温度与饲粮维生素C水平对后备蛋鸭血清免疫和抗氧化指标的影响

本试验旨在研究温度与饲粮维生素C水平蛋鸭的血清免疫和抗氧化指标的影响.选取12周龄金定鸭216只,温度设低温(2±1)℃和适温(18±1)℃2个水平;饲粮中的维生素C添加水平分别为0、200和800 mg/kg.试验共6个处理,每个处理6个重复,每个重复6只试验鸭.试验期为6周.试验结果表明:1)低温使血清维生素C浓度显著降低了27.78%(P＜0.05),对氧化氢酶(CAT)、总抗氧化能力(T-AOC)、丙二醛(MDA)、白介素2(IL-2)、免疫球蛋白(IgG、IgA、IgM)、生长激素(GH)、胰岛素(Ins)、胰岛素样生长因子(IGF-I)、瘦素(Lep)、皮质醇(Cort)、三碘甲状腺原氨酸(T3)和甲状腺素(T4)的含量影响显著(P＜0.05);2)饲粮中添加200 mg/kg维生素C时,血清维生素C、IGF-I、Lep水平显著升高(P＜0.05),Cort浓度显著降低(P＜0.05);3)温度和维生素C的交互作用对Cort的含量的影响极显著(P＜0.01),对IGF-I、Lep、IgG和IgA的含量影响显著(P＜0.05),对GH、Ins、维生素C、L3、T4及各个抗氧化指标的影响没达到显著水平(P＞0.05).结果提示,低温影响后备蛋鸭血清维生素C的浓度,但饲粮中添加200 mg/kg维生素C时,可提高在低温条件下的后备蛋鸭血液维生素C的水平、提高血液中Lep和IGF-I的浓度、增强机体抗氧化和抗寒冷应激能力.     

极端干旱区大气边界层厚度时间演变及其与地表能量平衡的关系

主要采用ECMWF的地表和大气产品分析了中国西北极端干旱区大气边界层厚度与地表能量通量的时间变化特征,同时,结合探空加强观测分析了大气边界层演变的可能因素.得出:西北极端干旱区大气边界层厚度呈现出季节性的年际和年代际变化,夏季大气边界层厚度呈下降趋势,春、秋季节呈现出先增加后降低的趋势,冬季以阶段性降低趋势为主,20世纪80年代是大气边界层厚度的转折时期；感热通量是极端干旱区大气边界层发展的主要热力因素；由于夏季净辐射量、地气温差、粗糙度以及风速等因子随时间演变而呈降低趋势,潜热通量呈增加趋势,导致了边界层高度形成的热力作用减弱,边界层厚度降低；同时,粗糙度和风速也是大气边界层发展的主要动力因素,由于边界层粗糙度和风速降低,促使垂直风切变减小,湍流动力作用减弱,也会导致边界层厚度降低.     

在EnergyPlus中建立单盘管、双风机空调系统的模型

概述了用于建筑节能的单盘管、双风机的空调（SCTF）在整个建筑模拟程序EnergyPlus中的模拟模型的概念及发展。     

浅析严格控制钢筋保护层厚度的原因及其保证措施

论述了钢筋砼保护层厚度控制的重要性及钢筋砼保护层防控措施。     

热压温度对热压过程中板坯芯层温度变化影响的研究

纤维板热压过程中板坯芯层温度是否能迅速达到胶的固化温度是影响产品质量和生产率的重要因素之一。板坯热压过程中的传热速率受很多因素影响,如热压温度、板坯含水率、密度和厚度等,其中热压温度是生产中较易控制的工艺参数之一。通过探讨热压过程中板坯芯层温度变化规律与热压温度的关系,研究不同热压温度对板坯芯层温度变化的影响,为优化热压工艺条件提供理论依据。     

Tree identity surpasses tree diversity in affecting the community structure of oribatid mites (Oribatida) of deciduous temperate forests

The role of tree diversity and identity as determinants of soil animal community structure is little understood. In a mature deciduous forest dominated by beech we identified clusters of one, two and three tree species of beech, ash and lime allowing to investigate the role of tree species diversity and identity on the density and community structure of oribatid mites. To relate oribatid mite community structure to environmental factors we measured leaf litter input, fine root biomass, mass of organic layers, topsoil pH and C and N content. We expected oribatid mite density to increase with increasing tree diversity, but we expected the effects of tree species identity to override effects of tree diversity. Further, we hypothesized the density of oribatid mites to be reduced by the presence of beech but increased by the presence of lime and ash. As expected tree diversity little affected oribatid mite communities, whereas tree species identity strongly altered density and community structure of oribatid mites. However, in contrast to our expectations the density of oribatid mites was highest in presence of beech indicating that many oribatid mite species benefit from the presence of recalcitrant litter forming thick organic layers. Especially Oppioidea benefited from the presence of beech presumably due to an increased availability of food resources such as fungi and nematodes. Lower density of oribatid mites in monospecific clusters of lime and ash suggests that oribatid mites did not benefit from high quality litter of these species. Notably, large and strongly sclerotized oribatid mite species, such as Steganacarus magnus and Chamobates voigtsi, benefited from the presence of ash and lime. Presumably, these large species better resist harsh microclimatic conditions in shallow organic layers.     

Relation of Seed Structures to Soybean Cultivar Difference in Pre-germination Flooding Tolerance

Abstract

Flooding during germination inhibits the sprouting and emergence of soybean [Glycine max (L.) Merr.], reducing subsequent growth and yield. Previous studies revealed that cultivars tolerant to pre-germination flooding have a mechanism of reducing water absorption speed (WAS) during the initial stage of inundation; however, seed structures involved in WAS have not been fully clarified to date. The objectives of this study were to identify possible seed structures responsible for cultivar difference in WAS and pre-germination flooding tolerance. WAS of two tolerant cultivars (Peking and Williams) and two susceptible cultivars (Nakasennari and Enrei), which were identified in our previous study, was compared in relation to seed structures. In Peking, WAS was markedly lower than that of the other cultivars, either in intact seed or seed with the seed coat removed, suggesting that both the seed coat and the embryo have a mechanism of reducing WAS in this cultivar. WAS of the hilum side tended to be higher than that of the back side, and sealing of the micropyle significantly lowered WAS, showing that the micropyle rather than the hilum appeared to be responsible for the higher WAS of the hilum side regardless of cultivar. A comparison of cross section area of the hilum revealed that the tolerant cultivars tended to have a larger area than the susceptible cultivars, suggesting that an inner space of the hilum can act as a reservoir at the initial stage of inundation, thereby reducing WAS in tolerant cultivars.     

漂卵砾石地层沉井法施工大型调压井技术

喜儿沟水电站调压井深度102m,调压井上部65 m地质条件为冲洪积漂卵砾石层,用沉井法施工调压井,使开挖时的临时支护措施和井筒永久结构相结合,有效避免井壁坍塌,大大降低了安全风险.在漂卵石地层,采取先中间、后预留,对称、均匀地削薄土层,有效地避免了沉井被挟持的现象；在软硬相间不均匀地层,采取先硬基、后软基,有效地避免了刃脚变形和井壁开裂；在胶结砾岩地层,使用液压破碎锤破除胶结砾岩,有效地解决了反铲开挖困难、钻爆开挖效果不佳的问题.并针对出渣量大这一问题,因地制宜地采取了合理的出渣方案,大大提高了出渣效率.喜儿沟水电站调压井沉井法的顺利施工,可供同类工程参考.     

依普黄酮对骨质疏松症笼养蛋鸡OPG和RANKL表达的影响

选用200只24周龄健康海兰褐蛋鸡,随机分为4组:对照组(基础日粮中含钙3.55％)、低钙组(日粮合钙1.27％)、试验Ⅰ组(依普黄酮8 mg/kg,低钙日粮)和试验Ⅱ组(依普黄酮20 mg/kg,低钙日粮),观察依普黄酮对骨质疏松症笼养蛋鸡血清及骨骼骨保护素(Osteo protegerin,OPG)/核因子-相受体活化因子配体(Receptor activatorof NF-κB ligand,RANKL)表达的影响.结果显示:与低钙组相比,30 d时,试验Ⅰ组和Ⅱ组血清OPG分别显著升高33.12％和60.19％(P＜0.05)；60 d时,试验Ⅰ组和Ⅱ组血清OPG分别显著升高35.89％和61.59％ (P＜0.05)；30 d时,试验Ⅰ组和Ⅱ组血清RANKL分别极显著降低63.85％和70.87％(P＜0.01)；60 d时,试验Ⅰ组和Ⅱ组血清RANKL分别极显著降低69.98％和72.85％ (P＜0.01).与低钙组相比,试验Ⅰ组和Ⅱ组骨组织OPG平均光密度分别显著(P＜0.05)和极显著(P＜0.01)升高,试验Ⅰ组和Ⅱ组蛋鸡骨组织RANKL平均光密度极显著低于低钙组蛋鸡(P＜o.01).试验Ⅰ组和Ⅱ组OPG/RANKL值高于低钙组.结果表明,低钙日粮中添加依普黄酮对蛋鸡骨质疏松症可起到一定改善作用,这可能与OPG上调,RANKL下调,影响RANKL信号通路,使其骨量增加,骨结构改善密切相关.     

关于单层刨花板热压机设计中的几个要点

本文论述了热压机在刨花板生产过程中的重要地位 ,分析了单层热压机的优缺点 ,从热压机框架结构、液压系统、热压板、油缸分布等几方面进行了详尽的论述 ,并分析了设计要点。