ObjectiveTo investigate the prevalence of 15 skin diseases in adolescents from Liangshan prefecture in Sichuan Province.Methods A stratified cluster random sampling method was used to select subjects.Adolescents from 2 urban and 3 rural middle schools were investigated,who were required to fulfill self-report questionnaires and received physical examinations by doctors.ResultsA total of 7747 adolescents aged from 12 to 20(15.86 ± 1.86) years were included in the investigation,and skin diseases were present in 6379 adolescents,with a total incidence of 82.34％.In average,each subject suffered from 1.3372 ± 0.96861 skin diseases.Of the adolescents,4698(60.64％) had acne,2219(28.64％) freckle,966(12.47％) lichen pilaris,792(10.22％) eczema or dermatitis,511(6.60％) urticaria,195(2.52％) papular urticaria,37 (0.48％) vitiligo,55 (0.71％) psoriasis,166 (2.14％) verruca vulgaris,168 (2.17％) flat wart,317 (4.09％) tinea manus and pedis,142 (1.83％) tinea corporis,62 (0.80％) chloasma,26 (0.34％) nevus flammeus,15 (0.19％) nevus of ota.Male adolescents showed a higher incidence of acne(63.91％ vs.58.50％),but a lower incidence of eczema,lichen pilaris,freckle,chloasma and psoriasis compared with female adolescents.The incidence of acne,vitiligo,psoriasis and melasma were higher,while that of freckele was lower(25.93％ vs.29.58％ ) in Yi adolescents than in Han adolescents.Increased incidence of acne and papular urticaria and decreased prevalence of urticaria,freckle,melasma and lichen pilaris were observed in urban adolescents compared with rural adolescents.ConclusionsThe prevalence of skin diseases is high in adolescents from Liangshan prefecture.Of these 15 skin diseases,acne,freckle,lichen pilaris,eczema and urticaria are the 5 most common diseases in the area.Differences exist in the incidence of skin diseases between male and female,Han and Yi,urban and rural,adolescents.

OBJECTIVE： To establish a method for simultaneously determining the contents of 6 volatile components such as eugenol， methyl eugenol， isoeugenol， α-asarone， alkaloid and myristyl ether in Zhachong shisan. METHODS：Volatile oil was extracted by steam distillation and analyzed by gas chromatography. The chromatographic column was ov-1701， with hydrogen flame ionization detector. The carrier gas was nitrogen， the inlet temperature was 220 ℃， the detector temperature was 240 ℃， the flow rate was 1.0 mL/min， the injection volume was 1 μL， the split ratio was 10 ∶ 1， with programmed temperature. RESULTS： The linear ranges of eugenol， methyl eugenol， isoeugenol， α-asarone， costunolide and myristyl were 2.00-12.00， 1.00-6.00， 0.60-3.60， 0.05-0.30， 0.05-0.30， 0.60-3.60 mg/mL（r＝0.999 9）. The detection limits were 0.01， 0.01， 0.02， 0.01， 0.01， 0.01 mg/mL， respectively； the limits of quantification were 0.05， 0.03， 0.06， 0.02， 0.02， 0.03 mg/mL， respectively. RSDs of precision， stability and reproducible tests were all lower than 3％； average recovery rates were 99.33％-100.04％， RSDs were 0.02％-0.35％ （n＝6）； RSDs of durability test were all lower than 5％. CONCLUSIONS： The established method was simple and reproducible. It can be used for simultaneous determination of the contents of 6 volatile components in Zhachong shisan.