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Search Results: 1 - 10 of 294777 matches for " 李海侠 "
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一类带有比率依赖型反应函数的捕食-食饵模型正解的存在性和多重性

- , 2016, DOI: 10.3785/j.issn.1008-9497.2016.02.006
Abstract: 讨论了一类带有Crowley-Martin和比率依赖反应函数的扩散捕食-食饵模型.首先利用局部分歧理论考察了系统关于强半平凡解处产生正解的存在性,再运用扰动理论得到了正解的稳定性.最后借助全局分歧理论和不动点指数理论给出了正解多重性的条件.
Abstract:A diffusive predator-prey model with Crowley-Martin and ratio-dependent type functional responses is considered. Firstly, the existence of positive solutions which are relative to the strong semi-trivial solutions is investigated based on the local bifurcation theory. Moreover, by use of the perturbation theory, we obtain the stability of positive solutions. Finally, multiple conditions of positive solutions are determined by resorting to the global bifurcation theory and fixed point index theory. Results have shown the existence of stable solutions and multiple solutions under certain conditions.
带有保护区域的加法Allee效应捕食-食饵模型的共存解
Coexistence solutions for a predator-prey model with additive Allee effect and a protection zone


- , 2015, DOI: 10.6040/j.issn.1671-9352.0.2014.582
Abstract: 摘要: 讨论了一类带有保护区域和加法Allee效应的扩散捕食-食饵模型。首先讨论了平凡解和半平凡解的稳定性, 接着考察了非常数正解的不存在性, 最后运用全局分歧理论得到了非常数正解的存在性条件。研究结果表明,在弱Allee效应下,当扩散系数适当且参数满足一定条件时,两物种能共存而且共存解稳定;当扩散系数充分大时两物种不共存。
Abstract: A diffusive predator-prey model with additive Allee effect and a protection zone is discussed. Firstly, the stability of trivial and semi-trivial solutions is investigated. Secondly, the non-existence of non-constant positive solutions is determined. Finally, the existence of non-constant positive solutions is obtained by using the global bifurcation theory. Under weakly Allee effect, the results indicate that the two species will coexist and the coexistence solutions are stable when the diffusion coefficient is suitably chosen and the parameters satisfy certain conditions. Furthermore, the two species cannot coexist when the diffusion coefficients are sufficiently large
带有加法Allee效应的捕食-食饵模型共存解的惟一性和多解性

- , 2015,
Abstract:
带有加法Allee效应的捕食-食饵模型共存解的惟一性和多解性 Uniqueness and Multiplicity of Coexistence Solutions for a Predator-Prey Model with Additive Allee Effect

- , 2015,
Abstract: 利用不动点指数理论给出了一类带有加法Allee效应的捕食-食饵模型正解存在的充分条件,讨论了正解的惟一性和稳定性,运用扰动理论研究了参数b2充分大时正解的多重性.结果表明在一定条件下系统存在多重解和惟一解
一类扩散食物链模型正解的多重性和唯一性
Multiplicity and uniqueness of positive solutions to a diffusive food-chain model


- , 2017,
Abstract: 研究了一类具有Crowley-Martin反应函数的食物链模型。首先利用全局分歧理论和度理论讨论了正解的存在性和多重性,得到了正解分歧的基本形状。接着运用扰动理论给出了正解的唯一性和稳定性条件,结果表明当d充分大时系统在一定条件下存在唯一且稳定的正解
一类竞争模型正解的唯一性和多重性
Uniqueness and multiplicity of positive solutions for a competition model


- , 2015, DOI: 10.7511/dllgxb201504017
Abstract: 研究了一类带有Holling Ⅲ型功能反应的竞争模型.首先通过计算不动点指标得到了正解存在的充分条件.其次运用线性算子扰动理论以及标准的椭圆方程正则性理论研究了正解的唯一性和全局稳定性.然后应用全局分歧理论和度理论考察了正解的多重性.最后用数值模拟对所得理论结果进行了验证.研究结果表明参数满足一定条件,该模型存在多重解和全局吸引的唯一解.
A competition model with Holling type Ⅲ functional response is studied. Firstly, by calculating the fixed point index, the sufficient conditions of the existence of positive solutions are obtained. Secondly, using the linear operator perturbation theory and standard elliptic equations regularity theory, the uniqueness and global stability of positive solutions are investigated. In addition, the multiplicity of positive solutions is discussed by the combination of the global bifurcation theory and degree theory. Finally, the theoretical results obtained are verified by the numerical simulation. It is proved that the model has multiple solutions and only one unique globally attractive solution for a suitable range of parameters.
一类食物链模型正解的存在性和惟一性
,王玉萍
- , 2018,
Abstract: 研究了一类带有Crowley-Martin反应函数的食物链模型.运用不动点指数理论给出了正解存在的充分条件,进而利用扰动理论和分歧理论讨论了正解的惟一性.结果表明参数c和d对正解的惟一性有很大的影响
艾比湖沙拐枣的花部特征与繁育系统
志成,,,
园艺学报 , 2015, DOI: 10.16420/j.issn.0513-353x.2014-0869
Abstract: 野外定点观察艾比湖沙拐枣(calligonumebi-nuricum)的花部特征和开花进程,运用杂交指数、花粉/胚珠比、花粉活力及柱头可授性、人工授粉试验等方法对其繁育系统进行测定。结果表明:在自然条件下,艾比湖沙拐枣5—7月开花,群体花期约70d,单花花期4~6d,单花开放进程分为5个阶段:花蕾期、初开期、盛开期、衰落期和凋谢期。艾比湖沙拐枣的花为两性花,在花朵开放的整个过程中花药始终高于柱头。雌雄异熟,雄蕊先熟,花粉在开花1~4d具有较强的活力,柱头在开花2~5d可授性较强。杂交指数等于5,花粉/胚珠比为2464,结合人工授粉试验结果可以确定其繁育系统为异交为主,部分自交亲和,需要传粉者。访花昆虫主要有蜂类、蚁类、蝇类、甲虫类,其中蜂类数量最多,是有效的传粉者。
美国科学引文索引收录核医学期刊分析
史书,,徐昕,杨华
中国科技期刊研究 , 2011,
Abstract: 介绍SCI-E收录核医学期刊情况,并对期刊国别、年发文量、发文类型、影响因子、总被引频次、自引率、作者国家分布做了统计分析。
自适应立方卷积图像插值算法
春龙,,王华峰
北京航空航天大学学报 , 2014, DOI: 10.13700/j.bh.1001-5965.2013.0621
Abstract: 图像插值是图像处理的一项重要技术,可适用于多个领域,近年来多使用该技术进行图像缩放.针对传统图像缩放算法边缘处理效果较差、边缘检测插值算法复杂度高的问题,提出一种有效增强边缘轮廓的自适应立方卷积插值算法.该算法结合边缘梯度变化和立方卷积插值的特点,使得图像在平坦和纹理区域均能取得理想效果.实验结果表明,与基于边缘检测的插值算法相比,该算法具有较低的复杂度,平均运算时间降低了3.19s;与立方卷积算法相比,图像峰值信噪比有较大的提高,峰值信噪比增加了0.89dB.
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