中国城市市辖区的空间结构及演化机制   总被引：1，自引：0，他引：1  

朱建华  戚伟  修春亮 《地理研究》2019,38(5):1003-1015

本文提出了市辖区6种空间结构类型：圈层式、组合式、并排式、独立式、包围式及飞地式,并总结了6种类型的主要特征。通过对中国市辖区分布格局及演变分析,发现城市规模等级越高,市辖区数量越多、人口密度越大。6种类型城市分布情况为圈层式结构城市集中在东部地区,组合式结构城市在东北地区分布最密,独立式结构城市大多分布于中西部,包围式结构城市中部地区最多,并排式和飞地式结构城市在全国分布比较均衡。市辖区空间结构的一般演化路径为“独立式-并排式-组合式-圈层式”,圈层式结构会继续优化,通过“内城合并、外城扩张”向第三、四圈层发展。文章最后分析了增设、拆分与合并市辖区三种行政区划调整方式的影响因素及作用机制。  相似文献   

电力公司集中规模2009年第四批勘测设计项目招标公告     

《中国勘察设计》2009,(7):79-79

一、甘肃省电力公司（以下简称“招标人”）委托甘肃光明电力工程咨询监理有限公司（以下简称“招标代理机构”）,采用公开招标方式邀请有兴趣的合格投标人（以下简称“投标人”）就甘肃省电力公司勘测设计集中规模招标2009年第四批项目招标提交密封的有竞争性的投标文件。详细内容参见“甘肃省电力公司2009年勘测设计集中规模第四批公开招标项目表”。  相似文献   

新中国成立以来前三次珠穆朗玛峰地区大规模科学考察     

《地图》2005,(4):39-39

1959-1960年,中国科学院和国家体委组织的中国珠穆朗玛峰登山科学考察队完成了以珠穆朗玛峰为中心的7000平方千米的从海拔2500米至6500米范围的科学考察,此次考察队员有地质、地貌、测量、气象、水文、植物、动物等专业的46名科学工作者参加,分成地质组、地貌组、水文组、植物组、动物组等具体的小组分别对珠峰周围进行科学考察。  相似文献   

江门市2007年食品制造业气象服务效益评估   总被引：1，自引：1，他引：0  

胡丽华  黄江辉  袁锡沛 《广东气象》2009,31(5):35-36

2007年12月-2008年2月,选择江门市食品制造业中颇有代表性的李锦记（新会）食品有限公司为对象,应用专家评估法———德尔菲法,就其最近几年来对各类气象服务的敏感度、需求度、满意度及气象服务效益等进行了调查评估。结果表明：食品制造业各个生产环节（流程）对气象敏感度高、依赖性强,气象服务效益贡献率较高。  相似文献   

Trends and scales of observed soil moisture variations in China   总被引：3，自引：0，他引：3  

聂肃平  罗勇  朱江 《大气科学进展》2008,25(1):43-58

A new soil moisture dataset from direct gravimetric measurements within the top 50-cm soil layers at 178 soil moisture stations in China covering the period 1981-1998 are used to study the long-term and seasonal trends of soil moisture variations, as well as estimate the temporal and spatial scales of soil moisture for different soil layers. Additional datasets of precipitation and temperature difference between land surface and air (TDSA) are analyzed to gain further insight into the changes of soil moisture. There are increasing trends for the top 10 cm, but decreasing trends for the top 50 cm of soil layers in most regions. Trends in precipitation appear to dominantly influence trends in soil moisture in both cases. Seasonal variation of soil moisture is mainly controlled by precipitation and evaporation, and in some regions can be affected by snow cover in winter. Timescales of soil moisture variation are roughly 1-3 months and increase with soil depth. Further influences of TDSA and precipitation on soil moisture in surface layers, rather than in deeper layers, cause this phenomenon. Seasonal variations of temporal scales for soil moisture are region-dependent and consistent in both layer depths. Spatial scales of soil moisture range from 200-600 km, with topography also having an affect on these. Spatial scales of soil moisture in plains are larger than in mountainous areas. In the former, the spatial scale of soil moisture follows the spatial patterns of precipitation and evaporation, whereas in the latter, the spatial scale is controlled by topography.  相似文献   

High efficiency of heavy metal removal in mine water by limestone     

YAO Zhigang    ZHOU Lifa  BAO Zhengyu  GAO Pu    SUN Xingwang Key Laboratory of Continental Dynamics  Ministry of Education/Department of Geology  Northwest University  Xi’an  China School of Petroleum Resources  Xi’an Shiyou University  Xi’an  China State Key Laboratory of Geological Processes  Mineral Resources  China University of Geosciences  Wuhan  China Chuankou Oilfield  Yanchang Oilfield Administration Bureau  Shaanxi  Yan’an  China 《中国地球化学学报》2009,28(3):293-298

The removal of Cd, Cu, Ni and Zn from dilute mine water by using several geological materials including pure limestone, sand, carbonaceous limestone and brecciated limestone was performed on a laboratory scale. The results showed that to add geological materials in combination with sodium carbonate injection would notably enhance the efficiency of heavy metal removal to varying degrees. Pure limestone was found the best one among the four materials mentioned above for removing heavy metals from mine water. The removal efficiencies of pure limestone when it is ground as fine as 30–60 meshes are 58.6% for Cd, 100% for Cu, 47.8% for Ni, and 36.8% for Zn at 20°C. The optimum pH is about 8.9 to 9.1. The mechanism of higher effective removal, perhaps, is primarily due to co-precipitation under the control of calcite-related pH value. According to this research, Na₂CO₃ injection manners, including slug dosing and drip-wise, seemed to have little impact on the efficiency of heavy metal removal.  相似文献   

Raw mix designing, clinkerization and manufacturing of high-strength Portland cement from the limestone and clay of Darukhula Nizampur, Nowshera District, North-West Frontier Province （N.W.F.P.）, Pakistan     

Noor-ul-Amin  Tahir Shah  Khurshid Ali 《中国地球化学学报》2009,28(3):279-283

This paper covers the detailed version of the potential raw material deposits at Darukhula and the adjacent areas of Nizampur, the manufacturing of high-strength Portland cement samples from the same material and comparison of the physical and chemical parameters for resulting cement with British and Pakistan standard specifications, which include compressive strength, setting time, consistency, lechatelier expansion, Blaine and insoluble residue. It was found that the raw material available in the study area meets the standard specifications and the area is feasible for the cement plant installation. The area can provide raw material which is quite sufficient for the running of a cement plant.  相似文献   

基于DEA模型的甘肃省经济运行和环境管理效率评价研究   总被引：4，自引：1，他引：3  

邓晓红  徐中民  程怀文 《冰川冻土》2009,31(3):553-559

评价经济运行和环境管理效率是衡量城市运行功能的两个重要方面,对位于生态脆弱、经济发展相对落后的西部地区更显重要.利用DEA方法中的cRS模型,计算了甘肃省12个大、中城市的2003年和2004年的经济运行效率和环境管理效率指数,并结合使用CRS模型和VRS模型的运行结果判断出各城市的规模收益情况.结果表明:2003年这12个城市中有嘉峪关、金昌、白银、平凉、庆阳和陇南共6个城市实现了经济运行效率的DEA有效,同时,嘉峪关、金昌、白银、张掖、酒泉和定西这6个城市实现了环境管理效率DEA有效;2004年经济运行效率实现DEA有效的有嘉峪关、金昌、天水、庆阳和陇南,实现环境管理效率DEA有效的有嘉峪关、金昌、白银、平凉、酒泉和定西.在没有实现DEA有效的城市中除了兰州是规模收益下降外,其它的都处于规模收益上升阶段.结合评价结果,给出了建立城市经济运行效率和环境管理效率评价监测体系、合理分配资源投入的对策建议.  相似文献   

天津城市发展中工业经济结构的变化趋势研究   总被引：1，自引：0，他引：1  

罗若愚 《地域研究与开发》2005,24(5):38-41

文章采用Shift_share方法分析了天津城市发展中制造业内部产业结构的变动,指出天津经济结构调整的重点应当是促进社会资源流向技术密集型制造业部门,加快工业化的发展速度,不断提升制造业的技术结构,使天津成为技术密集型的制造业基地。  相似文献   

城市适度空间规模的成本-收益分析模型探讨   总被引：11，自引：0，他引：11  

俞勇军  陆玉麒 《地理研究》2005,24(5):794-802

本文根据城市作为社会经济的子系统运行的目的是实现其经济效益的最优化的假设,从经济学的角度解释了城市适度空间规模存在的理论依据。以江苏为例,对各地级市的人口规模、空间规模与经济发展水平的关系进行了模拟。结果显示,在人口空间结构不发生根本性变化的前提下,城市最佳空间规模是存在的,不同城市的最佳规模在当前水平下差异较大,在经济水平达到较高程度时将趋于一致。目前,江苏省地级城市的最佳人口规模为280万人,最佳空间规模为2030平方公里。本文的结论对于江苏省进行地级市的行政区划调整有一定的参考意义。  相似文献