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排序方式: 共有791条查询结果,搜索用时 15 毫秒
1.
Jong-Ok Woo 《Astrophysics and Space Science》1986,119(1):61-63
Our de-reddened fluxes, together with the ultraviolet measurements of Thompsonet al. (1978), have been compared with those of Kurucz's (1979) model atmospheres to derive effective temperatures of some O emission, Be and Ae stars. With the measured monochromatic fluxes we determined their angular diameters and luminosities. It is found that the majority of the stars are cooler than the Zero-Age Main Sequence (ZAMS), suggesting that they are slightly more evolved than ZAMS stars.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. The observations were made at the Observatoire de Haute Provence (France) and La Silla (E.S.O., Chile). 相似文献
2.
CHRIS W. LEE 《Geology Today》1991,7(4):133-136
Each year many hundreds, if not thousands, of Earth-science students visit the coastline at Ogmore-by-Sea, mid-Glamorgan. They study the excellent exposures of Lower Carboniferous Limestone, with their well-preserved coral and other shelly faunas, together with the presumed late Triassic 'breccias'* that rest unconformably on top. A study of the cements within the breccias may give an insight into syndepositional mineralization and the formation of sedimentary basins linked to the opening of the Atlantic in early Mesozoic times. 相似文献
3.
4.
Determination of the elastic modulus set of foliated rocks from ultrasonic velocity measurements 总被引:2,自引:0,他引:2
Ultrasonic measurements of compressional and shear wave velocities under hydrostatic pressure up to 70 MPa were carried out on cylindrical specimens cored across and along the foliation planes. Our measurements revealed that the foliation of the metamorphic rocks induces a clear velocity anisotropy between two orthogonal directions; faster along the foliation plane and slower across the plane in most rock types. All velocity components monotonically increase with the confining pressure, probably due to the closure of microcracks distributed in rock specimens. We determined the complete set of dynamic moduli of foliated metamorphic rocks with two assumptions; transverse isotropy due to the foliation and ellipsoidal seismic energy propagation from a point source. The calculated elastic moduli referring to different directions could be valuable for the design of various engineering structures in planar textured rock mass. 相似文献
5.
6.
为了支持玩具业,许多实验室需要分析各种复杂基体中的金属含量。人们关心的主要元素是铅,但很多其他有毒元素也具有潜在的威胁,尤其对于儿童。这些重金属元素包括锑、砷、钡、镉、铬、硒、汞和铅,累积在人体中将产生不利的影响。一些塑料和木制玩具,特别是表面色彩鲜艳的玩具被证实含有更高水平的铅和其他元素,儿童因接触易摄入,相关法规对产品表面含有这些元素的材料作了一些限制。为了保证玩具和其他物品的生产、流通和销售,有必要检测其中的重金属含量。不同的管理机构对各类样品中的元素提供了限量要求。在玩具安全性的欧洲标准EN71第3部分(已纳入ISO8124-3),其中在“特定元素的迁移”一节给出了玩具材料中元素迁移的 相似文献
7.
In this study, long-term (1777–1997) precipitation data for Seoul, Korea, wetness indices from eastern China, and modern observations are used to identify the interdecadal variability in East Asian summer monsoon precipitation over the last 220 years. In the East Asian monsoon region, two long-term timescales of dry–wet transitions for the interdecadal variability and quasi-40-and quasi-60-year timescales are dominant in the 220-year precipitation data of Seoul, as well as in the wetness indices over China.... 相似文献
8.
大兴安岭中生代两类流纹岩与玄武岩的成因联系 总被引:2,自引:0,他引:2
根据地质产状和地球化学特征大兴安岭中生代流纹岩类可划分为高Ti流纹岩和低Ti流纹岩。高Ti流纹岩类与亚碱性系列玄武岩类紧密伴生 ,两者在地球化学上构成连续变异系列。低Ti流纹岩类则与碱性系列玄武岩类构成地球化学双峰态。岩相学和地球化学研究表明 ,这两类流纹岩与该区同期玄武岩类有着密切的成因联系 :起源于地幔柱亏损成分的亚碱性系列玄武岩浆经过单斜辉石、斜长石、磷灰石、锆石的分离结晶 ,形成亚碱性系列低钾玄武岩→高钾玄武岩→高Ti流纹岩演化系列 ;起源于地幔柱富集成分的碱性系列玄武岩浆侵入下地壳 ,使下地壳岩石发生部分熔融 ,形成碱性系列玄武岩 -低Ti流纹岩双峰态组合 相似文献
9.
Evaluation of heavy metal contamination and implication of multiple sources from Hunchun basin, northeastern China 总被引:1,自引:0,他引:1
J.-W. Moon H.-S. Moon N.-C. Woo J.-S. Hahn J.-S. Won Y. Song X. Lin Y. Zhao 《Environmental Geology》2000,39(9):1039-1052
Present concentrations and distributions of heavy metals through profiles, surface soil, and stream sediment samples in the
Hunchun area, north-eastern China, were investigated to determine the elemental background values. This study also aims to
characterize potentially toxic materials such as pulverized fly ash (PFA) from power stations or ash and slag from coal used
domestically in urban areas, agrochemicals applied inappropriately, and urban sewage sludges from Hunchun City, as well as
to ascertain the possibility of natural enrichment through site characterization by mineralogical and geochemical investigation.
The distribution of contaminants in the alluvial soils (fluvisol) of this area has been influenced by several interacting
factors. The parent alluvial materials from weathered products of amphiboles have made coatings such as ferrihydrite, goethite,
and hematite. This natural inheritance factor is supported by the fact that the concentrations of weak acid-extractable (plant-available)
heavy metals are very low, except for Fe and Mn. However, in agricultural soils and adjacent stream sediments, an anthropogenic
input of Cd, Pb, Ni and Cr by agrochemicals is strongly suggested. Also, F contamination by coal combustion and the dissolution
of F-bearing minerals could cause some future problems. Wide distribution and significantly high concentrations of Cd, Fe,
Mn, and F in soils throughout the combination of pollutants originating from lithogenic and the anthropogenic sources pose
potential problems in utilizing water resources.
Received: 14 June 1999 · Accepted: 27 December 1999 相似文献
10.
Eleven years ago when this society held its Third General Meeting I had the opportunity of calling your attention to certain strange deposits and topographical features that came under my notice in certain parts of North China. I showed you a number of striated boulders that could not be attributed to mere 相似文献