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11.
TH. STELZNER K. HEIDE A. BISCHOFF D. WEBER P. SCHERER L. SCHULTZ M. HAPPEL W. SCHR
N U. NEUPERT R. MICHEL R. N. CLAYTON T. K. MAYEDA G. BONANI I. HAIDAS S. IVY-OCHS M. SUTER 《Meteoritics & planetary science》1999,34(5):787-794
Abstract— Weathering effects on meteorite finds from the Acfer region were studied by various analytical techniques and in dependence on the depth of sampling. In thin sections of weathered meteorites, weathering effects usually decrease from the outside to the interior of the meteorite. The results of evolved gas analysis indicate that variation in weathering between surface and core is not significant in respect to the formation of Fe-oxyhydroxides. The secondary alteration effects in the noble gases are distributed unevenly throughout the specimens, as seen in the nonsystematic differences observed for the heavy noble gases. Chemical analyses show significant enrichment of Ba and Sr in the outer parts of the weathered samples due to element contamination through aqueous solution. Iron, Ni, and Co are partly flushed from the system as the metal oxidation proceeds. Oxygen isotopes show increases in δ18O and δ17O with increasing terrestrial age. For a set of H3 chondrites, the degree of weathering determined from the water content was correlated with terrestrial ages and is discussed with respect to possible weathering mechanisms. 相似文献
12.
ABSTRACT The present study is based on field exploration and production records. The producing formation consists of consolidated continental sediments which are overlain by clays, sands and gravels. No areally extensive aquifers can be distinguished. The only zone of consistently high permeability is associated with a buried channel in the bedrock and is interrupted by a hydraulic barrier. Salt concentrations in the groundwater range from less than 500 ppm to over 2000 ppm. Groundwater temperatures range form 38 °F (3·3 °C) to 41 °F (5·0 °C). The sustainable yields of individual wells of the three-well field range from 60 igpm to 150 igpm with a combined maximum of 350 igpm. Pumping creates an elongated hydraulic depression which is interrupted by the barrier in one direction and causes major changes in water levels 2 miles distant in the other direction. Short and long-term water-level fluctuations suggest two sources of recharge: direct infiltration and lateral flow. Significantly different values of transmissivity (T) are computed from production tests of different lengths. Tests of duration of 10 to 500 min, 70 to 130 h, and several months yield values for T, in igpd/ft, of 10,000 to 50,000, 2000 to 6000, and 1300, respectively. From the three methods of attempted yield evaluation the one based on empirical relations between operating pumping rates and drawdowns yields the most satisfactory results. 相似文献
13.
TH. KREY 《Geophysical Prospecting》1969,17(3):206-218
The paper presents a discussion of some of the noise features of the VIBROSEIS SYSTEM *** ** Trademark of Continental Oil Company.
and their bearing on the determination of the optimally weighted stack. 相似文献
and their bearing on the determination of the optimally weighted stack. 相似文献
14.
TH. KREY 《Geophysical Prospecting》1980,28(3):359-371
The normal moveout velocity of a reflecting bed is a function of the dips and curvatures of all overlying velocity interfaces. Now let the (N– 1)th velocity interface be a non- (or badly) reflecting bed, whereas the other interfaces, including the base of the Nth layer, reflect satisfactorily, and let the velocities UN– 1 and UN of the (N– 1)th and Nth layer, respectively, be known. Then the normal moveout velocity for the base of the Nth layer, if known in one direction at a certain part of the surface of the earth, provides a second order differential equation in the horizontal coordinates x and y for the depth ZN – 1(x, y) of the unknown interface. The mathematics becomes rather simple in the case of two-dimensional geological structures. For this case and N= 2 the differential equation mentioned can be solved by stepwise integration or by iteration. One of the many possible applications of the new concept is the determination of the structure of the base of an overthrusting sheet. 相似文献
15.
地磁场的空间相关性及其在地震预报中的应用 总被引:13,自引:0,他引:13
中国科学院地球物理研究所第十研究室一组 《地球物理学报》1977,20(3):169-184
本文扼要叙述了震磁关系研究的现状,阐述了“震磁效应”分析的基本原理,提出了“空间相关”和“现象相关”两种“震磁效应”分析的基本方法。作者应用我国华北地区若干台站资料,以局部地区地磁场空间相关性的分析为基础,重点讨论了“空间相关法”,给出了具体震例分析的初步结果。最后,就有关“震磁效应”分析的几个问题进一步做了简要讨论。 相似文献
16.
17.
SVEND TH. ANDERSEN 《Boreas: An International Journal of Quaternary Research》1981,10(4):362-362
A symposium on the glacial refugia and migration paths of Central and North European trees was sponsored by the Løvenholm foundation and held at Løvenholm Castle in Jutland, Denmark, in July 1981. Twenty invited lectures were given by participants from twelve European countries. The symposium showed that it may be possible to identify the migration centres and the origin of local populations of the 相似文献
18.
19.
ABSTRACT Theoretically, a small drainage basin may be divided into equal areas of downward flow and upward flow of groundwater. In regions where surface water does not obscure the phenomena produced by groundwater, these areas can be differentiated by mapping springs, seepages, groundwater levels, flowing wells, chemical quality of water, natural vegetation, salt precipitates, quality of crops, soap holes, and moist and dry depressions. Mapping and interpretation of field phenomena have been carried out in a section of the Ghostpine Creek valley in a Prairie environment. The relief is gently rolling, the geology is simple, and the climate is cold, humid, and continental. The area of the “north flow-systems” is apportioned as follows: 26 per cent underlain by downward flow; 42 per cent underlain by a mid-line area; and 32 per cent underlain by upward flow. Noting that groundwater flow is nearly parallel to the water table in the vicinity of the mid-line these results comply with the above-mentioned theory of groundwater flow distribution in small drainage basins. Thus, the method is suggested for: 1. A reconnaissance study of the groundwater regime in certain areas, and 2. Specific problems related to groundwater in a Prairie environment, such as: finding suitable locations for dug-out type water supplies, estimating prospects for slough-draining and irrigation, and explanation of the development of certain soil types. For such purposes, the method appears to be competitive with test drilling. 相似文献
20.
TH. KREY 《Geophysical Prospecting》1976,24(1):91-111
It is well known that interval velocities can be determined from common-reflection-point moveout times. However, the mathematics becomes complicated in the general case of n homogeneous layers with curved interfaces dipping in three dimensions. In this paper the problem is solved by mathematical induction using the second power terms only of the Taylor series which represents the moveout time as a function of the coordinate differences between shot and geophone points. Moreover, the zero-offset reflection times of the nth interface in a certain area surrounding the point of interest have to be known. The n—I upper interfaces and interval velocities are known too on account of the mathematical induction method applied. Thus, the zero-offset reflection raypath of the nth interface can be supposed to be known down to the intersection with the (n—1)th interface. The method applied consists mainly in transforming the second power terms of the moveout time from one interface to the next one. This is accomplished by matrix algebra. Some special cases are discussed as e.g. uniform strike and small curvatures. 相似文献