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如果是同种物质，密度相同，可适用公式ρ=m1/V1=m2/V2=△m/△V；如果是不同种物质，当它们体积V相同时，可适用公式V=m1/ρ1=m2/ρ2=△m/△ρ．合理使用这两个公式，会很容易地分析某些复杂的密度问题。 相似文献
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众所周知，理想气体状态方程为pV=nRT．当气体1与气体2的T、p相同时，由pV=nRT可对比推出关系式V1/V2=n1/n2；T、V相同时可推出P1/P2=n1/n2．结合n=m/M、ρ=m/V还可推论出许多有用的关系式． 相似文献
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菅亚芹 《商情·科学教育家》2007,(7):154-154
1 物体密度大于水的密度的测量
仪器：量筒、纸筒（重量忽略，可装入量筒中）、水、细线。先在量筒中装入适量水，测出V1，再用细线拴住物体，投入水中，测出V2，取出物体凉干，然后把物体放入纸筒投入水中（使之能够漂浮），测出V3，然后根据F浮=G物：水g（V3-V1）=m物g，m物=水（V3-V1），V物=V2-V1，最后用密度公式求出物体的密度物=m物／V物=水（V3-V1）／（V2-V1）。 相似文献
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《中学生数理化(高中版)》2011,(12)
如图1所示，电源电动势E=50V，内阻r=1Ω,R1=3Ω，R2=6Ω.间距d=0．2m的两平行金属板M、N水平放置，闭合开关S，板间电场视为匀强电场． 相似文献
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陈玉花 《赤峰学院学报(自然科学版)》2006,22(1):6-7
用水热合成的方法制备[Ni（en）2]0．5 V3O7，X-射线单晶结构分析确定晶体属于单斜晶系，P2（1）／c空间群，晶胞参数：a=8．932（7）A，b=16．9862（4）／A，c=6．7140（1）A，β=111．68（3）^。，V=938．97A^3，z=2，De=1．907g／cm^3，R1=0．0586，ωRl=0．179．S=1．023 相似文献
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论证了有限个真子空间复盖不了整个线性空间，并以此得出几个与真子空间有关的重要定理和推论，为深入线性空间的性质讨论提供了依据． 相似文献
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设F2vq是Fq上的2v维辛空间,v是一个正整数。可知F2vq中满足0≤m1≤v的所有(m1,0)型全迷向子空间按子空间的包含关系构成秩为v的有限偏序集,由此可以证明该偏序集是一致偏序的。 相似文献
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设Tj（j=1,2,3）是与Schrodinge算子相关的Riesz变换,即 T1=（-△＋V）-1V,T2=（-△＋V）-1/2V-1/2,T3=（-△＋V）-1/2-1/2 ,本文主要考虑了交换子[b,Tj]=6Tj-Tjb（j=1,2,3）在Lp空间上的有界性．其中位势V（x）满足反向Holder不等式,△是拉普拉斯算子． 相似文献
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田学华 《山西教育(综合版)》2002,(6):37-37
1.常规测量。根据公式 ρ=mV,分项测量。天平测质量记作 m(液体的质量需借助杯分两步 :先测杯液质量记作m1,再测剩余杯液质量记作 m2 ,计算液体质量 m=m1- m2 ) ;量筒测体积记作 V(固体的体积需借助水分两步 :先测水的体积记作 V1,再测水和物的体积记作 V2 ,则 V=V2 - V1) ;计算结果 :ρ固 =mV2 - V1,ρ液 =m1- m2V 。2 .变换条件 ,用水取代量筒 ,测密度。例 :利用天平、水和杯、线 ,测出石块的密度。分析题时引导学生思考 ,天平、量筒测密度原理ρ=mV中 ,已知条件中无量筒 ,V已不能直接测出 ,需找一个等量代替 ,如何代替呢 ?学生追题… 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