带偏差变元的时滞微分模型的全局吸引性

本文考虑带偏差变元的红血球生存模型获得了其正平衡N~*是全局吸引子的充分条件，它推广和改进了文献〔2〕，〔3〕和〔4〕的结果．     

广义LESLIE矩阵模型的稳定年龄结构及其性质

〔1〕提出了一个描述生物种群动态的矩阵模型——广义Leslie矩阵模型。这个模型是Leslie矩阵模型的一个推广,它考虑了昆虫发育过程中个体在虫态发育历期上的差异。因此与普通Leslie矩阵模型相比,该模型更适于描述昆虫种群的动态。〔2〕对广义Leslie矩阵模型的渐近性质做了分析,给出了相应的稳定年龄结构的表达式,同时从马氏链的观点出发,给出了种群年龄结构渐近稳定或周期变化的充要条件。本文是〔2〕的继续,将给     

关于持久性的李雅普诺夫方法

本文在〔1〕,〔2〕的基础上,将持久函数的定义作了推广和扩充,并将稳定性理论思想方法系统引入持久性讨论中．得到了强持久的充要条件及永久共存的充分条件,并用上述结论讨论了Volterra模型的持久性．     

具收获与投放的三种群Volterra模型的周期轨道

本文在文〔2〕的基础上,研究三维动力系统的Lyapunov分枝问题．放宽了文〔2〕中关于向量场函数的限制,相应地给出从空间闭轨族扰动产生孤立周期解的判定方法．应用判定定理及椭圆函数的积分技巧,研究了具有收获与投放的三种群Volterra模型,得到了存在周期轨道的充分条件．     

植物的交配系统及其进化机制与种群适应

高等植物的繁殖方式远比高等动物的要复杂多样〔１,２〕,历来受到众多学者的关注。交配系统和作用于交配系统的选择力量,在达尔文时代的进化理论中就有着重要的地位〔３,４〕,达尔文本人对交配系统的进化结果也有着浓厚的兴趣〔５〕。植物交配系统方面的信息,对遗传育种〔６～１０〕、濒危物种遗传多样性检测的取样策略〔１〕、种质遗传资源的保护和利用〔１１～１５〕有着重要的理论指导意义。然而,交配系统与相关概念之间有一定的交叉重合,易引起术语和概念的混乱,笔者将首先探讨交配系统及有关概念的范畴。当然最引人关注的是交…     

两类肌型血管模型的浑沌现象

一、引言在探讨心肌梗塞的病理研究中,一些医学家认为动脉粥样硬化和动脉痉挛是导致发病的共同原因。为此目的,文〔1〕等探讨了肌肉力学的一般方程,文〔3〕导出了N型血管和S型血管的含集中参数的力学模型     

具有附加信息的一种线性模型的理论

文〔1〕在研究树木材积与胸径或树高的关系时,应用了具有附加信息的一种线性模型（称为随机限制模型）．本文对这种模型从理论上进行了研究,得到了统计量H及τ的分布密度函数,给出了分位数H-α及τ-α的简单近似算法,并证明了其合理性．     

抗菌素对于数种害虫的毒效试验

本工作收集了三十多种抗菌素(其中农用的14种)对蜡螟、粘虫、棉铃虫、桃蚜进行了毒效试验。结果表明同一抗菌素对不同昆虫的效果不同:在蜡螟中以放线菌酮、庆丰霉素、灭瘟素、土霉素、春雷霉素等毒效较高;对于粘虫和棉铃虫,只有灭瘟素效力较好;但在桃蚜中则灭瘟素的效果不及庆丰霉素。对于抗菌素引起昆虫死亡的原因进行了检查和讨论。     

黑龙江省小麦产量数学模型的建立及应用分析

本文根据在黑龙江省31个县、市进行的多年小麦农业生态联合试验,并运用双重组合设计〔1〕原理进行模型挂接,建立了黑龙江省小麦区域性农业生产数学模型,初步揭示了降水、土壤肥力及农肥、化肥对小麦产量的影响程度及相互间的变化规律,并应用模型对小麦产量形成过程进行了模拟和预测．     

槲皮素对凝血酶诱导的猪血小板肌动蛋白聚合的抑制作用

槲皮素对凝血酶诱导的猪血小板肌动蛋白聚合的抑制作用宋芝娟刘文梁念慈（广东医学院医用生化研究所,湛江５２４０２３）槲皮素（ｑｕｅｒｃｅｔｉｎ）有广泛的药理作用,如舒张血管〔１〕,抑制癌细胞ＤＮＡ合成〔２〕,诱发ＤＮＡ损伤〔３〕,抗超氧阴离子等〔４〕,...     

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.