In vitro-in vivo correlation and comparative bioavailablity of vincamine in prolonged-release preparations

Developing an in vitro dissolution test that gives good correlation with in vivo data for a particular drug product is an important objective. Available dissolution data of vincamine prolonged-release preparations show different in vitro release behavior at different pH using the conventional dissolution techniques. This does not allow development of an in vitro-in vivo correlation (IVIVC). In the present work, the flow-through cell (FTC) dissolution system (USP apparatus 4) was utilized to compare the release rate of three marketed prolonged-release oral formulations of vincamine; namely, a brand innovator formulation used as the reference and two formulations from different manufacturers as test products. Both the open and closed systems of FTC were used at variable pH. A comparative bioavailability study was then conducted in 16 healthy volunteers for a test versus the reference product by administering a single dose of 60 mg in a crossover design. Vincamine plasma concentrations were analyzed by a sensitive high-performance liquid chromatography (HPLC) method. This was followed by assessment of IVIVC according to level A as specified by USP 23; the absorbed fraction of vincamine was determined using the Wagner-Nelson method. The results indicated that the pH of the medium affects the release rate pronouncedly. The relative bioavailability based on C_max and AUC_0-12 were found to be 83.15% and 84.15%, respectively. Good correlation was obtained between fraction absorbed in vivo and fraction dissolved in vitro by applying the open system of the FTC. This technique gave the most favorable results with regard to the percentage vincamine released and the IVIVC     

用于煤层对比的一种新方法——灰色B型关联分析

本文根据文献[1]给出的 B 型关联分析的原理,在煤层对比中进行了初步尝试,取得了较好的效果.这种方法可以弥补传统煤层对比方法的某些不足,与回归分析、判别分析、聚类分析及灰色 A 型关联分析等数学分析方法相比其方法更简单。     

带测量误差的平稳信号相关函数的外推

本文首先给出带测量误差的一维平稳信号相关函数的外推;然后,在适当条件下给出二维平稳信号相关函数的两种外推.     

平衡二阶相关免疫函数的构造

构造了一大类平衡的二阶相关免疫函数，从而给出了二阶相关免疫函数个数的一个更好的下界公式     

一种基于Hadamard变换的相关辨识新方法

提出了一种新的基于Ｈａｄａｍａｒｄ变换的相关辨识方法。该方法用Ｍ序列作为辨识信号，用Ｍ矩阵与Ｈａｄａｍａｒｄ矩阵的相似关系，并通过Ｈａｄａｍａｒｄ变换计算系统的单位冲激响应。根据Ｇａｌｏｉｓ域理论，得到求相似变换阵的算法。文中还给出了部分仿真结果。     

Network security situation adaptive prediction model

Aiming at the low prediction accuracy of traditional network security situation prediction technology, a network security situation adaptive prediction model (NAP) is proposed. First, it extracts alarm elements and calculate network security situation time sequences based on the entropy correlation method. Then, the sequences are taken as the input of the sliding adaptive cubic exponential smoothing method with initial security situation predicted value sequences generated. Finally, the time-varying weighted Markov chain is used to predict the error value based on the error state and the initial predicted values are modified. Experimental results show that the NAP has a better prediction accuracy than other existing models.     

三参数对数正态分布的参数估计

运用线性相关系数优化法对三参数对数正态分布的参数Ｎ０，μ和σ给出了相应计算方法．疲劳性能测试数据在ｐ－ｌｇ（Ｎ－Ｎ０）坐标系中最大限度地呈现线性关系．实例表明直线拟合效果良好．     

超精密机床及其定位测量系统

分析了国内外起精密机床及其测量系统的发展，并在我国首次提出将双路双频激光测量系统用于超精密机床的在线测量．该系统具有采集速度快、结构紧凑、通用性好的特点，为超精密机床的研制奠定了基础．     

Hamiltonian性与邻域交

本文考虑图G的两个不相邻点的度及邻域交、得到如下结果:图G是2—连通简单图,独立数为口,最小度δ>n—2a+2,如果对于G的任意两个不相邻点u,v如下条件之一成立 d(u)+d(v)≥n |N(u)∩N(v)|≥α-1 则G是Hamiltonian。     

总平面布置单元的模糊聚类分析法

本文针对总平面优化布置系统中,首要解决的布置单元划分的问题,系统分析了布置单元聚类的样本元素(即工业企业有关设施)之间的相关关系。研究了确定相关关系的定量化方法,得出了总平面布置单元聚类的基本理论和分析方法——模糊聚类分析法,并结合实例验证了理论和方法的实用性。