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991.
992.
新疆巴里坤红井子地区石炭纪火山岩及其大地构造环境分析 总被引:7,自引:1,他引:7
通过对红井子地区石炭纪人山岩岩石学、岩石化学、稀土元素、微量元素等特征分析;认为该区石炭纪火山岩具岛弧火山岩和裂谷火山岩两种不同属性,其形成构造环境也存在明显差异。该区火山岩分别形成于三个不同的构造环境,即准噶尔岛弧带、博格达裂谷带及喀尔力克岛弧带。 相似文献
993.
994.
本文把地质作用中元素间的相关性划分为曲线相关、准线性相关和线性相关三种类型;并在建立反映岩浆、沉积作用过程中元素间相关关系的数学模型及其它工作的基础上,详细讨论分配系数、源区成分和作用过程等方面对地质作用中元素间相关关系的制约作用。进而获得批式熔融、结晶分异、岩浆混合、化学沉积、碎屑沉积等过程中元素间呈线性和(?)线性关系的一般特征和应用前景。最后还给出La/Ce相关性的应用实例。 相似文献
995.
在此介绍我们基于ASCA 和ROSAT 等X 射线天文卫星,对3C397 、G327 .11 .1 、G21 .50 .9 和RXJ1713 .73946 等超新星遗迹的物理特性进行的分析,简要地讨论了3C397 的非平衡电离双热分量和双极泡结构以及G327 .11 .1 和G21 .50 .9 中隐匿脉冲星的性质,并提出RXJ1713 .73946 和AD393 客星之间可能的关系。 相似文献
996.
A. Akylas I. Georgantopoulos A. Comastri 《Monthly notices of the Royal Astronomical Society》2001,324(2):521-528
We investigate the X-ray spectra of the type 2 Seyfert galaxies NGC 7172 and ESO 103-G35, using BeppoSAX observations, separated by approximately one year. We find that the X-ray spectra of both NGC 7172 and ESO 103-G35 can be well fitted using a power-law model with an Fe K α emission line at 6.4 keV. We did not find any statistically significant evidence for the existence of a reflection component in the X-ray spectra of these two galaxies. The continuum flux has decreased by a factor of approximately 2 during this period, in both objects. However, the spectral index as well as the absorption column have remained constant. We find weak evidence for the decrease of the normalization of the Fe K α emission line in a similar manner to the continuum in NGC 7172. We also report tentative evidence for a broad Fe K α line in agreement with previous ASCA observations. In contrast, in the case of ESO 103-G35 the line flux does not change while its width remains unresolved. 相似文献
997.
A.W. Jones R.J. Davis A. Wilkinson G. Giardino S.J. Melhuish H. Asareh R.D. Davies A.N. Lasenby 《Monthly notices of the Royal Astronomical Society》2001,327(2):545-551
We present the joint analysis of two 5-GHz interferometric surveys of the northern sky, taken with different baselines. The two surveys were carried out on the Jodrell Bank 5-GHz interferometer based at Manchester. The Maximum Entropy Method is used to check the consistency of the two surveys and the final two-dimensional maps are used, together with low-frequency full sky surveys, to put constraints on the Galactic spectral index. It is found that synchrotron emission is the dominant process at high Galactic latitudes below 5 GHz. 相似文献
998.
The first part of this article presents an analytic discussion of the linear properties of magnetohydrodynamic (MHD) wave propagation. Then, with a 2-dimensional, time-dependent, compressible MHD simulation subject to a self-consistent non-isothermal, non-uniform initial state, we study numerically the global propagation process following an initial pressure pulse applied at the base of the chromosphere. Our numerical results indicate that, if the pulse is applied near the pole, there are two modes, one fast, one slow of magnetoacoustic waves; whereas if the pressure pulse is applied near the equator, there is a fast mode and a standing disturbance located near the source. These results may help interpret the wave events observed by SOHO/EIT. 相似文献
999.
Before the observation of the 1974 U Ori eruption, it was considered that the Mira stars had only some regular OH variations. With this eruption, we realized that sometimes flares can occur in this type of star. In the course of an OH Mira star monitoring programme with the Nançay radio telescope, we have discovered a new eruptive type of OH maser emission in several sources. Especially, in early 1992, we observed a quickly rising 1665 Mhz emission in the Mira X Oph. The main characteristics of this flare were: large flux variations independent of the light curve; large degree of circular polarization; radial velocity emission close to the stellar velocity. 相似文献
1000.
Herbert L. Windom Suchada Silpipat Aurapin Chanpongsang Ralph G. Smith Manuwadi Hungspreugs 《Estuarine, Coastal and Shelf Science》1984,19(2):133-142
Sediment cores and grab samples were collected in the Upper Gulf of Thailand to determine sedimentation rates and to determine if metal concentrations reflect anthropogenic inputs.Accumulation rates of sediments in the Upper Gulf measured using the 210Pb method, appear to vary from ca. 4 to 11 mm yr?1. Sediment budgets suggest that little of the sediment delivered to the Upper Gulf by the major rivers is ultimately transported to the Lower Gulf. Metal concentrations in Upper Gulf sediments appear to be dominantly controlled by natural inputs. 相似文献