非线性接触率和种群动力学对SI传染病模型的影响

本文研究了具有一般非线性接触率和易感类中具有Logistic增长的SI传染病模型的正不变集、平衡位置以及平衡位置的稳定性．     

一类多分子生化反应系统的极限环

应用微分方程定性理论,研究了生化反应中一类多分子一级饱和反应的数学模型的极限环的存在性、不存在性和唯一性问题．     

具有外来感染者和急慢性阶段的流行病模型的动力学分析

建立和研究了一类具有外来感染者和急慢性阶段的流行病模型,我们假设单位时间内有常数量的外来感染者进入所研究地区,因而得到的模型仅有一个地方病平衡位置.我们证明了当α＜pμ时,地方病平衡位置是全局渐近稳定的.     

一类一级饱和反应系统的极限环

本文研究生化反应中一类饱和反应的数学模型：应用微分方程定性理论,完整地解决了该系统极限环的存在性、唯一性和不存在性等问题．     

应激性与适应性的判定

应激性特别强调刺激与反应的关系，而且刺激必须来自生物体以外的刺激；反应必须是生物体接受刺激后自身作出的反应。即：外界刺激存在，生物发生反应：外界刺激停止或消失，生物的反应停止：因此判断是否为应激性的依据主要有3：①是否存在外界刺激；②生物体是否对外界刺激作出了反应；③此反应是否     

一类可逆多分子饱和生化反应系统的非线性分析

研究生化反应中一类可逆多分子饱和反应系统x=a-xy^n cy^n 1,y=xy^n-cy^n 1-dy／(y 6),应用微分方程定性理论,完整的解决了该系统极限环的存在性、不存在性和唯一性问题。     

可逆两分子饱和反应动力系统的极限环

研究生化反应中一类可逆两分子饱和反应的数学模型dx/dt＝δ-xy cy^2,dy/dt=xy-cy^2-ay/b b,应用微分方程定性理论,完整地解决了该系统极限环的存在性,不存在性和唯一性。     

具有第Ⅲ类功能性反应的捕食者一食饵系统的定性分析

本文对具有第Ⅲ类功能性反应的捕食者一食饵系统作了较完整的定性分析,讨论了正平衡点的存在性和稳定性,得到了极限环的存在条件及稳定性定理,发展地运用了Ｐｏｉｎｃａｒé切性曲线法．     

一个食饵种群具有常数收获率和具有第Ⅲ类功能性反应的捕-食系统的定性分析

本文对一个食饵种群具有常数收获率的和具有第Ⅲ类功能性反应的捕食系统作了较完整的定性分析,讨论了分界线的相对位置和分界线环的存在性、稳定性,得到了极限环存在性和唯一性的条件．     

透性化嗜酸乳杆菌细胞转化亚油酸为共轭亚油酸的反应动力学

本实验旨在研究透性化嗜酸乳杆菌细胞生物转化共轭亚油酸的反应动力学。探讨了细胞浓度、底物浓度、反应体系pH值和温度等因素对生物转化共轭亚油酸反应速度的影响;建立了透性化嗜酸乳杆菌细胞生物转化共轭亚油酸的动力学模型。结果表明,透性化嗜酸乳杆菌细胞有利于共轭亚油酸的生物转化,最适细胞浓度、pH值和反应温度分别为10×1010ufc/mL、4.5和45℃;生物转化共轭亚油酸存在底物抑制现象,当亚油酸的浓度为0.6mg/mL时,反应速度达到最大值17.8μg/(mL·min)。在低亚油酸浓度下,反应初始阶段的反应规律与经典米氏方程相符,而在高亚油酸浓度下,存在底物抑制现象。在最适反应条件下建立了动力学模型,模型基本反映了共轭亚油酸的生物转化特性。     

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.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

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.