区域性地震过程对中国大陆洪水影响之初探     

姚清林 《气象与减灾研究》2008,31(4):34-42

为探讨地震、洪水（暴雨）间可能存在的链状关系,以1979--1990年为例,对中国及周围区域肘≥7地震的活动格局与中国大陆洪涝灾害的时空分布特征进行了分析研究。结果发现：类似于2005年西江洪水,不少大洪水（暴雨）也位于地震迁移线上或其附近。洪涝的发生时间有可能与震链的后震或前震比较接近,或与震链推移之进程基本吻合,反映了链程中的场态效应。震链之进程往往构成三角之类的几何体或兼具振荡特征,所围限区域在气象条件允许时,有可能发生强降雨;中国大陆若完全在“几何体”,可能当年洪涝灾害相对较弱。洪涝（暴雨）并非都与地震有关。某些震链“几何体”对降雨的影响可能与季风有关。强震对降雨往往有时空近程影响。震群或震链多线程指向点、端点、交会点、角夹持地带可能加剧洪涝。震链回迁或转折处往往是不同体系、单元、性质构造的复合点,震源应力变异点,形态与活动方式复杂。  相似文献   

我国近海生态系统食物产出的关键过程及其可持续机理   总被引：1，自引：0，他引：1  

唐启升  苏纪兰  张经 《地球科学进展》2005,20(12):1280-1287

围绕国家重点基础研究发展计划（973计划）项目“我国近海生态系统食物产出的关键过程及其可持续机理”,介绍了海洋可持续生态系统研究对我国社会与科技发展的意义、研究现状和发展趋势、拟解决的关键科学问题和预期目标,以及研究实施计划。该项研究的最终目标是从人类活动和自然变化两个方面认识我国近海海洋生态系统服务与产出功能,量化其生态容纳量及动态变化,预测生态系统的承载能力和易损性,寻求我国近海海洋可持续开发利用与资源环境相协调发展的途径。  相似文献   

A comparative analysis of multi-scalar regional inequality in China     

《Geoforum》2017

This paper investigates regional inequality across regions, provinces, prefectures, and counties in China from 1997 to 2010 using a comparative and multiscalar framework. Regional inequality is sensitive to geographic scales and regional heterogeneity. The year 2004 was a turning point for trends in inequality, when a new spatial regime started to emerge at the county-level in China. County-level inequality demonstrates a consistent upward trend despite a slight dip in 2005, which is different from a broad inverted U-shape trend at other geographic scales. Furthermore, intensifying inequalities are demonstrated between prefectures than within prefectures, within provinces than between provinces, and between regions than within regions. The underdeveloped Western region of China contributes the most to regional inequalities across counties and prefectures. Based on the heterogeneous characteristics of regional inequality, it is suggested that effective regional policies should adopt a geographic focus to reduce inequalities. Finally, a Markov chain technique is applied to predict the long-run properties of regional development in China. The results show that it is difficult for counties, prefectures and provinces to leapfrog from being less developed to well developed. This paper concludes that regional inequality in China in the long-run does not follow the neoclassical convergence hypothesis.  相似文献   

黄河流域水资源-能源-粮食的协同优化   总被引：3，自引：0，他引：3       下载免费PDF全文

彭少明  郑小康  王煜  蒋桂芹 《水科学进展》2017,28(5):681-690

黄河流域是中国重要能源和粮食主产区,然而水资源短缺已成为制约能源、粮食发展的关键要素。为优化流域水资源、能源、粮食之间的关系,引入协同学原理构建水资源-能源-粮食整体分析框架,建立具有总分结构、互馈关联的协同优化模型,采用多要素均衡智能算法,提出黄河流域粮食生产、能源开发与水资源调配一体优化的布局方案。结果表明,通过水资源-能源-粮食协同优化,2030年增加流域供水量23.98亿m3;优化了流域粮食生产布局,人均粮食产量提高12%;优选了能源产业规模和结构,煤炭开采、石油加工和火电总装机分别增加了2.86倍、4.08倍和0.80倍;在满足生活、生态环境用水的同时实现了粮食增收、能源增产。  相似文献   

深圳沿岸海域贝类重金属和贝类毒素污染状况分析          下载免费PDF全文

孙冉  王舟 《应用海洋学学报》2017,36(4):575-579

通过检测深圳沿岸海域7种贝类的重金属、麻痹性贝毒(PSP)和腹泻性贝毒(DSP)含量,了解其食用安全性.严格按照国家标准进行检测,采用SPSS 20.0对数据进行Kruskal-Wallis H检验和方差分析.结果表明:各种重金属和贝类毒素在样品中均有检出,汞污染状况良好;铜含量范围为0.52~109.65 mg/kg,超标率为13.67%;铅含量范围为0.01~3.60 mg/kg,超标率为68.35%;镉含量范围为0.015~7.807 mg/kg,超标率为53.96%.PSP和DSP检出率为100%,PSP含量范围为0.30~34.23 ug/100 g;DSP含量范围为1.88~38.41 ug/100 g.总体看来,样品铅、镉超标严重,不同种类贝类重金属含量具有差异且贝类毒素检出率较高,应引起有关部门的重视,加强该海域监测工作.  相似文献   

Food commodities, geographical knowledges and the reconnection of production and consumption: The case of naturally embedded food products   总被引：1，自引：0，他引：1  

Carol Morris  James Kirwan 《Geoforum》2010,41(1):131-143

This paper focuses on a particular group of food commodities, associated with the wider turn to ‘alternative food networks’, that are described as ‘naturally embedded food products’ (NEFPs). These are commodities (specifically meats and cheeses) that utilise grassland biodiversity as an input into production to positively influence, in various ways, the final qualities of the commodity. Building on the geographical literature on commodity circuits and analysing data derived from NEFP promotional materials and focus groups with urban and rural residents in the UK, the paper interrogates the geographical knowledges that are deployed by producers in the promotion of NEFPs and how these knowledges are accommodated and contested by consumers as they bring their own geographical knowledges to the interpretation of these commodities. The paper undertakes this task in order to problematise the extent to which alternative food networks in general and NEFPs in particular are bringing about a reconnection of producers and consumers and, concomitantly, a defetishisation of food, as is claimed for them by many of their policy and academic proponents. In the process the paper reveals how the food commodities associated with alternative food networks entail the creation of new and rival fetishes paradoxically as a result of efforts to ‘thicken connections’ between the production and consumption of food.  相似文献   

北京电子信息产业及其价值链空间分布特征研究   总被引：4，自引：1，他引：3  

卢明华  李丽 《地理研究》2012,31(10):1861-1871

作为主导产业部门之一的电子信息产业在北京具有较强的产业实力及较好的发展前景。本研究通过分析电子信息产业和大型电子信息企业主要价值链环节在北京的分布情况, 总结了电子信息产业及其价值链的空间分布特征。研究发现:北京市电子信息产业郊区化趋势明显且呈集聚分布, 大型电子信息企业主要价值链环节也呈集聚分布, 生产环节的远郊化明显, 呈现多中心空间结构;北京市主要电子信息产业集聚区呈现明显的功能分工、大型电子信息企业主要价值链环节呈现明显的区域分工。  相似文献   

旅行社供应链管理模式研究     

包曾婷  王虹 《云南地理环境研究》2012,24(1):92-97

随着旅游业的快速发展及旅游企业竞争的日趋激烈,旅行社供应链管理已成为旅行社与其他旅游企业提升市场核心竞争力,实现行业利润最大化的重要途径。在对旅行社实施供应链管理必要性分析的基础上,构建了旅行社供应链管理模式,并对其运作机理分为两个流程进行详细分析,以期为旅行社实施供应链管理提供一定的借鉴,推动整个行业的健康发展。  相似文献   

Photochemistry in the Arctic Free Troposphere: Ozone Budget and Its Dependence on Nitrogen Oxides and the Production Rate of Free Radicals     

Craig Stroud  Sasha Madronich  Elliot Atlas  Christopher Cantrell  Alan Fried  Brian Wert  Brian Ridley  Fred Eisele  Lee Mauldin  Richard Shetter  Barry Lefer  Frank Flocke  Andy Weinheimer  Mike Coffey  Brian Heikes  Robert Talbot  Donald Blake 《Journal of Atmospheric Chemistry》2004,47(2):107-138

Local ozone production and loss rates for the arctic free troposphere (58–85° N, 1–6 km, February–May) during the TroposphericOzone Production about the Spring Equinox (TOPSE) campaign were calculated using a constrained photochemical box model. Estimates were made to assess the importance of local photochemical ozone production relative to transport in accounting for the springtime maximum in arctic free tropospheric ozone. Ozone production and loss rates from our diel steady-state box model constrained by median observations were first compared to two point box models, one run to instantaneous steady-state and the other run to diel steady-state. A consistent picture of local ozone photochemistry was derived by all three box models suggesting that differences between the approaches were not critical. Our model-derived ozone production rates increased by a factor of 28 in the 1–3 km layer and a factor of 7 in the 3–6 kmlayer between February and May. The arctic ozone budget required net import of ozone into the arctic free troposphere throughout the campaign; however, the transport term exceeded the photochemical production only in the lower free troposphere (1–3 km) between February and March. Gross ozone production rates were calculated to increase linearly with NO_x mixing ratiosup to 300 pptv in February and for NO_x mixing ratios up to 500 pptv in May. These NO_x limits are an order of magnitude higher thanmedian NO_x levels observed, illustrating the strong dependence ofgross ozone production rates on NO_x mixing ratios for the majority of theobservations. The threshold NO_x mixing ratio needed for netpositive ozone production was also calculated to increase from NO_x 10pptv in February to 25 pptv in May, suggesting that the NO_x levels needed to sustain net ozone production are lower in winter than spring. This lower NO_x threshold explains how wintertime photochemical ozone production can impact the build-up of ozone over winter and early spring. There is also an altitude dependence as the threshold NO_x neededto produce net ozone shifts to higher values at lower altitudes. This partly explains the calculation of net ozone destruction for the 1–3 km layerand net ozone production for the 3–6 km layer throughout the campaign.  相似文献   

TM图像中桥梁目标识别方法的研究   总被引：18，自引：3，他引：15  

吴皓  刘政凯  张荣 《遥感学报》2003,7(6):478-484

提出了一种新的TM图像中桥梁目标的识别方法。算法充分利用了TM图像的特点,在底层处理中运用形态学的方法提取出潜在桥梁目标;在中层处理中使用链码表示目标并提取其特征参数;最后在高层处理中进行桥梁识别和一些后处理。算法识别速度快、准确率高,整个算法可以进行自动的识别,也可以有少量人工干预使得算法更稳健。实验证明该算法对于TM图像中的桥梁识别是很有效的。  相似文献