直喷式柴油机怠速工况燃烧循环波动分析

测量了怠速工况下直喷柴油机在不同供油提前角时的针阀升程及气缸压力,计算分析了各参数循环波动变化情况.结果表明,在怠速工况下,直喷柴油机平均指示压力的循环波动较大.随着供油提前角的增加,喷油提前,燃烧始点提前,最大燃烧压力增加,最大压力升高率变化不明显,它们对应相位提前,最大燃烧压力和平均指示压力的循环波动增加.通过对怠速工况各参数进行相关分析,讨论了影响最大燃烧压力波动的主要因素.     

Biomass,nitrogen and potassium dynamics in hydroponic rose production

Purpose: Roses are one of the ornamental species of major importance and economic value. Fertilisation programmes which maximise plant growth and quality, while minimising environmental impact are important. Here, we followed the N and K dynamics during rose development with the aim to define the nutrient demands as a basis for implementing fertigation programmes.

Materials and methods: Roses with one basal break were grown in a closed hydroponic system. Destructive samples were taken to determine dry weight, N and K content. In each sample, plants were sectioned into roots, rootstock, basal break, stems and leaves from the zone of active leaves and the zone of cutting flowers, as well as the flower bud in the latter.

Results: The shoots of the active leaves and cutting flowers zones exhibited a biphasic growth; dry weight, N and K increased after pruning of the zone of active leaves and the cutting flowers zone, however, in the second phase, total dry weight did not show a significant difference between the phenological phases, while the accumulation of N and K decreased throughout the entire plant.

Conclusions: Our results suggest that greenhouse roses develop a dynamic and complex balance between the aerial parts of the plants and the roots for storage and/or transport of photoassimilates, N and K. The total demand for N was 411 and 799?mg per plant for the initial shoot development of the active leaf zone and cutting flowers zone, respectively. The demand for K was 149 and 106?mg per plant for both shoots, respectively. The loss of N (555?mg per plant) and K (167?mg per plant) from roses plants to the root environment implies that lower fertiliser inputs can be used as these nutrients may be re-uptaken by new emerging roots.     

农业生物质资源木质纤维素及基质化利用研究进展

基质栽培是国内外现代化温室的主要栽培模式,其在设施园艺业的应用前景广阔,地方生物质资源基质替代或补充草炭基质势在必行。我国农业生物质资源种类繁多、来源广、富含大量木质纤维素,且这类物质具有结构坚硬、分解困难的特性。因此,木质纤维素降解是规模化快速基质生产的关键。为供促进农业生物质资源的基质化利用参考,简述农业生物质资源木质纤维素特点,农业生物质资源基质化利用及其木质纤维素降解的研究进展,指出农业生物质资源基质化木质纤维素降解的研究方向。     

Test on Seismic Behaviors of Reinforced Concrete Beams Composite Rehabilitation with Bonded Carbon Fiber Reinforced Polymer and Steel Plate

Neither the Carbon Fiber Reinforced Plastic nor the steel plate strengthening concrete components shows sufficiency in improving the structures' seismic behaviors independently, while they complement each other by the way of composite strengthening. Six reinforced concrete beams, five of which are strengthened, were comparatively and experimentally tested under low frequency cyclic load to investigate their mechanical performances such as characteristic of resilience, hysteretic curve, seismic behaviors, skeleton curve, degeneration of rigidity and loading capacity. It is indicated that the way of composite strengthening can boost the beams′ ultimate bearing capacity, ductility and deformability capacity effectively, and it can delay rigidity degeneration and improve the seismic behaviors of the beams. Also, the CFRP and steel plate can work together very well.     

Carbon Paste Electrodes for the Analysis of Some Agricultural Pollutants and Trace Metals

The present work is concerned with the voltammetric application of unmodified tricresyl phosphate carbon paste electrode （TCP-CPE） and in situ bismuth-film modified tricresyl phosphate-based carbon paste electrode （BiF-TCP-CPE）. The TCP-CPE was examined with the main objective of using it for the differential pulse voltammetric analysis of some neonicotinoid insecticides in aqueous Britton-Robinson buffer solution pH 7.0 as supporting electrolyte. After comparing the performance of the TCP-CPE with that of silicone oil carbon paste electrode, quantitative analysis of imidacloprid, thiamethoxam and clothianidin was performed in model solutions and real samples （river water and commercial insecticide formulations）. The in situ prepared BiF-TCP-CPE was tested for a simultaneous detection of selected heavy metal ions （Cd^2＋ and Pb^2＋） at a μg/dm^3 concentration level, using square wave anodic stripping voltammetric technique. The influence of different electrochemical pretreatments of the working electrode on the bismuth deposition and analyte signals were investigated. Film formation was studied at untreated, pre-cathodized and pre-anodized TCP-CPEs in the acetic buffer solution pH 4.6, containing 1 μg/cm^3 Bi （III）.     

治理林业“两危”几个财务问题的研究

治理林业“两危”必须遵循林业资金运动规律,建立适合林业特点的资金循环体制和营林会计标准体系;建立林业专业银行;理顺财政体制;提高固定资产折旧率,改革企业折旧制度。     

周期性“饥饿-再投喂”对大口黑鲈幼鱼补偿生长的影响

在水温(26.5±1.2)℃下,将体质量(45.70±0.56)g的大口黑鲈Micropterus salmoides幼鱼分为4组,饲养在采光大棚内的30m2水泥池中,每池40尾,D0组每天饱食投喂2次,D1、D2、D3组分别投喂6d、5d、4d,饥饿1d、2d、3d,持续8周,每组3个重复池塘,研究周期性“饥饿-再投喂”对大口黑鲈幼鱼补偿生长的影响。结果发现,随着每周饥饿天数的增加,大口黑鲈的末体质量和增重率均不同程度下降,但D1组与D0组无显著差异(P>0.05)。大口黑鲈的日摄食量随饥饿时间的增加而显著提高(P<0.05),但各组间无显著差异(P>0.05)。D1组的饲料利用效率和蛋白质效率与D0组无显著差异(P<0.05);而D2和D3组显著低于D0组(P<0.05)。试验结束时,鱼体粗蛋白和粗脂肪含量随饥饿时间增加而下降。D3组鱼的胃和肠道蛋白酶活性显著低于D0组(P<0.05);D1组的胃和肠道脂肪酶活性较高;D1和D2组胃淀粉酶活性较高,肠道淀粉酶活性则随着饥饿时间增加显著上升(P<0.05)。饥饿使大口黑鲈血清甘油三酯和总胆固醇含量降低,血清谷草转氨酶和谷丙转氨酶活性增加。血清生长激素水平随着饥饿时间增加而上升,类胰岛素生长因子-Ⅰ水平则下降(P<0.05)。结果表明:每周投喂6d饥饿1d的大口黑鲈饲料转化效率较高,实现了完全补偿生长,可供集约化养殖的科学投喂参考。     

展形的上界与下界估计

展形是一个重要且独特的代数特征量，它主要用于刻画特征值分布的稠密性。首先给出实对称矩阵展形的新的下界估计，然后给出 Toeplitz 矩阵、 Hankel 矩阵与循环矩阵的展形的上界估计，其结论是对已有结论的扩展。     

新型的甘油骨架上含硫的替加氟硫代磷脂缀合物合成与活性研究

氢氧化钾存在下，异丙醇／水作溶剂，室温下硫酚对替加氟的环甘油硫代磷脂缀合物发生亲核开环，高产率的得到新型的甘油骨架上含硫的替加氟硫代磷脂缀合物，经抗肿瘤活性测定，目标化合物具有良好的对人体膀胱癌细胞T-24和胃癌细胞BGC-823抑制作用．