排序方式: 共有231条查询结果,搜索用时 15 毫秒
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生活在墨西哥和南美洲许多国家的大孔雀,能突然在自己色调鲜明的尾羽中间显露出2个相当大的深色斑点,其形状酷似人的眼睛。鸟类学家观察后认为:这种“假眼”可以保护孔雀免遭猛禽的袭击。猛禽出现时,孔雀羽毛上深色的班点开始闪烁出鲜艳的黄色光亮,猛禽最害怕的就是这种黄光,因 相似文献
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Petrographic and geochemical characterization of seep carbonate from Alaminos Canyon,Gulf of Mexico 总被引:2,自引:1,他引:2
Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are common and usually filled with acicular aragonite crystals. XRD investigation shows that aragonite is the dominate mineral (98%). Peloids, clotted microfabirc and botryoidal aragonite are developed in carbonate and suggest a genesis linked with bacterial degradation of the hydrocarbons. The δ^13C value of bioclasts in carbonate is from -4.9‰ to -0.6‰, indicating that the carbon source is mainly from sea water as well as the small portion incorporation of the seep hydrocarbon. The microcrystalline and sparite aragonite shows the δ^13C value from -31.3‰ to -23.4‰, suggesting that their carbon is derived mainly from microbial degradation of crude oil. ^14C analyses give the radiocarbon age of about 10 ka. Rare earth elements (REE) analyses of the 5% HNO3-treated solution of the carbonates show that the total REE content of the carbonates is low, that is from 0.752 to 12.725 μg·g^-1. The shale-normalized REE patterns show significantly negative Ce anomalies. This suggests that cold seep carbonate is most likely formed in a relatively aerobic environment. 相似文献
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为了应对墨西哥发生的甲型H1N1流感病毒疫情,香港卫生当局把近年来爆发的流感[SARS、禽流感(H5N1)以及现在的甲型H1N1流感]疫情进行了分类疏理,尽管这是一件复杂且繁琐的事情。 相似文献
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墨西哥地处拉丁美洲和北美洲的衔接地带,是纵贯南、北美洲陆路交通的必经之地,其形状像一只倒放的羊角浮浸在大西洋和太平洋之间,素有“陆上桥梁”之称。国名“墨西哥”3个字是由纳瓦语“墨西特耳”演化而来的。欧洲人来此之前,当地有一支印第安人的游牧部落叫阿兹蒂克,他们所崇拜的战神叫“墨西特耳”。 相似文献
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正世界上90%的圣诞用品来自中国老外发愁过圣诞节,中国人发愁圣诞订单。离岁末虽还有一月有余,但世界上许多国家的圣诞集市马上就要开张了。与往年一样,人们将会去市场上逛一逛那些挂满了五颜六色小玩意儿的摊位,采购礼品送给朋友或装饰自己家的圣诞树。 相似文献
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为了明确Perdido带上Wilcox组油藏富集控制因素,以上Wilcox组油藏为研究对象,通过有效供烃范围、油输导方式、圈闭形成与生排烃期匹配关系及保存条件对比分析,探讨了Perdido带上Wilcox组油藏富集控制因素及成藏模式。研究认为,供烃区规模对油藏规模控制作用明显;上Wilcox组油藏存在顺源式、向源式和背源式3种垂向运移方式,其中,顺源式和向源式运移有利于油藏富集;圈闭形成与生排烃期匹配较好的油藏,供烃充足,油藏规模大;保存是油藏富集的必要条件,遭受严重破坏的油藏规模小;建立了Perdido带上Wilcox组3种油藏成藏模式,其中,“双侧供烃-顺源输导”和“单侧供烃-向源输导”有利于油藏富集,是该区寻找规模性油藏的有利模式。 相似文献
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提出了一种基于墨西哥帽小波的信号滤波的新方法-MWDA。它是一种化学计量技术,易于操作,被成功地应用到分析化学信号的处理中,MWDA即使处理信噪比为1的高噪声音信号,仍能莸满意的结果。 相似文献
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