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41.
国际贸易地理研究进展 总被引:1,自引:0,他引:1
全球化时代的技术进步和贸易自由化似乎逐渐将世界经济连为一体,但研究发现国际贸易仍然显著地受到地理因素影响。与此同时,经济地理学对国际贸易地理的理论建构存在欠缺,其对国际贸易研究的贡献目前集中于对国际贸易地理格局和贸易网络异质性的描述分析上。在此背景下,论文从生产、流通和消费3个方面归纳国际贸易研究对地理因素作用的理论建构和实证研究:① 生产上的地理差异经由机会成本差异促进贸易;② 流通上的地理差异经由贸易成本而抑制贸易;③ 消费上的地理差异经由市场需求地空间差异而影响贸易。通过总结贸易与制度变迁、贸易与集聚、贸易与不平等、贸易与创新、贸易与污染间的关系相关研究,论文认为当前国际贸易研究存在如下局限:① 并未深入讨论地理变量的内生性,即贸易可能反过来塑造地理差异而非仅由地理变量决定;② 相对缺乏多尺度、跨尺度视角,即贸易理论预测的宏观尺度贸易利得在中观、微观主体上并非均等分配,表现出显著的空间差异;③ 部分研究对产品异质性缺乏探讨,无法全面刻画贸易的差异化地理效应。据此,经济地理学未来对国际贸易研究的贡献可能在于运用多尺度、跨尺度联系的视角深入阐释贸易与地理的多维度异质性和复杂互动。 相似文献
42.
We evaluate three approaches to mapping vegetation using images collected by an unmanned aerial vehicle (UAV) to monitor rehabilitation activities in the Five Islands Nature Reserve, Wollongong (Australia). Between April 2017 and July 2018, four aerial surveys of Big Island were undertaken to map changes to island vegetation following helicopter herbicide sprays to eradicate weeds, including the creeper Coastal Morning Glory (Ipomoea cairica) and Kikuyu Grass (Cenchrus clandestinus). The spraying was followed by a large scale planting campaign to introduce native plants, such as tussocks of Spiny-headed Mat-rush (Lomandra longifolia). Three approaches to mapping vegetation were evaluated, including: (i) a pixel-based image classification algorithm applied to the composite spectral wavebands of the images collected, (ii) manual digitisation of vegetation directly from images based on visual interpretation, and (iii) the application of a machine learning algorithm, LeNet, based on a deep learning convolutional neural network (CNN) for detecting planted Lomandra tussocks. The uncertainty of each approach was assessed via comparison against an independently collected field dataset. Each of the vegetation mapping approaches had a comparable accuracy; for a selected weed management and planting area, the overall accuracies were 82 %, 91 % and 85 % respectively for the pixel based image classification, the visual interpretation / digitisation and the CNN machine learning algorithm. At the scale of the whole island, statistically significant differences in the performance of the three approaches to mapping Lomandra plants were detected via ANOVA. The manual digitisation took a longer time to perform than others. The three approaches resulted in markedly different vegetation maps characterised by different digital data formats, which offered fundamentally different types of information on vegetation character. We draw attention to the need to consider how different digital map products will be used for vegetation management (e.g. monitoring the health individual species or a broader profile of the community). Where individual plants are to be monitored over time, a feature-based approach that represents plants as vector points is appropriate. The CNN approach emerged as a promising technique in this regard as it leveraged spatial information from the UAV images within the architecture of the learning framework by enforcing a local connectivity pattern between neurons of adjacent layers to incorporate the spatial relationships between features that comprised the shape of the Lomandra tussocks detected. 相似文献
43.
价值链的空间重组正在深刻的改变着城市体系的经济景观,建立在价值链分工基础上的城市功能结构的研究已经成为经济地理学的重要课题。将中国上市公司500强企业网络划分为公司总部、商务服务、研究开发、传统制造、现代制造、物流仓储和批发零售七种类型功能区块,研究了中国城市价值链功能分工及其影响因素。结果发现:沿着价值链的功能分工已经成为中国城市体系经济景观的显著特征,功能多样化城市和功能专业化城市并存于中国城市体系,东部地区和城市密集地区的城市在价值链分工中占据了更好的地位;中国城市按照价值链中的优势功能可以划分为九种类型,少数城市转变为承载公司总部、研究开发、商务服务等多样化功能的高等级中心城市,而大量中小城市则转变为传统制造专业化基地;市场潜力、关键资源、区位条件、营商环境等城市属性特征是城市功能分工的重要影响因素,城市资源、区位可达性等属性特征的增强将提高城市成为总部基地、商务中心和研究基地的概率,而降低城市成为传统制造基地的概率。 相似文献
44.
城市的快速扩张诱发并加剧了城市热岛效应,对人类健康和生存发展提出严峻挑战,因此,探索城市组成对城市热岛的影响具有重要意义。本研究在传统城市热岛影响因子的基础上,重点分析城市组成与城市热岛的关系。以13个中国大城市为研究区,利用2015年夏季(6-8月)白天和夜间的MODIS LST数据计算城市热岛强度,并结合土地覆盖数据、人口、区位和气象数据,分析热岛强度和城市地表组成、地表空间格局、人口和区位4类因子的关系。研究结果表明:中国的13个大城市均存在不同程度的热岛效应,城市白天的热岛效应比夜间显著。影响城市白天热岛强度的主要因子为城市建筑用地和林地面积比例、城市建筑用地和林地平均斑块面积、城市建筑用地聚集度和人口密度。城市建筑用地和林地平均斑块面积、城市建筑用地聚集度和林地斑块密度是夜间热岛强度的主要影响因子。城市建筑用地面积和乡村林地面积的增加会导致城市热岛情况的加剧,而通过调节城市地表空间格局(减少平均建筑用地斑块面积和降低建筑用地斑块聚集度)可以更好地降低城市地表温度,减缓城市热岛效应。 相似文献
45.
Material dematerialization is a basic approach to reduce the pressure on the resources and environment and to realize the sustainable development. The material flow analysis and decomposition method are used to calculate the direct material input (DMI) of 14 typical mining cities in Northeast China in 1995-2004 and to analyze the demateri-alization and its driving factors in the different types of mining cities oriented by coal, petroleum, metallurgy and multi-resources. The results are as follows: 1) from 1995 to 2006, the increase rates of the DMI and the material input intensity of mining cities declined following the order of multi-resources, metallurgy, coal, and petroleum cities, and the material utilizing efficiency did following the order of petroleum, coal, metallurgy, and multi-resources cities; 2) during the research period, all the kinds of mining cities were in the situation of weak sustainable development in most years; 3) the pressure on resources and environment in the multi-resources cities was the most serious; 4) the petro-leum cities showed the strong trend of sustainable development; and 5) in recent years, the driving function of eco-nomic development for material consuming has continuously strengthened and the controlling function of material utilizing efficiency for it has weakened. The key approaches to promote the development of circular economy of min-ing cities in Northeast China are put forward in the following aspects: 1) to strengthen the research and development of the technique of resources' cycling utilization, 2) to improve the utilizing efficiency of resources, and 3) to carry out the auditing system of resources utilization. 相似文献
46.
近年来我国城市地理学主要研究领域的新进展 总被引:16,自引:0,他引:16
本文对改革开放以来中国城市地理学研究的新进展作了综述,尤其注重新领域的进展和主要观点的概括。本文涉及的主要领域包括:(1)城市化研究;(2)城市发展方针的研究;(3)城市体系研究;(4)城市内部空间结构研究。最后,在研究展望中作者指出,在社会主义市场经济体制下,应开展城市土地和住房以及国际大都市的研究。 相似文献
47.
Janice Monk 《The Professional geographer》1994,46(3):277-288
Feminist geography is now widely practiced internationally, but its development is usually reviewed from a temporal rather than a spatial perspective. This article assesses the varying extent and nature of feminist geography across countries, attempting to interpret differences in terms of cultural contexts and disciplinary trends. It is intended to stimulate reflection and does not claim to offer definitive interpretations. 相似文献
48.
这次会议是进入新世纪我局第一次工作会议,是一次总结过去,谋划未来的重要会议,开好这次会议对我局在新世纪实现新发展有着十分重要的意义.会议的主要内容是认真学习温家宝副总理的重要讲话精神,总结回顾"九五"地矿工作改革发展的基本情况,讨论修改我局"十五"改革发展纲要、"十五"前三年经济责任制考核办法和精神文明建设考核办法,安排部署2001年工作.下面我代表局党组作工作报告. 相似文献
49.
Many tens of severe earthquake damage patterns were revealed at the ancient city of Ayla. The seismic deformation patterns
are of various types, including systematic tilting of walls, systematic shifting and rotation of wall fragments and individual
stones, arch deformations and joints crossing two or more stones. Features of later repair, supporting walls and secondary
use of building stones suggest that the damage patterns can be explained by two historical devastating earthquakes: (I) revealed
in the constructions built during the late Rashidun period (644–656 A.D.); (II) revealed in the structures restored and/or
built during the Fatimid period (1050–1116 A.D.). The maximum observed intensity of both earthquakes at the studied site was
not less than IX (EMS98 scale). The sources of the seismic events were probably the Dead Sea Transform and Wadi Araba Faults
that cross the site obliquely. The last 1995 Nuweiba earthquake with maximum observed intensity VIII has also left its clear
traces in the excavated ancient Ayla buildings. The severity of the destruction was significantly increased because of site
effects. 相似文献
50.
Michael C. Ewers 《GeoJournal》2007,68(2-3):119-130
Urban areas compete with one another for people, goods, capital, ideas and other inputs of economic activity. Under the rubric
of globalization, instead of only maintaining or improving the initial stock of assets in a city, the power of a place to
attract outside flows of economic activity from elsewhere is increasingly important to economic development. Similarly, global
or world cities are characterized as the command and control points through which these global economic flows operate. In
response to the heightened mobility of highly-skilled labor across national borders, research has begun to examine the role
of international human capital as an economic flow. This paper will examine the role of places in determining where the highly-skilled
go in the global economy by viewing global city command and control functions as requiring unique labor flows. By reviewing
the evidence found in the literature, we can better understand the potential for urban areas to compete for highly-skilled
labor in the global economy. Known indicators of place attractiveness are assessed to examine the relationship between the
economic trajectories of cities and their labor requirements. Cities are situated between firms and states as the key place-based
actors which influence the mobility of highly-skilled labor. Finally, the paper also examines measurement issues and methodological
problems in creating indices of world cities as well as explores possibilities for new research. 相似文献