无限区间

Some conditions for weakly Persistence and extinction are obtained;In the second part, we respectively use C_h space and C_g space theorem to study the existence of periodic solutions of Lotka-Volterra equation with infinite delay, in the end we get the condition of the existense of periodic solutions and estimate the interzone of it.

第二部分利用相空间理论，分别以C_h空间和C_g空间为相空间研究了具有无限时滞的Lotka-Volterra方程周期解的存在性问题，给出了周期解存在的充分条件，并估计出了周期解的存在区间。

A two-tier overlay network model is presented in this paper. Some consecutive nodes form an unstructured group and different groups are connected by a globally structured overlay with the Chord protocol. The model uses the Hilbert-based level search and the dynamic load balancing policy of a two-tier ring structure on top of the overlay network.This strategy has not only the characteristics of load balancing but also enough flexibility for searching.

Chord模型可以保证搜索系统中特定数据对象的跳跃次数在O的范围内，但只能根据数据对象的键进行准确匹配查询，不支持多关键字、部分关键字、通配符或是参数取值区间组成的复杂查询[1]；其次，相容散列的理论证明了当系统中有N个结点和K个键值的情况下，在每个结点上运行O个虚拟结点时，每个结点的键值范围可以无限趋于K/N。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。