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191.
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193.
We present a correlation between radio and broad-line emission for a sample of radio-loud quasars that supports a close link between accretion processes and relativistic jets. BL Lac objects seem to follow the statistical behaviour of quasars, but with fainter broad-line emission. 相似文献
194.
195.
196.
We present NeV/MgV and SiVII/MgVII theoretical line intensity ratios as a function of electron densityN
e
and temperatureT
e
. These are shown in the form of ratio-ratio diagrams, which should in principle allow bothN
e
andT
e
to be deduced for the emitting region of the solar plasma. We apply these diagnostics in the solar atmosphere, and discuss
the available observations made from space. In most cases, however, we deduceN
e
andT
e
from the computed absolute line intensities in a spherically symmetric model atmosphere of the Sun. Possible future applications
of this investigation to spectral data from the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory
(SOHO) are briefly discussed. 相似文献
197.
Y. M. Pihlstrm J. E. Conway R. S. Booth P. J. Diamond B. Koribalski 《New Astronomy Reviews》1999,43(8-10)
We report on observations, with sub-parsec resolution, of neutral hydrogen seen in absorption in the λ=21 cm line against the nucleus of the active spiral galaxy NGC 5793. The absorption line consists of three components separated in both location as well as velocity. We derive HI column densities of 2×1022 cm−2 assuming a gas spin temperature of 100 K. For the first time we are able to reliably estimate the HI cloud sizes (≈15 pc) and atomic gas densities (≈200 cm−3). Our results suggest that the HI gas is not associated with the <10 pc region which presumably contains the H2O masers, but it is more distant from the nucleus, and is probably associated with the r1 kpc gas seen in CO. 相似文献
198.
余生晨 《物探化探计算技术》1999,21(2):159-160,164
本文利用经纬网在局部范围的直线性直线的平均freeman链码等于其上任意一点的链码的这一特性,达到自动分离经纬网与等值线的目的,为实现等值线图的自动矢量化打下了基础。 相似文献
199.
Both, observational and theoretical results support the close connection between bars and box/peanut‐shaped bulges in spiral galaxies. However, for the sub‐class of thick box/peanut‐shaped bulges, an environmental process instead of an internal mechanism is suggested to account for the prominence of the box/peanut component. In this paper a multiwavelength study of the morphology and the kinematics of a sample of thick box/peanut‐shaped bulges is presented. The results suggest a scenario in which interaction events play a significant role in the history of thick box/peanut‐shaped bulge galaxies. Most likely these sources have experienced a mass infall. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
200.
ZHAO Junyou GUO Aiju DING Keqin LIU Chuntu
Lecturer Petroleum University of China Shangdong P. R. China.
Engineer Zhongyuan Petrochemical Corporation Henan P. R. China.
Postdoctoral Fellow 《中国海洋工程》1999,(1)
-This paper carries out the analysis of mechanics of a grip system of three-key-board hydraulictongs developed for offshore oil pipe lines which has been successfully used in oil fields in China.The mainimprovement of this system is that a lever frame structure is used in the structural design,which reducesgreatly the stresses of the major components of the oil pipe tongs.Theoretical analysis and numerical calcu-lation based on thirteen basic equations developed show that the teeth board of the tongs is not easy to slipas frequently happens to other systems and is of higher reliability. 相似文献