Optimization on Preparation Conditions of Salidroside Liposome and Its Immunological Activity on PCV-2 in Mice

Table 1

Levels and code of variables chosen for Box-Behnken design.

Factors	Levels and range
	−1	0	1
: ammonium sulfate concentration (mol/L)	0.20	0.25	0.30
: ethanol injection volume (mL)	4	6	8
: temperature (°C)	40	45	50
: ethanol injection rate (mL/min)	2	3	4