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This review provides an introduction to presolar grains - preserved stardust from the interstellar molecular cloud from which our solar system formed - found in primitive meteorites. We describe the search for the presolar components, the currently known presolar mineral populations, and the chemical and isotopic characteristics of the grains and dust-forming stars to identify the grains’ most probable stellar sources. 相似文献
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The analysis of the kinematic properties of the Galactic thick disk based on data from modern catalogs of stellar radial velocities and proper motions is presented. A new aspect of new determination of the kinematic characteristics of the thick disk is that the selected objects define this disk’s properties near the plane of symmetry. The velocity dispersion of stars in the Galactic thick disk in the radial direction and the direction of the Galactic rotation have been determined. The stellar-velocity distribution in the direction of the rotation is asymmetric. The parameters of this asymmetry have been determined, and the lag of the rotational velocity of the thick disk relative to objects in the thin disk estimated. The value of this “asymmetric drift,” about 20 km/s, suggests larger spatial scales for the kinematic characteristics in the radial direction for the Galactic thick disk than for the thin disk. 相似文献
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HUI JIANG FREDRIK KLINGBERG 《Boreas: An International Journal of Quaternary Research》1996,25(4):271-282
A two-step climatic warming and oceanographic change during the Younger Dryas/Preboreal transition was registered by diatom, foraminiferal, mollusc, lithologic data and sediment accumulation rates in a high resolution sediment core from the Swedish west coast. An abrupt climatic warming in the surface water of the Kattegat occurred at c . 10 200 BP, resulting in a rapid increase in sea surface water temperatures. The attenuation of meltwater discharge into the Kattegat led to an increase in sea surface salinity. Consequently, the difference in salinity through the water column diminished. This change happened within less than 80 years. The warming of bottom water in the deeper parts of the region took place a few hundred years after the surface water warming. The climatic amelioration was recorded by increased meltwater discharge and a slight increase in abundance of relatively warm diatoms around 10 600 BP at the time of the recession of the Fennoscandian ice sheet. An increase in the number of arctic/subarctic benthic foraminifera shows that the bottom water temperature during this period was still relatively low. 相似文献
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《International Geology Review》2012,54(9):1643-1654
The classification of the tribe Bereselleae of the family Dasycladaceae is discussed in some detail. The genera Beresella, Samarella and Dvinella are placed in the tribe with Trinodella, being treated as a subgenus of Dvinella. A number of new species are described: four in Beresella, six in Dvinella subgenus Dvinella and two in Dvinella subgenus Trinodella. The stratigraphic occurrence of the tribe in the Carboniferous at a number of localities on the Russian Platform is represented and a strong generic-facies association is pointed out. A pattern of variation in morphological form with sediment type is also discussed. — W. Adey. 相似文献
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Books reviewed in this article:
Bate, R. H., Robinson. E. & Shcppard, L. M. (eds.) 1982: Fossil and Recent Ostracods.
Neale, J. W. & Brasicr, M. D. (cds.) 1981: Microfossils from Recent and Fossil Shelf Seas. 相似文献
Bate, R. H., Robinson. E. & Shcppard, L. M. (eds.) 1982: Fossil and Recent Ostracods.
Neale, J. W. & Brasicr, M. D. (cds.) 1981: Microfossils from Recent and Fossil Shelf Seas. 相似文献
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Alain Dabas 《Comptes Rendus Geoscience》2010,342(4-5):370-379
Among the basic variables that characterize the thermodynamic state of the atmosphere, wind is relatively poorly observed. Surface measurements by in situ sensors are numerous, but irregularly distributed over the globe. Upper level winds are characterized by radiosoundings that are reliable and accurate, but in a very limited number due to their expensive cost. They are complemented by wind measurements performed by commercial aircrafts, but these data are mostly acquired along the major flight routes at a cruising altitude of ~10 km. Radio sondes and aircrafts leave large gaps in the observation network that have been partly complemented for 10 years by an increasing amount of wind information derived from cloud tracking in satellite images, and more recently, surface winds by scatterometers. However, the observation capacity still suffers deficiencies as there is still no information in cloud-free parts of the atmosphere, and no complete vertical profiles except for the radiosoundings. They should be overcome with the launch in 2011 of the European satellite ADM-Aeolus, a space-based Doppler lidar currently under development at the European Space Agency. 相似文献
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KIEFFER BRUNO; ARNDT NICHOLAS; LAPIERRE HENRIETTE; BASTIEN FLORENCE; BOSCH DELPHINE; PECHER ARNAUD; YIRGU GEZAHEGN; AYALEW DEREJE; WEIS DOMINIQUE; JERRAM DOUGAL A.; KELLER FRANCINE; MEUGNIOT CLAUDINE 《Journal of Petrology》2004,45(4):793-834
The Ethiopian plateau is made up of several distinct volcaniccentres of different ages and magmatic affinities. In the NE,a thick sequence of 30 Ma flood basalts is overlain by the 30Ma Simien shield volcano. The flood basalts and most of thisshield volcano, except for a thin veneer of alkali basalt, aretholeiitic. In the centre of the province, a far thinner sequenceof flood basalt is overlain by the 22 Ma Choke and Guguftu shieldvolcanoes. Like the underlying flood basalts, these shieldsare composed of alkaline lavas. A third type of magma, whichalso erupted at 30 Ma, is more magnesian, alkaline and stronglyenriched in incompatible trace elements. Eruption of this magmawas confined to the NE of the province, a region where the lavaflows are steeply tilted as a result of deformation contemporaneouswith their emplacement. Younger shields (e.g. Mt Guna, 10·7Ma) are composed of Si-undersaturated lavas. The three maintypes of magma have very different major and trace element characteristicsranging from compositions low in incompatible elements in thetholeiites [e.g. 10 ppm La at 7 wt % MgO (=La7), La/Yb = 4·2],moderate in the alkali basalts (La7 = 24, La/Yb = 9·2),and very high in the magnesian alkaline magmas (La7 = 43, La/Yb= 17). Although their Nd and Sr isotope compositions are similar,Pb isotopic compositions vary considerably; 206Pb/204Pb variesin the range of 相似文献
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《《地质学报》英文版》2016,90(1):II-II
正Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the Geological Society of China,it has become more and more influential in earth sciences in China 相似文献
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《《地质学报》英文版》2016,90(2):II-II
正Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the Geological Society of China,it has become more and more influential in earth sciences in China and 相似文献
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舒德干 《《地质学报》英文版》2014,(2):I0002-I0002
正Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the Geological Society of China,it has become more and more influential in earth sciences in China and beyond.The journal is now indexed by SCI,CA and more than 20 other databases,with an impact 相似文献
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舒德干 《《地质学报》英文版》2014,88(4):I0002-I0002
正Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the 相似文献
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《《地质学报》英文版》2017,(2)
<正>Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the Geological Society of China,it has become more and more influential in earth sciences in China and 相似文献
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《《地质学报》英文版》2015,89(6):II-II
<正>Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the Geological Society of China,it has become more and more influential in earth sciences in China and beyond.The journal is now indexed by SCI,CA and more than 20 other databases,with an impact 相似文献
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SHU Degan 《《地质学报》英文版》2015,89(2):320
<正>Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the Geological Society of China,it has become more and more influential in earth sciences in China and beyond.The journal is now indexed by SCI,CA and more than 20 other databases,with an impact factor varying between 1.58 and 2.15 from year to year.It is co-published by the Geological Society of China and Wiley-Blackwell Co. 相似文献
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河南三门峡市实验室“三废”污染情况初探及思考 总被引:1,自引:0,他引:1
分析了实验室“三废”污染的现状、分布、数量、种类、;建议本着科学选择方法,节约使用试剂,适当处理和回收利用的原则来处理“三废”;强调“谁污染,谁治理”是化学工作者义不容辞的职责。 相似文献