共查询到20条相似文献，搜索用时 62 毫秒
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研究了含Allee效应的广义Logistic模型正平衡点的存在性及其稳定性,并讨论了最大可承受产量,利用Pontryain最大值原理确定了最优捕获策略。 相似文献
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研究一类HollingⅡ类功能反应的两个种群离散系统,得到该系统平衡点稳定性的充分条件.利用Pontryagin 最大值原理给出了系统最优捕获策略. 相似文献
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研究了一类具有食饵避难的Leslie-Gower捕食与被捕食系统的收获模型,讨论了平衡点的稳定性,考虑对食饵种群进行捕获,利用Hurwitz判据,得到了系统平衡点局部渐进稳定的充分条件,最后使用Pontryagin最大值原理得到了最优收获策略. 相似文献
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在此对两个食饵和一个捕食者的三种群收获模型进行定性分析，讨论正平衡点的局部稳定性和全局稳定性，并利用最优控制理论讨论了最优捕获策略． 相似文献
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研究一类具有相互干扰功能反应的捕食-食饵系统.对正平衡点的局部渐近稳定性和全局稳定进行了详细说明,证明了系统在正平衡点处是全局稳定的,并利用Pontrjagin最大值原理及最优控制理论,得到该系统的最优捕获策略.所得结果改进和推广了相关文献的主要结果. 相似文献
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建立了一类环境污染下治理污染物及捕获种群的Filippov系统,给出了各类平衡点及伪平衡点的稳定性。 相似文献
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应用微分代数理论和分叉理论,分析了具有捕获作用的广义捕食-被捕食模型在内部平衡点附近的局部稳定性,得到了不仅使系统在正平衡点处稳定,而且使经济利益达到理想水平的控制率． 相似文献
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本文讨论了具有互惠关系的几种群系统平衡点的稳定性,同时求出了对互惠系统的几种群同时进行捕获时,获得最大经济效益的条件 相似文献
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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
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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
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献
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GUO Bao-feng Xiao Da-wei 《重庆大学学报(英文版)》2005,4(3):129-133
Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator＇s Garden. Translating building data to the Virtual Reality Modeling Language （VRML） is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-ofdetail switching. 相似文献
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The awareness of individualism can be traced back to the period of American Revolution when the Declaration of Independence was produced.It expressed basic beliefs concerning freedom,equality,democracy,privacy and the relationship between people and government,which were exactly what the philosophy of individualism mostly dealt with at that time.This paper is to exploit the essence of individualism by analyzing the Declaration .The analysis enables us to reconsider its significance to the issue of America human rights and foreign policies. 相似文献
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李晓劲 《读与写:教育教学刊》2008,5(6)
Public speaking, as one kind of speech act, the speaker uses some pragmatic strategies, for example,the use of personal pronoun, in order to achieve effective communication. Speakers use the first personal pro-noun we and the second personal pronoun you conventionally, also there are some deviations in the use of person-al pronouns. However, theses kinds of uses have to be explained and understood in such a specific context. 相似文献
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宋少华 《读与写:教育教学刊》2008,5(5):3-5
This essay mainly studies the linguistic features of News English on stylistics.The study is made mainly on three aspects of News English.They are lexical features.sentence features and grammar features of News English.Through the study we find that News English,as a distinctive and new language.has its own lin-guistic features in words, sentences and grammar. 相似文献
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正Nong Luhuan had a wild dream when he was little.He wanted to become a cartoonist and publish books of his own.Now,the 22-year-old art design major at Sichuan Fine Art Institute has achieved his dream.His micro blog cartoon has more than 260,000 followers and he will publish his first book this week.农璐焕小时候有一个疯狂的梦想,他想成 相似文献
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正The hardest arithmetic to master is that which enables us to count our blessings.世界上最难的算术题是如何清点我们的祝福。According to legend,a young man while roaming the desert came across a spring of delicious crystal-clear water.The water was so sweet,he filled his leather canteen so he could bring some back to a tribal elder who had been his 相似文献