共查询到20条相似文献，搜索用时 62 毫秒
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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,(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
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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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《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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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