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51.
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通过对比间隔17yr (静止系12.5yr)的Sloan Digital Sky Survey (SDSS)、Keck LRIS (Low-Resolution Imaging Spectrograph)和Baryon Oscillation Spectroscopic Survey (BOSS)的光学光谱, 对宽线双峰射电类星体B3 1637+436A的吸积盘性质做了初步研究.该类星体的SDSS (2001年5月21日)和Keck LRIS (2003年6月28\lk 日)的连续谱没有明显差异, 而BOSS (2018月6月17日)连续谱在V波段比SDSS暗了约1.2星等.这3条光谱的Hα宽发射线均表现出明显的双峰轮廓. 和连续谱一样, 宽线双峰的发射线轮廓也被认为是来自于吸积盘.通过上述3条光谱的Hα宽线双峰的盘模型拟合发现: BOSS光谱的Hα宽线双峰可以用单个盘模型很好地拟合,谱线发射区距离中心黑洞约900--3000引力半径. 而SDSS和Keck LRIS的Hα双峰轮廓需要用两个盘模型拟合, 对应的吸积盘发射区有两个区域,其中一个发射区(``外盘'')与BOSS类似, 另一个发射区(``内盘'')位于约400--900引力半径范围内, 到中心黑洞的距离显著小于外盘. 结合连续谱的光变特征,推测内盘消失是造成SDSS/Keck LRIS光谱和BOSS光谱在连续谱和发射线轮廓上同时发生光变的主要原因. 相似文献
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提出了基于B/S架构的WebGIS城市车辆指挥调度系统框架,综合利用了GPS、GPRS等技术,实现了对城市车辆的指挥调度功能。 相似文献
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Tetraploid induction was carried out by inhibiting mitosis I in fertilized eggs ofChlamys farreri. Mitosis I was blocked with cold shock (5–7°C), Cytochalasin B (0.75 mg/L) and 6-dimethylaminopurine (6-DMAP) (60–75 mg/L)
when 60% fertilized eggs released polar body II at 20°C. At 4-cells embryo stage, the ploidy was determined by counting chromosome
number. In control groups, most embryos were diploids (72.22%) and aneuploids (24.78%). In Cytochalasin B, cold shock and
6-DMAP treated groups, tetraploids were respectively 10.51%, 4.08%, and 13.34%; aneuploids were 43.10%, 35.93% and 29.16%,
and triploids were 7.84%, 8.52% and 18.33%. At D-larva stage, ploidy was determined by flow cytometry (FCM). The ploidy analysis
of day 2 larvae showed diploids in control group and also in three treated groups. Juvenile scallops (0.2–0.3cm) which were
harvested in two control groups and two CB treated groups were all diploids through checking ploidy individually by FCM.
Contribution No. 3648 from the Institute of Oceanology, Chinese Academy of Sciences.
Contribution No. 238 from the Experimental Marine Biology Laboratory, Chinese Academy of Sciences.
Project funded by grant (No. 819-01-07) from the Chinese Science and Technology Ministry and also by “Hundred Talents Plan”
grant from the Chinese Academy of Sciences. 相似文献
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James L. Foster Gail Skofronick‐Jackson Huan Meng James R. Wang George Riggs Paul J. Kocin Benjamin T. Johnson Judah Cohen Dorothy K. Hall Son V. Nghiem 《水文研究》2012,26(22):3459-3471
The snowfall in the Baltimore/Washington metropolitan area during the winter of 2009/2010 was unprecedented and caused serious snow‐related disruptions. In February 2010, snowfall totals approached 2 m, and because maximum temperatures were consistently below normal, snow remained on the ground the entire month. One of the biggest contributing factors to the unusually severe winter weather in 2009/2010, throughout much of the middle latitudes, was the Arctic Oscillation. Unusually high pressure at high latitudes and low pressure at middle latitudes forced a persistent exchange of mass from north to south. In this investigation, a concerted effort was made to link remotely sensed falling snow observations to remotely sensed snow cover and snowpack observations in the Baltimore/Washington area. Specifically, the Advanced Microwave Scanning Radiometer onboard the Aqua satellite was used to assess snow water equivalent, and the Advanced Microwave Sounding Unit‐B and Microwave Humidity Sounder were employed to detect falling snow. Advanced Microwave Scanning Radiometer passive microwave signatures in this study are related to both snow on the ground and surface ice layers. In regard to falling snow, signatures indicative of snowfall can be observed in high frequency brightness temperatures of Advanced Microwave Sounding Unit‐B and Microwave Humidity Sounder. Indeed, retrievals show an increase in snow water equivalent after the detection of falling snow. Yet, this work also shows that falling snow intensity and/or the presence of liquid water clouds impacts the ability to reliably detect snow water equivalent. Moreover, changes in the condition of the snowpack, especially in the surface features, negatively affect retrieval performance. Copyright © 2011. This article is a U.S. Government work and is in the public domain in the USA. 相似文献