共查询到20条相似文献，搜索用时 203 毫秒
1.
谭宏武 《雁北师范学院学报》2014,(1):28-30
该文研究了一类具有阶段结构的SIS传染病模型,包括：定义了模型的基本再生数：讨论了模型的无病平衡点和地方病平衡平衡点的存在性;证明了无病平衡点和地方病平衡点的局部渐近稳定性;发现了饱和治疗会引起后向分支。 相似文献
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主要建立了一类带有饱和治愈率和饱和接触率的SIRS传染病模型,研究得到了该模型的无病平衡点及地方病平衡点的局部稳定性,同时,借助构造Liapunov函数,给出了无病平衡点和地方病平衡点全局渐近稳定的条件. 相似文献
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考虑肺部感染初始先天系统反应的动态模型,首先根据三次多项式方程根的判别式,得到了模型有正平衡点的条件,其次利用平衡点稳定性理论和中心流形定理讨论了在该条件下模型正平衡点的具体类型及稳定性,最后考虑了在平衡点处出现的鞍结点分支. 相似文献
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讨论了一类带有非线性传染率和垂直传染结构的SIRS模型,给出了模型的阑值定理,分析了平衡点的稳定性,证明了疾病消除平衡点和地方病平衡点的全局渐进稳定性. 相似文献
5.
张齐鹏 《南阳师范学院学报》2006,5(12):15-19
在充分接种的假设下,分析具有共同感染两种病毒的流行病模型,得到了基本再生数和侵入再生数的表达式,在一定的条件下,给出了模型的无病平衡点和边界平衡点,并证明了无病平衡点和边界平衡点的稳定性. 相似文献
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研究了一类具有心理因素影响的传染率函数和有医疗限制的治疗函数的SVIR传染病模型。讨论了模型平衡点的存在性,计算了基本再生数,通过Hurwitz判据得到无病平衡点和地方病平衡点的局部稳定性,用构造Lyapunov函数的方法证明无病平衡点的全局稳定性,最后利用第二加性复合矩阵判断地方病平衡点的全局稳定性。 相似文献
7.
彭霞 《成都航空职业技术学院学报》2019,35(2):51-52,78
本文建立具有一般功能反应函数和分布时滞的恒化器模型。首先证明了模型解得正性和有界性,然后计算得到基本再生数,分析了细菌灭绝平衡点、无感染平衡点和正平衡点的存在的条件。通过构造Lyapunov函数,得到细菌灭绝平衡点、无感染平衡点的全局稳定性。 相似文献
8.
研究了一类带时滞的HIV病毒的CD4＋细胞模型及它的平衡点的稳定性,当该模型满足一定条件时,它的平衡点稳定,当平衡点不稳定时研究了Hopf分支的存在性. 相似文献
9.
彭霞 《成都航空职业技术学院学报》2017,33(1)
本文建立了具有C-M发生率及潜伏期的HIV传染病模型。为了能更好的描述免疫反应对感染的影响,模型中采用更为一般的免疫产生率。计算得到基本再生数及免疫再生数,分析了无病平衡点,无免疫平衡点及免疫平衡点的存在性及唯一性。通过构造Lyapunov函数,得到无病平衡点,无免疫平衡点及免疫平衡点的全局稳定性。 相似文献
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本文研究了具McCulloch-Pitts型非线性双阈值二元离散神经网络模型平衡点的动力学性质.对给定的阈值范围,通过作变换把其平衡点的稳定性转化为零解的稳定性,证明了模型平衡点是全局指数渐近稳定的. 相似文献
11.
罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
12.
邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
13.
Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
14.
Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
18.
Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
19.
陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献