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111.
Zekai en 《Mathematical Geology》1998,30(7):767-787
Geological events are neither isotropic nor homogeneous in their occurrences. These two properties present difficulties for spatial modeling of regionalized variables. This paper presents a point cumulative semivariogram (PCSV) technique for quantifying the heterogeneity characteristics of the phenomenon concerned. The basis of the methodology is to obtain experimental PCSVs for each measurement point which led to estimation of radius of influence around each site. In addition, the experimental PCSVs provide basic information about the heterogeneity of the geological variable in the region, and furthermore many useful interpretations can be made concerning the regional variability of the variable. It provides the measure of cumulative similarity of a regional variable around any measurement site. Because PCSV is a means of measuring total similarity, maps at fixed similarity levels are provided in order to document the regional heterogeneity. Identification of heterogeneities depends on the comparison of fixed PCSV values at a multitude of irregularly scattered sites. The PCSV methodology has been applied to the regional seismic data of Turkey. 相似文献
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本文利用变参数回归分析建立了多口井的泥质岩储层裂缝密度模型。该模型的平均相对误差为13.5%,较常系数回归分析、BP网络模型进行裂缝预测的精度高(平均相对误差分别为38.7%、17.9%)。通过实际资料处理认为该油田在纵向上随时代变老,深度加深,裂缝密度降低。即从N22、N12到N1,平均裂缝密度从0.78条/m、0.5条/m降低到0.3条/m。在平面上,沿构造轴部裂缝最发育,平均裂缝密度N22、N12、N1层分别为0.58条/m、0.6条/m、0.3条/m。 相似文献
114.
Duke U. Ophori 《Hydrogeology Journal》1998,6(2):193-203
Flow of groundwater with variable density and viscosity was simulated at the Atikokan Research Area (ARA) in northwestern
Ontario, Canada. An empirical viscosity–concentration equation was modified to include total-dissolved-solids (TDS) data from
the ARA. The resulting equation was used successfully to estimate reasonably accurate viscosity values over the expected range
of temperature and concentration, in comparison with experimental values derived for sodium chloride solutions. A three-dimensional
finite-element code, MOTIF, developed by Atomic Energy of Canada Limited, was used in the simulations. The inclusion of the
effects of depth-increasing temperature and TDS-dependent fluid-density distribution, while maintaining only a temperature-dependent
viscosity relationship in a simulation, resulted in a more penetrative flow against expected buoyancy effects (i.e., the physics
of the system was not honored). Accounting for concentration in the viscosity equation caused water to be less penetrative
and more in accordance with the expected physics of the system. A conclusion is that fluid concentration should be considered
simultaneously in calculating the density and viscosity of a fluid during modeling of variable-density flow in areas underlain
by fluids with high TDS. Results of simulations suggest that both flow directions and magnitudes should be employed simultaneously
during the calibration of a model. Large-scale groundwater movement in the ARA may be analyzed with carefully selected vertical
no-flow boundaries. By incorporating the geothermal temperature gradient, groundwater recharge increases by 12%; thus, this
gradient plays a significant role in groundwater flow at the ARA. Variability in the fluid concentration at the ARA neither
decreases nor increases recharge into the groundwater system. The hypothesis that an isolated continuous regional flow system
may exist at depth in the ARA is not supported by these simulations.
Received, September 1996 Revised, September 1997, February 1998 Accepted, February 1998 相似文献
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116.
对北京天文台新近改造成的三通道高速光度计的结构和性能进行介绍,并给出了在兴隆站85公分望远镜的一些实测结果. 相似文献
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118.
Bayesian analysis of stage–fall–discharge models for gauging stations affected by variable backwater
Parsimonious stage–fall–discharge rating curve models for gauging stations subject to backwater complications are developed from simple hydraulic theory. The rating curve models are compounded in order to allow for possible shifts in the hydraulics when variable backwater becomes effective. The models provide a prior scientific understanding through the relationship between the rating curve parameters and the hydraulic properties of the channel section under study. This characteristic enables prior distributions for the rating curve parameters to be easily elicited according to site‐specific information and the magnitude of well‐known hydraulic quantities. Posterior results from three Norwegian and one American twin‐gauge stations affected by variable backwater are obtained using Markov chain Monte Carlo simulation techniques. The case studies demonstrate that the proposed Bayesian rating curve assessment is appropriate for developing rating procedures for gauging stations that are subject to variable backwater. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
119.
By applying the series expansion technique in the complex variable method established by Muskhelishvili, the plane elasticity problem for the stress and displacement field around a lined circular tunnel in conjunction with the consideration of misfit and interaction between the liner and the surrounding geomaterial is dealt with. The tunnel is assumed to be driven in a homogeneous and isotropic geomaterial. The coefficients in the Laurent series expansion of the stress functions are determined. The complex potentials in the liner and the surrounding geomaterial are explicitly derived, respectively. As an example, the case of a lined circular tunnel located in an isotropic initial stress field but subjected to uniform internal pressure is numerically considered. Numerical results indicate that the installation of tunnel liner can reduce the influences of the tunnel excavation on the in situ displacement and stress fields. However, the relative thickness and rigidity of the liner should be in an appropriate range. In addition, the effect of the tunnel excavation upon the displacement field is more significant than that upon the stress field. As far as the stress field in the surrounding geomaterial is concerned, when the ratio between the cover depth of tunnel and the tunnel radius is larger than 5, the results for the stress field in the paper are applicable. When the ratio between the tunnel depth and the tunnel radius is larger than 20, the results are applicable for the displacement field. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
120.