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41.
Summary Direct measurements of the thermal plasma parameters in the topside ionosphere reveal variations of the plasmasphere boundary in the dusk sector. The ACTIVE satellite's near-polar orbits at altitudes of 500 – 1800 km around winter solstice 1989 were used to study the bulge region of the plasmasphere during intervals with different levels of geomagnetic agitation. The narrow, sharply defined trough in electron concentration corresponding to the plasmapause under quiet conditions situated at L = 6 – 7 moved to lower L-values with increasing geomagnetic activity. This narrow trough can be found in all main ion constituents. During periods of moderate geomagnetic activity, following the onset of a weak magnetic storm, a portion of the plasmaspheric bulge region was separated from the main plasmaspheric body. This can be seen in the outer ionosphere as an inner narrow trough at lower L-value. Troughs in light ions need no longer coincide with this in electron concentration. He+ is the most sensitive constituent reflecting the dusk sector plasmaspheric situation at this altitude.Dedicated to the Memory of Professor Karel P 相似文献
42.
The densities of 36 water samples from the Huanghe River estuary and Bohai Bay were determinedby a magnetic float densimcter under three temperatures from 15℃ to 25℃.All the measured densities ofsamples were greater than that of the values calculated from the International Equation of State of Seawater.The differences between the measured and calculated densities increased with the decrease of salinities.The dif-ferences appeared exponentially correlated with[Ca~(2+)]/s,[Mg~(2+)]/s and[SO_4~(2-)]/s,and had"s"type curverelationship with the alkalinity in all salinity range.But in the salinity ranging from 25.72 to 31.57,therelationships were all linear.The density difference can be estimated from the equation △ρ(10~3kg·m~(-3))=(-2.79+236.5([Ca~(2+)]/s)/(-9.7464×10~(-3)+[Ca~(2+)]/s).It was the high alkalinity and[Ca~(2+)]/s that resulted in the measured densi-ties of seawaters being higher than the calculated densities in the Huanghe estuary and Bohai Bay. 相似文献
43.
Miroslav Krs František Novák Marta Krsová Petr Pruner Jiří Jansa 《Studia Geophysica et Geodaetica》1993,37(4):382-400
Summary This study is a follow up of the investigation of some magnetic properties and metastability of greigite in samples obtained from Miocene claystones in the Kruné hory (Erzgebirge) Piedmont basins (Bohemia). Three different methods of upgrading the smythite were applied; the magnetic properties of the concentrates are compared. The thermal conversion of smythite sets in at 200°C while greigite converts at 250°C. The first intermediate products to be formed are iron sulphides, marcasite clearly dominating over pyrite and pyrrhotite. Apart from a Fe3+ sulphate with a composition of Fe2(SO4)3, oxidation of these sulphides gives rise to -Fe2O3. The result of the subsequent decomposition of the mentioned sulphate is the formation of -Fe2O3, which retains the sulphate structure. The final product of the thermal decomposition at 800°C is -Fe2O3. In the smythite concentrate the conversion to Fe3+ sulphate and -Fe2O3 is about twice as intensive as in greigite. No direct conversion to -Fe2O3 was found. During the thermal process self-reversals of remanence were observed, in various samples as many as four reversals in the temperature interval from 340 to 590°C. The occurrences of self-reversals of remanence were only observed at high degrees of thermal demagnetization, of the order of 10–2 down to 10–3 in the temperature interval of sulphide origin (below 400°C), and of the order of 10–4 down to 10–6 in the temperature interval of Fe-oxides origin (above 400°C).Presented at the 3rd Conference on New Trends in Geomagnetism, Castle of Smolenice, Czechoslovakia, June 22–29, 1992 相似文献
44.
We analyse conditions of the innermost portion of an accretion disk and establish a set of equations for this region. A stable innermost region may exist, which can probably explain the observed UV and X-ray spectra, avoiding the unstable emission. We then discuss the detailed radial structure of a disk around a black hole for typical AGN parameters and obtain different kinds of- relationships for different regions of a disk. On the basis of this, we discuss the stability. A new type of cycle is present, which we call a double S shaped cycle. In this cycle, the extent of accretion rate variability is much larger than that in dwarf nova cycles. This probably solves the problem of violent variability of AGN. In the meantime, the very high accretion rate at the hottest state in limit cycles in the unstable region may provide continuous injection of matter to the jet and power the relativistic motion of the jet. 相似文献
45.
自1990年6月北京天文台太阳射电偏振仪投入实测以来,观测到一百多个“Spike”和短时标精细结构微波幅射,其中包括一些新的微波幅射特征。本文给出了主要的四点特征:(1)窄带辐射;(2)快速偏振逆转;(3)快速频率漂移;(4)不同时标的准周期振荡。 相似文献
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DUO Ji WEN Chunqi FAN Xiaoping GUO Jianci NI Zhiyao LI Xiaowen SHI Yuruo WEN Quan 《《地质学报》英文版》2006,80(6):954-956
A detrital zircon aged 4.1 Ga is discovered by the SHRIMP U-Pb method in a quartzite in Burang County, western Tibet. This is presently the oldest single-grain detrital zircon in China. The Th-U ratios of the two testing points of the 〉4.0 Ga zircon are between 0.76 and 0.86, indicating their magmatic origin. This discovery has offered an important age for investigating the geological evolution of the Qinghai-Tibet Plateau. 相似文献
49.
作为公益性财政拨款事业单位,省级地震系统实现开发富局,应该要从稳定项目收入,拓展自营收入,培育和发展生产点,推进制度创新着手。本文试图从预算和管理的角度对其作一点简单分析。 相似文献
50.