塔干柽柳的叶绿素荧光对沙尘暴天气的响应

 塔干柽柳(Tamarix taklamakanensis)是塔里木沙漠公路防护林主要树种之一,其光合作用和生长受到近年来频发沙尘暴的影响,这直接影响到沙漠公路的安全,为了确定这一影响的程度,利用叶绿素荧光测定仪PAM-2100,于2009年7、8月间,在塔克拉玛干沙漠腹地测定了典型沙尘暴前后塔干柽柳的叶绿素荧光参数的日变化,并计算沙尘暴前后塔干柽柳对光合能量的吸收和耗散比例,以此确定其能量利用策略的变化。结果表明,8月沙漠腹地正常天气下,柽柳以3种形式:Y(Ⅱ),Y(NO)和Y(NPQ)吸收利用散失的能量比例为40%∶20%∶40%,沙尘暴次日3者的比例为65%∶15%∶20%,沙尘暴使得吸收能量的比例增加,提高了吸收利用的光能;利用NPQ机制主动耗散多余能量增加耗散能量的比例,防止光合机构损伤;基本的结构性散失能量的比例稍稍下降,但基本保持稳定。沙尘暴可能造成物理上的破坏,但没有影响其光合机构的健康。降低吸收能量比例、保持较高NPQ机制散失能量以及维持结构性散失能量比例的相对稳定,是塔干柽柳耗散多余光能的重要能量调控手段,是长期适应沙漠腹地环境的结果。     

中国区域虚拟水战略优势度评价

提出虚拟水战略优势度的概念并对其概念内涵及影响因素进行分析,从4个方面构建包含12个具体指标的综合定量评价指标体系;运用数学方法对中国31个省级行政区虚拟水战略优势度进行定量评价.发现中国虚拟水战略优势度存在显著的地域差异,区域优势度等级存在"两头多,中间少"的结构特点和"东部高、西部低","南部和北部高、中间低"带状空间分布规律.其中北方4省市和东南8省区优势度最大,是全球虚拟水战略背景对其影响最深远的区域,也是中国虚拟水研究及虚拟水战略实践的关键区域.     

聚落形态演变与防洪功能变化的关系——以广东高要地区为例

高要地区特殊的地理环境与气候条件造成了历来严重的洪涝灾害。其历史洪水淹浸区和历史堤防范围等历史地理环境与该地区的“八卦”形态聚落分布存在着特殊的“同构”现象。通过图解分析与逻辑推理,解读了“同构关系”的内在成因：“八卦”形态是聚落防洪的最优形态;由于民国以前的高要地区区域防洪未完善,因此位于西江南岸缺乏堤防保护的洪涝区域内大量聚落采用了“八卦”形态的聚落被动防洪方式。高要地区“八卦”形态聚落分布与历代成堤区域的同构关系说明了区域防洪方略与聚落被动防洪方略互为补充、此消彼长的辩证关系。在区域防洪设施未完善的时代,聚落被动防洪方略作为防洪方略的重要补充,导致了聚落的特殊形态;而在区域防洪设施基本完善、有效保护聚落免受洪涝灾害影响的今天,聚落被动防洪方略的存在意义大为减弱,“八卦”形态逐渐瓦解改变。这是聚落形态演变的一个重要动因。区域防洪问题解决后,大量聚落不断地向低洼地区延伸,与当初的被动防洪方略已经互相矛盾。这种扩张是非理性、无序型的扩张。当前对聚落防灾的轻视心态,埋下了洪涝灾害的隐患。     

Implementation methods and economic impacts of national node strategies

Pilot reforms gradually implemented through key nodes have become an important pattern of regional development in China since the policy of reform and opening up was introduced in 1978. On the basis of an analysis of the evolution processes and characteristics of regional development policies in post-reform China, this paper develops the concept and analytical framework of national node strategies (NNS), defined as regional development strategies centered on specific spatial nodes, by addressing their theoretical basis and research scope. The regional economic impacts of NNS were explored quantitatively through the examples of the Shenzhen Special Economic Zone, Pudong New Area and Tianjin Binhai New Area in different stages of the reform and opening up. The results indicate that the evolution of China’s regional development policies can be divided into three stages: the exploration stage led by Special Economic Zones (SEZs), the expansion stage dominated by Economic Development Zones and the optimization stage featuring State-level New Areas and National Comprehensive Reform Pilot Areas. During all the three stages, NNS have played an important demonstrative and leading role and promoted the rapid evolution of China’s regional development policies from localized to widespread implementation, and the role of the government has also changed accordingly. As an innovative application and development of the growth pole theory in transitional China, NNS have become engines of regional development as well as important conduits of institutional innovations. NNS and regional development have achieved a benign coupling and formed a gradated regional development model. Empirical research indicates that NNS are an important method used by the government to guide and regulate regional economic development, with complex and diverse economic effects that differ depending on the stage of regional development and the spatial scale of analysis.     

Regional Evolution Features and Coordinated Development Strategies for Northeast China

1 Introduction Northeast China consists of the three provinces of Heilongjiang, Jilin and Liaoning. Since the founding of the People's Republic of China in 1949, this region has supported the whole country with huge quantity of grain, raw materials, primary products, and heavy industrial products at the cost of environment and resources, and thereafter became an old industrial base as well as an important marketable grain base in the whole country (Zhang et al., 2004). However, since the 19…     

论机检英文文献检索词的选取策略

英文文献计算机检索已发展到通过检索词匹配来实现,检索词的选取恰当与否直接影响着检全率和检准率。针对如何根据检索主题的要求及英语的语言特点,利用本专业知识、文化取向和检索知识选取英文文献计算机检索词,提出了选取英文文献计算机检索词的原则以及主题、英美语的差异等选取检索词的方法和技巧。     

全球价值生产的空间组织：以苹果手机供应链为例

采用2012年与2019年苹果手机全球供应商数据,基于GPN 2.0的相关理论建立分析框架,探索苹果手机全球生产网络中主要行动者类型、行动者策略、进入与退出动态、地理分异性、网络动力机制和战略耦合机制。该网络主要行动者是美国、日本、韩国、中国大陆、中国台湾省,布局全球生产网络的热点地区在亚洲;网络中有六类行动者,行动者策略是企业间控制与企业间合作,网络产生和演化的动力机制为成本-能力比率、市场需要、金融约束和风险环境,主要行动者通过本土创新、国际合作关系和生产平台战略耦合机制嵌入苹果手机的全球生产网络。最后,从转型创新模式、孵化自主供应链角度对中国行动者产业升级提出对策建议。     

长江经济带战略的背景及创新发展的地理学解读

国务院发布的《关于依托黄金水道推动长江经济带发展的指导意见》,是中央政府首次系统提出的覆盖长江流域的经济社会发展规划与建设意见,不仅是沿岸省市社会经济创新发展的指导文件,更是站在国家高度,应对国际政治经济格局发生深刻变化和国内社会经济发展面临重大历史转折的形势而提出的国家创新发展战略。本文首先分析了长江经济带战略提出的历史和经济地理背景,解读了国务院指导意见中有关长江经济带战略定位和发展重点,认为该战略的提出既是中国区域经济发展的历史必然,也是国家进入经济新常态的现实需要,具有鲜明的时代性、国际性。文章回顾了以往地理学界在长江资源开发和保护、社会经济发展中作出的重要贡献,提出了要进一步加强对长江经济带资源潜力和环境容量、空间结构调整、经济与环境协调发展等科学问题的研究。     

Advances in the Effects of Wind on Plants

Wind is a important factor. It can strongly affect development, growth and reproduction of terrestrial plants. The plant in wind environment can adapt to wind by special mechanism to decrease damage. This paper reviews the effects of wind on plant in phenotype, anatomy and root archetecture. Some plant species show a resistance strategy, but other species show an avoidance strategy. After the analysis of the restriction of current research in this area, the authors suggest that studies in the area should be extended to taking the whole plant as an integrated system rather than focusing on specific tissue level. Furthermore to understand the general mechanism across species, it is required to study different species from different environmental conditions. Advances in bioinformatics, molecular and physiological research will facilitate cross disciplinary studies to understand the complicated responses of plants to wind.     

石羊河下游农户的生计风险及应对策略——以民勤绿洲区为例

石羊河下游农户面临着严峻的风险冲击,使其生计脆弱性加剧。当前急需辨明农户面临的主要风险,探索阻碍农户抵御风险冲击的潜在因素,并依此找寻提高农户风险应对能力的对策措施。基于入户调查数据,分析了石羊河下游民勤绿洲区农户面临的主要生计风险及应对策略,并采用多元logistic模型分析了影响风险应对策略选择的因素。结果发现:1市场、教育及自然风险已成为农户面临的最主要生计风险,其中纯农户(全部劳动力均从事农业生产)与一兼户(非农收入比重50%)主要面临市场、教育及自然风险,二兼户(50%≤非农收入比重90%)为市场、健康及教育风险,非农户(非农收入比重≥90%)为教育、健康及养老风险;2减少消费、外出打工、动用储蓄、向亲友寻求帮助、向银行借贷是农户应对风险的主要策略,其中非农户的首选策略中居首位的是外出打工,其他三类农户均为减少消费;3人力资本、金融资本、社会资本是影响农户风险应对策略选择的最重要因素,物质资本次之,自然资本的影响最弱。最后,提出了提高农户风险应对能力的对策建议。