中文摘要：

通过对重离子熔合反应的系统研究，分别建立了计算俘获截面、复合核存活几率以及复合核形成几率的方法，并给出了理论计算值的系统误差。对于“超重稳定岛”附近的超重核，除了壳修正，准裂变势垒高度也会影响超重核的形成几率。基于Skyrme能量密度泛函得到的准裂变势垒高度，提出了描述复合核形成几率的解析表达式。对于“超重稳定岛”附近的超重核，除了壳修正，准裂变势垒高度也会影响超重核的形成几率。与此同时，基于该方法预言了合成新的超重元素Z=119和120的几个熔合体系的蒸发剩余截面。对于熔合反应50Ti＋240Bk，计算出来的最佳蒸发剩余截面大约为35fb。

英文摘要：

The fusion probability in ＂hot＂ fusion reactions leading to the synthesis of superheavy nuclei is investigated systematically. The quasi-fission barrier influences the formation of the superheavy nucleus around the ＂island of stability＂ in addition to the shell correction. Based on the quasi-fission barrier height obtained with the Skyrrne energy-density functional, we propose an analytical expression for the description of the fusion probability, with which the measured evaporation residual cross sections can be reproduced acceptably well. Simultaneously, some special fusion reactions for synthesizing new elements 119 and 120 are studied. The predicted evaporation residual cross sections for S~Ti＋249Bk are about 35 fb at energies around the entrance-channel Coulomb barrier. For the fusion reactions synthesizing element 120 with projectiles 54Cr and 58Fe, the cross sections fall to a few femtobarns which seems beyond the limit of the available facilities.