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超导材料
1911年,荷兰科学家昂内斯(Onnes)用液氦冷却水银时发现,当温度下降到4.2K( 268.98°C )时,水银的电阻完全消失.1913年昂内斯在诺贝尔领奖演说中指出:低温下金属电阻的消失“不是逐渐的,而是突然的”,水银在4.2K进入了一种新状态,由于它的特殊导电性能,可以称为超导态.后来他发现许多金属和合金都具有与上述水银相类似的低温下失去电阻的特性,这种现象称为超导电性,达到超导时的温度称为临界温度,具有超导电性的材料称为超导材料或超导体.
1933年,迈斯纳和奥克森菲尔德两位科学家发现,如果把超导体放在磁场中冷却,则在材料电阻消失的同时,外加磁场也无法进入超导体内,形象地来说,就是磁感线将从超导体中被排出,不能通过超导体,这种抗磁性现象称为“迈斯纳效应”.
根据临界温度的不同,超导材料可以被分为:高温超导材料和低温超导材料.但这里所说的“高温”只是相对的,其实仍然远低于冰点0℃,对常温来说应是极低的温度.20纪80年代是超导电性探索与研究的黄金年代.1981年合成了有机超导体,1986年缪勒和柏诺兹发现了一种成分为钡( Ba )、镧( La )、铜( Cu )、氧( O )的陶瓷性金属氧化物,其临界温度提高到了 35K .由于陶瓷性金属氧化物通常是绝缘物质,因此这个发现的意义非常重大,缪勒和柏诺兹因此而荣获了1987年度诺贝尔物理学奖.后来包括中国在内的世界上部分国家又陆续发现临界温度100K以上的高温超导材料.
高温超导材料的用途非常广阔,由于其具有零电阻和抗磁性,用途大致可分为三类:大电流应用(强电应用)、电子学应用(弱电应用)和抗磁性应用.大电流应用即前述的超导发电、输电和储能;电子学应用包括超导计算机、超导天线、超导微波器件等;抗磁性主要应用于磁悬浮列车和热核聚变反应堆等.
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请用适当的词完成下面的短文,并把所缺单词填写在指定的位置上。每个空只能填写一个形式正确、意义相符的单词。

    A big company wanted to find someone to work for them. Lots of young college students came to ____ for the job, but only a small part of them were left. And this time, the company didn't plan to choose the right persons ____ usual.

    Here came the day when they took the final interview. A big box full of papers was placed on the ____ to the interview room, and a few papers were lying around the box.

    The first student came. He hurried along the way to take the interview. “Who put this box in the middle of the road?” the student said to himself, ____ he did not try to move the box away. Instead, he passed around the box and continued his way.

    The second student came along and did the ____ thing. Then another came, and another. All of them complained (抱怨) about the box but ____ of them tried to move it. What's worse, someone even stepped on the papers and left without having a look at the things on the ground.

    Half an hour ____, a thin young man with glasses came. He was also among those who were left to take the interview. He saw the box and the papers around it. Without thinking twice, he stopped and began to ____ up the papers and put them into the box. Then he managed to move the box to the side. To his great ____, he found an invitation under the box. On it were the following words, “Congratulations, young man! You are the ____ person we are looking for! Would you like to join us?”

    Sometimes, you see, helping others is helping yourself.