周期

PartⅡ,Applying the developed and extended direct algebraic methods that presented in recent years and based on the 2+1 dimensional variable separation solutions,abundant Jacobi elliptic function doubly periodic waves and periodic propagating wave patterns for many 2+1 dimensional nonlinear wave models are obtained,and in long wave limit solitary waves are derived as well.

第二部分，本文拓展和推广(来源：a2AB7aC论文网www.abclunwen.com)了新近发展的几种典型的直接代数方法和基于分离变量解的间接方法，获得多个2+1维非线性波动模型丰富的雅克比椭圆函数双周期波解和周期传播波模式，并得到长波极限情形下存在的非线性孤立波。

Firstly, we consider SIQR epidemical models with continuous and pulse vaccinations; the reproduction numbers have been obtained for those models; by using Dulac function, we prove the global stabilities of equilibrium of SIQR model with continuous vaccination. In the SIQR epidemical models with pulse vaccinations, we have also discussed the existence of the infection-free periodic solution, the global stabilities of the infection-free periodic solutions, and the effectiveness of pulse vaccination and continuous vaccination policies has been compared for the two models.

文中首先考虑具有连续免疫接种和脉冲免疫接种的SIQR传染病模型，分别获得了它们各自的基本再生数；利用Dulac函数方法证明了具有连续免疫接种的SIQR模型无病平衡点的全局渐近稳定性；在脉冲免疫接种下SIQR传染病模型里，讨论了无病周期解的存在性，证明了该周期解的全局渐近稳定性，并且对连续和脉冲接种下的SIQR传染病模型的接种效率进行了比较。

About 11 years, in that period. This conclusion has important scientific significance for the solar dynamo theory.

是存在的，而且这一时期内太阳活动的周期也是正常的，即存在11a 左右的黑子周期，这直接关系到太阳发电机理论的正确性，具有重要的科学意义。

According to Easterling's calculations, the average annual return on the Dow during bear cycles was minus 4.2 per cent during the 20th century, while the average during bull cycles was 14.6 per cent.

伊斯特林的数据显示，在20世纪，道琼斯工业股平均价格指数在熊市周期的平均年回报率为-4.2%，而牛市周期的平均回报率则为14.6%。

A class of inverse eigenvalue problem for sub-periodic Jacobi matrices, as well as its properties, were discussed.

讨论了一类由谱数据构造子周期Jacobi矩阵的特征值反问题，以及子周期Jacobi矩阵的相关性质。

Considering that generation and maintain of small radius, high power beam is restricted by the compression ratio of electron gun, the effect of magnetic field on electron trajectories in transition region was analyzed.

分析了过渡区中电子注调节的基本原理，设计了一种渐变式的过渡区结构，其注腰半径为0.8mm，周期均匀磁场峰值为0.29T，周期为4.5mm，压缩比为22。

The construction procedures used to establish the theory are based on orthogonal and elementary matrix transformations and can, therefore, be developed to a numerically efficient algorithm.

第一部分，我们想利用状态和微分回馈控制把一个时变周期离散的系统正则化，在这部分我们找到一个可以正则化的充分条件，并利用构造方法证明在这充分条件之下可以构造出状态和微分回馈控制矩阵，使的这周期闭回路系统可以被正则化。

We can use the ellipsoidal model to calculate the relations of period derivation and braking index with average density.

而我们就可利用椭球模型来计算周期变率和制动系数同平均密度的关系；如果取平均密度约为2.2×10〓克/厘米〓，则周期变率约为5.4×10〓秒/秒，制动系数为-0.4。

In the paper,according to homogeneous balance principle and F-expantion method,some double-periodic exact solutions of a fifth-order KdV-like equation with variable coefficients are obtained in form of Jacobi elliptic function .

利用齐次平衡原则和F-展开法，求出了一个五阶变系数KdV-like方程的一些用Jacobi 椭圆函数表示的双周期解。并且在极限的情况下，得到了该方程的孤立波解和三角函数表示的周期波解

The solution of the equation and the period of the particle motion for a non-pertubated system are expressed exactly by means of Jacobian elliptic function and the 1-st kind elliptic integral.Melnikov function of the rotated periodic orbit is constructed,and also bifurcation of the system is analyzed by the method.

利用Jacobian椭圆函数和椭圆积分给出了系统的解和粒子运动周期，用Melnikov方法构造了旋转型周期轨道的Melnikov函数，并用这个方法分析了系统的局部分叉性质。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失