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对旱地驱动耙的工作部件—刀齿进行运动分析。建立运动学模型及仿真模型,探讨了主要参数对耕作过程的影响,为旱地驱动耙的设计和分析提供理论依据。 相似文献
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内蒙古自治区森林资源状况 总被引:3,自引:3,他引:0
文章以内蒙古第六次森林资源连续清查结果为依据,概述了内蒙古自治区森林资源及其生态状况,并针对存在主要问题提出森林资源保护与发展建议。 相似文献
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Petrosky CE, Schaller HA. Influence of river conditions during seaward migration and ocean conditions on survival rates of Snake River Chinook salmon and steelhead.Ecology of Freshwater Fish 2010: 19: 520–536. © 2010 John Wiley & Sons A/S Abstract – Improved understanding of the relative influence of ocean and freshwater factors on survival of at‐risk anadromous fish populations is critical to success of conservation and recovery efforts. Abundance and smolt to adult survival rates of Snake River Chinook salmon and steelhead decreased dramatically coincident with construction of hydropower dams in the 1970s. However, separating the influence of ocean and freshwater conditions is difficult because of possible confounding factors. We used long time‐series of smolt to adult survival rates for Chinook salmon and steelhead to estimate first year ocean survival rates. We constructed multiple regression models that explained the survival rate patterns using environmental indices for ocean conditions and in‐river conditions experienced during seaward migration. Survival rates during the smolt to adult and first year ocean life stages for both species were associated with both ocean and river conditions. Best‐fit, simplest models indicate that lower survival rates for Chinook salmon are associated with warmer ocean conditions, reduced upwelling in the spring, and with slower river velocity during the smolt migration or multiple passages through powerhouses at dams. Similarly, lower survival rates for steelhead are associated with warmer ocean conditions, reduced upwelling in the spring, and with slower river velocity and warmer river temperatures. Given projections for warming ocean conditions, a precautionary management approach should focus on improving in‐river migration conditions by increasing water velocity, relying on increased spill, or other actions that reduce delay of smolts through the river corridor during their seaward migration. 相似文献
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环境条件对重阳木生长的影响 总被引:1,自引:0,他引:1
对重阳木以通径分析方法分析其生长状况与环境条件的关系。结果表明:多行的重阳木与其生长状况呈较强的正相关关系,除直接作用外,根系半深埋,根系损害以及地面硬化等均可通过其对生长状况产生影响;根系正常与冠幅生长相关性较强,除直接作用外,多行,根系伤害以及地面硬化程度均可通过其对冠幅生长产生影响;单行的重阳木与树干生长关系密切,除直接作用外,根系深埋、根系伤害程度以及地面硬化程度均可通过其对树干生长产生影响;根系深埋推迟发芽时间,除直接作用外,单行以及地面硬化均可通过其对发芽时间产生影响。 相似文献
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Duarte R Simoes DM Franchini ML Marquezi ML Ikesaki JH Kogika MM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2002,16(4):411-417
The aim of this study was to evaluate the accuracy of serum beta-hydroxybutyrate (beta-OHB) measurements for the diagnosis of diabetic ketoacidosis (DKA) in dogs. One hundred sixteen diabetic dogs were prospectively enrolled in the study: 18 insulin-treated (IT) diabetic dogs that had a positive urine ketone test and 88 untreated, newly diagnosed diabetic dogs. Venous blood gas tensions and pH, serum glucose and urea nitrogen (SUN), and electrolyte (Na+, Cl-, and K+) and urine acetoacetate (AA) concentrations were measured concurrently with serum beta-OHB concentrations. On the basis of laboratory findings, the patients were assigned to I of 3 groups: diabetic ketoacidosis (n = 43); diabetic ketosis (DK, n = 41); and nonketotic diabetes (NDK, n = 31). Serum beta-OHB concentrations differed significantly (P < .001) among the study groups. Although marked differences in beta-OHB concentrations were found, a considerable overlap exists between the distributions of dogs with DK and those with DKA. The overall accuracy of beta-OHB determination as a diagnostic test for DKA, determined by the area under the receiver operating characteristic (ROC) curve, was 0.92. In the 1.9- to 4.8-mmol/L range, serum beta-OHB determination sensitivity varied from 100 to 35.7%, whereas specificity varied from 39 to 100%. The cutoff value of 3.8 mmol/L showed the best equilibrium between specificity (95%), sensitivity (72%), and likelihood ratio (14.8). We concluded that the quantitative measurement of serum beta-OHB may be a potential tool for diagnosing and monitoring ketosis and ketoacidosis in diabetic dogs. 相似文献