选用液压阀的注意事项

在液压系统设计中选用液压阀时，常常遇到一些影响系统工作性能又往往被忽视的问题，本文对这些问题进行了分析并提出处理的对策。     

关于超越整函数系数线性微分方程解的性质

该文研究了几种类型的整函数系数线性微分方程解的级、零点收敛指数,得到了它们的精确估计.     

有机同系物光电子能谱的一个递变规律

该文对有机同系物的同系线性规律进行了探讨,提出了一种有机同系物光电子能谱递变规律,其表达式为:p=a+b{(n-k)/[(n+t)+1]}用有机共轭体系和非共轭同系物的光电子能谱数据对该线性规律进行了验证．     

Synergistic effect of acute hypoxia on flow-induced release of ATP from cultured endothelial cells

Human umbilical vein endothelial cells (HUVECs) in primary cultures were perfused under normoxic or hypoxic conditions. These cells were stimulated twice for 3 min by increased flow (from 0.5 to 3.0 ml/min). Under hypoxic conditions the basal release of ATP was the same as under normoxic conditions, but during increased flow the release was greater (0.58±0.07>0.32±0.04 pmoles/ml/10⁶ cells (+78%), for the first period of stimulation; 0.39±0.05>0.22±0.03 pmoles/ml/10⁶ cells (+79%) for the second period). Further experiments with sequential increments in flow rate showed that under both normoxic and hypoxic conditions, a positive correlation existed between ATP release and the rate of flow but there was always more ATP released under hypoxic conditions regardless of the flow rate.HUVECs in secondary culture (second passage) were similarly stimulated. No differences were observed between normoxic and hypoxic conditions. In both cases, the quantity of ATP released during high flow (0.050±0.004 pmoles/ml/10⁶ cells) was significantly smaller than the quantity of ATP released during low flow (0.09±0.01 pmoles/ml/10⁶ cells).To conclude, since hypoxia alone did not affect ATP release, there appears to be a synergistic relationship between increased shear stress and hypoxia in the stimulation of ATP release from HUVECs. Moreover, the release of ATP under these conditions seems to be a property of highly differentiated endothelial cells.     

A mixture likelihood approach for generalized linear models

A mixture model approach is developed that simultaneously estimates the posterior membership probabilities of observations to a number of unobservable groups or latent classes, and the parameters of a generalized linear model which relates the observations, distributed according to some member of the exponential family, to a set of specified covariates within each Class. We demonstrate how this approach handles many of the existing latent class regression procedures as special cases, as well as a host of other parametric specifications in the exponential family heretofore not mentioned in the latent class literature. As such we generalize the McCullagh and Nelder approach to a latent class framework. The parameters are estimated using maximum likelihood, and an EM algorithm for estimation is provided. A Monte Carlo study of the performance of the algorithm for several distributions is provided, and the model is illustrated in two empirical applications.     

线性代数中几个定理的新证法

对线性代数中关于矩阵秩的几个公式与特征多项式的性质定理给出了新的证明方法，用齐次线性方程组解空间的理论证明了矩阵秩的６个定理，利用矩阵和的行列式定理给出了矩阵Ａ的特征多项式系数及Ａ的主子式关系定理的新证法。     

对多目标线性规划的λ－算法的修正

本文指出运用多目标线性规划λ－算法在某些情况下会得出错误的结果，分析了发生错误的原因，并给出修正的λ－算法．     

旋转叶轮内部全三维可压缩气动问题有限元统一解法

本文旨在建立旋转叶轮内部全三维可压缩气体流动问题（正问题、反问题、混合问题）的通用数学模型及其有限元统一解法，将三维正问题分析、叶片的完全三维设计以及三维叶片局部改型融合于同一种计算方法．     

多波长数据线性回归分光光度法同时测定微量钙和镁

文章采用多波长数据线性回归法，以酸性格兰Ｋ与钙、镁的显色体系同时测定钙和镁．应用氢氧化物及硫化物沉淀分离法有效地消除了常见元素对测定的干扰．将此法用于自来水样分析，所得结果满意．     

基于信号子空间线性预测的测向方法

文章分析了均匀线阵输出信号的信号子空间结构，提出了基于信号子空间线性预测的测向方法。理论分析和计算机仿真实验表明，通过信号子空间的线性预测．可以获得较高的角度分辨率。