816 resultados para 857
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贵州省关岭县新铺乡附近的晚三叠世早期地层瓦窑组底部产具重大科学意义的关岭生物群。关岭生物群产出地层中伴有大量大型碳酸盐岩结核。这些结核中部都有植物茎干,结核内的海百合、双壳、菊石、牙莆刺等生物化石含量明显高于结核周期的岩石,且有许多生物化石直接附着在植物茎干上。这类结核的形成,除化学沉积作用外,还有生物作用的影响。海百合、双壳类和菊石类栖息在植物茎干上营假浮生活,随着栖息生物量和化学沉积物灰泥的增加,逐渐沉积在海底形成结核。
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在滇西羊拉铜矿区发现了4层硅质岩, 该硅质岩具有低的TiO2, Al2O3与高的成矿元素(Cu, Au, Ag)含量特征. 硅质岩稀土元素总量很低, 其球粒陨石标准化配分模式为向右倾的曲线, 具有明显的负Eu异常与弱的正Ce异常, 与矿区早期形成的块状硫化物矿石、 矿石矿物及脉石矿物具有一致的稀土元素球粒陨石标准化配分模式, 而与成矿中晚期形成的夕卡岩型矿石及破碎带充填交代型矿石明显不同. 硅质岩的硅同位素组成与热水沉积的硅华及硅质岩一致, 它的铅同位素组成与块状硫化物矿石一致, 它的Rb-Sr等时线年龄为272 Ma ± 6 Ma, 与赋矿地层时代一致. 研究表明羊拉矿区硅质岩为典型的热水沉积硅质岩, 且与矿区块状硫化物矿体关系密切, 这为该矿床块状硫化物矿体为海底喷流热水沉积作用形成提供了直接的证据.
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北欧和北美的研究发现水库是典型的汞敏感生态系统,新建水库而引起的鱼体甲基汞污染问题已受到科学家的高度重视,而我国在这方面的研究比较薄弱。本论文选择乌江流域的6个水库作为研究对象,并根据年龄把这些水库划分为3个演化阶段,洪家渡、引子渡、索风营水库为初级演化阶段,普定、东风水库为中级演化阶段,乌江渡水库为高级演化阶段。对这6个水库总汞和甲基汞的输入和输出通量进行了研究,探讨了不同演化阶段的水库对总汞和甲基汞的“源/汇”作用,主要研究内容有以下三个方面:(1)各水库入出库河流中汞的分布特征;(2)大气降水中汞浓度及沉降通量的分布;(3)乌江流域不同水库汞的输入输出通量。通过本论文的研究,得出以下主要结论: 1. 乌江流域河流中总汞、颗粒态汞、溶解态汞、活性汞、总甲基汞、溶解态甲基汞的年均浓度分别为3.41±1.98、2.05±1.73、1.36±0.44、0.24±0.11、0.15±0.06、0.08±0.03 ng•L-1。与国内外其它河流的比较发现,总汞的浓度明显低于国外受污染的河流,略高于国外未受污染的河流。溶解态汞、活性汞、甲基汞的浓度略低于受污染的河流,与未受污染的河流基本相当。与同处在贵州喀斯特地区的阿哈湖、红枫湖、百花湖的入出库河流相比,总汞、溶解态汞、活性汞、甲基汞、溶解态甲基汞的浓度均明显偏低。 2. 水库的修建显著降低了出库河流中总汞、颗粒态汞的浓度,使总甲基汞和溶解态甲基汞的浓度升高,而且增加了出库河流中溶解态汞、活性汞、总甲基汞占总汞的比例。不同形态汞的沿程分布显示,梯级水库的修建改变了河流原有的汞的生物地球化学过程,使乌江多个河段的甲基汞升高,并且随着水库生态系统的不断演化,水库输出的甲基汞将增加,下游河流水体中甲基汞有继续升高的趋势。 3. 大气降雨中总汞、溶解态汞、颗粒态汞、活性汞、总甲基汞的浓度分别为7.49~149 ng•L-1、1.23~10.0 ng•L-1、5.76~142 ng•L-1、0.56~2.94 ng•L-1、0.08~0.82 ng•L-1,且以颗粒态汞为主,约占总汞比例的87%。总汞、溶解态汞、颗粒态汞、甲基汞的浓度有明显的季节变化趋势,冬春季高于夏秋季,而空间分布特征不明显。2006年总汞、甲基汞的年湿沉降通量为34.7±5.80 µg•m-2•yr-1、0.18±0.03 µg•m-2•yr-1,且主要受降雨量的影响。乌江流域降雨中总汞的浓度及其湿沉降通量远高于北美和日本,低于中国的一些城市地区(如长春和北京),而甲基汞的浓度和通量与其它地区相当。 4. 在乌江流域的不同水库中,降雨输入总汞和甲基汞的通量主要受降雨量和水库面积的影响,而与降雨的汞浓度间没有相关性。河流向水库输入总汞的量主要受河流流量的控制,而输入甲基汞和颗粒物的量受河流流量和浓度的影响。下泄水输出总汞、甲基汞、颗粒物的通量受浓度和流量的影响。由于流域面积/水面面积的比值较大,水库水量、总汞、甲基汞、颗粒物的输入以河流为主,分别占总输入的87%、80%、85%、86%。输出以下泄输出为主,下泄水输出的水量、总汞、甲基汞、颗粒物分别占总输出的80%、77%、86%、79%。 5. 从输入-输出通量的结果发现,各水库均表现为河流颗粒物输送的“汇”;除乌江渡水库外,其它水库均表现为总汞的“汇”;对甲基汞而言,引子渡、洪家渡、索风营水库表现为“汇”,而普定、东风、乌江渡水库则表现为“源”。 6. 普定和洪家渡水库中总汞的贮存率为56%和57%,明显高于其它水库,说明在上游有水库存在的情况下,水库对总汞“汇”的作用将降低。普定、东风、乌江渡水库中甲基汞的净通量分别为+69.4 g•yr-1、+368 g•yr-1、+857 g•yr-1,转化率为13%、73%、84%,说明甲基汞的净通量和转化率与水库的演化阶段有关,随着水库演化阶段的升高而增加,并且随着水库的不断演化,甲基汞将从“汇”变成“源”。
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The present paper studies focus on the symptoms of the post-traumatic stress disorder in adolescents post-disaster. 482 students from 6 secondary schools and 17 primary schools in the extremely severe disaster areas in Mianzhu, Sichuan province and 785 students from 3 primary schools and 9 secondary schools in the severe disaster areas in Baoji, Shaanxi respectively were surveyed on the symptoms of the post-traumatic stress disorder and the extent of disaster exposure after the Wenchuan earthquake. Self-compiled background information questionnaire and CRIES were used for the investigation. In this study, we contrast the extent of disaster exposure in the two areas in order to explore the related factors about the post-traumatic stress disorder in adolescent post-disaster. The main results of this paper can be summarized as follows: 1. There are significant positive corrections between the post-traumatic stress disorder and the extent of disaster exposure(get trapped in the earthquake、relatives and friends have been injured in the earthquake、look at relatives and friends dying in the earthquake).The more exposed in the disaster, the more serious symptom of the post-traumatic stress disorder. The trauma exposure indicators (get trapped in the earthquake, relatives and friends have been injured in the earthquake、look at relatives and friends dying in the earthquake)were all significant predictors for PTSD severity. 2. There are significant sex difference in the extent(F=8.750, p <0.05) and the incidence rate of PTSD(χ =20.735, df=5,p =0.001), the extent and the incidence rate of girls in Mianzhu is significantly higher than that of boys. 3. The age is also an influence factor of PTSD. The extent (F=7.246, p <0.001)and the incidence rate (χ =20.735, df=5,p =0.001)of PTSD get higher as adolescent in Mianzhu get older. 4. As the extremely severe disaster areas, the extent of disaster exposure of Mianzhu areas significantly higher than that of the severe disaster areas Baoji. However, there are not difference in the extent of PTSD between two areas(t=0.181,df=1265,p=0.857), there are only significant difference in the incidence rate of PTSD between two areas(χ =8.766,df=1,p=0.003), the incidence rate of PTSD in Mianzhu areas significantly higher than that of Baoji areas.
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Gillmore, G. Gilbertson, D. Grattan, J. Hunt, C. McLaren, S. Pyatt, B. Banda, R. Barker, G. Denman, A. Phillips, P. Reynolds, T. The potential risk from 222radon posed to archaeologists and earth scientists: reconnaissance study of radon concentrations, excavations and archaeological shelters in the Great cave of Niah, Sarawak, Malaysia. Ecotoxicology and Environmental Safety. 2005. 60 pp 213-227.
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Jackson, R. (2007). Language, Policy and the Construction of a Torture Culture in the War on Terrorism. Review of International Studies. 33(3), pp.353-371 RAE2008
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Second letter to nephew, Daniel Avery Whedon from Daniel D. Whedon dated May 16, 1881.
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Handwritten letter from Daniel D. Whedon to nephew, Daniel Avery Whedon. Dated November 30, 1881.
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Letter from Daniel D. Whedon to nephew. One of two dated May 16, 1881.
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Three page handwritten letter to nephew, Daniel Avery Whedon, from Daniel D. Whedon. Dated 11/14/1881.
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Letter from Daniel Whedon to nephew, Daneil Avery Whedon. Dated December 11 1868.
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Handwritten letter dated June 7, 1881, to nephew, Daniel Avery Whedon.
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Daniel Avery Whedon's four page letter to nephew, dated October 10, 1867.
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Hanwritten letter from Daniel Denison Whedon to nephew. Dated 08/09/1867.