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61.
An apparent decrease in total phosphorus concentrations of approximately 4.l μgP/L has been reported recently for the spring values of 1977 and 1978 in Lake Ontario. Investigation of the loading reduction for this period independent of sedimentation factors can account for only 10% of the change. The results indicate that changes in the sedimentation rate of total phosphorus during this period offer an explanation for the majority of the change in concentration.  相似文献   
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The number of firms using alliances as part of their corporate venturing or market entry strategies has surged over the past decade. Three common reasons cited for pursuing alliances are technology convergence, market access and alliance partners' complementary resources. This paper contrasts the alliance strategies of HP and IBM, two major competitors in electronic services (i.e. Internet-based 'e- service') businesses, using the Familiarity Matrix as a display tool to portray the strategies. Whereas the HP strategy is to attempt to establish its technology infrastructure as the standard e-services infrastructure on the Internet, IBM aims to position its IBM Global Services, rather than its technology, at the center of this ecosystem.  相似文献   
65.
Assessing ten years of unique personnel data from a large firm, this paper investigates how determinants of worker turnover differ between periods of corporate expansion and decline. Performance and career progress considerably reduce the hazard of job separation during downsizing for blue-collar workers, but are less important for white-collar workers. Effects of firm-tenure, occupation, education, training, part-time status, and gender are largely in accordance with the implications from existing models. But no model generates all patterns observed in the data. Age effects are sensitive to retirement options and discontinuous, dropping in response to the anticipation of becoming eligible for early retirement during downsizing and jumping at the actual retirement age.  相似文献   
66.
Using bald eagles to indicate the health of the Great Lakes' environment   总被引:1,自引:0,他引:1  
The bald eagle (Haliaeetus leucocephalus) is one of the most studied birds of North America, and a great amount of natural life‐history information, including the response of various stressors on the eagles' ability to reproduce, are well known. In Michigan, the eagle has been chosen to track the trends of bioaccumulative compounds of concern across watersheds in the state. The state has been divided into major watersheds, and 20% of these are surveyed each year. A control area in northern Minnesota, Voyageurs National Park, is also sampled annually. We report here on the methods used, the preliminary results of the 1999 field season, and how differences in mercury concentrations varied over a 10‐year period. Mercury in feathers of nestling eagles declined over time only in Lakes Michigan and Huron, but have not decreased among other subpopulations in Michigan. Concentrations of polychlorinated biphenyls (PCBs) and 4,4′‐DDE in blood plasma from nestling eagles have declined over time for most subpopulations; however, they remain greater for breeding areas associated with the Great Lakes' food web. Sea eagles of the genus Haliaeetus are a good sentinel species to track trends in bioaccumulative compounds in aquatic systems.  相似文献   
67.
Deciding on advertising appropriations is a common problem to all National Tourist Offices. The Austrian National Tourist Office now employs a decision support model allowing for inclusion of managerial judgments. In tourism, like elsewhere, application of standard optimization routines to marketing decision making is straight- forward, once the relationship linking market response to input has been modeled adequately. A tailor-made decision calculus procedure eliciting managerial judgments on the relative importance of the factors determining a receiving country's travel market share provides the weights otherwise inaccessible by objective parameter estimation. A tourism manager thus can evaluate countries as tourism generators and allocate an advertising budget accordingly.  相似文献   
68.
This paper examines the variables that determine the performance of countries at the Olympic Games as measured by a weighted sum of the medals won at the Sydney 2000 Games. While previous studies have identified the importance of a country's economic size and the resources available to sport, this paper examines nine more variables including the number of athletes representing each nation and some development indicators. Based on 2310 regressions, both traditional and restricted extreme bounds analysis show that only two variables are robust: the number of athletes and national expenditure on health. Thus, the final model recognises four explanatory variables that include these two as well as GDP and population.  相似文献   
69.
在国内首次应用模型水轮发电机组对三峡地下电站变顶高尾水洞方案进行水力过渡过程试验研究。对水轮机导叶实行分段关闭 ,并求出了二段关闭的最佳拐点 ,试验证实了二段关闭对减小尾水管进口的负压和机组转速上升有明显的作用。通过有关水力参数的测试 ,认为变顶高尾水洞可以满足各项技术要求 ,是一个减少山体开挖、节省投资的新型设计方案。在地下电站中具有广泛的应用前景  相似文献   
70.
坦努尔坝是约旦的第一座RCC坝。该坝RCC铺筑采用斜层施工,提高工数50%。大坝上游面,下游台阶,阶梯式溢洪道,止水面以及RCC与坝肩石灰岩的交界面均采用GE-RCC。质量控制测试数据表明,该坝达到了国际大坝委员会会刊不久将发表的RCC坝质量标准的优良等级。  相似文献   
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