排序方式: 共有30条查询结果,搜索用时 948 毫秒
11.
曹有挥 《安徽师范大学学报(自然科学版)》1999,(1)
旨在探讨长江下游集装箱港口体系的基本格局、功能结构与发展特征.文章首先阐述了全球集装箱运输的基本格局和长江下游集装箱港口体系的发展现状;然后通过对该集装箱港口体系的流量、流向结构分析,认为现阶段该港口体系仍属东亚一些大型远洋集装箱枢纽港口的支线港群,体系内部的职能分工机制开始发育,但尚不完善;最后采用系统动力学模型对长江下游集装箱港口体系的集装箱吞吐量进行了预测,预测结果表明,该集装箱港口体系的发展现状远不适应形势发展的需要,未来该港口体系将形成以上海港为中心枢纽港、江苏四港为干线喂给港的相互协调、功能互补的远洋集装箱枢纽港群 相似文献
12.
13.
<正>别名:锅鹤、玄鹤分布:内蒙古、乌苏里江流域繁殖;长江下游越冬(国家一级保护动物)大型涉禽。全长约100厘米。体羽主要为暗石板灰色,并缀有褐色。眼部、额和前顶有密集的黑色刚毛;头顶皮肤裸露部为朱红色;头部其余部分 相似文献
14.
吴越文化概述 总被引:14,自引:0,他引:14
董楚平 《杭州师范学院学报(社会科学版)》2000,(2):10-13
吴越文化是长江下游的区域文化 ,其中心文化区是太湖、钱塘江流域。七千年间 ,吴越文化的民族性发生过沧桑巨变 ,楚败越以前基本上是夷越文化 ,秦灭越后基本上是汉族文化。民族性格前后有别 ,不可混为一谈 ,《汉书 .地理志》的说法不可信从。上下七千年的广义吴越文化 ,仍有共同的个性特征 ,那就是 :柔、细、雅。从汉代到明清 ,吴越地区多出科技、文艺人才 ,缺乏军政雄才。《红楼梦》是吴越文化的样品 相似文献
15.
16.
长江下游地理信息系统的渔业资源生物多样性研究 总被引:1,自引:0,他引:1
根据2004年4~6月长江下游9个采样点的渔获数据,利用Shannon-wiener指数公式计算得到长江下游渔业资源的信息指数值.在GIS的支持下利用数据插值、分级、栅格图形加权平均和数学运算模型等空间分析方法对长江下游渔业资源生物多样性进行了综合的分析和评价.结果表明,南通以下江段渔业资源多样性指标的分级地位是比较低的,南通以上江段渔业资源多样性指标的分级地位相对较高. 相似文献
17.
沉积物中保留下来的信息载体可较准确地反映古环境变化,沉积物粒度与磁化率是沉积物中反映沉积环境变化的重要指标.研究了长江下游南通段河漫滩沉积剖面的粒度和磁化率特征,由此识别出长江下游南通段现代洪水事件.粒度分析表明,样品偏态系数为负偏,表明沉积物粒径总体相时较大,反映水流量大,搬运能力强.根据砂、粉砂、粘土百分含量变化,可将剖面分6层,呈粗-细-粗-细-粗-细变化.这与磁化率特征是一致的,磁化率呈高-低-高-低-高-低变化.将磁化率、中值粒径和近百年降水量变化对比分析发现,磁化率与沉积物中值粒径呈负相关关系.而沉积物粒度与降水量呈正相关关系.推断第1、3、5层的沉积特征指示该阶段水量较大(洪水期),第2、4、6层沉积特征指示水量较小,约130 a以来长江下游南通段至少发生3次较大的洪水,其中第5沉积层对应的洪水规模可能最大. 相似文献
18.
Zircon U-Pb geochronology of the volcanic rocks from Fanchang-Ningwu volcanic basins in the Lower Yangtze region and its geological implications 总被引:3,自引:0,他引:3
Jun Yan HaiQuan Liu ChuanZhong Song XiSheng Xu YaJun An Jia Liu LiQun Dai 《科学通报(英文版)》2009,54(16):2895-2904
The latest eruptions in two important Mesozoic volcanic basins of Fanchang and Ningwu located in the middle-lower reaches of the Yangtze River formed the bimodal volcanic rocks of the Kedoushan Formation and ultrapotassic volcanic rocks of the Niangniangshan Formation, respectively. The representative volcanic rocks of the two Formations were selected for LA-ICPMS zircon U-Pb dating. The results indicate that there exist a large amount of magmatic zircons as indicated by high Th/U ratios in these volcanic rocks. The weighted mean age of 21 analyses is 130.7±1.1 Ma for the Kedoushan Formation, and that of 20 analyses is 130.6±1.1 Ma for the Niangniangshan Formation. These U-Pb ages are interpreted to represent the formation times of the volcanic rocks. In combination with other known geochronological data for Mesozoic volcanic rocks from the Lower Yangtze region, it is proposed that the latest volcanic activations in the Jinniu, Luzong, Fanchang and Ningwu volcanic basins probably came to end prior to ca. 128 Ma. There is no significant time interval between the early and later volcanic activities in the Luzong and Ningwu basins, suggesting a short duration of volcanic activities and thus implying the onset of an extensional tectonic setting at about 130 Ma in the Lower Yangtze region. Integrated studies reveal that the Early Cretaceous magmatic activities and their geochronological framework in the Lower Yangtze region are a response to progressively dynamic deep processes that started with the transformation of tectonic setting from compression to extension, followed by delaminating of the lower part of the thickened lithosphere, lithospheric thinning, asthenosphere upwelling, and crust-mantle interaction. 相似文献
19.
20.