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I.IntroductionStalagmiteshavebeenappliedtouseashighresolutionpaleoclimaticindicatorssincetheannualgrowthbandingwasrecognizedinstalagmites[1,2].Annualgrowthbandingcanbemanifestedinseveralmannersdefinedby1)alternatingfluorescentandnon-fluorescentcalcite[3,4];2)…  相似文献   
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Butterflies are widely studied due to their key ecosystem functions.For this reason,they are used in ecosystem assessment,formulating conservation plans and in raising the environmental awareness.Quantification of different factors affecting diversity of butterflies is important for their effective conservation.In this study,we investigated abiotic and biotic factors affecting species richness and community composition of butterflies along an elevational gradient in Manang region,central Nepal.We also tested if butterfly species follow the Bergmann’s rule.A total of 57 butterfly species belonging to 39 genera and 8 families were recorded in the study area.Out of a total of 127 plant species identified in the study region,only 67 plant species were visited by butterflies as nectar sources.Species richness of butterflies increased with increasing elevation.Species richness was significantly higher in places with shrubs compared to other places and also in autumn than in summer.Species richness of butterflies also depended on composition of plant species occurring at the localities.Butterfly species composition varied among sampling localities.It was also determined by habitat type,elevation,sampling time,plant species and interactions of elevation×time.The relationship between butterfly size and elevation was in the opposite direction than expected according to the Bergmann’s rule.In conclusion,protection of butterfly diversity can only be achieved by protecting different habitats across the diverse physiography of the region and different plant species,in particular herbs and shrubs.Our results do not support the Bergmann’s rule for butterflies along an elevational gradient in our region.  相似文献   
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The intense study of coleopteran inclusions from Spanish(Albian in age) and French(Albian-Santonian in age) Cretaceous ambers,both of Laurasian origin,has revealed that the majority of samples belong to the Polyphaga suborder and,in contrast to the case of the compression fossils,only one family of Archostemata,one of Adephaga,and no Myxophaga suborders are represented.A total of 30 families from Spain and 16 families from France have been identified(with almost twice bioinclusions identified in Spain than in France);13 of these families have their most ancient representatives within these ambers.A similar study had previously only been performed on Lebanese ambers(Barremian in age and Gondwanan in origin),recording 36 coleopteran families.Few lists of taxa were available for Myanmar(Burmese) amber(early Cenomanian in age and Laurasian in origin).Coleopteran families found in Cretaceous ambers share with their modern relatives mainly saproxylic and detritivorous habits in the larval or adult stages,rather than wood-boring behavior.Fifteen of the coleopteran families occur in both the Lebanese and Spanish ambers;while only five are present in both Spanish and French.Considering the paleogeographic proximity and similarity of age of the Spanish and French ambers,the small number of taxa found in common at both areas is surprising.The ancient origin for the Lebanese and Spanish ambers,the paleogeography(including some barriers for terrestrial biota) and the local paleohabitats are factors that may explain the dissimilarity with the French specimens.Wildfires are believed to be a more likely cause of resin production during the Cretaceous than infestation by beetles.Current knowledge of the beetle species found in the Cretaceous ambers is introduced.  相似文献   
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Plutonic rocks from the Mineiro Belt, Brazil record a delayed onset of the transition from TTG to sanukitoid-type magmatism(high Ba-Sr), starting during the Siderian magmatic lull when little juvenile magma was added to the continental crust. Rocks mostly belong to the calc-alkaline series, meta-to peraluminous and originally "Ⅰ-type",meaning that oxidized magmas were formed by partial melting of subducted material. The temporal distribution and apparent secular changes of the magmas are consistent with the onset of subduction-driven plate tectonics due to an increase of the subduction angle and opening of the mantle wedge. New isotopic analyses(Sm-Nd whole rock and Lu-Hf in zircon)corroborate the restricted juvenile nature of the Mineiro Belt and confirm the genetic link between the Lagoa Dourada Suite,a rare ca. 2350 Ma high-Al tonalite-trondhjemite magmatic event, and the sanukitoid-type ca. 2130 Ma Alto Maranhao Suite. U-Pb dating of zircon and titanite constrain the crystallisation history of plutonic bodies; coupled with major and trace element analyses of the host rocks, they distinguish evolutionary trends in the Mineiro Belt. Several plutons in the region have ages close to 2130 Ma but are distinguished by the lower concentration of compatible elements in the juvenile high Ba-Sr suite.  相似文献   
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有四种方法可以获得深部岩石类型的性质及其几何特征的信息。它们是:(1)通过对构造侵位而露出地表的露头的直接观察;(2)玄武岩和金伯利岩中捕虏体的研究;(3)遥感信息(如地震、磁法);(4)理论计算(如基于下部地壳平均成分的计算)。上述各种途径的综合,可以得出更为合理的模式,捕虏体则提供了特定地区最原始的特征,同时也提供了在较大范围内变化的信息,而这些样品都是通常情形下达不到的高压下的产物。相平衡的实验研究表明,随成分的变化,榴辉岩的矿物组合在具正常地热梯度(40mw/m~2)克拉通的下部地壳和上地幔中的许多岩石类型中是稳定的。然而,热流研究、理论模拟及捕虏体的地质温压研究均表明,一些地壳构造活动强烈的地区(如年轻  相似文献   
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Deck.  WL  马树庆 《气象科技》1996,(3):31-35
农业气象学的发展历程WayneL.Decker(密苏里-哥伦比亚大学)1引言农业气象学涉及农业生产与销售对大气的响应,如何利用天气预报,利用气候风险分析和改变环境来避免或减轻天气灾害。本文谈的农业气象包括农业气候学。新的世纪即将来临,有必要回顾一下农...  相似文献   
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近源观测表明,加 里齐克雷斯特附近发生的5次M3.8-5.2地震伴有地震成核现象。这些地震突然发生。随之节奏放慢趋地平静,然后加快节奏,以最高矩速率释放出能量。用经验格林函数对仪器和路径效应作反褶积运算结果显示,地震起始的复杂性是一种震源效应,在地震成核现象初期到达且迅速递增的P波支持了Mori和Kanamori研究所得到的结论:这些地震没有象Iio所观测到的那种量级之差的缓慢起始相。  相似文献   
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