纳米管的生物效应和毒性

在使用3-(4,5-二甲基-2-噻唑)-2,5-二苯基溴化四唑(MTT)比色法和毒物学方法研究由碳纳米管引起的生物组织——鸡胚胎纤维原细胞的性质的改变,以及碳纳米管对细胞产生的毒性后,发现碳纳米管会对鸡胚胎纤维原细胞增殖造成影响,不过它对这个生物组织的毒性很小,大约一级。     

Using a Box–Cox transformation in the analysis of longitudinal data with incomplete responses

We analyse longitudinal data on CD4 cell counts from patients who participated in clinical trials that compared two therapeutic treatments: zidovudine and didanosine. The investigators were interested in modelling the CD4 cell count as a function of treatment, age at base-line and disease stage at base-line. Serious concerns can be raised about the normality assumption of CD4 cell counts that is implicit in many methods and therefore an analysis may have to start with a transformation. Instead of assuming that we know the transformation (e.g. logarithmic) that makes the outcome normal and linearly related to the covariates, we estimate the transformation, by using maximum likelihood, within the Box–Cox family. There has been considerable work on the Box–Cox transformation for univariate regression models. Here, we discuss the Box–Cox transformation for longitudinal regression models when the outcome can be missing over time, and we also implement a maximization method for the likelihood, assumming that the missing data are missing at random.     

特种Nafion溶液制备及其在PEMFC中的应用研究

Nafion溶液在燃料电池、电极修饰、电化学分析、电化学催化等领域具有广泛用途。采用特种高沸点溶剂,获得了溶铸性能优良Nafion的溶液。比较溶铸Nafion膜与原始Nafion膜的IR光谱可以看出,Nafion溶液制备方法未对Nafion膜的化学组成与分子结构产生影响,但溶铸膜的分子排列更加规整有序。将该溶液在PEMFC中应用,其性能优于目前的商品水-醇体系Nafion溶液。     

103气相色谱仪三例故障维修

通过三例故障现象的分析,介绍103气相色谱仪热导池检测器、热导池温度控制器和微电流放大器的工作原理。     

植物根尖细胞有丝分裂的周期性

本文采取一天当中对大蒜根尖细胞进行几个时间取材实验。结果表明:植物体细胞和其它生物体细胞一样其繁殖过程有自身的规律性,在生长区内大蒜根尖细胞有着周期性的分裂。     

GTEM Cell的坐标变换分析

文献［１］提出用坐标变换将ＧＴＥＭｃｅｌｌ变换成均匀矩形偏心同轴线，然后用数值方法求解场分布，但是其变换后的二阶偏微分方程存在错误。文中经过严格的推导，获得了正确的结果，纠正了文献［１］中的错误。     

一种双层小区结构中的切换控制策略

在宽带码分多址双层小区结构系统中提出了一种基于小区覆盖范围和信号能干比判决的切换策略,切换策略使用了基于概率的动态资源预留方案,即在切换时,如果系统中没有空闲资源,则对切换呼叫进行排队。通过仿真表明,该切换策略相对于采用固定资源预留的切换策略,在轻负荷的条件下对话音呼叫的阻塞概率有一定的改善。     

信息化背景下发展型农村地区手机使用人群分化研究——基于晋南村庄的实证调查

随着农村信息化的迅猛发展和手机迅速的普及,手机使用逐渐进入人们的学习、工作和生活之中,改变着人们的思维和行为方式,打破传统人群基于人缘、血缘、地缘、为纽带的人群共同成员感和归属感,进而导致农村地区人群也在走向分化。以晋南村庄的手机使用情况的实地调查数据为依托,采用定性和定量的分析方法,从体制依存和自我依存的两个角度进行分析把握,结果表明,在信息化背景下的手机使用过程使得村庄人群存在明显的分化。结合以上分析,对这种现象进行了初步的了解和掌握,进而探讨这种现象对社会带来的价值与意义。     

The analysis of some biological data

This paper considers the building of stochastic models and the related analysis of discrete data in two biological problems, The first arises from the reproduction of yeast cells, while the secondis concerned with the aggregation of nucleoli. Galton-Watson and aggregation models are constructed for the respective processes and their goodness of fit to the data tested     

Generalized phase I-II designs to increase long term therapeutic success rate

Designs for early phase dose finding clinical trials typically are either phase I based on toxicity, or phase I-II based on toxicity and efficacy. These designs rely on the implicit assumption that the dose of an experimental agent chosen using these short-term outcomes will maximize the agent's long-term therapeutic success rate. In many clinical settings, this assumption is not true. A dose selected in an early phase oncology trial may give suboptimal progression-free survival or overall survival time, often due to a high rate of relapse following response. To address this problem, a new family of Bayesian generalized phase I-II designs is proposed. First, a conventional phase I-II design based on short-term outcomes is used to identify a set of candidate doses, rather than selecting one dose. Additional patients then are randomized among the candidates, patients are followed for a predefined longer time period, and a final dose is selected to maximize the long-term therapeutic success rate, defined in terms of duration of response. Dose-specific sample sizes in the randomization are determined adaptively to obtain a desired level of selection reliability. The design was motivated by a phase I-II trial to find an optimal dose of natural killer cells as targeted immunotherapy for recurrent or treatment-resistant B-cell hematologic malignancies. A simulation study shows that, under a range of scenarios in the context of this trial, the proposed design has much better performance than two conventional phase I-II designs.