生态学数学模型参数优化估计的遗传算法

本文提出用遗传算法,对生态学中的一些数学模型参数进行优化估计,并以崔-lawson方程为例．尝试了遗传算法的效果．结果表明,该方法性能良好,可望成为生态学中各类非线性模型辨识的有效参数．     

一类生物数学模型参数反演的Picard压缩映射方法

微分方程（组）系统是常见的一类生物数学模型．我们利用模型对应的Picard算子的压缩性和Collage定理,提出一类模型参数的反演算法,并通过数值例子说明了方法的有效性．     

脉冲-扩散周期竞争系统解的渐近行为

研究了在周期变化环境中具有扩散及种群密度可能发生突变的两竞争种群动力系统的数学模型．模型由反应扩散方程组以及初边值及脉冲条件组成．文章建立了研究模型的上下解方法,获得了一些比较原理．利用脉冲常微分方程的比较定理以及利用相应的脉冲常微分方程的解控制和估计所讨论模型的解,研究了系统模型的解的渐近性质．     

肺微循环内血液流动的数学模型：组织液流动的情形

本文提出了肺微循环的一维连续介质整体模型,将毛细血管网模型化为形如管道的多孔介质,在考虑毛细血管与组织及肺泡之间的物质交换的条件下,提出了组织液流动情形的数学模型,并得到了封闭形式的分析解．最后作了分析比较,说明本文提出的数学模型所得近似结果与生理学中采用的公式是一致的．     

Miami模型的生态学应用

Ｍｉａｍｉ模型是第一个用环境变量估算全球净初级生产力的数学模型．但常被批评为缺乏理论基础．经过分析可以发现其基本模型结构是符合生态学原理的．Ｍｉａｍｉ模型的估算精度不高,主要是由于变量选取不当和单因子模型独立估算造成的．针对其固有的缺陷,可以通过优选环境变量和建立复合模型的方法加以改进,达到提高精度的目的．改进后的模型在宏观大尺度生产力空间分布在模拟上仍有生命力     

向日葵籽实产量预测数学模型的研究

根据2年10个点次的田间试验结果建立了由数粒法、盘重法和盘径法预测向日葵籽实产量的回归数学模型,并根据1994年4个点次的产量实测结果对各模型的可靠性进行了验证．结果表明,三种方法建立的模型均有效、可靠．但在我国向日葵科研和生产实践中,以盘径法最为实用,建议推广应用．     

吸入性麻醉药动力学模型定量分析

从机理分析的角度研究了吸入性麻醉药使用过程中在诱导期的数学模型,采用室分析方法,建立了人体血药浓度的药代动力学模型和吸入药量模型,并求出其精确解．然后以七氟谜用药累积记录为研究对象,进行了数值计算,算得药代动力学模型和吸入药量模型与实际测量数据的相关系数分别为0．9865和0．8874．最后给出模型拟合曲线．     

不健全资料的参数关联分析法

首先建立相关变量取值随时序变化的数学模型,而后,利用模型中能够反映变量几何形状的适宜参数,提出了参数关联度的概念．从而解决了观测值非一一对应、且不齐的相关变量关联分析问题．同时给出一种较高拟合精度的非等间隔序列的灰色建模方法．     

人类群体开展竞技活动的数学模型及其定性分析

文章建立了人类固定群体和非固定群体开展竞技活动的数学模型,并对固定群体模型作了定性分析．     

苹果树新梢生长动态的数学模型

研究苹果树新梢生长动态,建立了一类反映植物生长动态的数学模型．所建模型不仅包含了经典的植物生理模型如 Ｌｏｇｉｓｔｉｃ方程等,而且能很好地表达不同树势的红富士新梢生长动态．     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.