大震前P波出射角和方位角的异常变化     

郭瑞芝  冯德益  陈化然 《大地测量与地球动力学》1995,(3)

给出了数字化地震记录Ｐ波初始部分平均出射角和方位角的分析处理方法，研究了山西大同ＭＬ＝６．１级地震以及唐山ＭＬ＝５．６级地震前出射角与方位角出现的异常变化，并对地震前地震波动力学特征的这一类前兆异常现象进行了初步讨论。  相似文献   

WATER　RESOURCES　TRANSFORMATION　AND　WATER　QUALITY　VARIATION　IN　THE　URUMQI　RIVER　BASIN     

曲耀光  骆鸿珍 《中国地理科学(英文版)》1995,5(4):325-335

ＷＡＴＥＲＲＥＳＯＵＲＣＥＳＴＲＡＮＳＦＯＲＭＡＴＩＯＮＡＮＤＷＡＴＥＲＱＵＡＬＩＴＹＶＡＲＩＡＴＩＯＮＩＮＴＨＥＵＲＵＭＱＩＲＩＶＥＲＢＡＳＩＮＱｕＹａｏｇｕａｎｇ（曲耀光）；ＬｕｏＨｏｎｇｚｈｅｎ（骆鸿珍）（ＬａｎｚｈｏｕＩｎｓｔｉｔｕｔｅｏｆＧ...  相似文献   

Comment on the paper “Fast tidal cycling and the origin of life” by Richard Lathe     

P. Varga  K.R. Rybicki 《Icarus》2006,180(1):274-276

We show that the fast tidal cycling postulated by Lathe [Lathe, R., 2004. Icarus 168, 18-22] is not a plausible mechanism to explain the origin of life on Earth about 3.9 Ga ago. The value of LOD at this remote epoch was probably comprised between 15 to 17 h, and the Earth-Moon distance was only about 20% smaller than nowadays, implying that the tidal frequencies and amplitudes were not so dramatically different from the present ones as stated in Lathe's paper.  相似文献   

An explanation for the soft X-ray excess in active galactic nuclei   总被引：1，自引：0，他引：1  

J. Crummy  A. C. Fabian  L. Gallo  R. R. Ross 《Monthly notices of the Royal Astronomical Society》2006,365(4):1067-1081

We present a large sample of type 1 active galactic nuclei (AGN) spectra taken with XMM–Newton , and fit them with both the conventional model (a power law and blackbody) and the relativistically blurred photoionized disc reflection model of Ross & Fabian. We find that the disc reflection model is a better fit. The disc reflection model successfully reproduces the continuum shape, including the soft excess, of all the sources. The model also reproduces many features that would conventionally be interpreted as absorption edges. We are able to use the model to infer the properties of the sources, specifically that the majority of black holes in the sample are strongly rotating, and that there is a deficit in sources with an inclination >70°. We conclude that the disc reflection model is an important tool in the study of AGN X-ray spectra.  相似文献   

近江牡蛎3个种群生化遗传变异的研究     

黄荣莲  杜晓东  张运银 《广东海洋大学学报》2006,26(3):3-7

用同工酶电泳方法研究广东省官渡、阳江和汕尾的近江牡蛎(Ostea rivularis)的遗传变异。分析了11种同工酶20个的位点,其中出现13个位点显示为多态。结果表明官渡、阳江、汕尾种群的多态位点比例分别为0.200、0.200、0.500。官渡和阳江种群间,官渡和汕尾种群间以及阳江和汕尾种群间的遗传距离(D)分别为0.0451,0.1125,0.1088。  相似文献   

Interannual variability of water ice clouds over major martian volcanoes observed by MOC     

Jennifer L. Benson  Philip B. James  Ryan Remigio 《Icarus》2006,184(2):365-371

Using Mars Global Surveyor Mars Orbiter Camera daily global maps, cloud areas have been measured daily for water ice clouds associated with the topography of the major volcanoes Olympus Mons, Ascraeus Mons, Pavonis Mons, Arsia Mons, Elysium Mons, and Alba Patera. This study expands on that of Benson et al. [Benson, J.L., Bonev, B.P., James, P.B., Shan, K.J., Cantor, B.A., Caplinger, M.A., 2003. Icarus 165, 34-52] by continuing their cloud area measurements of the Tharsis volcanoes, Olympus Mons and Alba Patera for an additional martian year (August 2001-May 2003) and by also including Elysium Mons measurements from March 1999 through May 2003. The seasonal trends in cloud activity established by Benson et al. [Benson, J.L., Bonev, B.P., James, P.B., Shan, K.J., Cantor, B.A., Caplinger, M.A., 2003. Icarus 165, 34-52] for the five volcanoes studied earlier are corroborated here with an additional year of coverage. For volcanoes other than Arsia Mons, interannual variations that could be associated with the large 2001 planet encircling dust storm are minimal. At Arsia Mons, where cloud activity was continuous in the first two years, clouds disappeared totally for ∼85° of LS (LS=188°-275°) due to the dust storm. Elysium Mons cloud activity is similar to that of Olympus Mons, however the peak in cloud area is near LS=130° rather than near LS=100°.  相似文献   

Viscous overstability and eccentricity evolution in three-dimensional gaseous discs     

Henrik N. Latter  Gordon I. Ogilvie 《Monthly notices of the Royal Astronomical Society》2006,372(4):1829-1839

We investigate the growth or decay rate of the fundamental mode of even symmetry in a viscous accretion disc. This mode occurs in eccentric discs and is known to be potentially overstable. We determine the vertical structure of the disc and its modes, treating radiative energy transport in the diffusion approximation. In the limit of very long radial wavelength, an analytical criterion for viscous overstability is obtained, which involves the effective shear and bulk viscosity, the adiabatic exponent, and the opacity law of the disc. This differs from the prediction of a two-dimensional model. On shorter wavelengths (a few times the disc thickness), the criterion for overstability is more difficult to satisfy because of the different vertical structure of the mode. In a low-viscosity disc a third regime of intermediate wavelengths appears, in which the overstability is suppressed as the horizontal velocity perturbations develop significant vertical shear. We suggest that this effect determines the damping rate of eccentricity in protoplanetary discs, for which the long-wavelength analysis is inapplicable and overstability is unlikely to occur on any scale. In thinner accretion discs and in decretion discs around Be stars overstability may occur only on the longest wavelengths, leading to the preferential excitation of global eccentric modes.  相似文献   

Periodic long-term X-ray and radio variability of Cygnus X-1     

Pawe&#; Lachowicz  rzej A. Zdziarski  Alex Schwarzenberg-Czerny  Guy G. Pooley  Shunji Kitamoto 《Monthly notices of the Royal Astronomical Society》2006,368(3):1025-1039

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The white dwarf luminosity function – I. Statistical errors and alternatives     

Enrique M. Geijo  Santiago Torres  Jordi Isern  Enrique García-Berro 《Monthly notices of the Royal Astronomical Society》2006,369(4):1654-1666

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Addendum: Dark matter in elliptical galaxies – II. Estimating the mass within the virial radius     

《Monthly notices of the Royal Astronomical Society》2006,370(3):1582-1582

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