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51.
试验选用30头干奶牛随机分成试验Ⅰ组、Ⅱ组及对照组(Ⅲ),观察中药“保健增乳乐”对围产期奶牛血液生化指标的影响。在此基础上,异地选择10头干奶牛随机分成试验组(Ⅰ)和对照组(Ⅱ)进行了重复试验。结果显示:中药“保健增乳乐”能显著地降低产后奶牛血清谷草转氨酶(SGOT)、血清γ—谷氨酰转肽酶(Sγ—GT)、血清碱性磷酸酶(SALP)的活性(P<0.05),血清酮体含量(KB)、血清甘油三酯(TG)含量显著减少(P<0.01)。血糖(G)含量升高(P<0.05)。血清钙、无机磷的含量维持正常水平。结果显示中药“保健增乳乐”能有效地改善围产期奶牛的肝脏功能,维持奶牛的正常代谢,预防奶牛围产期的营养代谢性疾病。 相似文献
52.
A fast splitting procedure for classification trees 总被引:1,自引:0,他引:1
This paper provides a faster method to find the best split at each node when using the CART methodology. The predictability index is proposed as a splitting rule for growing the same classification tree as CART does when using the Gini index of heterogeneity as an impurity measure. A theorem is introduced to show a new property of the index : the for a given predictor has a value not lower than the for any split generated by the predictor. This property is used to make a substantial saving in the time required to generate a classification tree. Three simulation studies are presented in order to show the computational gain in terms of both the number of splits analysed at each node and the CPU time. The proposed splitting algorithm can prove computational efficiency in real data sets as shown in an example. 相似文献
53.
In the binary single constraint Knapsack Problem, denoted KP, we are given a knapsack of fixed capacity c and a set of n items. Each item j, j = 1,...,n, has an associated size or weight wj and a profit pj. The goal is to determine whether or not item j, j = 1,...,n, should be included in the knapsack. The objective is to maximize the total profit without exceeding the capacity c of the knapsack. In this paper, we study the sensitivity of the optimum of the KP to perturbations of either the profit or the weight of an item. We give approximate and exact interval limits for both cases
(profit and weight) and propose several polynomial time algorithms able to reach these interval limits. The performance of
the proposed algorithms are evaluated on a large number of problem instances. 相似文献
54.
On the Effect of Probability Distributions of Input Variables in Public Health Risk Assessment 总被引:1,自引:0,他引:1
A central part of probabilistic public health risk assessment is the selection of probability distributions for the uncertain input variables. In this paper, we apply the first-order reliability method (FORM)(1–3) as a probabilistic tool to assess the effect of probability distributions of the input random variables on the probability that risk exceeds a threshold level (termed the probability of failure) and on the relevant probabilistic sensitivities. The analysis was applied to a case study given by Thompson et al. (4) on cancer risk caused by the ingestion of benzene contaminated soil. Normal, lognormal, and uniform distributions were used in the analysis. The results show that the selection of a probability distribution function for the uncertain variables in this case study had a moderate impact on the probability that values would fall above a given threshold risk when the threshold risk is at the 50th percentile of the original distribution given by Thompson et al. (4) The impact was much greater when the threshold risk level was at the 95th percentile. The impact on uncertainty sensitivity, however, showed a reversed trend, where the impact was more appreciable for the 50th percentile of the original distribution of risk given by Thompson et al. 4 than for the 95th percentile. Nevertheless, the choice of distribution shape did not alter the order of probabilistic sensitivity of the basic uncertain variables. 相似文献
55.
This paper presents findings of a survey on manufacturing strategy practices adopted by the Indian machinery manufacturing companies (IMMC). Based on the survey, three companies have been selected for detailed case studies. Their experiences in the manufacturing strategy process are analyzed. Although the companies represented diversity in terms of product type, sales volume, and geographic location, they share several commonalties including use of advanced manufacturing technologies and use of several improvement techniques. The process of strategy formulation varied among the companies in terms of participants, complexity and degree of formalization. Competitive priorities, order winners and critical success factors are also identified for these companies. Based on strategic manufacturing issues, manufacturing competence index and business performance index for the companies has been worked out. 相似文献
56.
57.
目的:运用德尔菲法构建一套科学、可操作的公立医院绩效评价体系。方法:采用文献法研究国内外绩效评价理论,结合问卷结果形成初始量表。通过德尔菲法对指标进行两轮筛选及优化。结果:初步形成由“社会效益”、“质量安全”、“运行效益与效率”为基本结构的指标体系,包括3个一级指标、13个二级指标和72个三级指标。结论:该指标体系重点关注医院公益性及内涵质量,对公立医院绩效评价具有一定参考意义。 相似文献
58.
运用图模型理论研究冲突视角下中欧班列运营过程中运输订单商业竞争战略,构建“渝新欧”班列运营商、“苏满欧”班列运营商和昆山IT企业之间的商业竞争冲突模型。利用TOPSIS法评估班列的运输效率,确定决策者偏好,通过计算均衡解获得符合各决策者利益的理性对策。借助灵敏度分析研究决策者偏好改变对模型冲突结果的影响。研究表明:在竞争中,运输效率较低的一方可以通过降低价格弥补自身劣势而获得订单;运输效率较高的一方只有通过降价才能获得订单。该研究为班列运营商提供利益冲突中的商业竞争战略,能为顾客企业选择高效合理的运输线路提供有效的战略决策,同时亦能为宏观调控者规范市场、提高市场运输效率提供有效的政策启示。 相似文献
59.
传统研究对股票市场平稳性分析中大多采用市场指数抽样方式,分析方法和数据采样的差异一定程度上解析了现有研究结论中的不一致性。从市场指数构建原理入手可探究抽样分析的局限,作为系列个股的加权值,市场指数无法精确刻画市场所有个股的波动情况。实证时采用A股市场所有个股数据开展全样本分析,这更符合大数据分析理念,统计出个股分析结果继而对A股市场波动进行判定将更加系统和可靠。在不考虑结构突变的情形下,分别计算出ADF检验、KPSS检验和PP检验三种方法的结果;全样本分析结果表明A股市场年度股价数据更多地呈现出平稳性特点,而且,个股数据检验结果与市场指数检验结果存在显著差异。 相似文献
60.
核设施运营单位的核应急能力评价是核设施运营单位风险评估及核应急管理的重要内容,构建核设施运营单位的核应急能力评价体系可以提升核设施运营单位的核应急响应能力和管理能力。在对某4个核设施运营单位的20位专家进行两轮咨询的基础上,结合已有国内外研究成果,并采用临界值法对评价指标进行筛选,建立了一个包含3项一级指标,13项二级指标,38项三级指标的核设施运营单位核应急能力评价指标体系。指标体系综合考虑了影响核设施运营单位的核应急能力的主要因素,涵盖了核设施运营单位的核应急工作的各个方面,且各指标之间相对独立,操作方便,实施起来简单易行,可协助发现核设施营运单位在应急响应能力方面存在的问题,对核设施运营单位的核应急能力建设起到积极的促进作用。 相似文献