一类被开发的捕食系统的定性分析

讨论了一类食饵种群被开发的两种群捕食系统: dx/dt=x(a0+a1x-a2x2-a3y3)-h0, dy/dt=y(x-1)其中a0>0,a2>0,a3>0,h0>0,a1不定号.文中主要讨论了系统平衡点的行为以及系统的稳定性.用Pioncare切性曲线法及Dulac函数法讨论闭轨不存在的充分条件;用Hopf分支方法及张芷芬唯一性定理证明了极限环的存在性与唯一性.同时对相应结论的生态学意义给予了说明.     

短梗霉多糖发酵过程特征的研究

本文针对短梗霉多糖发酵过程,经研究建立了基于逻辑方程和Luedeking—Piret方程的动力学模型： dx／dt=肛x(1一x／xm) dP／dt=m1x十m2(dx/dt) ds／dt=-b1x-b2(dx／dt)-b3(dP／dt) 其流变特性由初始时的牛顿流体转变为典型的假塑性非牛顿流体并遵从指数方程,即：τ=Kγn随发酵过程进行,发酵液的表观粘度增大,体积氧传质系数减小。搅拌转速的增加有利于提高体积氧传质系数。流变指数n、稠度系数K、气液传质系数Kla。与菌体浓度x、多糖浓度P、搅拌转速N及表观粘度ηa间分别有如下经验方程; k=1．2×10-2X2.43 n=0．461(P／Pm)0.07(x／xm)0.216 KLaDi2=1．48×104(D:N2)0.71(ηW)0.15 Dg ηa     

一类具功能反应的食饵-捕食者两种群模型的定性分析

对具功能反应的食饵-捕食者两种群模型x=xg(x)-y( )(x),y=y(-d+e( )(x)).在g(x)=α-baα,( )(x)=cxα(a,b,c＞0,1/2≤α＜1)且α使函数f(x)=x1/a在(-∞,+∞)上为偶函数时进行了研究,讨论了该系统平衡点的稳定性态,系统无环的充分条件以及在正平衡点外围存在惟一稳定极限环的条件.     

六种犁头尖属植物(天南星科)的核型研究

报道了 6种 8个居群犁头尖属 ( Typhonium Schott)植物的核型 ,其结果如下 :( 1 )独角莲 ( T.gigan-teum)北京居群 2 n=4 x=5 2 =4 4m+ 7sm+ 1 st;( 2 )鞭檐犁头尖 ( T.flagelliforme)金平居群 2 n=3x=2 4 =3m+ 9sm( 4 SAT) + 1 2 st,河内居群 2 n=4 x=32 =7m+ 2 0 st+ 4sm+ 1 t;( 3)单籽犁头尖 ( T. calcicolum)西畴居群2 n=4 x=5 2 =2 1 sm+ 2 3m( 5 SAT) + 8st;( 4 )犁头尖 ( T.blumei)重庆居群 2 n=4 x=5 2 =4 0 m( 1 SAT) + 1 2 sm( 3SAT) ;( 5 )马蹄犁头尖 ( T.trilobatum)西双版纳居群 2 n=2 x=1 8=4 sm( 2 SAT) + 1 2 m+ 2 st,河内居群 2 n=2 x=1 8=2 st+ 9m+ 7sm;( 6 )金慈菇 ( T. roxburgii)个旧居群 2 n=2 x=1 8=8sm+ 1 0 m( 2 SAT)。其中鞭檐犁头尖 2 n=2 4、32 ,金慈菇 2 n=1 8均为首次报道 ,同时分析讨论了本属植物染色体基数和倍性的多样性及其可能的原始基数     

三种群合作系统的全局渐近性态

考虑三种群合作系统:dχi/dt=χi(b-∑j3=1αijχj),χi(0)>0,b>0,αij<0,i≠j,i,j=1,2,3,完整地分析了其全局渐近性态:证明了该系统不存在闭轨,给出了正平衡点存在且全局渐近稳定的充要条件,证明了若系统不存在正平衡点,则所有解均趋于无穷.     

一类Kolmogorov系统的动力性质

用定性分析的方法对一类Kolmogorov系统(dx)/(dt)=x(a_0-a_11x a_2x~(n-1)-a3x~n a_4xy~m),(dy)/(dt)=y(b_1x~n-b_2),进行了研究．讨论了系统平衡点的性态,给出了系统无闭轨的充分条件以及存在唯一稳定极限环的条件．包含并推广了文献[3]的相关结果．     

中国芋属植物染色体数目及5个种的核型报道

对中国 8种 (包括 1变种 )芋属 (ColocasiaSchott)植物的体细胞染色体数目和其中 5个种的核型进行了报道。结果分别为 :异色芋C heterochromaH .LietZ .X .Wei,2n =2x =2 8=1 8m 1 0sm ;龚氏芋C gongiiC .L .LongetH .Li,2n =2x =2 8=1 8m (4SAT ) 1 0sm(4SAT) ;贡山芋C gaoligongensisH .LietC .L .Long ,2n =2x =2 8=2 4m 4sm ;李氏香芋C lihengiaeC .L .LongetK .M .Liu ,2n =2x =2 8=1 8m (1SAT ) 6sm 4st;花叶芋C bicolorC .L .LongetL .M .Cao 2n =2 8;紫杆芋C lihengiaeC .L .LongetK .M .Liuvar.nigraC .L .Long 2n =3x =4 2 ;大野芋C gigantea (Bmume)Hookf.,2n =2x =2 8=2 2m 4sm 2st;山芋C konishiiHayata 2n =2 8。除李氏香芋、龚氏芋、大野芋和山芋外 ,其余染色体数目均为首次报道。在核型方面 ,异色芋、龚氏芋、李氏香芋、贡山芋的核型均为首次报道     

生化反应中一类三次系统的极限环

研究生化反应中一类三次系统：dx/dt=-x-Ф1（x）＋yФ2（x）,dy/dt=a0＋Ф1（x）-yФ2（x）其中Ф1（x）=Ax^3＋ax^2＋bx＋B,Ф2（x）=cx^2＋dx＋e．较完整地解决了该系统极限环的存在性,唯一性与不存在性等问题．     

功能反应函数为x~(1/2)的食饵-捕食系统的定性分析

本文运用Liapunov第二方法,论证了功能反应函数为x～(1/x)的食饵-捕食系统x=x-ax-2~3-x~(1/x)y,βy=-sy βx~(1/x)y-εy~2唯一正平衡点的稳定性．其次将该系统化为二次微分系统Ⅲ类方程的标准形式,进而研究了极限环的存在唯一性问题．     

一类具稀疏效应生态系统的极限环

研究如下一类具稀疏效应的生态系统模型dx/dt=bx^2(κ-x)-bxy/1 hx,dy/dt=cy dxy/1 hx。应用微分方程定性理论,对该系统的平衡点进行了分析,给出了极限环存在唯一性及不存在的参数范围。     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV