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1.
唐山海岸带土地利用格局的情景模拟 总被引：10，自引：3，他引：7
本文以唐山海岸带为研究区,基于2000年和2005年TM遥感影像,运用3S技术,通过人机交互目视解译提取了精度较高的两期该区土地利用/土地覆被数据.以2000年土地利用数据为基期,选取距农村居民点距离、距城镇距离、距道路距离、距河流距离、距海岸线距离、地下水埋深、土壤类型、成因地貌、工程地质条件9个自然和社会经济因素作为驱动因素,运用CLUE-S模型模拟了2005年的土地利用类型空间格局,并用2005年的实际解译数据加以验证.结果表明:正确模拟比例达88.95%,Kappa指数为0.8711.说明CLUE-S模型能够较准确地模拟小尺度海岸带地区的土地利用,土地覆被变化.在此基础上又分别模拟了自然增长、土地结构优化、经济发展、生态保护4种情景方案下2015年研究区的土地利用格局.结果表明:在不同情景方案下的土地利用,土地覆被格局存在显著的空间差异,对该区域制定合理的土地管理政策有着指导意义. 相似文献
2.
基于CLUE-S模型的罗玉沟流域多尺度土地利用变化模拟 总被引：7，自引：0，他引：7
CLUE-S模型是适用于较小尺度的区域土地利用变化空间格局动态研究的模型。为了探索CLUE-S模型在小流域的适用性及最佳适用尺度,本文以甘肃天水罗玉沟流域为研究区,根据2001年和2008年两期土地利用数据,在筛选出的7类土地利用变化驱动因素的基础上,以2001年土地利用数据为基期,利用不同的空间尺度（25m×25m、50m×50m、75m×75m、100m×100m、和125m×125m）,运用CLUE-S模型进行了流域2008年的土地利用空间格局的模拟,并以2008年土地利用现状图加以验证。结果表明：CLUE-S模型在罗玉沟流域的适用性很好。模型模拟的最佳尺度为50m,在该尺度下耕地、园地、林地、草地、居民用地、水域和未利用地的Kappa指数依次为95.71%、88.97%、90.68%、74.66%、74.53%、96.89%、81.94%,总Kappa指数值为92.34%。说明CLUE-S模型能够准确地模拟小流域尺度的土地利用变化。在此基础上又分别模拟了自然增长、经济发展、生态保护等3种情景下罗玉沟流域2020年的土地利用格局。结果表明：在不同情景下,土地利用变化均主要发生在大于15°的坡地上,在开发利用过程中应适当采取生态保护与水土流失防治措施,防止造成流域生境的破坏。 相似文献
3.
区域土地利用竞争模拟模型与应用——以江西省为例 总被引：1，自引：0，他引：1
本研究构建了区域土地利用竞争模拟模型,实现了对区域土地利用变化过程的模拟.区域土地利用竞争模拟模型包括非空间模块和空间模块两个主要模块.非空间模块基于可计算一般均衡建模思想,用以模拟区域经济发展、社会发展与生态环境发展驱动的土地利用变化需求.空间模块以多分类Logit模型为主体,用以实现区域土地利用变化需求的空间分配,输出区域土地利用格局图.江西省2000年-2005年的土地利用变化模拟检验结果表明,区域土地利用竞争模拟模型对江西省2005年的土地利用格局模拟总体精度达到77.68％,尤其是对林地的模拟精度达到86.87％.因此,区域土地利用竞争模拟模型能够用于区域土地利用变化模拟. 相似文献
4.
沽源县土地利用格局的多尺度模拟与分析 总被引：9，自引：2，他引：9
基于由遥感和数字高程模型数据源得到的土地利用、地形、河流、湖泊、道路，以及城镇和农村居民点等空间数据，本文运用Logistic回归模型对河北省沽源县耕地、林地和草地的空间分布格局进行了模拟。为了分析土地利用格局模拟过程中的尺度相关性特征，本文分别在100m×100m、250m×250m、500m×500m、750m×750m和1000m×1000m共5个空间模拟尺度的基础上构建了相应的土地利用格局模拟模型。结果显示，在不同的模拟尺度上，土地利用格局模拟模型的变量数目与变量系数都存在一定的差异，表明土地利用格局与其决定因素之间的关系包含一定的
尺度相关性特征。比较不同模拟尺度上模型的拟合优度，发现当模拟尺度为500m时，耕地、林地和草地格局模拟模型的拟合优度均达到最高（ROC值分别为0.745，0.738和0.714）。研究结果揭示了沽源县土地利用格局形成与演变的重要决定因素，这为进一步研究该县未来的土地利用动态变化情景奠定了基础；研究结果也可以为沽源县及其相似地区的土地利用规划决策提供科学依据。 相似文献
5.
经济快速增长区土地利用信息图谱构建 总被引：5，自引：0，他引：5
基于1980年~2005年江苏省环太湖地区4期土地利用遥感数据,在地学信息图谱理论和GIS技术支持下,构建了4个时序单元的土地利用格局信息图谱、土地利用分类信息图谱和土地利用转移信息图谱。图谱构建结果表明,25年来江苏省环太湖地区土地利用变化既具有明显的时空分异特征,又具有相似的转移图谱。复合应用CLUE-S和Markov模型对江苏省环太湖地区2015年的土地利用进行模拟,弥补原有土地利用信息图谱研究缺乏未来模拟的不足。从模拟结果得知,由于规划指标的控制且随着土地集约利用的深化,江苏省环太湖地区在2015年建设用地增加和耕地减少的幅度将降低。苏锡常都市连绵区仍是江苏省环太湖地区土地利用变化的“热点”区域。 相似文献
6.
城郊农业区土地利用变化及动因分析——以四川南充市高坪区为例 总被引：4，自引：0，他引：4
根据1885年、2004年的土地利用现状图、土地详查资料以及实地收集数据，在GIS技术支持下，利用数学模型分析了南充市高坪区近20年间土地利用变化及其动因。研究表明：20年来，研究区土地利用类型的面积变化为12 050hm2，占该区总土地面积的14.84%，主要表现为园地、城市工业用地和交通用地的增加和未利用地和耕地的减少；区域土地利用空间格局发生较大变化，斑块数目增加2 921个，斑块面积均有由大到小的变化趋势，土地利用类型多样性和破碎度增加，优势度降低；除园地、交通用地以外，其他土地类型都有分散分布的趋势；不同的土地利用类型重心在不同的方向上有不同的移动距离； 影响城郊农业区土地利用变化的因素主要是城市化和政策导向。 相似文献
7.
经济快速增长区土地利用信息图谱构建——以江苏省环太湖地区为例 总被引：1，自引：0，他引：1
基于1980年～2005年江苏省环太湖地区4期土地利用遥感数据,在地学信息图谱理论和GIS技术支持下,构建了4个时序单元的土地利用格局信息图谱、土地利用分类信息图谱和土地利用转移信息图谱.图谱构建结果表明,25年来江苏省环太湖地区土地利用变化既具有明显的时空分异特征,又具有相似的转移图谱.复合应用CLUE-S和Markov模型对江苏省环太湖地区2015年的土地利用进行模拟,弥补原有土地利用信息图谱研究缺乏未来模拟的不足.从模拟结果得知,由于规划指标的控制且随着土地集约利用的深化,江苏省环太湖地区在2015年建设用地增加和耕地减少的幅度将降低.苏锡常都市连绵区仍是江苏省环太湖地区土地利用变化的"热点"区域. 相似文献
8.
土地利用和土地覆盖变化研究的目标与方法 总被引：2，自引：1，他引：1
土地利用／土地覆盖变化（ＬＵＣＣ）是一个多学科研究领域,其主要目的在于了解和预测对全球变化和可持续发展具有重要影响的土地利用和土地覆盖变化动态。ＬＵＣＣ研究的主要议题包括以下几个方面：·土地覆盖变化格局;·土地利用变化过程;·全球和区域综合模型;·建... 相似文献
9.
基于CLUE-S模型和Markov模型的城镇土地利用变化模拟预测——以江苏省常熟市辛庄镇为例 总被引：11，自引：1，他引：10
基于高分辨率遥感影像解译得到江苏省常熟市辛庄镇4期土地利用历史数据,首先对CLUE～S模型的预测精度进行验证,然后利用CLUE—S模型和Markov模型相结合的方法对研究区未来土地利用变化进行3种不同情景的模拟预测,并系统分析了各情景下土地利用变化的时空特征。结果表明,CLUE—S模型在乡镇小尺度的土地利用变化模拟预测效果较好,精度较高。各情景下,建设用地的快速增长仍将在未来的土地利用变化中占据主导地位,且均以消耗大量的水田为代价,河流密布、交通便捷和经济发达的区域将是未来耕地非农化的“热点”区域。生态保护情景和基本农田保护情景对未来土地利用变化的调控效果较好,林地、水体、水田和旱地受到了更好的保护,并在一定程度上抑制了建设用地的肆意蔓延。 相似文献
10.
本文利用DLS模型,在中国的9个土地利用分区上分析了栅格水平上土地利用变化的机理,设定了土地利用时空格局变化的不同情景,模拟了基准情景和发展生物能源政策情景下各土地利用分区2010年～2025年土地利用时空格局变化。从发展生物能源情景的模拟结果,可以看出,在各种影响因素的综合作用下,各种土地类型之间相互竞争及其在空间分配上的演替规律。结果表明：发展生物能源情景下内蒙古及其沿线区、黄淮海区和黄土高原区的土地利用变化都有较大的变化,而东北区变化不明显,基本处于平稳状态。从整体来看,林地在各区都有不同程度的增加。模拟结果可为决策者制定土地利用规划提供科学依据。 相似文献
11.
A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
12.
Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
13.
A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
14.
Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
15.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
16.
Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
17.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
18.
《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
19.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
20.
Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment. 相似文献