共查询到20条相似文献，搜索用时 421 毫秒
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《The Professional geographer》2013,65(2):208-214
This paper considers the appropriateness of typologies of urban retailing areas based on multivariate functional data. The findings of a case study in which statistical and graphical methods were employed within the framework of multivariate ordination are presented. It is shown that the functional attributes of retail areas are closely associated with their location, accessibility, quality, morphology, size, period of development, and socioeconomic character. 相似文献
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略论地理学文献的发展特征-兼论地理文献研究的实际意义 总被引：1，自引：0，他引：1
本文主要讨论地理文献特征,阐明文献分布的规律. 地理学是研究地表各种自然、人文现象的内在联系及演变规律的科学.它富于综合性、区域性,又是和许多学科交叉叠合的一门跨界学科.地理学的这些性质、特征必然反映到文献上来.地理文献的使用寿命比一般学科文献要长;地理文献的来源或分布要比一般学科文献格外分散.本文通过对若干文摘期刊及书刊引用文献统计分析,表明从事地理研究所参考引用的期刊文献,仅25%左右来自地理期刊,从事综合及总结性研究时高于这个此例,从事部门地理或带有技术性研究时低于这个比例.大部分参考文献则来源于相关学科期刊,这是地理工作者经常要比较多时间翻阅各种书刊去搜集资料的原因. 最后,本文阐述了从事地理文献研究对了解地理学发展趋势、选择课题、查找文献以及改进文献管理工作的实际意义. 相似文献
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Mark Woodall Robert G. Cromley R. Keith Semple Milford B. Green 《The Professional geographer》1980,32(4):412-420
Recent federal court decisions have emphasized the need to eliminate schools whose racial composition varies from that of the whole district by more than a fixed percent. A linear programming model is presented to assist school administrators in developing desegregation plans that comply with these guidelines. An efficient solutional technique that exploits the special structure of this model increases problem-size capabilities. A study of the Columbus City School District examines the tradeoffs involved at different levels of desegregation. 相似文献
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Robert B. Potter 《The Professional geographer》1981,33(2):208-215
This paper considers the appropriateness of typologies of urban retailing areas based on multivariate functional data. The findings of a case study in which statistical and graphical methods were employed within the framework of multivariate ordination are presented. It is shown that the functional attributes of retail areas are closely associated with their location, accessibility, quality, morphology, size, period of development, and socioeconomic character. 相似文献
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GIS与土壤溶质运移模型结合研究进展 总被引：4，自引：2，他引：4
地理信息系统对土壤溶质模型研究而言，使用者的要求与GIS所能提供的功能之间，还存在巨大的差距。出于对环境问题的关注，土壤中水分及溶质运移的规律及其对环境的影响，成为当前研究的热点。随着对土壤溶质运移模型研究的深入，一方面由于田间土壤特性具有很大的空间变异；另一方面，在实际应用中，往往溶质运移的宏观特征而非微观特征，具有更重要的意义。将溶质运移模型与GIS技术结合，定量研究空间尺度的溶质运移，成为溶质运移研究的必然发展趋势。由于计算机软硬件技术的发展，GIS正处于一个高速发展的时期。将GIS与溶质运移模型相结合，或者进一步，以GIS理论和技术为基础，建立基于GIS的溶质运移模型，将对溶质运移的规律及其对环境的影响，做出更深入和准确的描述。 相似文献
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本文依据 1 989/ 1 990和 1 990 / 1 991南极夏季在普里兹湾邻近海域所获取的拖网样品 ,对大磷虾 (Euphausia superba Dana)的种群结构进行了分析。体长频数分布表明 ,种群中主要包括4个年龄组 ,即 1 + 、2 + 、3 + 、和 4+ 龄。 5 + 和 5龄以上的高龄组所含比重很小 (<3 %)。雌性临产个体 (3 DF)的体长频数分布表明 ,大磷虾的初次性成熟年龄为 3龄。生殖群体也以 3 +龄为主 ,4+龄次之。种群组成存在着明显的地区差异。普里兹湾以北海域是典型的双态分布 ,1 + 龄占有相当大比重 ;测区东西两侧以成体虾为主 ,极少有 1 + 龄虾。种群组成的年际变化也是明显的 ,特别表现在补充群体 (1 + 龄 )的强度上 相似文献
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Cort J. Willmott 《自然地理学》2013,34(2):184-194
Traditional methods of evaluating geographic models by statistical comparisons between observed and simulated variates are criticized. In particular, it is suggested that the correlation coefficient (r), its square and tests of their statistical significance are inadequate for such purposes. The root mean squared error (RMSE) and related measures as well as a new index of agreement (d) are alternatively presented as superior indices for making such comparisons. Arguments are made for increasing the number of digital algorithms and data plots being published. 相似文献
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北疆铁路沿线主要城市环境质量评价 总被引：1，自引：0，他引：1
运用系统工程的思想，建立了干旱区区域环境质量综合评价指标体系，选取了城市大气、地表水、地下水、固体废弃物、绿化覆盖率等作为评价因子，提出城市环境质量影响程序的等级划分和标准体纱。用多因素模糊综合评价模型，对这个带状区域的城市环境质量作了评价，在单项因子评价的基础上，又用加权迭加法进行了总体评价，从而获得了该区域环境质量的总况，为区域开发决策提供了科学依据。 相似文献
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本文对我国大陆200个站的平均月降水量序列进行谐波分析.结果表明:头三个谐波已足以描写我国大陆降水的季节变化特征,其中一波尤占优势.不同降水年变类型区域及其间的过渡在一波图上表现很清楚. 相似文献
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In this paper a criterion is described for the construction of experimental designs for the evaluation ofcalibration models in analytical chemistry.The proposed criterion seeks a compromise between theD-optimal designs for estimating the parameters of different polynomial models.A computer algorithmis presented for a sequential construction of experimental designs using the optimality criterion.Theperformance of the optimality criterion and the computer algorithm is elaborated for the problem ofdiscrimination between a first-to a third-degree polynomial for the calibration of analytical methods.Anexperimental design consisting of replicate measurements at five distinct levels equally spaced over thecalibration range proved a good solution. 相似文献
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Philip W. Suckling 《自然地理学》2013,34(1):49-57
Relationships between the coefficient of variability and the logarithm of extrapolation distance are established by an assessment of the spatial coherence of solar radiation. Equations for different confidence levels and daily and monthly time intervals are presented. These relationships are utilized in an assessment of the adequacy of the solar radiation data network in the contiguous United States. Results indicate that the present network maintained by the federal government provides adequate coverage on a monthly basis for all but 5% of the area for an error tolerance of ±10% at a 90% confidence level. However, on a daily basis, very inadequate spatial coverage is provided. 相似文献
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湘赣粤桂边地区即南岭地区区位优势独特，资源优势明显，政策优势灵活，交通通讯日益便利，区域内资源、产业和市场具有很强的集聚性和趋同性。建立湘赣粤桂边经济区，即南岭经济区，不仅是必要的，也是可行的。文中分析建立南岭经济区的必要性、可行性及有利条件、制约因素，提出建立南岭经济区的战略定位、区域布局及发展目标，并就建立南岭经济区的主要政策措施进行了探讨。 相似文献
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全新世以来永定河洪水的发生规律 总被引：2，自引：0，他引：2
本文通过对永定河流域内全新世地层、考古遗址和历史文献的综合分析,表明在距今约10000—9500年、7700—7500年、5200—4600年、3200—3000年、1900—1700年前以及公元1801—1896年间,永定河流域曾出现过六次暴雨洪水频繁发生的时期。 相似文献
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Burrell E. Montz 《The Professional geographer》1982,34(4):416-423
The adoption of hazard mitigation measures by those in vulnerable areas is the result of a complex process involving many variables. This study investigates the potential impact one variable, location, has on adoption. The findings suggest that adoption of measures that require little planning and are highly visible are related to location. 相似文献
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本文概要介绍了我国２１世纪发展白皮－《中国２１世纪议程》;全面列举了国际社会对西北地区第一批优先项目支持的承诺,勾勒了西北地区“可持续发展之路”的轮廓。 相似文献