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91.
Mike?H.?AllsoppEmail author Johan?N.?M.?Calis Willem?J.?Boot 《Behavioral ecology and sociobiology》2003,54(6):555-561
Sections of brood from colonies of the Cape honeybee ( Apis mellifera capensis), the African honeybee ( A. m. scutellata), and hybrid bees of the two races were exchanged between colonies to study the effect of different brood-origin/nurse-bee combinations on development of caste characters. When Cape larvae were raised by African workers the amount of food provided almost doubled in comparison with Cape larvae reared by their own workers. In contrast, African larvae raised by Cape workers were provided with only half the amount they received from their own workers. After the bees emerged, we found a large degree of plasticity in characters related to caste differentiation, which corresponded closely to the amount of food provided. Super-fed Cape bees had enlarged spermathecae, were heavier than normal workers and developed more rapidly, and had reduced pollen combs, all typical for a more queen-like condition. Ovariole numbers did not appear to be enhanced by additional feeding. Cape bees that behave as social parasites in African bee colonies were most queen-like in the characters studied, albeit within the range that was found for Cape bees from normal colonies, suggesting within-colony selection for characters that enhance reproduction.Communicated by R. Page 相似文献
92.
"开放型"区域资源策略探析--以浙江省为例 总被引:1,自引:0,他引:1
本文从区域资源安全的内涵出发,以浙江省为研究对象,在分析了省域资源条件及供给现状的基础上,提出了构建“开放型”区域资源安全体系的总体思路。 相似文献
93.
Methods for life cycle assessment of products (LCA) are most often based on the general prevention principle, as opposed to the risk minimization principle. Here, the desirability and feasibility of a combined approach are discussed, along with the conditions for elaboration in the framework of LCA methodology, and the consequences for LCA practice. A combined approach provides a separate assessment of above and below threshold pollution, offering the possibility to combat above threshold impacts with priority. Spatial differentiation in fate, exposure, and effect modelling is identified to play a central role in the implementation. The collection of region-specific data turns out to be the most elaborate requirement for the implementation in both methodology and practice. A methodological framework for the construction of characterization factors is provided. Along with spatial differentiation of existing parameters, two newly introduced spatial parameters play a key role: the sensitivity factor and the threshold factor. The practicability of the proposed procedure is illustrated by an example of its application. Providing a reasonable data availability, the development of separate LCA characterization factors for the respective assessment of pollution levels above and below environmental threshold values seems to be a feasible task that may add to LCA credibility. 相似文献
94.
徐州红色旅游资源开发探讨 总被引:5,自引:0,他引:5
市场调查与分析显示,红色旅游资源在徐州市旅游资源开发中占据重要地位。徐州红色旅游资源的开发必须坚持高标准与高质量建设、区域合作、政府投资和市场化运作相结合、旅游产品活化四大原则。在徐州红色旅游资源开发战略举措上,建议采取坚持打造精品、加大宣传促销力度和整合徐州文化旅游资源、适时建设“军事文化大观园”三大战略举措。 相似文献
95.
96.
在分析区域开发中的环境规划所存在问题的基础上,阐述了区域环境规划的主要内容、规划目标和程序,提出了编制区域环境规划的建议. 相似文献
97.
B. N. Lohani Pakorn Adulbhan 《Journal of the American Water Resources Association》1979,15(4):1028-1038
ABSTRACT: Linear programming is the simplest of all the optimization techniques used in regional water quality management studies; but the technique can optimize only one goal. When there are multiple goals with the same or different priorities, goal programming is a useful decisionmaking tool. This paper illustrates the application of goal programming to a regional water quality management problem where the following two goals are considered: (1) minimize the total cost of waste treatment, and (2) maintain the water quality goals (dissolved oxygen) close to the minimum level stated in the stream standards. 相似文献
98.
Peter G. Ashton James B. Pickens Coryell Ohlander Bruce Benninghoff 《Journal of the American Water Resources Association》1980,16(4):738-744
ABSTRACT: Decisionmaking associated with the Nation's 1.7 billion acres of forest and range land has become increasingly complicated because of the rise in competition for resource use and in the awareness of environmental and social effects. This system analysis approach uses four models to synthesize pertinent masses of information into measures of economic, environmental, and social impacts. The system results can be used to help evaluate alternative national programs. The models are:
99.
C. T. K. Ching 《Journal of the American Water Resources Association》1981,17(3):454-457
A significant research problem is the assessment of impacts associated with growth and/or decline in a regional economy. A relevant method for analyzing such problems is the Leontief input/output model. Associated with these models are economic multipliers measuring total changes in sales, income, and employment. In this paper, the author contends resource multipliers are equally relevant. The specific form of these multipliers are defined. Water multipliers for a two-county region in central Nevada are presented and their uses described. 相似文献
100.
Howard T. Odum W. Kemp Maurice Sell Walter Boynton M. Lehman 《Environmental management》1977,1(4):297-315
New concepts and insights concerning human and natural systems in the coastal zone are emerging from recent energy analysis and synthesis studies. By using new concepts for measuring the quality of energy, one can express the work of ecosystems and human economies in equivalent terms. From energy models and new energy quality evaluations, one can learn what kinds of coastal systems maximize power, are competitive, economically vital, and likely to have a survival advantage.Energy analysis and synthesis is aided by energy circuit diagrams. Models of the coastal zone that emphasize the change in external driving functions related to world energy sources provide insights and some predictive abilities that are not found in economic studies, since money flows alone do not evaluate external driving energies.This paper suggests four procedures for coastal planning: 1) calculation of investment ratio in units of equal quality to determine which projects are economic in a broad sense, 2) development of energy signatures for coastal ecosystems, 3) determination of which interface ecosystems develop the best energy flows, and 4) development of regional models that include the main features of human and natural ecosystems. 相似文献