共查询到20条相似文献，搜索用时 859 毫秒
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J.M.ANDRADE D.PRADA S.MUNIATEGUI Department of Analytical Chemistry Universidade da Corun La Zapateir E- Corun Spain B.GOMEZ M.PAN Analytical Laboratory Complejo Industrial Repsol Petróleo S.A.de La Corun Poligono Bens Corun Spain Author to whom correspondence should be addressed. 《地理学报(英文版)》1993,(5)
This paper deals with a typical question encountered in all industrial analytical laboratories:are all thetests performed in the laboratory to characterize the final product really necessary?In this work the cross-validation technique,Procrustes rotation techniques and statistical variable selection have been used toreduce the 26 initial British Petroleum and ASTM kerosene specification tests to ten'essential'ones.Statistical as well as chemical considerations were used to select the optimum subset of original variablesto be retained from all the possible ones. 相似文献
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A curve-fit model of the relationship between soil pH (A horizon) and climate forms the basis of a map of predicted pH for the conterminous United States. This map was produced with the aid of a large climatic data base, a computer mapping program and subroutines to map modeled values of soil pH. Patterns of pH follow well-recognized patterns of climate, although the pH of 7 line deviates greatly from Marbut's line dividing pedalfers from pedocals. The overall accuracy of the map and model was checked using a validation data set. Geographic patterns of pH are realistic, although land use, topography, and parent material may cause local variations about the predicted mean for a given region. Several apparently anamolous map patterns were also checked but found to be accurate. Prediction of the detailed pattern of pH will require variables in addition to climate. 相似文献
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TAN Fang-Lin 《湿地科学》2007,5(2):105-110
Spartina is a kind of very important and invasive grass. In its native range, it is very important for erosion control, fish, wildlife, and estuary reclamation. Therefore, it was introduced to many countries. Since 1963, it was introduced to China. Up to now, it was intentionally or accidentally planted nearly all estuaries in the east coast of China and the area was estimated over 0.1×106 hm2. As other introduced plants, Spartina grows very vigorously in China, and this caused many environmental and economical problems. So, it is an emergency to develop a Spartina control strategy of China. In the paper, the history of Spartina introduction in China was reviewed, and several methods which were probably feasible for China to control Spartina were introduced, including physical/mechanical (such as mowing, digging, and dredging), chemical, and biological methods. Before taking any measurments to control Spartina, 2 things should be done. The first was to develop a plan and make an inventory; the second was to select a feasible method according to local climatic, economic, social, and ecological conditions. It was suggested that it would be very important to assess the possible effect of control methods on the environment in order to prevent from causing other environmental problems. 相似文献
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The organizational separation of management and other quaternary activities from production operations in American manufacturing has resulted in a divergent pattern of production and headquarter locations. We examine the external control relationships that arise from this separation between headquarter location and branch plant operations in nonmetropolitan Kentucky. Although corporate headquarters have diffused to the Sunbelt, no shift was found in the corporate control of branch plants in Kentucky. Nonmetropolitan manufacturing in Kentucky was oriented toward the metropolitan centers of the traditional manufacturing belt rather than the newer corporate centers of the South. Also control relationships are more likely to be local among smaller factories. Large plants having more autonomy in production or producing finished goods were more likely to be owned by a distant firm located in a large SMSA. 相似文献
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《The Professional geographer》2013,65(4):332-342
The organizational separation of management and other quaternary activities from production operations in American manufacturing has resulted in a divergent pattern of production and headquarter locations. We examine the external control relationships that arise from this separation between headquarter location and branch plant operations in nonmetropolitan Kentucky. Although corporate headquarters have diffused to the Sunbelt, no shift was found in the corporate control of branch plants in Kentucky. Nonmetropolitan manufacturing in Kentucky was oriented toward the metropolitan centers of the traditional manufacturing belt rather than the newer corporate centers of the South. Also control relationships are more likely to be local among smaller factories. Large plants having more autonomy in production or producing finished goods were more likely to be owned by a distant firm located in a large SMSA. 相似文献
6.
胡最 《云南地理环境研究》2007,19(1):67-70
控件子类化技术是当今成熟的编程技术，在程序的界面开发和对话框设计中有着广泛的应用。子类化属性是程序语言中控件的重要属性，通过对MFC的标准控件进行子类化扩展，能够设计出各种美观、实用且具有特殊功能的控件来美化程序界面。结合子类化方法的重要原理，作者首先分析了子类化技术在GIS系统开发中的应用，并总结了在GIS程序开发过程中一些较为实用的控件子类化方法。最后以在VC.NET开发环境中设计子类化控件实例进行了分析说明。 相似文献
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青海省防治沙漠化区划研究 总被引：10，自引：2，他引：8
按照区划的原则和依据,将青海省沙漠化土地划分为4区10个亚区。柴达木盆地荒漠区划分为冷湖风蚀区、格尔木流沙区、都兰流沙区、德令哈戈壁区和乌兰固沙区5个亚区;共和盆地半荒漠区划分为共和流沙区和贵南流沙区2个亚区,青海湖盆地环湖区只划分1个亚区;青南高寒区划分为可可西里风蚀区和黄河上游阶地风蚀风积区2个亚区。针对各亚区沙漠化土地现状和特点,提出了合理开发方向和防治途径。 相似文献
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LAND DEGRADATION AND ITS CONTROL STRATEGIES IN CHINA 总被引：1，自引：0，他引：1
Yang Chaofei Dapartment of Natural Conservation National Environmental Protection Agency Beijing People''s Republic of China 《地理学报(英文版)》1997,(2)
Ｈｕｍａｎ-ｉｎｄｕｃｅｄｌａｎｄｄｅｇｒａｄａｔｉｏｎａｓａｃｅｎｔｒａｌｔｈｅｍｅｏｆｄｅｓｅｒｔｉｆｉｃａｔｉｏｎｉｎｔｈｅｗｏｒｌｄｒｅｆｅｒｓｔｏｄｅｃｌｉｎｅｏｒｌｏｓｓｏｆｂｉｏｌｏｇｉｃａｌｏｒｅｃｏｎｏｍｉｃｐｒｏｄｕｃｔｉｖｉｔｙｃａｕｓｅｄｂｙｉｒｒａｔｉｏｎａｌｈｕｍａｎａｃｔｉｖｉｔｉｅｓ.ＡｃｃｏｒｄｉｎｇｔｏａｓｓｅｓｓｍｅｎｔｏｆＵＮＥＰａｂｏｕｔ3.6ｂｉｌｌｉｏｎｈａｏｆｌａｎｄｉｎｏｖｅｒｏｎｅｈｕｎｄｒｅｄｃｏｕｎｔｒｉｅｓｈａｖｅｂｅｅｎａｆｆｅｃｔｅｄｂｙ… 相似文献
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论广州市建设国际大都市大气环境质量控制 总被引：1，自引：1，他引：1
建设国际大都市要求有优美的环境和清新的空气，广州市与国际大都市比较还有较大差距。本文分析了影响广州市大气质量的重要因素和主要大气污染物的发展趋势，提出了控制广州市大气环境质量的对策。 相似文献
10.
铁路沙害整治及其研究方向 总被引：3，自引：2，他引：3
概述了铁路沙害状况及沿线主要自然地理特征，对３０多年来研究建立的５种铁路沙害防治体系结构模式进行了剖析，评价分析了每个防沙体系的不同结构和功能、体系的整体特征以及推广应用的主要条件；同时针对铁路安全运输生产的特点，提出了铁路沙害整治的研究方向。 相似文献
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减压沉井在滑坡治理工程中的应用 总被引：2，自引：1，他引：1
对罗家塘滑坡的成因类型、影响因素及形成模式等进行了详细的分析,并对滑坡稳定性进行了认真的验算,论证了降低承压水头对治理滑坡所起到的关键性作用,在此基础上,设计了抽水降压与沉井支挡相结合的综合治理方案,介绍了减压沉井的结构特点和排布方法,指出了施工过程中应用注意的问题。 相似文献
14.
四川紫色土退化及其防治 总被引：2，自引：2，他引：2
四川紫色土的物理性退化、构造性退化,以及营养性退化中的氮素贫化、有效磷缺乏和有机质贫化等都比较严重。这主要受母质、生态和侵蚀等因素的影响。防治紫色土退化的措施有:重建紫色土生态保护系统,改土培肥以增强土壤“体质”和实施保护性耕作等。划分出四川紫色土退化防治区,并分区提出了防治途径。 相似文献
15.
大阿尔玛京卡河流域的雪崩与治理 总被引：1，自引：0，他引：1
大阿尔玛京卡河流域危险主要出现在中山森林－草原带和高山雪冰带。受局地气候、地貌与环境的综合作用，流域雪崩规模小、路程短，多见全程雪崩；雪崩类型单调，以干、湿雪崩占统治地位，在９０％以上，雪崩发生地点集中，而且每年都有出现，只有数量上的差异性。在西风气流的控制下，冬季积雪层的变质过程具温度梯度变质特征。积雪层负温梯度大，雪层深霜的发育和生长迅速，呈出“干寒型”积雪的基本特征。雪崩对道路、居民点和建筑 相似文献
16.
中国的耕地沙化及防止技术措施 总被引：6，自引：0，他引：6
耕地沙化是人类不合理地开发利用耕地及风力、水力等外力共同作用的产物, 主要分布于我国干旱、半干旱及部分半湿润的北方地区, 南方丘陵山区也有分布, 总面积256.21万hm2。通过耕地沙化的原因分析, 提出必须综合应用林草、农业、水利措施, 才能有效地防止耕地沙化。 相似文献
17.
乌吉线沙害整治措施探讨 总被引：3，自引：0，他引：3
乌吉铁路穿越乌兰布和沙漠边缘, 平沙地区段路基积沙严重, 影响线路正常运营。为了保护路基免受沙埋, 铁道部科学研究院西北分院自1982年起在该线K85地段(本井)建立了防沙试验工点, 通过多年的研究工作, 取得了若干成果。 相似文献
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塔里木河水化学变化及其控制途径 总被引：5，自引：0，他引：5
内陆干旱地区的生态环境退化,除沙漠化、盐渍化外,水质盐化也是一个十分突出的问题。塔里木河1958年前是一条淡水河,全河各段河水矿化度没有超过1g/l的。现塔里木河每年只有3个月的淡水期,3个月是1—3g/l的微咸水,6个月为大于3g/l的咸水。塔里木河水质盐化主要是人为活动改变了地区性的水盐与水量平衡,所以,今后在干旱地区进行水土资源开发,必须注意水盐与水量平衡。 相似文献
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云南省防洪空间信息系统构建 总被引：4，自引：1，他引：4
通过讨论应用地理信息系统（GIS）技术，立足现实对相关空间数据进行集成和整合处理，实现防洪空间信息的数字化、标准化，为优化防汛指挥工作手段提供基础。系统数据库饭知不同比例尺精度的空间基础数据以满足不同目的的需求，对相关水文、防洪设施、全省洪涝风险和重点区风险图、土地利用等图件进行系统整合。系统有较强的管理功能和分析功能，可提高云南省防洪空间信息的共享度和系统有效管理，为政府统一组织和指挥抗洪救灾提供重要的辅助决策支持手段。 相似文献