中文摘要：

收集了射电选和X射线选BL Lac天体的射电数据（包括核和延展光度），并计算了它们的核主导系数R。研究显示：射电选BL Lac（RBLs）天体的总射电光度是X射线选BL Lac（XBLs）天体的2个量级。详细分析得到这种差别主要是来自于核光度的差别因为延展光度差别只有1个量级。研究RBLs和XBLs的核（延展元）光度与核主导系数之间的关系，发现延展元光度与核主导系数负相关．而核（总）光度几乎与核主导系数没有相关。

英文摘要：

In this paper, we collect the radio data （core and the extended luminosity） for the radio selected and X - ray selected BL Lacertae objects, and calculat their core - dominance parameter R. Our results show that the total radio luminosity of radio selected BL Lacertae objects- RBLs is two decades higher than that of X - ray selected BL Lacertae objects - XBLs. A detailed analysis suggests that the difference is from the fact that the core luminosity of RBLs is two decade of decades more powerful than that of XBLs since the extended luminosity is only a decade more powerful than that in the XBLs. We also investigate the correlation between the core/extended luminosity and the core - dominance parameter, the extended luminosity is anti -correlated with the core -dominance parameter, however, there is almost no correlation between the core/total luminosity and the core -dominance parameter for each subclass.