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91.
城市开发边界的划定能够合理引导城市空间的有序发展,控制其无序蔓延。论文以典型的资源型城市贵溪市为研究区,从空间适宜性评价、人口承载力、城市规模以及城市总体规划和土地利用总体规划(简称“两规”)衔接等方面探索有效的城市开发边界划定方法。空间适宜性评价综合考虑自然、空间可达性和生态条件,运用聚类分析法确定区域内不宜作为开发建设的生态底线区域和适宜建设开发区域的高低等级,以此确定城市开发边界的发展方向。通过灰色预测GM(1,1)模型预测研究区2020年人口总量,并基于土地资源和水资源承载力验证当地所能容纳的最大人口总量,同时确定城市规模和划定城市开发边界。以空间适宜性评价、人口承载力、城市规模预测、两规衔接和空间形态控制等方法倒逼缩减建设用地,从而划定城市发展的刚性和弹性增长边界。  相似文献   
92.
The present study was initiated to examine urinary α1-microglobulin (α1-MG-U) levels among non-smoking women in the general population in Japan. A previously established database on spot urine samples from adult woman volunteers in 10 non-polluted areas all over Japan was re-examined. The data examined were on α1-MG-U, cadmium, calcium, magnesium and zinc levels in urine (Cd-U, Ca-U, Mg-U and Zn-U, respectively), urinary creatinine (CR or cr), urine specific gravity (SG or sg), smoking habits and age. Thus, 8975 never-smoking women were selected for statistical analyses. The grand geometric mean (GM) for α1-MG-U among the population was 2.1?mg/L or 2.5?mg/g?cr, depending on the correction for urine density. It was 1.1?µg/L or 1.3?µg/g?cr for GM Cd-U. The inter-area difference in α1-MG-U was <1.5?mg/g?cr or <0.7?mg/L; the area with the highest or lowest GM Cd-U was not always highest or lowest in GM α1-MG-U. The correlation coefficient (0.53) between log?Cd-U and log?α1-MG-U (both without urine density correction) became substantially smaller when the analyte levels were corrected for CR (0.25) or SG (0.26). In multiple regression analysis, the power of influence of the five independent variables (log?Cd-U, Ca-U, Mg-U, Zn-U and age) in combination was small (R 2?≦?0.13). In contrast, logistic regression analysis suggested that α1-MG-U might be elevated as a function of an increase in Cd-U, depending on the cut-off values. Discussion was made on dose (Cd-Ucr) and response (α1-MG-Ucr) relationship based on information available in literatures to show that the increment in α1-MG-Ucr per Cd-Ucr was much greater when Cd-Ucr was large, e.g., in excess of 10?µg/g?cr.  相似文献   
93.
中国经济增长具有典型的政府主导特征,通过构造一个包含城镇和农村经济产出的社会福利函数来分析政府主导型经济增长对城乡收入差距的影响关系,并基于中国城镇化发展实际分析了人口流动对城乡收入差距的影响,在此基础上提出研究假说,统计中国1997—2014年省际面板数据,采用泰尔指数测度城乡收入差距并分别进行静态和动态回归分析与检验。静态研究发现政府主导和人口流动显著地拉大了城乡收入差距,但是二者的交互项对城乡收入差距的确具有收敛效应,即随着人口流动的增加,政府主导对城乡收入差距的边际贡献会降低,同样随着政府主导的提升也会降低人口流动对城乡收入差距的边际贡献,这种影响关系在分区域的回归中依然成立,并通过了稳健性检验;动态研究发现全国和分区域中城乡收入差距的变动存在显著的正向路径依赖特征,全国层面政府主导显著地拉大了城乡收入差距,而人口流动及其与政府主导的交互项则显著地缩小了城乡收入差距,但分区域来看政府主导和人口流动对城乡收入差距的影响存在显著的区域异质性,并通过了稳健性检验。因此缩小城乡收入差距不应设置单一的政策目标,需要建立多方面的政策配套体系,逐步矫正政府主导型经济中造成的政府职能异化,精准识别地方财政收支量的规模和结构条件,扩大涉农业务投资的规模,激活农村经济发展活力;在城乡户籍制度改革中进一步打破城乡分割藩篱,大力发展非农产业,增加农民的非农就业机会,促进农民的非农化就业和城镇化迁移,提升城镇化发展质量;最终通过一系列的配套性制度安排,旨在加强支持农业发展和农村建设,促进农民收入增长的制度供给,实现城乡共享发展。  相似文献   
94.
人口与可持续发展   总被引:6,自引:0,他引:6  
有限的资源不能支撑无限增加的人口,面对高速增长的人口,人们产生了种种不同的认识。本文分析了人口增长与食物供给,人口增长与生态环境和经济发展的矛盾;阐述了最大人口容量及经济最优人口计算需要考虑的因素和基本;提出我国必须坚持严格控制人口增长的政策,这是可持续发展的需要。  相似文献   
95.
对生活垃圾处置计划管理政策的意义、生活垃圾处置计划指标测算模型建立的意义和作用进行分析,对建立模型的因素、计算公式、计算流程等进行详细说明,并对3个典型区县的实际情况进行了计算和分析,总结了模型存在的问题和完善方向。  相似文献   
96.
Basic trends in the structural dynamics of the meadow-steppe carabid fauna over the period from 1970 to 1997 have been analyzed. Data on changes in the abundance and composition of dominant species are reported. Transformation of carabidocenoses is mainly accounted for by an increased humidity of the climate and the related mesophytization of forest–steppe ecosystems.  相似文献   
97.
This paper examines the temporal change and spatial variation of population pressure on the ecological environment in China. We have collected sufficient data from the statistical yearbooks of 31 provincial administrative areas in 1990, 1995, 2000, 2005, and 2010. Using a geographic information system (GIS) and relevant models, we analyzed the trend of the population pressure on ecological environment and the change of the gravity center of ecological environment quality. We conclude that: (1) generally, population pressure on the ecological environment in China was becoming higher during 1990–2010, especially in some areas where the population and environment were in serious imbalance and the ecological environment experienced severe pollution; (2) during a certain period, population pressure on the ecological environment was becoming lower in some areas, but the ecological environment was getting worse; (3) the areas with super-high population pressure on the ecological environment were Beijing, Tianjin, and Shanghai; (4) the gravity center of population pressure on the ecological environment and the center of ecological environment quality move differently during the study time period, but the general trend was similar – both of them were moving from west to east. Based on the analysis, this paper also provides some policy suggestions on the control of ecological environment quality.  相似文献   
98.
In this paper, an approach to simulate the spatial distribution of urban population is proposed using urban land use and population statistical data through the geographical information systems (GIS). Then, the spatial population distribution of Urumqi as a case is simulated by the approach mentioned above and its varying patterns are analyzed by the raster population surface. As a result, producing raster population surface is more accurate and natural than the traditional choropleth map of population density. Concerning the spatial population distribution of Urumqi, the population density declines from south to north and the population distribution mainly presents' "T-type", the population distribution presents multicentre agglomeration and the population distribution of the districts shows different features. The population density varies significantly with the increase in the distance from central business district (CBD). Finally, it is found in this paper that the development history of districts, terrain and traffic road are main factors that have an influence Urumqi's population distribution. This paper tries to provide more accurate population data for the plan and management of urban land, traffic and public facilities in order to enrich the researches on urban population distribution.  相似文献   
99.
丝栗栲种群生命过程及谱分析   总被引:25,自引:2,他引:25  
以种群生命表及生存分析理论为基础,编制丝栗栲种群静态生命表,绘制存活曲线,死亡率曲线,亏损度曲线,死亡密度函数曲线。积累死亡函数曲线和危险率函数曲线,分析种群生命过程。结果表明,丝栗栲有2个死亡高峰,存活曲线趋于Deevey-Ⅱ型。并应用谱分析方法研究丝栗栲种群动态,结果表明,在丝栗栲种群自然更新过程中存在着明显的周期性。  相似文献   
100.
Abstract: The lack of concrete instances in which conservation and development have been successfully merged has strengthened arguments for strict exclusionist conservation policies. Research has focused more on social cooperation and conflict of different management regimes and less on how these factors actually affect the natural environments they seek to conserve. Consequently, it is still unknown which strategies yield better conservation outcomes? We conducted a meta‐analysis of 116 published case studies on common resource management regimes from Africa, south and central America, and southern and Southeast Asia. Using ranked sociodemographic, political, and ecological data, we analyzed the effect of land tenure, population size, social heterogeneity, as well as internally devised resource‐management rules and regulations (institutions) on conservation outcome. Although land tenure, population size, and social heterogeneity did not significantly affect conservation outcome, institutions were positively associated with better conservation outcomes. There was also a significant interaction effect between population size and institutions, which implies complex relationships between population size and conservation outcome. Our results suggest that communities managing a common resource can play a significant role in conservation and that institutions lead to management regimes with lower environmental impacts.  相似文献   
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