23422
Thus , to reveal subtle metabolic changes under the condition of fever and to explore its mechanism , an ultra performance liquid chromatography coupled with a quadrupole time - of - flight mass spectrometry metabonomics approach was employed to investigate the urine biochemical characteristics of yeast - induced pyrexia rats .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None