Expression and clinical significance of PI3K and MMP⁃9 in bronchoscopic alveolar lavage fluid of children with severe pneumonia in PICU 
JIANG Jiali, CHEN Ting, TONG Wenjia, DING Jie, XU Weihua.
The Journal of Practical Medicine . 2023, (15): 1939 -1944 .  DOI: 10.3969/j.issn.1006-5725.2023.15.014