藏南罗布莎蛇绿岩豆荚状铬铁矿中的铂族元素和贱金属合金   总被引：8，自引：1，他引：8  

白文吉  Paul T. Robinson  方青松  杨经绥  颜秉刚  张仲明  胡旭峰  周美夫 《地球学报》2004,25(4):385-396

铂族元素和贱金属合金矿物选自西藏南部罗布莎蛇绿岩的豆荚状铬铁矿石中,包括Os-Ir、Os-Ir-Ru、Pt-Fe、Ir-Ni-Fe、Fe-Ni-Cr和Fe-Co,它们都具有成分上的广阔变动。此外还见到少量的金刚石、石墨、SiC和未定名的Cr-C、Fe-Si等合金;自然Fe、Ni、Cr、Cu和Si。这些合金和自然元素矿物是选自于铬铁矿的人工重砂样品中,但是有些矿物呈包裹体或呈连晶与铬尖晶石共生。它们大多为半自形和它形的颗粒状矿物,偶有完好晶体保存,矿物粒径0．05～0．5mm。有些矿物颗粒呈浑圆形,认为是液态乳滴。富Ru的铂族元素合金,Fe-Ni、Fe-Co合金,以及自然铁和自然镍,可以被解释成由铂族硫化物蚀变物。但是Pt-Fe、Os-Ir、Ir-Ni-Fe、FeSi合金、自然Si、FeO(方铁矿)等,认为是来自地幔的外来(捕虏)晶体,是被地幔柱搬运到浅部的,最后被铬铁矿浆捕获并成为其包体。  相似文献   

Extracts of the seaweed Bifurcaria bifurcata display antifungal activity against human dermatophyte fungi     

CARVALHO G.Loic  SILVA Raquel  GONCALVES J.Maria  BATISTA T.Maria  PEREIRA Leonel 《海洋湖沼学报（英文）》2019,(3):848-854

Bifurcaria bifurcata is a seaweed of the Order Fucales(Ochrophyta,Phaeophyceae)that can be found all year round along the Portuguese Atlantic shore.Although it is considered edible in some countries,its biotechnological potential has not yet been assessed in detail and here we report its antimicrobial potential against human dermatophyte fungi.Three samples were harvested from Baleal Island(Peniche,Portugal)harvested in winter(BbPe);from Aguda Beach(Arcozelo,Vila Nova de Gaia,Portugal),harvested in autumn(BbAg)and a sample obtained by culturing the Aguda sample under laboratory conditions(BbLC).A broth macrodilution assay was applied to determine the MIC(minimum inhibitory concentration)and MLC(minimum lethal concentration)of the B.bifurcata extracts.Results show that the BbPe MeOH extracts were the most effective and had higher antifungal activity against all the tested dermatophyte strains than the BbLC and BaAg extracts[Epidermophyton floccosum FF9(100–200μg/mL MIC;200μg/mL MLC),Microsporum canis FF1(400μg/mL MIC;≥400μg/mL MLC),Trichophyton mentagrophytes FF7(100μg/mL MIC;>800μg/mL MLC),M.gypseum CECT 2908(800μg/mL MIC;≥800μg/mL MLC),T.mentagrophytes var.interdigitale CECT 2958(800μg/mL MIC;≥800μg/mL MLC),T.rubrum CECT 2794(200μg/mL MIC;≥400μg/mL MLC)].In fact,only E.floccosum FF9 was sensitive to BbAg and BbLC MeOH extracts.To our knowledge,this is the first report of antifungal activity of B.bifurcata against human dermatophyte fungi.  相似文献   

FAST Pulsar Database. I. Polarization Profiles of 682 Pulsars     

P.F.Wang  J.L.Han  J.Xu  C.Wang  Y.Yan  W.C.Jing  W.Q.Su  D.J.Zhou  T.Wang 《天文和天体物理学研究(英文版)》2023,(10):73-177

Pulsar polarization profiles form a very basic database for understanding the emission processes in a pulsar magnetosphere. After careful polarization calibration of the 19-beam L-band receiver and verification of beamoffset observation results, we obtain polarization profiles of 682 pulsars from observations by the Five-hundredmeter Aperture Spherical radio Telescope(FAST) duringthe Galactic Plane Pulsar Snapshot survey and other normal FAST projects. Among them, polarization profiles of about ...  相似文献   

Studying the Equilibrium Points of the Modified Circular Restricted Three-body Problem: The Case of Sun–Haumea System     

I.Nurul Huda  B.Dermawan  M.B.Saputra  R.Sadikin  T.Hidayat 《天文和天体物理学研究(英文版)》2023,(11):234-244

We intend to study a modified version of the planar Circular Restricted Three-Body Problem(CRTBP) by incorporating several perturbing parameters. We consider the bigger primary as an oblate spheroid and emitting radiation while the small primary has an elongated body. We also consider the perturbation from a disk-like structure encompassing this three-body system. First, we develop a mathematical model of this modified CRTBP.We have found there exist five equilibrium points in this modified CRTB...  相似文献   

3D Kinematics of Classical Cepheids According to Gaia EDR3 Catalog     

V.V.Bobylev  A.T.Bajkova 《天文和天体物理学研究(英文版)》2023,(4):3-16

The kinematics of about 2000 classical Cepheids of the Milky Way with data from Gaia EDR3 catalog has been studied.For some of these stars,there are line-of-sight velocities.On the basis of the nonlinear rotation model,the parameters of the rotation curve of the Galaxy were determined.The circular linear rotation velocity of the nearsolar neighborhood around the Galaxy center was V₀=236±3 km s^-1 for the assumed Sun’s galactocentric distance R₀=8.1±0.1 kpc.Analysi...  相似文献   

Characteristic Study of the Boundary Layer Parameters over the Arabian Sea and the Bay of Bengal Using the QuikSCAT Dataset     

V. HAMZA  C. A. BABU  T. P. SABIN 《大气科学进展》2007,24(4):631-6432007

The marine atmospheric boundary layer (MABL) plays a vital role in the transport of momentum and heat from the surface of the ocean into the atmosphere. A detailed study on the MABL characteristics was carried out using high-resolution surface-wind data as measured by the QuikSCAT (Quick scatterometer) satellite. Spatial variations in the surface wind, frictional velocity, roughness parameter and drag coefficient for the different seasons were studied. The surface wind was strong during the southwest monsoon season due to the modulation induced by the Low Level Jetstream. The drag coefficient was larger during this season, due to the strong winds and was lower during the winter months. The spatial variations in the frictional velocity over the seas was small during the post-monsoon season (～0.2 m s-1). The maximum spatial variation in the frictional velocity was found over the south Arabian Sea (0.3 to 0.5 m s-1) during the southwest monsoon period, followed by the pre-monsoon over the Bay of Bengal (0.1 to 0.25 m s-1). The mean wind-stress curl during the winter was positive over the equatorial region, with a maximum value of 1.5×10-7N m-3, but on either side of the equatorial belt, a negative wind-stress curl dominated. The area average of the frictional velocity and drag coefficient over the Arabian Sea and Bay of Bengal were also studied. The values of frictional velocity shows a variability that is similar to the intraseasonal oscillation (ISO) and this was confirmed via wavelet analysis. In the case of the drag coefficient, the prominent oscillations were ISO and quasi-biweekly mode (QBM). The interrelationship between the drag coefficient and the frictional velocity with wind speed in both the Arabian Sea and the Bay of Bengal was also studied.  相似文献   

STUDY OF MORPHOLOGICAL CHANGE OF THE KUSHIYARA AND MONU RIVERS BY REMOTE SENSING     

M. J. B. ALAM R. ALAM  M. UDDIN T. NAHAR 《国际泥沙研究》2007,22(2):160-168

The Kushiyara and Monu rivers are two of the major river systems in the northeast region of Bangladesh. Analyzing satellite images of the Kushiyara and Monu rivers between 1990 and 1997, it was found that significant changes occurred at five distinct locations; i.e., Ahmadpur, Monumukh, Raysrr, Kaprangibari and Telibil. The amount of change was measured as 168.34 ha by using a plani-meter. Transportation of sediment was the major contributing factor of morphological change. The total average sediment concentration of Kushiyara and Monu rivers was found to be 16889.6 ppm per year during the study period by applying the Engelund and Hansen equation approach. Protection work has been suggested at the vulnerable locations.  相似文献   

Attenuation characteristics of peak acceleration in North China and comparison with those in the eastern part of North America     

BI-QUAN WANG  FRANCIS T WU  YIN-JU BIAN 《地震学报(英文版)》1999,12(1):26-34

ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｔｈｅｆｉｒｓｔｔｉｍｅｉｎｔｈｅｗｏｒｌｄｔｏｇｅｔｔｈｅｓｔｒｏｎｇｍｏｔｉｏｎｒｅｃｏｒｄｓｏｆａｄｅｓｔｒｕｃｔｉｖｅｅａｒｔｈｑｕａｋｅｗｈｅｎｔｈｅＬｏｎｇＢｅａｃｈｅａｒｔｈｑｕａｋｅｏｎＭａｒｃｈ１０,...  相似文献   

近场强地面运动的三维模拟：由破裂方向性推断盆地边缘效应     

Inoue  T 王梅 《世界地震译丛》1999,(5):38-42

神户地震造成严重破坏的地区呈狭窄的带状分布是１９９５年兵县南部（神户）地震非常显著的特征。形成强地面运动放大的过程至今未见阐述。通过构造一个掩埋于靠近盆地的走滑断层的一个Ｍ＝７地震的动力学破裂过程,我们模拟了由破裂方向性产生的盆地边缘效应。通过三维有限差分法计算了频率达１Ｈｚ的速度的地面运动地震图。峰值地面速度曲线的状态显示,当断层与盆地边缘平行时,峰值地面运动在沿盆地边缘一个宽度在几公里范围的狭  相似文献   

北祁连造山带的形成与背景   总被引：100，自引：4，他引：96  

葛肖虹  刘俊来 《地学前缘》1999,6(4):223-230

北祁连山是发育在新元古代大陆克拉通背景上的板内造山带,它的形成经历了三个构造发展阶段;（１）早古生代是克拉通裂解的拗拉槽而不是大洋盆地,其西延部受阿尔金断裂左行错移约３５０－４００ｋｍ,对应于塔里木盆地北部的满加尔－阿瓦提坳陷,它们共同构成了“西域板块”这上的震旦纪－早古生代的拗拉槽,早古生代末“祁连事件”使拗拉槽闭合形成古祁连山。（２）晚古生代－中三叠世古祁连山遭受产,作为新克拉人  相似文献