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应用圆形分布法对蒙阴县１９５６１９７７ 年４ 种自然疫源性疾病发病的时间分布规律进行了探讨。结果表明，４ 种自然疫源性疾病均存在季节性升高的特征，差异具有高度显著性（ Ｐ＜ ０ ．０１） 。
The circular distribution method was used to investigate the time distribution of four natural epidemic diseases in Mengyin County in 1956 and 1977. The results showed that there were seasonal increases in the four natural epidemic diseases, and the differences were highly significant (P < 0.01).