一类捕食模型正平衡解的分支和稳定性

讨论了一类推广的捕食 - 食饵生态模型的平衡态系统在第三类边界值条件下一类严格正解的存在性和稳定性.首先给出了更具有一般性的可解性条件,并结合极值原理分别得到两类半平凡解(u0,0),(0,v0)的存在惟一性,利用局部分歧的技巧证明了系统在(u0,0)和(0,v0)点处出现分支现象,从而得到了正解分支;然后运用线性算子扰动理论和分支解的稳定性理论得出这类正解的稳定性,即当I<0时,系统在(u0,0)附近的正解是稳定的,而当I>0时,正解不稳定;当(I~)＜0时,系统在(0,v0)附近的正解是稳定的,而当＞0时,正解不稳定,其中I,(I~)是两个积分.     

一类积分微分方程初值问题的正解

本文研究初值问題 x′=g(t,x,Tx) x(0)=x_0的正解,其中 Tx=φ_0(t)+integral from n=0 to 1 h(s,t)x(s)ds证明了初值问题的正解、最大解、最小解的存在性,并将所得结果应用于二阶常微分方程,得到正解的存在性。     

一类四阶常微分方程的正解

讨论了四阶常微分方程边值的问题u^(4) βu^n＝au=ψ(t)f(u)，u(0)=u(1)=u^n(0)=u^n(1)＝0的正解存在性，利用锥拉伸与压缩不动点定理，给出了至少有一个正解存在的充分条件，并且建立了多个正解的存在性结果。     

四阶奇异微分方程边值问题的多重正解

利用锥上的不动点指数原理研究了一类四阶奇异微分方程边值问题正解及多重正解的存在性,得到当参数λ属于某一区间时,算子方程x(t)=λAx(t)正解的存在性理论.     

一类二阶微分方程最终正解的单调性

研究了一类二阶非线性微分方程(a(f)x')'+P(t,x)=Q(t,x,x')最终正解的单调性,给出了判断其最终正解单调的充分条件,并用例说明了主要结论.     

三阶三点脉冲边值问题多个正解的存在性

利用Leggett-Williams不动点定理,研究了一类三阶三点脉冲边值问题多个正解的存在性.首先给出了其3个正解的存在性,进一步还给出了2n-1个正解的存在性.最后给出了一个例子.主要结果改进、推广了GuoLJ(2007)和LiuY(2009)的一些结果.     

含双参数的非线性二阶脉冲微分系统的正解

研究一类带有双参数的非线性二阶m点脉冲微分系统正解的存在性并讨论正解不存在的情况,其中非线性项可有不同性质,系数a1(t)和a2(t)均Lp可积.通过构造一个特殊的锥,结合不动点指数理论,得到了参数λ和μ在不同条件下正解存在性定理,并在λ很小时得到了正解不存在性定理.     

拟线性二阶方程三点边值问题对称正解的存在性

研究一维p-Laplace方程(p(u′(t)))′+q(t)f(t,u(t),u′(t))=0关于三点边值u(t)=u(1-t),u′(0)-u′(1)=u(1/2)对称正解的存在性.利用Avery-Peterson不动点定理得出该问题在一定的条件下至少存在3个对称正解及在f的适当假设下至少存在2n+1个对称正解.     

一类泛函微分方程周期正解的个数

研究一类带有一个参数的非线性泛函微分方程x'(t)=a(t,x(t))x(t)-λb(t)f(x(t-τ(t)))的周期正解的个数问题.利用锥压缩锥拉伸不动点定理,解决该类方程周期正解的存在问题.给出根据参数判断该类方程存在1个、2个,以及不存在周期正解的充分条件.结果表明,这些充分性条件简单,容易验证.     

带有特殊非线性项的Dirichlet问题正解的确切个数

用时间映像原理研究一维Minkowski空间给定平均曲率方程Dirichlet问题正解的确切个数及分歧图, 其中参数λ>0, L>0. 在λ满足一定的条件下, 分别得到了非线性项为f(u)=u(e^u-1)和f(u)=e^u-1时该问题没有正解、 恰有一个正解和恰有两个正解的结果.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that