共查询到20条相似文献，搜索用时 15 毫秒
1.
Loess mounds are made of gray-yellow loess materials and the number is over 200 in the area of over 1000 km2 on the alluvial or marine-built plains south of Laizhou Bay (Figure 1). 1 The formal and distributional characteristics of loess mounds 1.1 Formal characteristics The plane forms of loess mounds are irregular oval or round. Their major axes are in north-south trending, most of them are 300 to 500 m long, with smaller ones tens m long, and individual larger ones more than 1,000 m … 相似文献
2.
XUYong GUOTengyun YANGGuoan 《地理学报(英文版)》2005,15(1):53-60
The eco-environmental restoration has been a chief task of the western development strategies carried out by the central and local governments of China since the late 1990s, and the ecological de-farming has been regarded as a powerful measure for the ecological restoration in the Loess Plateau and the upper reaches of the Yangtze River. “Relieving and de-farming” (RD) and“rebuilding terrace and de-farming” (RTD) are two more mature ones among various de-farming modes. Taking the loess hilly-gully region as a case, this paper summarized the basic characteristics of RD and RTD modes, calculated the sizes of de-farming slope farmland, rebuilt terraces, enlarged garden plots and restored vegetation, and compared the differences of two modes in terms of de-farming area, ecological reestablishment index, investment demand amount and benefits. The results showed that RTD mode has many advantages, including suitable investment, sufficient grain supply and great benefits, and will be the best ecological reestablishment mode in the loess hilly-gully region, and RD mode which is being carried out in this region should be replaced by RTD mode as soon as possible. 相似文献
3.
Paleoenvironmental implications of new OSL dates on the formation of the “Shell Bar” in the Qaidam Basin,northeastern Qinghai-Tibetan Plateau 总被引：4，自引：0，他引：4
A geological feature in the Qaidam Basin known as the “Shell Bar” contains millions of freshwater clam shells buried in situ. Since the 1980s, this feature in the now hyper-arid basin has been interpreted to be lake deposits that provide evidence for a warmer and more humid climate than present during late marine isotope stage 3 (MIS 3). Global climate during late MIS 3 and the last glacial maximum, however, was cold and dry, with much lower sea levels. We re-investigated the feature geomorphologically and sedimentologically, and employed optically stimulated luminescence (OSL) dating to verify the chronology of the sediments. We interpret the Shell Bar to be a remnant of a river channel formed by a stream that ran across an exposed lake bed during a regressive lake phase. Deflation of the surrounding older, fine-grained lacustrine deposits has left the fluvial channel sediments topographically inverted, indicating the erosive nature of the landscape. Luminescence ages place the formation of the Shell Bar in MIS 5 (~113–99 ka), much older than previous radiocarbon ages of <40 ka BP, but place the paleoclimatic inferences more in accord with other regional and global climate proxy records. We present a brief review of the age differences derived from 14C and OSL dating of some critical sections that were thought to represent a warmer and more humid climate than present during late MIS 3. We attribute the differences to underestimation of 14C ages. We suggest that 14C ages older than ~25 ka BP may require re-investigation, especially dates on samples from arid regions. 相似文献
4.
Min Cao Fang Zhang Jianyi Yang 《International journal of geographical information science》2013,27(7):1349-1363
Cellular automata (CA) have been used increasingly to simulate complex geographical phenomena. This paper proposes a CA model for simulating the evolution of dynamic positive and negative (P–N) terrains in a small loess watershed. The CA model involves a large number of attributes, including the state of P–N terrains, distance to the shoulder-line, neighbourhood condition and topographic factors. Topographic factors include the slope gradient, aspect, slope length, slope variation, aspect variation, plan curvature, profile curvature, relief amplitude and flow accumulation. The CA model was applied to simulate the evolution of P–N terrains in an indoor, small loess watershed under artificial rainfall. The transition rules for CA were constructed automatically using a decision-tree algorithm. The derived transition rules are explicit for decision-makers and helpful for generating more reliable terrains. The simulation produces encouraging results in terms of numeric accuracy and spatial distribution, in agreement with natural P–N terrains. The iterative processes show that loess negative terrains continuously erode positive terrains. The development of a loess sinkhole near the centre gully head was reproduced as well, which shows the function of loess sinkholes in the formation of loess channel systems. 相似文献
5.
Journal of Geographical Sciences - The mountainous and hilly region plays an important role in ecological safety and production in China. However, recent studies have poorly characterized the... 相似文献
7.
我国是世界上采金最早的国家之一。大约四千多年以前，中国人已开始采金。商、周时代，掌握了黄金的冶炼和冷加工技术。汉、唐、宋、元、明、清各代，山东、黑龙江和云南等地，都出现过采金热潮。我国历史上采金以砂金为主。唐朝刘禹锡有一首名的《浪淘沙》词： 相似文献
8.
地理教学中存在着“点”、“线”、“面”三要素，与《福建省历年高中地理会考提要》中指出的3种能力要求一一对应。本文旨在通过三要素与3种能力的对应关系，阐述在高中地理教学中注意把握和理顺它们的关系，以全面提高地理教学的整体质量。 相似文献
9.
当前教师在创设教学情境上主要存在如下误解和偏差：重视认知性,忽视情意性;强调生活化,弱化地理性;追求真实性,误解虚拟性等。只有正确处理好三者的关系,才能营造出魅力四射、充满活力的课堂。 相似文献
10.
Xiang Chen Mei-Po Kwan 《International journal of geographical information science》2013,27(5):941-961
In classical time geography, an individual travel path is composed of a chain of visits, with each visit being a flexible activity between two fixed activities at two known stations. In reality, individuals tend to carry out trips with much variation and complexity, with multipurpose trips being a prominent and pervasive phenomenon. There is limited research to date on multipurpose trips in time-geographic analysis by geographic information system (GIS) scientists, or more specifically, multiple flexible activities between two fixed stations. To fill this gap, this article proposes four models for identifying the choice set with multiple flexible activities under space–time constraints. The models are derived through set-theoretic formalism based on the concept of trip chaining. The structure of the four models establishes a theoretical framework for conceptualizing trip-chaining behaviour with respect to the fixity of activities and the number of fixed stations as destinations or origins. They provide fundamental and rigorous apparatus for studying complex individual activity–travel patterns in many applied contexts when multipurpose trips are involved. This article also describes implementation of the models with a real transportation network as a way of validation. 相似文献
11.
12.
《土地管理法》第四十三条规定:"任何单位和个人进行建设,需要使用土地的,必须依法申请使用国有土地;但是,兴办乡镇企业和村民建住宅经依法批准使用本集体经济组织农民集体所有的土地的,或者乡(镇)村公共设施和公益事业建设经依法批准使用农民集体所有的土地的除外。前款所称依法 相似文献
13.
正新疆哈密市位于新疆维吾尔自治区最东端,91°06′33″E～96°23′00″E,40°52′47″N～42°49′00″N。东部、东南部与甘肃省酒泉市肃北县、安西县、敦煌市为邻;南接巴音郭楞蒙古自治州若羌县;西部与吐鲁番地区鄯善县毗邻;北接天山与伊吾县、巴里坤县为邻,总面积84977平方千米。哈密市建设能源基地的思路是"煤"飞"色"舞,"风""光"无限,产业配套、科学发展。"煤"飞指的是作为能源之都,要实现煤的二次转换,"煤从空中走,电送全中国"。"色"舞指的是哈密的有色金属,随着东天山有色金属成矿带被列入西部大开 相似文献
14.
一、设计思路
上海市地理课程标准指出“国家地理的介绍不必面面俱到,要突出国家间自然与人文的特征性差异。如有的可突出其人文特征,有的可突出其自然特征;有的可突出其地理位置的优势;有的可突出其风土人情; 相似文献
15.
最近一个时期,我国江苏、广东、江西、浙江、广西、四川等地相继出现地表局部塌陷形成坑洞的情况,有网友戏称为“天坑”。而地球的另一端似乎也不平静,南美洲危地马拉也出现了一个直径30米的巨大“天坑”。 相似文献
16.
历史上的首尔
有“汉江畔明珠”美称的首尔是座历史悠久且拥有众多称谓的城市。经考古专家对汉江两岸出土的大批石器和陶器的考证，在新石器时代，首尔周边地区就有人居住。朝鲜半岛三国鼎立时代，即公元前18年百济王朝在此建都，始称慰礼城，意为“我们的城”。公元392年和475年，来自北方的高句丽占领此城，475年改称南平壤，因位于平壤以南而得名。高句丽王朝在行政管理上于474年曾在此设置北汉山郡。而后统一的新罗时代，即相当于我国唐朝年间，新罗真兴王16年，称为汉山州；景德王时即公元757年改称汉州。公元904年又改称杨山。 相似文献
17.
18.
著名的农民画之乡——陕西省户县的“户”字,原来的写法为“”(读音与“户”同[hu])。1964年,经陕西省人民委员会报请国务院批准,改“县”为现在今使用的“户县”。“县”改为“户县”,还得从郭沫若先生的一篇文章说起。1964年5月3日,《人民日报》发表了郭沫若先生的长篇文章《日本的汉字改革和文字机械化》。文章提出:“应该大力压缩通用汉字的数量”,“好些生僻字眼的地名,请把它们改换成同音的常用字”。当时,胡乔木同志在杭州休养,看了郭老文章以后,就给当时的中共中央西北局书记刘澜涛写了一封信说:郭老意见很好,陕西就有不少难认难读… 相似文献
19.
以健康养生为特色,集度假、休闲、健身于一体的温泉旅游,已成为市场热点,温泉经济更被称之为朝阳产业中的朝阳。目前,拥有丰富温泉资源的辽宁正在倾力打造“全国温泉旅游第一大省”。而久负盛名的大连成园温泉山庄则以鲜明的特色和优势,成为辽宁温泉产业发展的样板之一。 相似文献
20.