共查询到20条相似文献，搜索用时 62 毫秒
1.
利用单调算子的迭代方法,给出了一类四阶两点边值问题x(4)(t)+f(t,x(t))=0(0≤t≤1),x(0)=x’(0)=x(1)=x’(1)=0的对称正解. 相似文献
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本文讨论如下方程-x″ a(t)x(t)=f(t,x(t),x(α(t))),t∈J=[0,T]x(0)=x(T),x′(0)=x′(T)多重正解的存在性.所得结果推广了已有文献中的结果。 相似文献
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卫雪梅 《中山大学学报论丛》2000,20(5):1-5
确定函数偶（u,a(s))的问题：{ut=(a(u)ux)x u(0,t)=f1(t),u(1,t)=f2(t);u(x,0)=u0(x),ux(0,t)=g(t)解的唯一性. 相似文献
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运用改进的Amann三解定理来研究一类二阶微分方程周期边值问题{x'(t)=f(t,x(t)),t∈l x(0)=x(2π),x'(0)=x'(2π),得出了其解的多重性,并举例说明了所得结果的应用. 相似文献
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祁正红 《数理化学习(高中版)》2006,(17)
一、直接法例1已知f(x)=x2(x≥0)x(x<0),g(x)=x(x≥0)-x2(x<0),则x<0时,f[g(x)]为()(A)-x(B)-x2(C)x(D)x2解:当x<0时,g(x)=-x2<0,所以f[g(x)]=g(x)=-x2,选(B).求复合函数的解析式,先求内层函数,再求外层函数,另外,分段函数要注意变量的范围.二、换元法例2已知f(1-cosx)=sin2x,求f(x).解:令1-cosx=t则cosx=1-t,-1≤1-t≤1,所以0≤t≤2.所以f(t)=1-(1-t)2=-t2+2t(0≤t≤2)所以f(x)=-x2+2x(0≤x≤2)三、配方法例3f(x-1x)=x2+x12.求f(x).解:f(x-1x)=x2+x12=(x-1x)2+2,所以f(x)=x2+2.四、待定系数法例4已知f(x)=3x-1,f[h(x)]=g(x)=2x+3,h(x)为x… 相似文献
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杜睿娟 《兰州石化职业技术学院学报》2013,13(1):78-80
在障碍带条件下研究三阶时滞微分方程边值问题xm(t)=f(t,(τ),x'(t),x”(t)),t∈[0,1]x(t)=0,τ≤t≤0,x'(f)=x'(1)=0,f∈[0,1)解的存在性,其中τ≥0;f:[0,1]×R3→R为连续函数. 相似文献
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左锦辉 《绵阳师范学院学报》2008,27(5)
考虑如下 ut=a2uxx p(t)u(x,t) (x,t)∈(0,l)×(0,T)u(x,0)=ψ(x) x∈[0,l]β u/x(l,t) γu(l,t)=ψ(t) t∈[0,T]u(x0>,t)=φ(t) x0∈[0,l],t∈[0,T]边界反问题,此问题是一个线性热传导反问题.其数学模型是热力学的热传播的控制,主要是通过边界上的热流来决定初边界上的热流或者内部的温度.在对其边界上的热流给出测量值的先验假设下,证明了其解的稳定性,同时也给出了计算方法. 相似文献
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研究一类四阶非线性波动方程的初边值问题:{utt-Δu-Δut-Δutt=μ|u|p-1u f(x,t),u|(e)Ω×(0,t)=0,u(x,0)=u0(x),ut(x,0)=u1(x);(1)得到了其广义解的存在性. 相似文献
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本在实Banach空间E中考虑非线性微分方程的Cauchy问题：x′(t)=f)t,x(t)),x(0)=x0(Ⅰ) 及非线性Volterra型积分微分方程的初值问题x′=H（t,x(t),(Tx)(t)),x(0)=x0(Ⅱ）其中：(Tx)(t)=∫0k(t,s)x(s)ds利用a-Lipschitx非紧性条件弱的一般非紧性条件及MONCH不动点定理证明了问题（Ⅰ）及（Ⅱ）的解的存在性,对于Cauchy问题（Ⅰ）,本降低了[4]中关于f一致连续性要求,对于（Ⅱ）,放宽了[2]中的非紧性条件。 相似文献
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翟新平 《黔南民族师范学院学报》2006,26(6):21-23,42
本文运用Leray-Schauder原理研究障碍带条件下二阶微分包含两点边值问题x″∈F(t,x,x′),t∈[0,1]x(0)=A,x(1)=B解的存在性. 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
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献
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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
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正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse. 相似文献
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《今日中学生》2014,(9)
正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between 相似文献