中文摘要：

在巨正则模型下,利用两相似反应系统的同质异位素产额比之差（Isobaric yield ratio difference,IBD）,研究中等质量余核化学势与反应系统的关联。结果表明,两相似反应系统的Δμ/T之差Δμ21/T对两反应系统双中质比（N/Z）21很敏感,说明Δμ/T对反应系统具有依赖性。同时发现,当（N/Z）21=1.17时,两反应系统不同余核的Δμ21/T趋于一个常数,说明在这两个系统中,利用IBD和同位旋标度方法获得的对称能信息更合理,且符合得更好。

英文摘要：

Background： Chemical properties of projectile residues are important in studying the symmetry energy using isobaric yield ratio （IYR） and isoscaling methods. Purpose： The correlation between chemical properties of intermediate mass residues and reaction systems is to be studied. It is hoped that the symmetry energy information can be extracted more precisely. Methods： In the framework of the grand-canonical ensemble theory, the △μ/T difference between two heave-ion reactions, which was labeled as △u21/T, was extracted by using isobaric yield ratio difference （IBD） method. Results： By comparing the △μ21/T among six different combinations ^48Ca＋^9Be/^40Ca＋^9Be, ^48Ca＋^9Be/^58Ni＋^9Be, ^64Ni＋^9Be/^40Ca＋^9Be, ^64Ni＋^9Be/^58Ni＋^9Be,^58Ni＋^9Be/^40Ca＋^9Be, ^48Ca＋^9Be/^64Ni＋^9Be, it was proved that △u/T depends on the reaction system. In different reactions, the values of A,tdT were not fixed. When the double neutron-to-proton ratios （N/Z）21=1. 17, △u21/T can be approximately a constant. Conclusion： Symmetry energy can be more reasonable in isoscaling and IBD methods, when double neutron-to-proton ratios （N/Z）21=1.17 between two similar reaction system.