关于p~k元域中的n方元素

设 F为 pk元域 ,n为正整数 .本文建议 F中的 n方元素的概念 ,给出 n方元素的特征性质 .最后 ,给出 n方元素的应用     

Effect of dipyridamole on glomerular mesangial cell ecto-5′-nucleotidase expression

Although dipyridamole has been extensively studied as an anti-aggregating agent, its mechanism of action has not been elucidated. Cultured mesangial cells were treated with dipyridamole 1–100 M from 6–72 h. Ecto-5-nucleotidase activity approximately doubled (from 115±11 to 226±14 nmol/min/mg) after treatment with 100 M dipyridamole for 72 h. This effect was concentration- and time-dependent. Cycloheximide, an inhibitor of protein synthesis, did not alter basal 5-nucleotidase activity. However, it prevented stimulation by 5 M dipyridamole. Adenosine availability at the receptor sites was increased by dipyridamole and S-(p-nitrobenzyl)-6-thioinosine (NBTI), which inhibit adenosine uptake into the cell. Addition of dipyridamole or NBTI to the adenosine-treated mesagial cells produced an additive increase in ecto-5-nucleotidase activity. Dipyridamole, through its effect on extracellular adenosine and ecto-5-nucleotidase, may have an influence upon regulation of the glomerular microcirculation.     

Bacterial phytotoxins: Mechanisms of action

Many species of phytopathogenic procaryotes produce toxins that appear to function in disease development. The affect the plant in different ways, the end result of which is the elicitation of chlorosis, necrosis, watersoaking, growth abnormalities or wilting. The most extensively studied toxins cause chlorosis. They specifically inhibit diverse enzymes, all critical to the plant cell. This inhibition results in a complex series of metabolic dysfunctions ultimately resulting in symptom expression. Substances causing growth abnormalities consist of known phytohormones and other compounds with plant hormone-like activities, but which have no structural relationship to the known hormones. The former act in the usual manner but, because of their elevated levels and imbalances, the host's regulatory mechanisms are overwhelmed and abnormal growth results (hyperplasia, shoot or root formation); the mechanisms of action of the latter group are unknown. High molecular weight, carbohydrate-containing substances, also acting in unknown ways, cause tissue watersoaking or wilting. Likewise, we know little about toxins causing necrosis except for syringomycin which affects ion transport across the plasmalemma.     

一类输水线路的最佳布线问题

主要解决了如下问题 :对于从河流L取水并输送到L同岸的两个用水点A、B的输水工程 ,当修建各段输水管道的耗资系数分别为k1 ,k2 ,k3时 ,如何确定抽水点P及分水点O才能使加权和值W =k1 OA k2 OB k3OP为最小 .     

两层广义线性规划

给出二层广义线性规划最优解极点可达性的一个充分条件 .此外 ,利用容许集的极点与下层问题可行集的极点间的关系给出“第 k最好”算法的一种快捷、方便的实现 .算例表明算法是有效的 .     

可允许极拓扑K(X,X′),(K)(X,X′),u(X,X′)与Dierolf拓扑F(μ),F(μ*)

指出K(X,X′)拓扑与K(X,X′)拓扑之间,u(X,X′)拓扑与K(X,X′)之间以及u(X,X′)拓扑与F(μ)(或F(μ*))之间均无固定强弱关系,是不可比较的.     

判定k-点连通图与k-边连通图极小性的定理

主要研究了判定ｋ－点连通图是极小的充要条件和ｋ－边连通图是极小的必要条件。     

对称r—循环阵的结构及其特征值

给出了复数域上对称ｒ－循环阵（ｒ＝±１）特征值的统一形式，并给出了循环长度为ｋ的ｋ循环阵化为简单ｋ循环阵的方法。     

2 n×2 n矩阵的k次幂

设A是2n×2n矩阵,根据矩阵的性质,得到了2n×2n矩阵A的k次幂,推广了P.J.Blatz,Kenneth S和Williams的相关结果.     

kNN算法在文本分类中的改进

kNN算法用已归类的数据训练分类器,它是一种基于实例研究（instance_based learning）文本分类算法,本文在研究kNN算法的基础上,结合k邻近法和最近特征线法的思想,提出了新的分类方法,k最近特征线法（k nearest feature line,kNFL）,将其运用于文本分类中,汲取了kNN算法和NFL算法的优点,降低了偶然误差,提高了算法适应性和分类精度。