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排序方式: 共有285条查询结果,搜索用时 218 毫秒
251.
ZHENGZhuo WANGJianghua WANGBing LIUChunlian ZOUHeping ZHANGHua DENGYun BAIYan 《科学通报(英文版)》2003,48(5):497-502
The results of sedimentary characteristics,grain-size,clay mineral,C/N and pollen analysis reveal the evolution history of the Shuangchi Maar Lake of Hainan Island as well as the short-term climate variations in tropical areas.It is testified that the Maar sediment system was sensitive in recording the rapid climate changes in the Holocene.These multidisciplinary results demonstrate that the thermal maximum in the Holocene climate lasted from 7200 to 2700 aBP,with serveral abrupt ephemeral vibrations occurring between 7250-6120aBP and at around 4460,3850 and 2700 aBP.In the late Holocent,particularly at -2700 aBP,a distinct environmental change indicating an important climate transition in the tropical eastern Asia was recorded,probably responding to the enhancement of ENSO phenomena in the Pacific Ocean.In addition,the high-resolution algae record clearly indicates periodical climate fluctuations at 500 a cyclicity during the last 2500 years. 相似文献
252.
海南岛沙质海岸侵蚀的初步研究 总被引:4,自引:0,他引:4
海南岛沙质海岸侵蚀明显,通过野外调查、定位测量及图件对比,对该类海岸的侵蚀状况及侵蚀原因进行了初步分析与探讨。 相似文献
253.
陈礼贤 《广西民族大学学报》2002,(2)
通过对居住于北海市斜阳岛上的疍民的生产方式和生活方式的个案考察 ,试图揭示在社会转型过程中位处海岛的海疍文化的变迁规律及其特征 相似文献
254.
作者在历年的海滨动物采集中,整理出洞头岛潮间带贝类108种。不同底质条件下,以岩礁相的种类、生物量、栖息密度最高;砾石块石相次之;泥滩中生物较贫乏,沙滩中最少。本文还就贝类在潮间带的生活类型、在不同潮区的分布及数量分布作了描述,对几种经济贝类的利用、资源保护作了分析。 相似文献
255.
G. Ganem L. Granjon K. Ba J. -M. Duplantier 《Cellular and molecular life sciences : CMLS》1995,51(4):402-410
Generally rodents are found to be larger on islands than on the mainland. However, there are some exceptions to this rule, and the aim of this paper is to examine one of them. On the mainland of Senegal,Mastomys huberti occupies humid habitats. However, it occurs also on dry and sandy islands (Saloum delta), where its representatives are dwarf. Since water availability appeared to be the limiting factor in these islands when compared to the mainland, we studied water turnover characteristics in relation to body size, in mainland and island populations at the end of the dry season, under both field and laboratory conditions. All populations were found to be water balanced in their natural habitats. They presented similar rates of water turnover, even though island animals were subjected to stronger constraints than mainland ones. Laboratory experiments suggested that the physiological plasticity of one of the island populations may be reduced. Island populations have a higher kidney size to body weight ratio than those from the mainland. We propose that smaller size in the islands allows the maintenance of water balance with a smaller amount of water, and that a higher ratio of kidney filtration surface to body size may helpMastomys huberti to survive in dry islands. We discuss the factors responsible for body size variability and variation in water exchange characteristics and conclude that different factors could explain body size variation among island populations, depending on the species considered and the ecological constraints met within the islands. 相似文献
256.
海南岛具有海洋生物生长繁殖的优越自然环境据资料统计,潮间带的生物量,以藻类为最多,占总生物量的62.8%全省有700余种藻类,本文叙述了本岛主要大型海藻资源的产地、产量及其经济价值,海藻增养殖及其加工利用方面的概况,并对不足之处提出建议. 相似文献
257.
本文就南海、东海及台湾板块构造演化的若干问题展开讨论。我们认为南海海盆是在被动大陆边缘的基础上张开的,而不是弧后扩张的产物;台湾不是活动岛弧.而是典型的岛弧‘大陆碰撞带,并将台湾与鲁马拉雅地区的构造作了对比;吕宋至台湾的板块边缘显示出板块俯冲至碰撞的转化.南海东缘板块边界演化的基本趋势是.从俯冲到碰撞.进而形成极性相反的新俯冲带.南海海盆终将成为被地块全面包围的残留盆地;南海的开合表现为威尔逊旋回的复杂形式。认为冲绳海槽尚未出现伴有新洋壳形成的海底扩张作用.冲绳海槽是弧后裂陷.而非弧后扩张的产物。 相似文献
258.
何晨青 《温州大学学报(自然科学版)》2010,(1):56-60
英国在19世纪下半叶的外交政策被描述为“光辉孤立”,这是英国在强国林立的欧洲保持自身政策灵活性和追求利益最大化的关键。就政治因素来看,“光辉孤立”是均势外交的一种表现,但深究其文化渊源,“光辉孤立”是英国政治传统中的保守主义和功利主义、外交文化中的制衡观念以及不列颠民族特性和岛国文化的综合结果。 相似文献
259.
叶舒宪 《广西右江民族师专学报》2011,(4):9-14
文章对编撰《宝岛诸神——台湾的神话历史古层》的缘由,撰写的过程、框架、内容进行了说明,并列举了参考书目和延伸阅读。 相似文献
260.
Coastal plain evolution in southern Hainan Island, China 总被引:2,自引:0,他引:2
The coast of southern Hainan Island is characterized by wide sandy embayments, which consist of ( i) drowned valleys bounded by steep bedrock hills and only locally receiving sediments, and embayments of various dimensions covered either by (ii) alluvial-deltaic deposits or by (iii) sands of coastal beach ridges/barriers and associated elongated lagoons. During the late Tertiary-Pleistocene the area has experienced isostatic and eustatic movements associated with neotectonics and climatic changes. Such history isrecorded in terraces at various altitudes (SO, 40, 20 m asl) and sequences of coastal sand ridges/baymouth bars. The Holocene variations in sea level and climate are recorded in the dated coastal ridges, coral reef and beachrock. Conditions suitable for reef development started about 8000 a BP. The GPR profiles also show that the internal structures of the sand ridges have composite nature being formed by several superimposed secondary ridges. 相似文献