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In this paper, numerical methods for flow simulation in the well vicinity are discussed. Flux truncation errors are analyzed on gridblocks near the well. Due to the singularity of the well, standard numerical schemes are not efficient for near well flow simulations. To improve simulation accuracy, a new methodology, using a change of coordinates to make near well pressure linear, is presented for the singularity modelling. Based on this new approach, two numerical schemes, a two-point flux approximation scheme and a multi-point one, are proposed. These schemes are accurate for the near well modelling and are suitable for any kinds of gridblocks. 相似文献
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本文介绍了测度地图信息量的原理及方法,提出一种测度地图信息量的改进方法—特征信息量法,并在1:1万、1:5万、1:25万、1:100万地形图上分别选出图上100 cm2、实地域相重的三种地区,即居民地稀疏区(高山)、居民地中密区(丘陵)、居民地稠密区(平原)进行试验,最后对地图信息量进行评价并提出改进意见。 相似文献
87.
三维地理信息系统中几何特征的误差模型 总被引:1,自引:0,他引:1
史文中 《武汉大学学报(信息科学版)》1998,(1)
本文提出了三维地理信息系统中几何特征的误差模型。基于面表示的三维GIS的特征被分为点、线段及线,该模型给出这些特征的一种误差描述,即围绕着这些几何特征的量测值的一个范围。 相似文献
88.
文中阐述了中国数字地震台网数据管理中心(CDSN DMC)日常工作软件的升级和升级后新软件的主要功能,并结合新软件的主要命令及运行实例,对升级后软件的实际应用作了简要叙述。 相似文献
89.
A three-dimensional, three-phase numerical model is presented for simulating the movement of immiscible fluids, including
nonaqueous-phase liquids (NAPLs), through porous media. The model is designed to simulate soil flume experiments and for practical
application to a wide variety of contamination scenarios involving light or dense NAPLs in heterogeneous subsurface systems.
The model is derived for the three-phase flow of water, NAPL, and air in porous media. The basic governing equations are based
upon the mass conservation of the constitutents within the phases. The descretization chosen to transform the governing equations
into the approximating equations, although logically regular, is very general. The approximating equations are a set of simultaneous
coupled nonlinear equations which are solved by the Newton-Raphson method. The linear system solutions needed for the Newton-Raphson
method are obtained using a matrix of preconditioner/accelerator iterative methods.
Because of the special way the governing equations are implemented, the model is capable of simulating many of the phenomena
considered necessary for the sucessful simulation of field problems including entry pressure phenomena, entrapment, and preferential
flow paths. The model is verified by comparing it with several exact analytic test solutions and three soil flume experiments
involving the introduction and movement of light nonaqueous-phase liquid (LNAPL) or dense nonaqueous-phase liquid (DNAPL)
in heterogeneous sand containing a watertable.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
90.
A systematic investigation of the effect of configurations of stochastically distributed fracture networks on hydraulic behaviour for fractured rock masses could provide either quantitative or qualitative correlation between the structural configuration of the fracture network and its corresponding hydraulic behaviour, and enhance our understanding of appropriate application of groundwater flow and contaminant transport modelling in fractured rock masses. In this study, the effect of block sizes, intersection angles of fracture sets, standard deviations of fracture orientation, and fracture densities on directional block hydraulic conductivity and representative elementary volume is systematically investigated in two dimensions by implementing a numerical discrete fracture fluid flow model and incorporating stochastically distributed fracture configurations. It is shown from this investigation that the configuration of a stochastically distributed fracture network has a significant quantitative or qualitative effect on the hydraulic behaviour of fractured rock masses. Compared with the deterministic fracture configurations that have been extensively dealt with in a previous study, this investigation is expected to be more practical and adequate, since fracture geometry parameters are inherently stochastically distributed in the field. Moreover, the methodology and approach presented in this study may be generally applied to any fracture system in investigating the hydraulic behaviours from configurations of the fracture system while establishing a ‘bridge’ from the discrete fracture network flow modelling to equivalent continuum modelling in fractured rock masses. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献