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1.
深圳填海造地动态变化及其驱动因素分析   总被引:2,自引:0,他引:2  
基于海岸地貌基本概念界定填海造地范围在现代海岸带平均高潮位以下。基于多期遥感影像,利用单波段影像提取及影像二值化处理辨识深圳填海造地的动态变化数据。根据1978-1985年、1986-1994年、1995-1998年、1999-2004年4个时间段的填海数据解析结果,分析了在深圳这一典型的快速城市化地区城镇化进程中填海造地的起始阶段、快速阶段、增速阶段到理性阶段的阶段性过程。在此基础上,对深圳填海造陆的驱动力进行分析,建立了填海造地的综合驱动框架模型;归纳了区位因素、政策因素、社会经济因素和自然生态因素四大填海驱动力,并结合深圳的城市发展进程与深圳填海的不同阶段对每一因素的驱动作用进行了剖析。  相似文献   

2.
Landsat TM images of Tarim Basin in western China for 1986, 1999 and 2004 were analyzed for quantifying the patterns of landscape change relating to changes in water supply. Results showed that vegetation area and NDVI mostly decreased from 1986 to 1999, and increased from 1999 to 2004, while changes in desert area displayed an inverse pattern. Saline alkali soil showed a tendency of increase from 1999 to 2004. Spatially, percentage of vegetation area decreased and percentage of desert area increased with distance from the river in the upper section, while such patterns were not observed for both the middle and the lower sections. Landscape displayed a pattern of fragmentation from 1986 to 1999 and integration from 1999 to 2004. Shape of vegetation patches tended to become more regular from 1986 to 1999 and more irregular from 1999 to 2004. Our results indicated hydrological control of spatio-temporal variations of vegetation and landscape pattern in arid regions. Water diversion can be effective for raising the local groundwater level and improving plant growth, but its effect is largely restricted to areas adjacent to the water pathway.  相似文献   

3.
中国耕地数量下降之剖析:1986~1995年   总被引:17,自引:0,他引:17  
本文从不同的数据来源对比和分析了1986至1995年之间中国耕地资源数量下降的状况,并对其构成进行了详尽的剖析。指出农业结构调整(指耕地改为园地、林地、牧地、鱼塘)占地是耕地减少的主要原因,达到总量的62%;其次是三项建设(国家建设、集体建设和农村建房),占总量的21%;第三是灾害毁地,占总量的17%。针对存在的问题,本文提出了加强土地用途管制等对策。  相似文献   

4.
南极海豹类生态学   总被引:1,自引:0,他引:1       下载免费PDF全文
描述了南极海豹的种类组成、资源量和种类状况等一般性生态学问题,着重讲述了这些海豹在研究全球变化中所起的作用等科学前沿问题;同时,就海豹研究在各国际组织中的地位阐述了意见。  相似文献   

5.
Singapore experienced an extraordinary demographic transition from a population growth of over 4% per year in the late 1950s to around 1.6% in the 1990s and below replacement fertility since 1986. In 1987 official government policy shifted to measures for increasing fertility. This paper explores whether Singapore's pronatalist policies can reverse the demographic transition. The present policies aim to selectively increase fertility among the well educated. By 1987 the slogan switched from "stop at two" to "have three, if you can afford it." The policy included tax relief for a third child and other measures to encourage a third child. The policies are expected to have a different influence on society according to one's education, income, and family size. The government target is to selectively increase population by 40% over 25 years. Singapore's transition may follow the theory that low fertility is attained in societies where kin relationships are less important than personal educational achievements. The three ethnic groups responded differently to educational and fertility policies. The Chinese acquired the best education and attained the lowest fertility. The Chinese, who comprised 76% of total population in 1986, continued to have low fertility, while increases occurred among the Malays and the Indians. Future trends are considered difficult to predict. A survey conducted in 1992 in Ang Mo Kio among 489 reproductive age respondents revealed that Malays had the earliest marriage and first births before the age of 25 years (75% of Malays and 50% of Indians). The Chinese had their first child at 25 years or older. Without controls for the age of the mother, a strong statistically significant association was found between ethnic group and age at marriage and age at first birth. The relationship was not supported for current fertility. A comparison of women married for 5 years or less and 5 years or more revealed that women in recent marriages showed a greater likelihood of postponing marriage and childbirth for all ethnic groups. Since 1987, third order births as a percentage of all births increased from 21.47% before 1987 to 23.11% during 1987-92, which only suggests the favorable impact of the pronatalist policy. Educational changes are likely to become more influential in affecting choice of family size.  相似文献   

6.
中国省际经济趋同的定量分析   总被引:34,自引:2,他引:32  
本文参照 Coulombe的趋同模型 ,并根据中国的实际作出调整 ,以此分析了我国 1 978~ 1 999年各省区经济的趋同问题。研究结果如下 :各个地区之间存在条件趋同 ,趋同的速度大约为 4.5 % ;在趋同的过程中 ,东部沿海大部分地区都已达到或接近其稳定状态 ,而西部地区则大多在稳定状态值附近波动 ;本文还给出了我国各省相对人均 GDP的稳定状态值 ;实证分析的研究结果指出东部先行优势对长期稳定状态值有巨大影响 ,这说明市场经济体制的建立与完善 ,外资的引进 ,先进的技术 ,区位优势等因素对经济发展的重大作用。  相似文献   

7.
Place-based social exclusion: redlining in the Netherlands   总被引:2,自引:0,他引:2  
Manuel B Aalbers 《Area》2005,37(1):100-109
'Redlining' is a form of place-based exclusion. It is widely documented in the US, but not in Europe. This paper focuses on a comparative analysis of redlining practices in the two largest cities of the Netherlands: Amsterdam and Rotterdam. It shows that redlining was common practice in Rotterdam in 1999. In 2001, no signs of redlining were found in Rotterdam. However, 'yellowlining' (lower loan-to-value ratios) was still common in some parts of Rotterdam. In Amsterdam, no neighbourhoods were faced with redlining in either 1999 or 2001. However, in 1999 some neighbourhoods were yellowlined. This paper aims to get a better understanding of the nature and the institutional context of redlining in the Netherlands by explaining how the differences in redlining practices between Amsterdam and Rotterdam, and between 1999 and 2001, can be explained. The National Mortgage Guarantee as well as socio-historical, and housing and mortgage market differences and changes, are instrumental in explaining these differences in redlining practices.  相似文献   

8.
This paper attempts to explore the temporal and spatial nature of the marginal revenue of land, total factor productivity (TFP) change and its three components: technical change (TC), technical efficiency change (TEC) and scale efficiency change (SEC) as seen in Chinese agricultural production from 1995 to 1999. Based on county-level data, the study utilized both stochastic frontier and mapping analyses methods. The results show that growth in the marginal revenue of land was diverse across various regions, where most gain occurred in eastern coastal zone, while loss was in Northwest and North China. China has experienced moderate decreases in annual TFP change (-0.26%) with considerable regional variations. Specifically, the administrative intervention in grain production and the deterioration of the agricultural technology diffusion system led to a moderate drop in annual TFP change. County-level mapping analyses took into account interregional variances in TFP and its components. Regarding components of TFP, TEC differences explain the majority of regional dispersions in TFP. As developed areas in China, the Huang-Huai-Hai region and the Beijing-Tianjin-Tangshan economic zone face the challenges of land conversion and grain security amidst the process of urbanization.  相似文献   

9.
吕爽  孙铁山  孙瑜康 《地理研究》2022,41(11):3036-3050
随着全球城市创新网络的日益密切,区域创新研究开始由城市本地创新转向网络视角下城市间的知识溢出。本文使用专利数据测度了中国278个地级及以上城市间技术邻近水平,在此基础上引入知识复杂度分析框架讨论城市间技术邻近的不同类型,并利用2007—2019年的城市面板数据实证检验了基于不同类型技术邻近的知识溢出的差异。研究发现:① 城市间的技术邻近与城市知识多样性和遍在性有关,多样化和专业且遍在化的知识结构更容易在城市间产生技术邻近;② 城市间技术邻近与知识存量不存在显著的相关关系,但受到知识结构的影响而呈现出不同类型,具有多样化知识结构特征的城市间技术邻近平均程度最高且内部差异最小;③ 基于不同类型技术邻近的知识溢出有较大差异,与知识遍在性相比,知识多样性所带来的技术邻近更有利于城市间的知识溢出,在知识多样性的基础上,知识遍在性会强化这种效应。  相似文献   

10.
本研究利用1979—2012年欧洲中期天气预报中心(ECMWF)的ORAP5(Ocean Reanalysis Pilot 5)海洋/海冰再分析资料和ERA-Interim气象再分析资料,采用回归分析方法,分1979—1998年和1999—2012年两个时间段探讨了南半球热带外地区气候变化对两种不同形态ENSO的响应特征。结果表明,南半球热带外区域气候在1999年前后两个时段对ENSO的响应表现出了较大的年代际变化特征。1979—1998年南半球热带外气候变量对Nio3指数在时间上的相关性和空间上的响应强度都普遍大于Nio4指数,说明这一时段东部型ENSO对南半球热带外区域气候变化的影响要更强一些。在1999—2012年,不同形态ENSO与气候变量的相关性大小并无明显的规律,而且空间响应场的差异性并不大。海平面气压、风场和气温对ENSO变化的响应在南半球冬季表现最为强烈,在夏季最弱。三者在1999—2012年秋季对Nio3指数和Nio4指数的响应场中出现了纬向三波数结构。1999—2012年冬季,有异于海平面气压和风场,在罗斯海和阿蒙森海海域海表气温对Nio4变化的正响应明显强于对Nio3的响应,该特征在混合层温度中也有体现,表明海表气温随ENSO的变化受海洋特征变化影响较大。混合层深度和混合层温度的响应场之间存在很大的相关性,混合层温度响应在秋季表现最强,春季最弱,混合层深度响应与之相反。在1979—1998年,海冰密集度对不同Nio指数变化的响应差异主要出现在海冰结冰季节,而海冰厚度对不同Nio指数变化的响应差异在夏季表现较强。海冰密集度和厚度对Nio3变化响应的年代际差异在秋冬季节更加明显,对Nio4变化响应的年代际差异在秋、冬、春季都较明显。  相似文献   

11.
李琳  熊雪梅 《地理研究》2012,31(11):2017-2030
目前国际学术界对地理邻近与创新论题的研究囿于静态分析视角。本文从产业集群生命周期视角出发分析地理邻近对集群演化不同阶段创新的动态影响机制,并据此提出理论假说;以我国六大汽车产业集群为研究对象,通过曲线拟合,对集群的动态演化过程进行实证分析,结果表明,目前我国六大汽车产业集群均处在快速成长期,均未到达成熟期;采用动态聚类分析法分别对六大汽车产业集群演化阶段进行划分,不同集群的划分界限不一;在此基础上,建立地理邻近与不同演化阶段集群创新绩效之间的计量模型并进行实证分析,得出以下重要结论:(1)地理邻近对集群演化初期和成长期创新的影响显着为正,成长期的影响效应大于初期;(2)同一演化阶段的不同集群地理邻近影响效应存在显着差异;进而提出针对性政策建议。  相似文献   

12.
文萍  周素红 《地理研究》2022,41(4):1212-1226
流动人口家庭化迁移可能对其在城市的职住关系产生影响。本研究基于广州市居民日常出行调查数据,考察流动人口在不同家庭化迁移状态下的职住关系,并与本地市民进行比较。研究发现:广州市流动人口职住临近特征明显,但随着家庭化迁移程度提高,职住距离增长,并接近本地市民水平。相较于个体单独迁移,夫妻共同迁移由于难以同时实现职住临近,职住距离更长;子女和老人随迁情境下,流动人口职住区位郊区化特征明显,因为郊区能以较低成本满足家庭生活对住房和住区环境的更高要求,但该情境下整体职住距离增幅较小且不显著。多数家庭化迁移的流动人口仍存在不稳定流动特征,以租房为主,租金规避需求与环境提升需求并存,需要相关政策加以关注。  相似文献   

13.
This paper attempts to explore the temporal and spatial nature of the marginal revenue of land, total factor productivity (TFP) change and its three components: technical change (TC), technical efficiency change (TEC) and scale efficiency change (SEC) as seen in Chinese agricultural production from 1995 to 1999. Based on county-level data, the study utilized both stochastic frontier and mapping analyses methods. The results show that growth in the marginal revenue of land was diverse across various regions, where most gain occurred in eastern coastal zone, while loss was in Northwest and North China. China has experienced moderate decreases in annual TFP change (-0.26%) with considerable regional variations. Specifically, the administrative intervention in grain production and the deterioration of the agricultural technology diffusion system led to a moderate drop in annual TFP change. County-level mapping analyses took into account interregional variances in TFP and its components. Regarding components of TFP, TEC differences explain the majority of regional dispersions in TFP. As developed areas in China, the Huang-Huai-Hai region and the Beijing-Tianjin-Tangshan economic zone face the challenges of land conversion and grain security amidst the process of urbanization.  相似文献   

14.
适度人口取决于生态、经济和土地等多要素的综合承载力。介绍了生态足迹模型的基本概念和计算方法,并运用该模型对兵团1995—2008年的生态足迹和生态承载力进行了计算,在此基础上对兵团的1995—2010年的生态适度人口进行了估算。结果表明,1995—1999年兵团的实际人口虽然在增加,但相对于生态适度人口并没有出现过剩;2000—2010年兵团生态适度人口在不断下降,实际人口和过剩人口却在不断增加。兵团目前已经出现了过度人口和生态赤字,人地矛盾相对紧张,生态适度人口规模是不合理的。  相似文献   

15.
Mechanisms of kin selection have been studied to explain how siblings grow together, but the findings remain controversial. This can be ascribed to the use of single indicators without considering other factors. Three ecotypes of Arabidopsis were used to examine kin responses of siblings growing together. Plant traits of leaves, plant shape, reproductive activity, and roots were investigated. We found that Arabidopsis recognized their kin neighbors, showed selective responses to distinct plant traits among ecotypes, and modes of responses were dependent on neighbor's growing distance. If single traits were used to judge kin response performance, the results were chaotic. However, by developing and studying an integrated performance value based on multiple traits, we determined that Ler showed similar integrated performances at all planting distances, while the integrated performance of Col was ranked mainly as medium distancedistance> small distance> large distance, which suggested kin cooperation. However, in comparison to medium and small distances, at which performance was consistent with kin recognition, we found that at large distance, strangers of Ws performed better than kin plants, which suggested competition. Thus, we conclude that kin recognition could be affected by plant competition conditions that are the result of growing distance, and that the integrated performance of individuals was more suitable to evaluate kin interactions of plant species.  相似文献   

16.
贵州土地石漠化类型时空演变过程及其评价   总被引:26,自引:6,他引:20  
构建了贵州20世纪80年代、90年代和21世纪初等3期历史石漠化数据,利用其空间变换和数学模型详细探讨和评价了石漠化的时空演变过程,研究发现:(1)研究时段内贵州省石漠化总面积变化不明显,但石漠化内部类型之间的相互演变非常显著,各类型之间的演变具有转移、多变、"此消彼长"的特点.(2)石漠化的时空演变过程可分为单变方式、层变方式、返变方式等3种基本类型,其中以层变方式为主.单变方式为辅.返变方式较少.(3)石漠化正向演变与逆向演变并存,治理速度赶不上恶化速度,两者的比值为82.29%,局部治理,整体恶化.(4)各石漠化类型总的演变速率是398.31 km2·a-1,石漠化等级越高,演变速率越慢.(5)石漠化演变频率最快的是中度石漠化和潜在石漠化.轻度石漠化的演变频率明显低于中度石漠化.对石漠化的空间演变区域特征和影响因子做了宏观的定性分析、并根据石漠化演变特点对综合治理提出了相应的建议.  相似文献   

17.
张建忠  孙根年 《地理研究》2012,31(11):2104-2414
旅游地的成长是一个由发现引入、加速成长、走向成熟到最终衰退的生命过程。旅游地生命周期理论是关于旅游地成长的管理理论,在实践中必须采用动态的管理措施来实现旅游产品创新和旅游地系统提升。运用旅游地生命周期理论,以1986~2010年乔家大院旅游人次、游客增长率以及指数模拟曲线等指标系统分析了大院旅游地生命周期。研究表明:乔家大院旅游地经历了4个阶段,即:探索阶段(1986年以前)、参与阶段(1987~1995年)、发展与巩固阶段(1996~2008年)、衰退阶段(2009年~至今).乔家大院已经进入“衰退期”,不仅要对资源整合营销,而且要改善旅游环境,营造良好运营氛围的战略;同时适应市场需求,深挖文化因子;实行产品差异化策略,打造特色大院旅游产品和提升大院旅游地体验性,打造大院体验旅游创新产品。  相似文献   

18.
中国城市交通运输发展水平等级差异变动特征   总被引:7,自引:1,他引:6  
曹小曙  张利敏  薛德升  王大鹏 《地理学报》2007,62(10):1034-1040
选取中国183 个城市的1991 年、1995 年、1999 年和2003 年4 个时间段的统计数据, 在Arcmap 软件中采用自然断裂法进行等级划分, 将城市交通运输总体发展水平的等级划分为5 级, 利用SPSS 统计分析软件进行分析, 得到1991-2003 年中国城市交通运输发展水平等级差异变动特征: 中国城市交通运输发展水平等级呈现明显的“纺锤形”结构, 交通运输发展水平明显高于平均发展水平的城市个数和明显低于平均发展水平的城市个数所占比例低于32%, 68%以上的城市其交通运输发展水平接近全国平均水平; 发展水平较高的城市在以省区为单位的空间分布上呈现集中-分散-分散-集中的特征, 而等级较低的城市在空间上呈现分散无规则分布格局; 中国城市交通运输发展水平的等级差异呈现“U” 形变化, 1991- 1995 年差距逐渐缩小, 1995-1999 年差距逐渐增大, 1999-2003 年差距逐渐缩小, 但各时间段内的变动幅度不大; 城市交通运输发展水平上升的城市在空间分布上集中于河南、山东、江苏等省, 城市交通运输发展水平下降的城市集中于黑龙江、吉林、陕西、湖北和湖南等省。  相似文献   

19.
刘春芳  王川  刘立程 《地理研究》2018,37(2):419-432
以地处三大自然区过渡地带的榆中县为案例,分析了1995-2015年县域及内部分区生境质量演变的时空特征,借助地理探测器模型分析并探索了生境质量影响因素及其机制。结果表明:① 全县生境质量变化保持稳定并略有提升,县域内部生境质量变化呈现出由南向北递减的三级梯度特征;② 全县生境质量的地带间与地带内差异均趋于缩小,北部黄土高原区持续加大,中部平原区连续下降,南部山区则先缩小后增大;③ 全县及县域内部的影响因素及机制因为地理尺度的差异而不同。自然环境变量对生境质量变化发挥着基础和关键性的作用,社会经济变量呈现出减小的态势,而政策调控变量对生境质量的影响则越来越大,各因子间的协同增强效应推动了生境质量的变化。  相似文献   

20.
以寿光蔬菜产业集群为例,运用ArcGIS 10.0软件的空间邻近分析,Ucinet软件的社会网络分析以及多元线性回归模型从多维邻近性视角探究蔬菜集群企业的地理邻近、关系邻近特征及两者在集群企业创新中的影响。研究表明:蔬菜集群企业具有明显的地理集聚特征,企业的空间邻近有利于集群创新氛围的形成;集群企业及各创新主体间拥有紧密的关系邻近网络,关系网络中多核心节点,促使创新资源、隐性知识、新技术等的扩散与传播;进一步回归分析表明,关系邻近对蔬菜产业集群创新作用更显著,永久性地理邻近在寿光蔬菜产业集群创新中仍然起到正向作用,但作用要弱于关系邻近。说明多元关系邻近在集群创新过程中能够对消除过度的地理邻近、单一关系邻近造成的创新锁定起到作用,同时还为全球化背景下农业集群创新提供新的渠道。  相似文献   

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