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排序方式: 共有785条查询结果,搜索用时 15 毫秒
1.
Doklady Earth Sciences - Experimental results and geological observations suggesting the existence of a deep hydrocarbon cycle are presented. During immersion hydrocarbons accumulated in the...  相似文献   
2.
The results of an analysis of the possible effect of auroral electron fluxes on the effective recombination coefficient αeff in the ionosphere are presented. It is shown that the αeff value in the E-region of the ionosphere is determined mainly by the physical-chemical properties of the medium. In the F1-layer of the ionosphere, the effective recombination coefficient becomes dependent on both the value of the energy flux and the type of the energy spectrum of the auroral electron flux.  相似文献   
3.
In downhole microseismic monitoring, accurate event location relies on the accuracy of the velocity model. The model can be estimated along with event locations. Anisotropic models are important to get accurate event locations. Taking anisotropy into account makes it possible to use additional data – two S-wave arrivals generated due to shear-wave splitting. However, anisotropic ray tracing requires iterative procedures for computing group velocities, which may become unstable around caustics. As a result, anisotropic kinematic inversion may become time consuming. In this paper, we explore the idea of using simplified ray tracing to locate events and estimate medium parameters. In the simplified ray-tracing algorithm, the group velocity is assumed to be equal to phase velocity in both magnitude and direction. This assumption makes the ray-tracing algorithm five times faster compared to ray tracing based on exact equations. We present a set of tests showing that given perforation-shot data, one can use inversion based on simplified ray-tracing even for moderate-to-strong anisotropic models. When there are no perforation shots, event-location errors may become too large for moderately anisotropic media.  相似文献   
4.
Mizandrontsev  I. B.  Kozlov  V. V.  Ivanov  V. G.  Kucher  K. M.  Korneva  E. S.  Granin  N. G. 《Water Resources》2020,47(1):122-129
Water Resources - Data on the vertical distribution of dissolved methane in Baikal water column are analyzed. The zone of open lake now shows an increase in the concentrations of dissolved methane...  相似文献   
5.
The article reviews the results of photo geological study of the lunar surface in terms of selection of most favorable landing sites from the point of view of science merit and safety for the Luna—Glob mission descent module.  相似文献   
6.
Izvestiya, Atmospheric and Oceanic Physics - Data from synthetic aperture radars (SAR) provide new opportunities for observing and studying local katabatic winds (bora and foehn) over the seas in...  相似文献   
7.
Several Snowball Earth periods, in which the Earth has been (almost) totally glaciated, are known from Earth history. Neither the trigger for the initiation, nor the reason for the ending of such phases, are well understood. Here we discuss some mechanical effects of the impact of asteroids 5–10 km in diameter on the Snowball Earth environment. An impact of this scale is the largest impact that is statistically predictable for 10–60 Myr time periods. The impact cratering itself (shock waves, impact crater formation) is not powerful enough to change the natural climate evolution path on Earth. However, the products of impact (mainly—water vapor) can be quickly distributed over a substantial part of the globe, influencing the global circulation (e.g., facilitating cloud formation). It is a question for future studies to confirm if such an event (which is possible statistically during this interval) may or may not have influenced the global climate of the Snowball Earth, and/or contributed to deglaciation.  相似文献   
8.
Guseva  E. N.  Ivanov  M. A. 《Solar System Research》2019,53(6):411-422
Solar System Research - We have analyzed the spatial and age relationships of volcano-tectonic units that have developed on the surface of Venus: groove belts, coronae, and rift zones. Most of the...  相似文献   
9.
Solar System Research - The ionization-type cosmic dust detector METEOR-L is being developed for the lunar orbiter Luna-26 and is designed to study the distribution of meteoric bodies in space by...  相似文献   
10.
Doklady Earth Sciences - Gold placers of two streams that drain Permian dislocated terrigenous deposits overlying Cambrian metagabbroids and metadiorites in southern Sikhote-Alin have been studied....  相似文献   
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