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排序方式: 共有909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.
In radio astronomy, the Ultra-Long Wavelengths (ULW) regime of longer than 10 m (frequencies below 30 MHz), remains the last virtually unexplored window of the celestial electromagnetic spectrum. The strength of the science case for extending radio astronomy into the ULW window is growing. However, the opaqueness of the Earth’s ionosphere makes ULW observations by ground-based facilities practically impossible. Furthermore, the ULW spectrum is full of anthropogenic radio frequency interference (RFI). The only radical solution for both problems is in placing an ULW astronomy facility in space. We present a concept of a key element of a space-borne ULW array facility, an antenna that addresses radio astronomical specifications. A tripole–type antenna and amplifier are analysed as a solution for ULW implementation. A receiver system with a low power dissipation is discussed as well. The active antenna is optimized to operate at the noise level defined by the celestial emission in the frequency band 1 ? 30 MHz. Field experiments with a prototype tripole antenna enabled estimates of the system noise temperature. They indicated that the proposed concept meets the requirements of a space-borne ULW array facility.  相似文献   
3.
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   
4.
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   
5.
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   
6.
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   
7.
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   
8.
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   
9.
Doklady Earth Sciences - A residual tilt after a teleseismic earthquake is described in this work. The results of static and dynamic modeling of this event fit the measured values. The conditions...  相似文献   
10.
Ivanov  M. S.  Lapshin  V. B. 《Doklady Earth Sciences》2021,497(2):310-313
Doklady Earth Sciences - This paper analyzes measurement data on the ionic composition of the upper atmosphere at altitudes of 810–830 km in the period from 2009 to 2018; the measurements...  相似文献   
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