In chapter two, we establish a kind of new class age-structure SEIR epidemic model with impulsive vaccination and nonlinear infectivity, which contains ODEs and PDEs at the same time.
第二章，建立了一类新的带有脉冲接种的类年龄结构SEIR流行病模型，并考虑其具有非线性传染率。 该模型既含有常微分方程，又含有偏微分方程。
参考来源 - 传染病模型和脉冲微分系统的动力学研究·2,447,543篇论文数据，部分数据来源于NoteExpress
The result shows that the Tree class structure replacing the age structure is suitable for studying the structure and dynamics of Castanopsis fargesii population.
结果表明，应用立木级结构代替年龄结构研究栲树种群的结构和动态特征是适用的。
But stand volume descents to a great extent, age class and stand density structure are maladjusted badly, and the number of stand growth is low.
但蓄积量大幅下降，林分的龄组、密度结构严重失调，林分生长量偏低。
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