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每年的12月25日（December 25th）是基督教徒纪念耶稣诞生的日子，是西方社会最为隆重的Christmas，称为“圣诞节”。从12月24日到翌年1月6日为圣诞节节期。圣诞节本来是基督教徒的节日，后来逐渐成为一个全民性的节日，是西方国家一年中最重要的节日。西方人以红、绿、白三色为圣诞色，圣诞节来临时，家家户户都要用圣诞色来装饰。红色有圣诞花和圣诞蜡烛，绿色的是圣诞树。 相似文献
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教学过程Step 1.Warm-up 1.Listen and sing the song"Jingle Bells"(渲染圣诞节的气氛)2.Free talk T:Boys and girls,what day is today?What holiday(节日)is coming?S:It’s Christmas.T:I like Christmas very much.Do you like Christmas?S:Yes,we do.T:When’s Christmas?S:It’s on the 25th of December.T:What do people usually do at Christmas? 相似文献
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December 25th is Christmas Day.Christmas is an important holiday in the United States.On this day,most families get together for a big dinner.They exchange presents and visitfriends.The Christmas tree is an important part of the Christmas holiday.Most families buy atree.The family decorate (装饰) the tree together. 相似文献
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提起圣诞节,大家一定会想到圣诞老人、圣诞礼物。那么圣诞节是怎么由来的呢?来,一起走进下文!Christmas,originating as a contraction of Christ's mass, is an annual holiday celebrated on December 25 to mark and honor the birth of Jesus Christ, although the date is not considered to be the actual birthday of Jesus. Not 相似文献
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波浪 《小雪花(小学生成长指南)》2006,(12)
小朋友,今天给你们介绍的这个节日Boxing Day可不是拳击节。那是什么呢?其实,这个节日啊,被称为节礼日。什么是节礼日啊?你来看看吧。 Boxing Day is one of the bank holidays(公众假日) of England. It's the day following(接着的) Christmas(圣诞节). It's on December 26th. On this day, people often give presents(礼物)to each other. They also give presents to postmen(邮递员), dustmen(清扫工) and so on. So Boxing Day is the day when people open the presents.Boxing Day is one of thebank holidays(公众假日)o… 相似文献
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Mona likes December because（因为）she love‘s Christmas（圣诞节）．She can play happily and receive（收到）many gifts（礼物）．And she doesn’t like June because it of ten rains（下雨）at that time． 相似文献
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周顺伍 《语数外学习(初中版)》2006,(12)
Christmas is a holiday that is celebrated around the world. Many of the old customs are still carried out in America. Swedish families start to celebrate their Christmas on December 13th, St. Lucia' s Day. The eldest daughter wears a white dress and a wreath(花冠) with seven lighted candles on her head. She gives the family coffee in bed. 相似文献
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采用离体花粉培养技术,研究了不同浓度的细胞外钙对百合花粉萌发和花粉管生长的影响.结果表明：在0.01％ Ca2＋度下花粉萌发和花粉管生长速率最快,高于或低于这个浓度,花粉管生长速率和萌发速率都显著被抑制.将快速生长的花粉管,转入Ca2＋浓度为03％的培养基中,花粉管的生长在几秒种内就被抑制.长时间0.3％ Ca浓度培养导致花粉管呈波浪形状.这种改变是不可逆的,当用pectinase处理或降低培养基中的钙浓度时,花粉管破裂.这些结果说明钙作为花粉管生长调节信号,对花粉管的生长具有直接作用和间接作用. 相似文献
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为研究一种新型强化传热管的传热效果,对光管、普通翅片管和螺旋槽式翅片管在不同流量条件下的传热特性进行了比较研究.实验中管程工质为水蒸气,壳程通入饱和液态水作为冷源.结果表明,螺旋槽式翅片管的换热量明显高于光管和普通翅片管,并且随着流体流量的增加,传热效率的提高也更加明显.当蒸汽温度140℃时,螺旋槽式翅片管沸腾传热系数... 相似文献
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HUANG Wei-jun DENG Xian-he ZHOU Shui-hong 《重庆大学学报(英文版)》2006,5(1):8-12
1 Introduction A well known method to increase heat transfer from a surface is to roughen the surface by use of regular geometric roughness elements, such as transversely-ridged tube, spirally-ridged tube or converging-diverging tube, etc., on the surface… 相似文献
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The filling construction of permeable geosynthetic tubes is considered. First, an analytical approach is developed to determine the internal pressure, tension and shape of the cross section of a geosynthetic tube based on its volume. An analytical solution for the drainage rate of the tube is then derived. The course of the filling construction is divided into several time intervals and the volume of the tube after each interval is obtained from the equilibrium of flow calculated from the drainage rate and filling rate. The validity of our analytical approach is tested by comparing our results with previously published experimental result. The results of this comparison indicate that our method is applicable for simulating the filling construction of permeable geosynthetic tubes. 相似文献
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With isopentane as working fluid, the heat transfer performances for corrugated, nodal and horizontal grain tubes are simulated. The structural parameters of the three kinds of tubes are compared with those of the plain tube. The numerical results using computational fluid dynamics are validated with theoretical values. For the corrugated, nodal and horizontal grain tubes, the heat transfer enhancements(HTEs) are 2.31—2.53, 1.18—1.86 and 1.02—1.31 times of those of the plain tube, respectively. However, the improved HTEs are at the expense of pressure losses. The drag coefficients are 6.10—7.09, 2.06—11.03 and 0.53—1.83 higher, respectively. From the viewpoint of comprehensive heat transfer factor, the corrugated tube is recommended for engineering applications, followed by the horizontal grain tube. 相似文献
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余泽红 《湖南广播电视大学学报》2004,(4):95-96
王村公路大桥是一座中承式特大桥，此类大桥施工的关键在于钢管拱肋的制作安装、管内混凝土浇注和钢管的防腐处理。施工质量的好坏直接影响到桥梁的使用安全和使用寿命。 相似文献
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介绍了一种用于强化管壳式换热器壳侧传热和支撑管束的螺旋折流片新型结构,该结构是对换热器管子相间地套上螺旋折流片以产生旋涡流动.研究模型是在正方形布置的4个管子中的2个对角管子套上螺旋折流片后形成的通道,利用FLUENT软件对该上述四管通道模型的流场和温度分布情况进行了数值模拟;分析了四管通道模型中螺旋折流片对强化传热和流动阻力随雷诺数的变化关系的影响.算例结果显示该新型结构可比相同尺寸的光管通道中的情形传热系数提高约40%～55%,同时也将伴随较高的流动阻力.可以相信螺旋折流片式换热器将会在许多工业领域有良好的应用前景. 相似文献
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In this article, we report some experimental results on the behaviour of the flame of a candle kept at the bottom of a glass tube, which is open at the top and closed at the bottom. Thus, the supply of oxygen for the continuous burning of the flame is possible only from the top open end of the tube. We find that the candle burns steadily below a critical tube height. Above this height, the flame oscillates in size, and a further increase in tube height leads to the flame extinguishing quickly. 相似文献
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Rats were given alternating 1-min access to two tubes containing sucrose solutions that varied in concentraton (32% vs. 2%, 32% vs. 4%, 32% vs. 8%, and 32% vs. 16%). Lick rate for 32% sucrose was higher when the alternative tube contained a lower concentration solution than when both tubes contained 32% (a positive-contrast effect), and lick rate for the lower concentration solution (2%, 4%, 8%, or 16%) was lower when the alternative tube contained 32% than when both tubes contained the lower concentration solution (negative contrast effect). Proportion of licks made for 32% under contrast conditions tended to match the proportion of concentration available from that tube. Regression analysis of the ratio of licks made to the two tubes under contrast conditions as a function of ratio of concentrations available indicated a good fit to a power function with an exponent of 1.13, within the range of those typically found in human magnitude estimation studies of relative sweetness. 相似文献