润色：We performed a systematic search for BAL that has shifted in velocity between two epoch from a BAL catalog including 2005 SDSS quasars and identified 23 quasar candidates By adding another two sour

We conducted a systematic search for Broad Absorption Line (BAL) quasars that have experienced a shift in velocity between two separate observations. Our search was based on a BAL catalog consisting of 2005 SDSS quasars, and we identified 23 initial candidates. After including two additional sources from previous literature, we assembled a sample of 25 quasar candidates, representing the largest collection of line velocity shifts to date. In the multiple spectra collected for these 25 quasars, we detected a total of 56 BAL systems, including 56 C iv BALs and 25 Si iv BALs. Of these, 35 absorption systems exhibited a velocity shift phenomenon, including 30 C iv BALs and five Si iv BALs.

Based on the properties of these identified BALs and the spectra, we have produced several statistical results. Firstly, we found that as the time interval between observations increased, the BALs tended to exhibit larger velocity-shift values. Secondly, compared to BALs without velocity shift, those with velocity shifts tended to show larger absolute values of both radial velocities and fractional variations in trough equivalent widths. Thirdly, we observed significant moderate anticorrelations between the fractional flux variations of the continuum and fractional variations in trough equivalent widths for both C IV and Si IV BALs. This suggests that the primary driving factor of BAL variability in our sample of quasars is fluctuations in the ionizing continuum. Finally, based on the characteristics of the BAL variations and our observations of (3), we hypothesize that the majority of BAL outflows in these 25 quasars are impacted by the background radiation energy