关于抑制物对肿瘤生长直接效果模型的数学分析

本文研究一个用于描述抑制物对肿瘤生长直接作用效果的数学模型,该模型是对Byrne和chaplain相应模型的一个改进.我们分别在c_1=c_2=0和c_1>0,c_2>o但很小两种情况下研究了该模型解的存在性和解在t→∞时的渐近状况,证明了未血管化的肿瘤在某些情况下趋于消失,而在另一些情况下趋于一个休眠态,且抑制物总能减小肿瘤的半径.     

NONEXISTENCE OF POSITIVE SOLUTION OF A CLASS OF NONLINEAR DIFFERENCE EQUATION

In this paper, a class of nonlinear difference equations are investigated. The sufficient conditions for the nonexistence of positive solutions are obtained. The results in this paper improve ones in [2].     

复微分方程组亚纯解的分量的Nevanlinna特征估计

本文讨论了一类复微分方程组的亚纯解的分量的Nevanlinna特征估计,利用亚纯函数Nevanlinna值分布理论,得到了一个有关方程组亚纯解的分量的Nevanlinna特征估计定理.该结果推广了高凌云等人的一些结果.     

一类非线性差分方程正解的不存在性

本文研究一类非线性差分方程及其对偶方程,给出了方程不存在正解的充分条件,所得结论改进了[1]的结果。     

INSTABILITY OF TRAVELING WAVES OF THE KURAMOTO－SIVASHINSKY EQUATION

Iatroduct     

一类脉冲微分方程零解的稳定性

本文研究了一类在非固定时刻的脉冲微分方程。利用Lyapunov第二方法,建立了零解为稳定,渐近稳定及不稳定的判别准则。结果表明脉冲可能影响甚至改变相应的无脉冲时的微分方程的稳定性。文中还给出一例说明所得主要结果的应用。     

論矩陣的一種變換

<正> 在本文中,數域限定為複數域.我們要來研究如下的變換:(1)(它將方陣A變成方陣B),式中P表示任意正則陣,P表示P的元素的共軛救構成的陣.所有的變换(1)顯然成羣.這種變換現在姑稱之為種變換.如果二方陣A與B可由一個種變換變此成彼,我們就說,A與B是對相似的.     

添加捷径对环状DEDS的影响分析

研究具有环性拓扑的离散事件动态系统添加捷径后的时序性能变化问题.分析了添加捷径对周期长度和周期时间的影响.发现添加少量捷径即可使周期长度为1的概率有显著提高.     

直交多項式級数的求和

<正> 1.設φ_o(x),φ_1(x),…是区間(a,b)上之一系列的就范直交函数,孟孝夫証明:当級数∑(a_n log log_n)~2收斂时,直交函数級数 a_oφ_o(x)+a_1φ_1(x)+…+a_nφ_n(x)+…(1)在{φ_o(x)}的直交区間中,几乎到处可用正阶蔡查罗(Cesaro)求和法——(C,a)求和法,a>0——求和.当a=1时,这个定理还有波尔根(Borgen)和卡契馬尔茲(Karczmarz)     

STRUCTURE OF POSITIVE SOLUTIONS OF A CLASS OF QUASILINEAR ORDINARY DIFFERENTIAL EQUATIONS

The existence and uniqueness of positive solutions for a class of quasilinearordinary differential equations with a large parameter are obtained. It is shownthat the flat core of positive solutions can exist. So some results of [1-3] aresharpened.     

GENERALIZATION OF THE NOTION OF FUNDAMENTAL GROUP

The classical definition of fundamental group for a topological space is based on the pathwise connectedness. A space with less path will not be able to be described effectively by its fundamental group. The author introduces a definition of generalized fundamental group for a given topological space by means of its own connectedness. For a well-behaved space, e.g., a locally pathwise and semilocally simply connected compact metric space, the generalized fundamental group coincides with the classical one.     

ADDITIVE FAMILIES OF INVARIANTS OF FORMS OF DEGREE d

Abstract

Let d be a positive integer, and F be a field of characteristic zero. Suppose that for each positive integer n, I _n, is a GL _n,(F)- invariant of forms of degree d in x₁, …, x _n, over F. We call {I _n} an additive family of invariants if I _p+q (f ⊥ g) = I _p(f).I _q(g) whenever f; g are forms of degree d over F in x _l, …, x _p; …, x _q respectively, and where (f ⊥ g)(x _l, …, x _p+q) = f(x ₁, …, x _p,) + g (x _p+1, …, x _p+q). It is well-known that the family of discriminants of the quadratic forms is additive. We prove that in odd degree d each invariant in an additive family must be a constant. We also give an example in each even degree d of a nontrivial family of invariants of the forms of degree d. The proofs depend on the symbolic method for representing invariants of a form, which we review.     

幂等矩阵的组合的可逆性

本文研究了两个幂等矩阵P与Q的组合aP+bQ-cPQ-dQP-ePQP (其中a,b,c,d,e∈(C),a≠0,b≠0)的可逆性. 利用P-Q的可逆性及幂等矩阵的性质,得到了aP+bQ-cPQ-dQP-ePQP可逆的一些充要条件. 推广了J. J.Koliha 和 V.RakoA(c)eviA(c)[1]及Zuo Kezheng[2]的结论.     

NOTES ON NILPOTENCY OF NIL SUBRINGS OF ENDOMORPHISM RINGS OF MODULES

Abstract

A family K of right R-modules is called a natural class if K is closed under submodules, direct sums, infective hulls, and isomorphic copies. The main result of this note is the following: Let K be a natural class on Mod-R and M ε K. If M satisfies a.c.c. (or d.c.c.) on the set of submodules {N ? M: M/N ε K}, then each nil subring of End(M_R ) is nilpotent.     

INTERSECTION OF PRIME SUBMODULES AND DIMENSION OF MODULES

The aim of this paper is to study the conditions by which a P-prime submodule can be expressed as a finite intersection or union of P-prime submodules. Also corresponding to dimension and rank of modules, some equivalent conditions for a ring to be a Dedekind domain are given.     

A NOTION OF COMPLETENESS OF TOPOLOGICAL STRUCTURES

A connector U on a space S is a function from S to the power set of S such that each x in s belongs to its image. The image of x is denoted by xU. In other words, the relation {(x,y): y ? xU, x ? S) is a reflexive binary relation. A space with a certain set of connectors is a generalization of topological spaces as well as uniform spaces. In this paper, a notion of completeness of such a space is introduced. This completeness corresponds to completeness of uniform spaces if a set of cannectors meets the conditions of uniformity. Compactness of topological Spaces is a special case of the completeness.     

COMPARISON OF PRODUCTS OF THE VARIETIES OF LIE ALGEBRAS

Abstract

In Fortes (2001), we introduced a notion of order for associative pairs and we obtained a Goldie-like characterization of left orders in a semiprime pair coinciding with its socle. In this paper, we take up again that notion of order to establish a Faith-Utumi theorem, which studies left orders in a prime pair coinciding with its socle.     

STRUCTURED MODELS OF PATTERN FORMATION OF TREE POPULATIONS

ABSTRACT. The problem of mathematical modeling of the phenomenon of appearance and forming of allocated tree subpopulations, called gap, locus, cenon is studied. Such a subpopulation (not a single tree) is considered as an individual object of the forest community. A mathematical model describing the phenomenon of cenon formation as a result of natural dynamics of initial heterogeneous tree subpopulation is suggested. The model is constructed in the framework of a structural population model of one generation with distributed values of parameters and initial states. The “biological basis” of cenon formation is the so-called discriminating death. It is shown that this component of death accounted for the model results in the formation of the comparatively homogeneous subpopulation from the initial heterogeneous sub-population of trees.     

GLOBAL ANALYSIS OF A CLASS OF CUBIC SYSTEMS

ＧＬＯＢＡＬＡＮＡＬＹＳＩＳＯＦＡＣＬＡＳＳＯＦＣＵＢＩＣＳＹＳＴＥＭＳＷａｎｇＸｉａｎ（王现）（ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙ，南京大学，邮编：２１００９３）Ａｂｓｔｒａｃｔ：Ｔｈｅｐａｐｅｒｇｉｖｅｓａｃｏｍｐｌｅｔｅｇｏｌｂａｌｐｈａｓｅｐ...     

函数集的完全性

1.:敲g(x)篇〔一二,二]上之非降的有界缝差两数,业具有性鬓(K)s‘二一0,一。(:);f--:.,。g。尹(:)!d:一郁匕,(‘一”,”;dg)篇在〔一二,司上定羲业且满足修件:,一{户,(柳dg(·)}青<一,>l的可测蝮值函数族{f(幻}.封龄一徊乙“(一二,侧d刃中之子族凌B(幻},若由f(劣)(乙,(一二,二:dg),夕>1生+上夕q=1,及f--:ha”“’“““’一0纷{B(x)}之任何B(哟成立必滇致f(幻在〔一二,司上规乎虚虚等焚零则释{B(x)}在乙“(一二,侧dg)中完全. 函数族的完全性是舆函数横造的一些简题很有阴保的.徙【l]我们知道{e‘”}豁。是在乙,(一二,州dg),,>1,中完全的,…