偏航系统的极限环振动

本文用定性分析方法处理气流导致的偏航振动方程,对于偏航矩的Fourier展式的n次谐波截断式,证明了在相柱面上,系统恰有n-1个极限环。     

二连通图的最长圈

本文证明:设G为n阶2连通图,D(x)={y|y∈V(G),d(x,y)≤2},d_d~*(x)表示D(x)中所有的点的度排成的非减度序列:d_1~*,d_2~*,…,d_j~*,d_(j+1)~*,…,d_(|D(x)|)~*中当下标j=d(x)时的度。δ_0=min{d(x)|x∈V(G)},D(δ_(i-1))={x|x∈V(G),d(x)≥δ(i-1)}(i=1,2,…,k),δ_i=min{d_(d(x))~*|x∈D(δ(i-1))}(i=1,2,…,k)且δ_0<δ_1<δ_2<…<δ_(k-1)≤δ_k,则C(G)≥min{n,2δ_k}。此外也给出δ_k的算法。     

控制迹与线图的泛圈性

设u与v是圈G中的两个任意给定的顶点,本文给出图中存在连接u和v的控制迹的一个充分条件.若图G的阶n≥5,又对一切xy∈B(G)都有d(x) d(y)≥n,本文证明线图L(G)是点泛圈的,且可使得与任一点关连的各个图几乎一个套一个,即几乎是可扩充的.     

Hamilton有向图的一个新的充分条件

设D是n(≥2)阶强连通有向图.猜想:如果D中每一对不相邻且有公共外邻或公共内邻的顶点x,y都有d(x) d(y)≥2n-1,那么D是Hamilton有向图.文章证明了当n≥7时,若D中每一个不相邻且有公共外邻或公共内邻的顶点x,y都有d(x) d(y)≥(5n)/2-5,则D是Hamilton有向图.当3≤n≤6时,存在非Hamilton有向图D满足D中每一对不相邻且有公共外邻或公共内邻的顶点x,y都有d(x) d(y)≥(5n)/2-5.     

全对称2n-1次系统的中心焦点与极限环分支

本文研究了全对称2n-1次系统，求出了原点的前n-1阶焦点量，得出了该系统的中心条件及它在整个相平面上最多可扰动出n-1个小振幅极限环．     

一类二次系统的全局结构

目的讨论一类二次系统极限环的惟一性及给出全局结构图。方法运用Lienard方程组理论及环域定理对此类二次系统极限环的惟一性进行讨论,并运用分支理论讨论异宿环的稳定性。结果得到了此类系统极限环的存在惟一性及不存在性和异宿环稳定及不稳定的完整结果。结论得到了一类二次系统极限环的惟一性,给出了参数取值不同时的7种全局结构图。     

Synopsis of the life cycles of Digenea (Platyhelminthes) from lagoons of the northern coast of the western Mediterranean

The present document reports on the large amount of data relating to digenean parasites recorded from or known to be present in various hosts in lagoons of the northern coast of the western Mediterranean, which has been compiled from the literature of more than a century. In these lagoons, at least 72 nominal species of digeneans have been recorded. This total corresponds to approximately 12% of the 584 “marine” digenean species reported for Europe. Data are provided on the life cycles of 56 digenean species. The life cycle has been totally elucidated for 44 species (25 from fish, 19 from birds), and partly for the other 12 species (seven from fish, five from birds). This means that the life cycle is known for 61.1% of the recorded fauna (44/72) and partly for 16.7%, but remains unknown for 22.2%, making it, in this respect, one of the best understood digenean marine faunas in the world. In addition, a checklist is provided dealing with the cercarial and metacercarial forms recorded from lagoons of the northern coast of the western Mediterranean, which have been described only on the basis of characters of these larval stages and which remain without demonstrated links to a corresponding sexual adult stage in a vertebrate.     

一个定理证明的商榷

指出关于生化反应中微分方程权限环存在性的一个证明中的错误，重新给出了证明。     

On the Gracefulness of the Digraphs n·Cm＊

A digraph D（V, E） is said to be graceful if there exists an injection f ： V（G） →{0, 1,... , ｜E｜} such that the induced function f＇ ： E（G） --~ {1, 2,… , ｜E｜} which is defined by f＇ （u, v） = [f（v） - f（u）] （rood ｜E｜＋ 1） for every directed edge （u, v） is a bijection. Here, f is called a graceful labeling （graceful numbering） of D（V, E）, while f＇ is called the induced edge＇s graceful labeling of D. In this paper we discuss the gracefulness of the digraph n- Cm and prove that n. Cm is a graceful digraph for m = 15, 17 and even