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121.
超补偿理论及其在虫害控制中的意义 总被引:3,自引:0,他引:3
本文较为系统地阐述了作物对虫害损伤的超补偿理论,表明超补偿广泛存在于各种作物中,并对超补偿所需条件、基本原因以及与害虫控制的关系作进一步讨论。 相似文献
122.
Damodar S. Airan 《Journal of the American Water Resources Association》1973,9(5):1035-1040
ABSTRACT: Piped water supply and sewerage have been taken almost for granted in the developed countries. However, most people in the United States have little knowledge of the condition of public health amenities in the developing countries. The paper reviews the importance, background and current status of water and wastewater facilities in India. The relative situation in urban and rural areas, conventional practices in environmental hygiene, the programs for improvement and the problems involved with possible solutions are given. The case history of a town is also included for illustrative purposes. 相似文献
123.
Bennett EM 《Environmental management》2003,32(4):476-487
Understanding the magnitude and location of soil phosphorus (P) accumulation in watersheds is a critical step toward managing runoff of this pollutant to aquatic ecosystems. Here, I examine the usefulness of urban–rural gradients, an emerging experimental design in urban ecology, for predicting extractable soil P concentrations across a rapidly urbanizing agricultural watershed in southern Wisconsin. I compare several measures of an urban–rural gradient to predictors of soil P such as soil type, slope, topography, land use, land cover, and fertilizer and manure use. Most of the factors that were expected to drive differences in soil P concentrations were found to be poor predictors of Bray-1 (extractable) soil P, which ranged from 4 to 660 ppm; while there were several significant relationships, most explained only a small proportion of the variation. A multiple linear regression model captured approximately 37% of the variation in the data using the urban–rural gradient, topography, land use, land cover, manure use, and soil type as predictors. There was a significant relationship between Bray-1 P concentration and each of the urban–rural gradients, but these relationships explained only between 2.6% and 3.3% of the variation in P concentrations. Extractable P concentration in soils, unlike some other ecosystem properties, is not well predicted by urban–rural gradients. 相似文献
124.
125.
E. Earl Whitlatch Peggy L. Asplund 《Journal of the American Water Resources Association》1981,17(2):310-314
ABSTRACT: The cost of water service to rural residents is very high compared to urban areas. This is true even after subsidization by Farmers Home Administration (FmHA) loans and grants. Capital cost data on 44 projects financed by the Ohio office of the FmHA during the period August 1968 to January 1977 are used to derive cost equations for 26 components of rural water distribution systems. These components represent 92 percent of the capital cost of the pipeline distribution systems studied. The data can be used to economically design rural water supply systems from a capital cost viewpoint. More data are needed on operation and maintenance costs as well as central and cluster well costs before totally economic system designs can be undertaken. 相似文献
126.
Timothy R. Lazaro 《Journal of the American Water Resources Association》1977,13(1):149-151
ABSTRACT: Small, rural communities (less than 2500 population) in general do not have governmental staffs with the breadth required to satisfactorily implement and enforce a drainage ordinance. This fact has serious implications in rural Planning. Within a six-country rural area of Southwest Virginia, the circuit riding town manager program has been successfully conducted. The circuit riding town manager is a planning staff member who acts in the capacity of a town manager (assistant to the mayor) for five small towns, any one of which alone could not afford to support the services of such a professional. This note recommends that a circuit riding technical ordiance administrator program could be developed along the same lines. In this manner, the technical ordinance program for serveral small communities could be successfully implemented. 相似文献
127.
李志刚 《城市环境与城市生态》1998,11(4):27-30
酒泉地区城镇类型较多,城镇体系中的许多关系需要统筹协调,本文侧重从城镇的规模和空间关系分析,城乡一体化和区一发展,基础产业和环境建设等三个角度,探讨了区域城市可持续发展问题。 相似文献
128.
The dyadic level of conceptualization and analysis: A missing link in multilevel OB research?
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Despite burgeoning multilevel research in organizational behavior over the past two decades, our understanding of dyadic relationships at work remains underdeveloped. Focusing on leader–member exchange, we discuss conceptual and methodological challenges that have hampered research at this level and illustrate how and why such analysis might provide new insights. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
129.
事件树分析过程中事件树的编制和分析方法缺乏系统性,导致实际运用中事件树的编制缺乏可操作性。从目标系统的选择、环节事件逻辑关系的确定、定量分析中基本数据的来源和确定方法等三个问题进行了系统研究,并以可靠性的相关理论为基础,提出"从控制和影响初始事件发展演化的角度,调查分析对初始事件做出响应的安全功能,按系统工作原理对目标系统进行重构,构建目标系统的功能结构图,画出系统的可靠性框图"入手,对"传统的事件树绘制程序"进行修正,解决了事件树分析过程中目标系统的选择、环节事件逻辑关系的确定以及定量分析基本数据的确定方法等问题。修正后的方案对实现事件树的正确编制和系统分析逻辑更清晰,操作指导性更强。 相似文献
130.
Planning,governance and rural futures in Australia and the USA: revisiting the case for rural regional planning 总被引:2,自引:0,他引:2
T.H. Morrison Marcus B. Lane Michael Hibbard 《Journal of Environmental Planning and Management》2015,58(9):1601-1616
Rural regions in post-industrial countries confront significant new challenges, particularly in relation to climate, biodiversity, unconventional resource development and energy. Yet at a time when the contours of these challenges are still being sketched, and preliminary, planned interventions undertaken, the practice of rural planning finds itself at a low ebb. We examine two ‘critical cases’, one each from Australia and the USA, to explore the issues and options for capacity of rural regional planning to surmount these new challenges. Our examination indicates the urgent need for a renewed discourse on rural regional planning. 相似文献