中文摘要：

一个图G的邻接矩阵A（G）是n×n矩阵,如果vi和vj相邻,那么它的（i,j）位置为1,否则为0.图G的谱半径是邻接矩阵A（G）的最大特征值.本文确定了在所有的树和所有的二部单圈图、二部双圈图、二部三圈图、二部四圈图、二部五圈图以及二部拟树图中所对应的具有最大谱半径的图.

英文摘要：

The adjacency matrix A（G） of a graph G is the nxn matrix with its（i,j）-entry equal to 1 if vi and vj are adjacent,and 0 otherwise.The spectral radius of G is the largest eigenvalue of A（G）.In this paper we determine the graphs with maximum spectral radius among all trees,and all bipartite unicyclic,bicyclic,tricyclic,tetracyclic,pentacyclic and quasi-tree graphs,respectively.