Cao Shi-Ying, Song Zhen-Ming, Qin Yu, Wang Qing-Yue, Zhang Zhi-Gang. Difference in filament and spectrum broadening induced by femtosecond pulses in argon gas with a temperature gradient at different positionsJ. Acta Physica Sinica, 2009, 58(6): 3971-3976. DOI: 10.7498/aps.58.3971