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秦松涛 《湘潭师范学院学报(社会科学版)》2000,21(6):27-30
在定义了R^2的单调范数以后,得到了RS集对两个最佳元逼近的新特征。当X是p一致凸Banach空间,证明了凸集对两个元的最佳同时逼近必是 p阶强唯一的（p＞1）。 相似文献
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本文在一类具有中间性和强中间性的集M上考虑了如下的极小化问题: inf‖F(x,Q)‖得到了极小化解的特征刻划和唯一性定理。利用这些结果,我们得到了通常的单边联合最佳逼近的一些结论。本文的结果推广了文[5] 中的某些结论。 相似文献
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本文在一般线性赋范空间内提出点集的最小偏离问题,给出了最小偏离点的存在性与唯一性的各种充分性判据及其对于最佳逼近元唯一性问题的应用. 相似文献
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设■与■分别表示线性赋范空间（X,‖·‖）的对偶空间（X,‖·‖）的强拓朴与弱拓朴.本文利用凸集的隔离定理证明了Mazur定理及凸集的最佳逼近元存在性定理的对偶定理。同时证明了:对X中的凸集G,当X是可分Banach空间时,有 相似文献
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研究连续函数的最佳Chebyshev指数逼近问题,得到了最佳逼近的存在性、唯一性及特征性等方面的结果,揭示了最佳Chebyshev指数逼近与人们熟知的Chebyshev多项式逼近有极其相拟的特征性质． 相似文献
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本文在局部Haar条件下，讨论了紧空间上非线性Dunham型Chebyshev同时逼近，得到了同时逼近为局部最佳的充分必要条件，给出了与非线性同时逼近问题等价的相关线性同时逼近问题；证明了极小集的存在性，在这个极小集上的局冲淡最佳逼近为局部最佳的；获得了区间上非线性同时逼近的交错定理；证明了非线性同时逼近的a阶（a≥1)的强唯一常数等于其相关线性同时逼近的a阶强唯一常数。 相似文献
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本文讨论了Orlicz空间中的联合最佳逼近问题，得到了Orlicz模和Luxemberg模联合最佳逼近的特征定理、唯一性定理和存在定理。 相似文献
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本文讨论了局部Haar条件下变形的非线性L逼近，得到了包括交错定理在内的特征定理、唯一性和强唯一性定理。 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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《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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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献