA. Hydrochemical results indicate that evaporated disposal water has moved at least 100 m in an easterly direction
and that there is negligible movement of brines in a southerly direction towards the River Murray. The model is used to consider
various management scenarios. Salt-load movement to the River Murray was highest in a "worst-case" scenario with irrigation
employed between the basin and the River Murray. Present-day operating conditions lead to little, if any, direct movement
of brine from the basin into the river.
Electronic Publication 相似文献
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Solute recycling from irrigation can be described as the process that occurs when the salt load that is extracted from irrigation wells and distributed on the fields is returned to the groundwater below irrigated surfaces by deep percolation. Unless the salt load leaves the system by means of drains or surface runoff, transfer to the groundwater will take place, sooner or later. This can lead to solute accumulation and thus to groundwater degradation, particularly in areas where extraction rates exceed infiltration rates (semi-arid and arid regions). Thus, considerable errors can occur in a predictive solute mass budget if the recycling process is not accounted for in the calculation. A method is proposed which allows direct simulation of solute recycling. The transient solute response at an extraction well is shown to be a superposition of solute mass flux contributions from n recycling cycles and is described as a function of the travel time distribution between a recycling point and a well. This leads to an expression for a transient ‘recycling source’ term in the advection–dispersion equation, which generates the effect of solute recycling. At long times, the ‘recycling source’ is a function of the local capture probability of the irrigation well and the solute mass flux captured by the well from the boundaries. The predicted concentration distribution at steady state reflects the maximum spatial concentration distribution in response to solute recycling and can thus be considered as the solute recycling potential or vulnerability of the entire domain for a given hydraulic setting and exploitation scheme. Simulation of the solute recycling potential is computationally undemanding and can therefore, for instance, be used for optimisation purposes. Also, the proposed method allows transient simulation of solute recycling with any standard flow and transport code. 相似文献
484.
Pre‐ and post‐test analyses of the structural response of a three‐storey asymmetric reinforced concrete frame building were performed, aimed at supporting test preparation and performance as well as studying mathematical modelling. The building was designed for gravity loads only. Full‐scale pseudo‐dynamic tests were performed in the ELSA laboratory in Ispra. In the paper the results of initial parametric studies, of the blind pre‐test predictions, and of the post‐test analysis are summarized. In all studies a simple mathematical model, with one‐component member models with concentrated plasticity was employed. The pre‐test analyses were performed using the CANNY program. After the test results became available, the mathematical model was improved using an approach based on a displacement‐controlled analysis. Basically, the same mathematical model was used as in pre‐test analyses, except that the values of some of the parameters were changed. The OpenSees program was employed. Fair agreement between the test and numerical results was obtained. The results prove that relatively simple mathematical models are able to adequately simulate the detailed seismic response of reinforced concrete frame structures to a known ground motion, provided that the input parameters are properly determined. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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487.
If the force field acting on an artificial Earth satellite is not known a priori with sufficient accuracy to represent its observations on their accuracy level, one may introduce so-called pseudo-stochastic parameters into an orbit determination process, e.g. instantaneous velocity changes at user-defined epochs or piecewise constant accelerations in user-defined adjacent time subintervals or piecewise linear and continuous accelerations in adjacent time subintervals. The procedures, based on standard least-squares, associated with such parameterizations are well established, but they become inefficient (slow) if the number of pseudo-stochastic parameters becomes large. We develop two efficient methods to solve the orbit determination problem in the presence of pseudo-stochastic parameters. The results of the methods are identical to those obtained with conventional least-squares algorithms. The first efficient algorithm also provides the full variance–covariance matrix; the second, even more efficient algorithm, only parts of it. 相似文献
488.
Mechanisms of Cenozoic deformation in the Bohai Basin, Northeast China: Physical modelling and discussions 总被引:2,自引:0,他引:2
The Bohai Basin is a petroliferous Cenozoic basin in northeast China (Fig. 1(a)) and has apparent geo- metrical and kinematic similarities with the other Meso-Cenozoic extensional basins located along the eastern margin of the Eurasian Plate[1,2]. Its architec- ture and Cenozoic stratigraphy have been well under- stood from several decades of petroleum exploration. Previous studies have suggested that the Bohai Basinis a typical extensional basin and has two tectonic evolution phases, rift… 相似文献
489.
Masao Ohno Tsutomu Sato Kenji Notsu Hiroshi Wakita Kunio Ozawa 《Pure and Applied Geophysics》2006,163(4):647-655
Anomalous water level changes were observed at two wells associated with seismic swarm activity off Izu Peninsula on March,
1997. These are coseismic water level drops followed by gradual postseismic water level rise at the time of large earthquakes
during the swarm activity. The post-seismic water level rises, which can be fitted by an exponential function with a time
constant of about six hours, are explained in terms of the horizontal pressure diffusion due to the pressure gradient in the
aquifer induced by the coseismic static strain. 相似文献
490.
The coastal zones are facing the prospect of changing storm surge statistics due to anthropogenic climate change. In the present study, we examine these prospects for the North Sea based on numerical modelling. The main tool is the barotropic tide-surge model TRIMGEO (Tidal Residual and Intertidal Mudflat Model) to derive storm surge climate and extremes from atmospheric conditions. The analysis is carried out by using an ensemble of four 30-year atmospheric regional simulations under present-day and possible future-enhanced greenhouse gas conditions. The atmospheric regional simulations were prepared within the EU project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). The research strategy of PRUDENCE is to compare simulations of different regional models driven by the same global control and climate change simulations. These global conditions, representative for 1961–1990 and 2071–2100 were prepared by the Hadley Center based on the IPCC A2 SRES scenario. The results suggest that under future climatic conditions, storm surge extremes may increase along the North Sea coast towards the end of this century. Based on a comparison between the results of the different ensemble members as well as on the variability estimated from a high-resolution storm surge reconstruction of the recent decades it is found that this increase is significantly different from zero at the 95% confidence level for most of the North Sea coast. An exception represents the East coast of the UK which is not affected by this increase of storm surge extremes. 相似文献