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101.
Gary R. Huss Elizabeth Koeman‐Shields Amy J. G. Jurewicz Donald S. Burnett Kazuhide Nagashima Ryan Ogliore Chad T. Olinger 《Meteoritics & planetary science》2020,55(2):326-351
NASA's Genesis mission was flown to capture samples of the solar wind and return them to the Earth for measurement. The purpose of the mission was to determine the chemical and isotopic composition of the Sun with significantly better precision than known before. Abundance data are now available for noble gases, magnesium, sodium, calcium, potassium, aluminum, chromium, iron, and other elements. Here, we report abundance data for hydrogen in four solar wind regimes collected by the Genesis mission (bulk solar wind, interstream low‐energy wind, coronal hole high‐energy wind, and coronal mass ejections). The mission was not designed to collect hydrogen, and in order to measure it, we had to overcome a variety of technical problems, as described herein. The relative hydrogen fluences among the four regimes should be accurate to better than ±5–6%, and the absolute fluences should be accurate to ±10%. We use the data to investigate elemental fractionations due to the first ionization potential during acceleration of the solar wind. We also use our data, combined with regime data for neon and argon, to estimate the solar neon and argon abundances, elements that cannot be measured spectroscopically in the solar photosphere. 相似文献
102.
厄尔尼诺与亚洲季风对港澳地区降雨影响 总被引:3,自引:1,他引:3
分析研究了香港1853~1997年(145年)、澳门1901~1997年(97年)的月和年降雨量的一些特征。主要结论是:(1)香港、澳门年降雨量存在准2~6年的周期振荡,澳门年降雨量有很强的长期趋势,香港年降雨量无明显趋势;(2)香港、澳门年内雨量的峰值出现在西南季风期(6月和8月),而谷值在东北季风期(12月);(3)EI Nino事件年,香港、澳门年降雨量距平百分率多为正,降雨偏多。在La Nila事件年,香港、澳门年降雨量距平百分率多为负,降雨偏少。 相似文献
103.
分析了广西的基本区情条件,揭示了广西区域开发格局的空间变动趋势,提出了广西新世纪实施可持续发展战略的举措,即加强以交通为主的基础设施建设,开发以洪水河为主的水能资源,加快建设成为南中国西南东输的枢纽;调整和优化产业结构,确立主导产业的市场地位,提升优势产业的市场竞争力;加快城乡转型的进程,提高城镇化的水平和质量,控制人口增长、提高人口质量,治理环境污染;制度创新, 优化经济布局的区域结构。 相似文献
104.
取二色裂江珧 (Pinna bicolor)的消化盲囊、肾脏、后闭壳肌肌肉、外套膜和鳃等 5种组织 ,用垂直板聚丙烯酰胺凝胶电泳对酯酶 (EST)和过氧化物歧化酶 (SOD)同工酶在上述组织中的表达和分布进行了比较研究 ,并对酶谱表型及位点表达进行了分析。结果表明 ,二色裂江珧组织内的 EST和 SOD存在不同程度的组织特异性 ,EST共检测出 15条酶带 ,SOD检测出 8条酶带 ,且两种同工酶在消化盲囊中活性最高。推测 SOD由 2个座位编码 ,可分为 s- SOD二聚体和 m- SOD四聚体 相似文献
105.
106.
Abstract— Abundances and isotopic compositions of noble gases in metal and graphite of the Bohumilitz IAB iron meteorite were measured. The abundance ratios of spallogenic components in metal reveal a 3He deficiency which is due to the diffusive loss of parent isotopes, that is, tritium (Tilles, 1963; Schultz, 1967). The diffusive loss likely has been induced by thermal heating by the Sun during cosmic‐ray exposure (~160 Ma; Lavielle et al, 1999). Thermal process such as impact‐induced partial loss may have affected the isotopic composition of spallogenic Ne. The 129Xe/131Xe ratio of cosmogenic components in the metal indicates an enhanced production of epi‐thermal neutrons. The abundance ratios of spallogenic components in the graphite reveal that it contained small amounts of metal and silicates. The isotopic composition of heavy noble gases in graphite itself was obtained from graphite treated with HF/HCl. The isotopic composition of the etched graphite shows that it contains two types of primordial Xe (i.e., Q‐Xe and El Taco Xe). The isotopic heterogeneity preserved in the Bohumilitz graphite indicates that the Bohumilitz graphite did not experience any high‐temperature event and, consequently, must have been emplaced into the metal at subsolidus temperatures. This situation is incompatible with an igneous model as well as the impact melting models for the IAB‐IIICD iron meteorites as proposed by Choi et al. (1995) and Wasson et al (1980). 相似文献
107.
沙尘暴天气是毛乌素沙漠边缘内蒙古、甘肃、宁夏、陕西等地区春末夏初特有的一种灾害性天气。应用欧洲中心再分析资料的气压场和各种物理量场,选取了5个沙尘暴个例,分析了沙尘暴时期各层气压场的特征和物理量的空间结构。结果表明:蒙古高压是影响沙尘暴的主要天气系统。在沙尘暴发生时,蒙古高压前部整层都为宽广而强劲的西北气流,从地面可伸展到200 hPa附近,其物理属性是干、冷,其前部近乎于东北—西南向的区域,是锋区的密集带,也是各种物理量表现最为敏感的区域,垂直速度场为上升运动区,涡度场为正涡度区,高—低层散度差值场为正值,这些物理量都为沙尘暴的发生起到了推动和加强作用。 相似文献
108.
N. G. Konopleva G. Yu. Ivanyuk Ya. A. Pakhomovsky V. N. Yakovenchuk Yu. A. Mikhailova E. A. Selivanova 《Geology of Ore Deposits》2015,57(7):614-625
The occurrence, morphology, and composition of rinkite are considered against the background of zoning in the Khibiny pluton. Accessory rinkite is mostly characteristic of foyaite in the outer part of pluton, occurs somewhat less frequently in foyaite and rischorrite in the central part of pluton, even more sparsely in foidolites and apatite–nepheline rocks, and sporadically in fenitized xenoliths of the Lovozero Formation. The largest, up to economic, accumulations of rinkite are related to the pegmatite and hydrothermal veins, which occur in nepheline syenite on both sides of the Main foidolite ring. The composition of rinkite varies throughout the pluton. The Ca, Na, and F contents in accessory rinkite and amorphous products of its alteration progressively increase from foyaite and fenitized basalt of the Lovozero Formation to foidolite, rischorrite, apatite–nepheline rocks, and pegmatite–hydrothermal veins. 相似文献
109.
M. Yu. Khlopov R. V. Konoplich R. Mignani S. G. Rubin A. S. Sakharov 《Astroparticle Physics》2000,12(4):367-372
The existence of macroscopic regions with antibaryon excess in the baryon asymmetric Universe with general baryon excess is the possible consequence of practically all models of baryosynthesis. Diffusion of matter and antimatter to the border of antimatter domains defines the minimal scale of the antimatter domains surviving to the present time. A model of diffused antiworld is considered, in which the density within the surviving antimatter domains is too low to form gravitationally bound objects. The possibility to test this model by measurements of cosmic gamma ray fluxes is discussed. The expected gamma ray flux is found to be acceptable for modern cosmic gamma ray detectors and for those planned for the near future. 相似文献
110.
The West Kunlun orogenic belt is located at the conjunction of the paleo-Asian tectonic system and the Tethys tectonic system.
Petrological and mineralogical studies of the Early Cambrian metamorphic surface crust in this region have shown that in case
the metamorphism reached low-temperature granulate facies, the typical mineral assemblage is biotite-garnet-silimanite-K feldspar-plagioclase-quartz.
The peak metamorphic temperatures are within the range of 720–740°C and the pressure is 0.6 GPa ±. Three types of metamorphic
zircon have been detected in the metamorphic rocks: the complex inclusion-bearing type ; the early relic zircon inclusion-bearing
type; and the inclusion-free type. SHRIMP age determination of these three types of metamorphic zircon have revealed that
these zircons were formed principally during 400–460 Ma, indicating that pre-Cambrian metamorphic surface crust rocks underwent
low-temperature granulite facies metamorphism during the Caledonian. In combination with the geological characteristics of
this region, it is considered that when the oceanic basin was closed, there occurred intense intracontinental subduction (type
A), bringing part of the Early Cambrian metamorphic basement in this region downwards to the lower crust. Meanwhile, there
were accompanied with tectonic deformation at deep levels and medium- to high-grade metamorphism. This study provided important
chronological and mineralogical evidence for the exploration of the evolutionary mechanism and process of the West Kunlun
Early Paleozoic.
Part of the results from the research project “ Research on the West Kunlun pre-Cambrian tectonic events” under the program
“ Research on the important geological problems of China’ s pre-Cambrian” (No. 200113900070) sponsored by the China National
Geological Surveying Bureau. 相似文献