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排序方式: 共有124条查询结果,搜索用时 15 毫秒
61.
Abstract Under a sustainable groundwater development and quality management project over a semi-arid granite terrain, several rainwater harvesting structures were proposed based on geophysical investigations in the study area. In order to validate the site suitability and check the efficacy of the recommended recharge structures in terms of source sustainability, certain hydrological tests, such as infiltration studies, were conducted within the recharge area of these structures. Infiltration rate estimation using a double-ring infiltrometer normally results in an exponential decay relationship with high initial infiltration rate followed by gradual reduction until, ultimately, a stabilized rate is attained. In this paper, we present the results of infiltration tests conducted using a double-ring infiltrometer (under constant head condition) within the tank bed area of a proposed percolation tank site. The results showed unique features in the infiltration rate at different time intervals within the total experimental period: a staircase-like evolution with intermittent stabilization for a short duration. Based on the integrated approach of geophysical investigations, hydrological tests, and supported by physical evidence, the infiltration behaviour observed over the study area was considered to be due to the lithological stratification with different permeability and textural conditions. Citation Andrade, R. & Muralidharan, D. (2011) The influence of litho-stratification on the infiltrating water front in a granite terrain. Hydrol. Sci. J. 56(5), 907–915. 相似文献
62.
Large cliff failures have often been characterized by their size in terms of the horizontal eroded area at the cliff top, and the maximum local retreat of the coastline. Field studies suggest that the frequencies of these two quantities decrease as power laws of their respective magnitudes, defining two different decay exponents. Moreover, the horizontal area increases as a power law of the maximum local retreat, identifying a third exponent. This observation indicates that the geometry of cliff failures are similar for different magnitudes. It is shown that, under a ‘scaling hypothesis’, the exponents satisfy a precise mathematical relation that relates the exponent of the distributions of magnitudes of events and their geometry – a relation that could be useful to validate the analysis of field catalogs. In order to understand the observed scenario, a numerical model of rocky coast erosion is developed. Despite its minimal character, it reproduces the observed cliff failure statistics. Strikingly, the model precisely reproduces the geometric similarity of cliff failures observed in the field. These results suggest that the theory of percolation, which underlies the erosion model, can possibly be used as a guide to decipher the physics of rocky coast erosion and could provide precise predictions of the statistics of cliff collapses. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
63.
致密气储层孔喉分形特征及其与渗流的关系--以鄂尔多斯盆地下石盒子组盒8段为例 总被引:1,自引:0,他引:1
选取鄂尔多斯盆地盒8段16块致密砂岩样品进行恒速压汞测试,结合同位样品核磁共振实验,分析了致密气储层孔喉分布特征;在此基础上,运用分形几何原理和方法,开展了致密气储层孔喉分形研究,并表征了分形与储层渗流特征和孔隙结构参数的关系。结果表明:致密气储层有效孔隙被亚微米-微米级孔喉所控制,其中孔隙主要为大孔和中孔,喉道由微喉道、微细喉道和细喉道所组成;致密气储层孔隙分布不具分形特征,而孔喉整体和喉道则符合分形结构,且分别对应分形维数D1和D2;基于储层孔喉分形结构与其渗流特征,将盒8段致密气储层孔喉分形结构划分为2种类型:Ⅰ型表现为阶段式分形特征,以进汞压力1 MPa为界,大于1 MPa孔喉具有分形特征,且储层阶段进汞饱和度主要由喉道贡献,反之,孔喉不符合分形特征,其进汞饱和度增量由孔隙贡献;Ⅱ型为整体式分形,进汞饱和度几乎全由喉道贡献。储层孔喉分形维数与渗透率、平均喉道半径和主流喉道半径存在较好的负相关性,与微观非均质系数呈现较明显的正相关性,而与孔隙度、平均孔隙半径和平均孔喉半径比之间没有明显的相关性。 相似文献
64.
为研究储层微观孔隙结构和建立微观渗流模型,本文通过对东营凹陷沙三中亚段H152井区的典型低渗透储层岩样进行CT(computed tomography)扫描及图像处理,建立了微观尺度的数字岩心模型;继而经过对该模型进行分析和计算,提取了储层孔喉网络模型,在三维空间上直观、清晰地显示了不同尺度的孔隙及喉道的形态、大小和分布;最后通过对孔隙结构特征、孔隙度、渗透率和压降等动静态参数的分析和计算,建立了储层岩样的微观渗流模型。根据算法对比和参数分析结果认为:与传统中值滤波相比,非局部均值滤波算法可在相似性比较的基础上进行滤波处理,从而提高模型的准确性;基于CT的数字岩心建模可为地质研究提供可靠的数字模型;根据近似等压面假设的微观渗流数值模拟分析了流体渗流特征,为揭示低渗透储层流体渗流规律提供了一种新的途径。 相似文献
65.
66.
遥感油气勘探对伊犁盆地的评价 总被引:3,自引:0,他引:3
遥感油气勘探技术是通过遥感影像的构造解译及烃类微渗漏信息的提取并结合其他地质资料,对目标区进行油气有利聚集区的预测及评价。利用这一勘探技术着重对伊犁盆地的构造特性、承压盆地、构造阶地、烃类微渗漏信息等进行了解译和提取,总结出伊犁盆地油气藏预测的九大要素,确定了3条油气聚集带和14个油气远景区。 相似文献
67.
岩溶区水工建筑渗漏问题,与岩溶发育特征及其规律有密切关系,文拟从岩溶水动力循环条件,岩溶的立体空间配置,岩溶陷落等几个方面,对岩溶区的水库渗漏问题加以阐述。 相似文献
68.
Overland‐flow triggering on rough surfaces was investigated using an understanding‐oriented model. The model was based on conditioned‐walker technique and developed to simulate and analyse the evolution of puddle connection on numerically generated rough surfaces. The percolation theory gave a theoretical framework to formalize model outputs and to study overland‐flow scaling. Overland‐flow triggering appeared consistent with a percolation process. A scale‐change exponent was suggested. New insights based on the concept of transfer distance of water were emphasized. Transfer distance enabled us to analyse the water redistribution inside a field and helped to define rainfall efficiency when infiltration occurred. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
69.
70.
We investigated the dependence of hydraulic properties on the spatial scale of intrinsic and artificial heterogeneity, applying
harmonic pore pressure testing to two varieties of Fontainebleau sandstone at various periods and effective pressures. Blocks
with porosities of about 5 and 8% were chosen exhibiting a permeability of about 2·10−19 and 1·10−13 m2, respectively. The permeability of the less permeable variety strongly depends on sample size. Artificial heterogeneous rock
samples were prepared by stacking pieces of the two sandstone varieties perpendicular and parallel to the main flow direction.
The perturbation of the fluid flow owing to the interfaces between pieces of the same variety is controlled by the orientation
of and subordinately by the effective stress on the interfaces. Constraints on conduit geometry derived from the effect of
interfaces indicate that interconnectivity is more important than pore radius at the lower porosity. The effective permeability
of alternating stacks of the two varieties differs tremendously for the two interface orientations; arithmetic and harmonic
averages coincide with the effective properties parallel and perpendicular to the main flow, respectively. When the oscillation
period is varied two regimes are observed, one with constant permeability at long periods and a second with decreasing permeability
for decreasing period at short periods. Order of magnitude considerations of penetration depth suggest that this period dependence
may be related to heterogeneity. 相似文献