共查询到20条相似文献，搜索用时 62 毫秒
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利用解析方法和几何不等式理论，研究了四面体外接球半径与内切球半径之间的关系，建立了四面体外接球半径与内切球半径的几个不等式，推广了四面体Euler不等式。 相似文献
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建立了关于四面体二面角平分面面积与四面体外接球半径、内切球半径以及中线之间的一些几何不等式,其中一些不等式改进了三维Euler不等式.此外,我们提出两个猜想. 相似文献
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利用距离几何的理论与方法研究了欧氏空间中n维单形的几何不等式的稳定性,从两个单形的＂偏正＂度量证明了n维单形四个重要几何不等式的稳定性,并给出这些几何不等式的稳定性版本。 相似文献
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研究了Ceva四面体的几何不等式问题，建立了四面体与其Ceva四面体的外接球半径与内切球半径的以下两个不等式：R′R^2≥3^2r^3,R′R^2≥3^5r′^3 相似文献
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本文利用几何不等式理论和解析的方法。研究了单形内任意一点到各n-1维超平面的距离与单形的外接球半径和内切球半径间的关系,建立了两个新的几何不等式,推广了已有的结果。 相似文献
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应用几何不等式理论与解析方法，研究了单形外接球半径与内切球半径之间的关系，建立了涉及单形外接球半径与内切球半径的一些几何不等式，从而加强了著名的n维Euler不等式． 相似文献
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陈士龙 《合肥师范学院学报》2012,(6):14-15,22
本文应用几何不等式理论和解析的方法,研究了n维欧氏空间En中n维单形的Finsler-Hadwiger不等式和n维Euler不等式,建立了关于单形的两个新的几何不等式,推广了已有的结论。 相似文献
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陈士龙 《安徽教育学院学报》2012,30(6)
本文应用几何不等式理论和解析的方法,研究了n维欧氏空间En中n维单形的Finsler-Hadwiger不等式和n维Euler不等式,建立了关于单形的两个新的几何不等式,推广了已有的结论. 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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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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《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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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献