全文获取类型
收费全文 | 97篇 |
免费 | 2篇 |
国内免费 | 13篇 |
专业分类
大气科学 | 10篇 |
地球物理 | 22篇 |
地质学 | 68篇 |
海洋学 | 5篇 |
天文学 | 2篇 |
综合类 | 3篇 |
自然地理 | 2篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 26篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2007年 | 3篇 |
2005年 | 3篇 |
2003年 | 1篇 |
2002年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 3篇 |
排序方式: 共有112条查询结果,搜索用时 93 毫秒
101.
RAKESH KUMAR 《Geophysical Prospecting》1973,21(3):560-578
The theoretical horizontal resistivity profiles over an outcropping vertical dyke for various parameters-electrode spacing, vein-width and resistivity contrast—with inline alpha, beta and gamma-Wenner electrode systems are described. The resistivity profiles present a most bewildering variety of shapes as compared to those in resistivity soundings. The analysis of type curves suggests suitable electrode configuration for detection of wide, moderately wide, and thin veins. The negative apparent resistivity values on the gamma anomalies for resistive vein over certain vein-widths of higher positive values of resistivity reflection factor contradict the concept of apparent resistivity hitherto held. 相似文献
102.
An analysis of amplitudes of refraction records of some shallow refraction profiles shot primarily for detailing the near-surface structure in a granitic terrain has yielded information on refractor properties: reduced amplitudes are plotted on amplitude-distance graphs. The negative power n to which distance should be raised to represent (elastic) amplitude decay with respect to distance due to spreading of the critically refracted wave involved is examined. Computed values of this “spreading index”n are close to n = 2 as predicted by the theory. With this value of n, amplitude data are processed to determine residual attenuation attributable to elastic absorption in the bedrock. A graphical approach for this purpose from comparison of amplitude-distance graphs with the plots of amplitude decay due to spreading which is applicable to flat and horizontal refractor situations is suggested. Assuming residual attenuation to represent absorption in the granite bedrock, the computed coefficients of absorption, which vary from 0.5 to 3.90 km?1 for a frequency of 50 Hz, are obtained. From amplitude graphs of reversed profiles it is shown that the amplitude differences plot bears a relation to lateral velocity changes in the refractor. From comparison of practical amplitude decay graphs with those computed for different subsurface models, it appears possible to detect fractured rock occurrences in the refractor. 相似文献
103.
104.
1 INTRODUCTION Bivalve shells are found in biologically productive coastal regions encompassing the surf zone, tidal entrance and estuarine waters near the entrances. An example of a beach composed exclusively of shells (about 97% of the surficial sedimentary material) is the beach at John o'Groats in Scotland (Raymond and Hutchins, 1932; Komar, 1976). Southern Gulf Coast of Florida in USA (Runsak et al., 1966; Austin, 1971) and the banks of Lower Medway estuary in England (Kirby,… 相似文献
105.
A simple extension of our previous work in which digital filters were developed to transform dipole resistivity measurements over layered earth to Schlumberger ones leads us to the development of filters for transforming the latter to the former. As in the previous work we use a sampling interval of 1/6 In 10 in designing the filters that are both accurate and fast in operation. 相似文献
106.
Several new features are described which facilitate an automatic, more meaningful, and more accurate interpretation of gravity anomalies associated with approximately two-dimensional mass distributions. These include a provision for fixed points on the bounds of a distribution, outward dipping boundaries, calculation of the gravity effect at individual elevations of stations, smoothing of models and end-corrections for distributions of limited strike length. It is possible to obtain distributions about a median plane; these distributions are sensitive to shape and allow estimates of optimum depths and minimum density contrasts for the anomalous masses. 相似文献
107.
Spatio-temporal cross-shore profiles and textural characteristics are the key parameters for understanding dynamics of the inter-tidal sedimentary environment.This study describes short-term dynamics of the inter-tidal sedimentary environment at beaches along the micro-tidal coast.Further a correlation is estimated in cross-shore morphodynamics and textural characteristics of surface sediments.The sedimentary environment is examined for a complete annual cycle using monthly collected cross-shore profiles and sediment samples.The Devbag beach(northern side) and Ravindranath Tagore beach(southern side) at the Kali river mouth,Karwar,west coast of India are characterized from extremely gentle to average slope,and broadly composed of unimodal sands.The sedimentary environment is significantly composed of textures having fine to medium sand,well to moderately sorted,fine to coarse skewed,and platykurtic to leptokurtic in nature.During the annual cycle a reversal pattern is observed between the two adjacent beaches,where a slower rate of sediment accretion is observed at Devbag beach while Ravindranath Tagore beach exhibited erosion.The beach dynamics along with the propagation of south-west(SW) and south-west-west(SWW) waves towards the coast significantly exhibit a dominance of northward sediment transport with the existence of a northerly alongshore current.In addition,the study reveals that an eroded beach may not be significantly identified composed of coarse grains.The poor correlation in morpho-sedimentary characteristics reveals the prediction of grain characteristics based on beach profile and vice-versa is unrealistic. 相似文献
108.
J C JOSHI TANKESHWAR KUMAR SUNITA SRIVASTAVA DIVYA SACHDEVA 《Journal of Earth System Science》2017,126(1):3
Maximum and minimum temperatures are used in avalanche forecasting models for snow avalanche hazard mitigation over Himalaya. The present work is a part of development of Hidden Markov Model (HMM) based avalanche forecasting system for Pir-Panjal and Great Himalayan mountain ranges of the Himalaya. In this work, HMMs have been developed for forecasting of maximum and minimum temperatures for Kanzalwan in Pir-Panjal range and Drass in Great Himalayan range with a lead time of two days. The HMMs have been developed using meteorological variables collected from these stations during the past 20 winters from 1992 to 2012. The meteorological variables have been used to define observations and states of the models and to compute model parameters (initial state, state transition and observation probabilities). The model parameters have been used in the Forward and the Viterbi algorithms to generate temperature forecasts. To improve the model forecasts, the model parameters have been optimised using Baum–Welch algorithm. The models have been compared with persistence forecast by root mean square errors (RMSE) analysis using independent data of two winters (2012–13, 2013–14). The HMM for maximum temperature has shown a 4–12% and 17–19% improvement in the forecast over persistence forecast, for day-1 and day-2, respectively. For minimum temperature, it has shown 6–38% and 5–12% improvement for day-1 and day-2, respectively. 相似文献
109.
110.