共查询到20条相似文献，搜索用时 62 毫秒
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发光二极管是一种较新颖的半导体器件。它不但具有一般晶体二极管的单向导电性能,而且在正向电压的作用下,会发出优美的形色光来。它的工作电流小。常用的发光二极管有磷化镓红色发光二极管和磷砷化镓红色发光二极管,还有发绿光发黄光的,用发光二极管可作如下的两个物理演示实验: 一、晶体二极管的单向导电性取一只发红光的磷化镓发光二极管LED,一只30Ω限流电阻,3 V直流电源。连接如图一电路。当把LED的正极(标记为外壳上有尖角)接A端,负极接B端,合上开关K,则LED发出显亮的红色光来,再把LED的正负极 相似文献
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王长福 《数理天地(初中版)》2010,(3):37-37
题 发光二极管（Light Emitting Diode）是半导体二极管的一种,常简写为LED,它可以将电能转化成光能,具有单向导电性．当给发光二极管加上正向电压后,产生自发辐射的荧光．当改变电路中的电流时,可实现红黄绿蓝橙多色发光,当小电流通过时为红色,随着电流的增加,可以依次变为橙色,黄色,最后为绿色．发光二极管的工作电流一般在10～20mA范围内． 相似文献
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关于发光二极管和半导体照明的探讨 总被引：1，自引：0，他引：1
针对近年来国内外非常重视照明用发光二极管（LED）的研制与开发，简要介绍了发光二极管的发展现状及其特点，并讨论了研发照明用LED所需要解决一些技术关键问题，指出这类照明系统将获得广泛应用。 相似文献
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阿联酋首都迪拜注定要创造更多的人间奇迹。Tameer公司将在迪拜一座33层的大厦上竖立一块高达100米的LED（发光二极管）广告屏。据说．即使是在1．5公里之外的人也可以看到这个LED广告屏上播出的清晰画面。目前，设计团队遇到的最大问题并不是LED屏本身的技术问题，而是如何解决好大楼内部的采光问题，毕竟LED屏要遮挡整个大厦的一面。 相似文献
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半导体照明也叫LED，是半导体发光二极管的意思，随着1962年第一只半导体发光二极管的诞生，一种体积小、寿命长、安全低压、节能、环保的新型照明灯具就进入了科学家的视野，他们认定，这类新型的固态照明（包括半导体照明和固体发光材料照明两种，后目前进展较慢）必将带来人类照明领域的第三次革命。 相似文献
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LED照明,现在连我们这些普通人听起来都不算稀奇。但如果不是今年的诺贝尔奖物理奖颁给了三位蓝色发光二极管的发明者,或许我们还未意识到它对人类的重要性——诺贝尔评选委员会甚至在其授奖声明中直播:"白炽灯照亮了20世纪,LED灯则点亮了21世纪。"2014年10月7日,赤崎勇、天野浩和中村修二因发明了高效能的蓝色发光二极管(LED)而被授予诺贝尔物理学奖。红色和绿色的LED在上世纪五六十年代已经由多个实验室创造出来,但高效能的蓝色LED却要经历又一个三十年才最终被制造出来,这不禁让人心生疑问——为什么蓝色LED这么难造?发光二极管是一种靠电流在半导体材料中流动而发光的电子器件。LED能够发出波长范围从红外线到紫外线的光。 相似文献
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青云 《青少年科技博览(中学版)》2015,(1):5-6
人工点火开始了人类照明领域的第一次革命,而爱迪生发明的白炽灯被公认为第二次照明领域的革命。现在,环保节能的LED照明则标志着第三次照明革命的到来。由于在LED照明上的贡献,3名科学家获得2014年诺贝尔物理学奖。LED是英文Light Emitting Diode的缩写,意思是发光二极管,是一种能将电能转化为光能的半导体电子元件,人们把利用LED制成的灯泡叫LED灯。攻克难题 相似文献
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照明技术的革命——高亮度发光二极管的发展及应用 总被引：1，自引：0，他引：1
方来付 《中国科教创新导刊》2001,(3):11-13
全光谱发光二极管（ LED）的应用正变得越来越广泛，精明的商家正在竞相开发白色发光二极管以取代爱迪生已发明了近一个世纪的白炽灯泡。 爱迪生之所以备受称道首先是因为他发明了电灯泡，当然还有其他发明，如留声机、油印机和检票机等。大多数发明已在近十年内被数字技术所替代，而他所发明的电灯到目前为止依然继续闪耀。现在，在电灯发明 120年之后，照明技术的进步已经使电灯也面临着严重的威胁。为了实现从传统的电灯照明到 LED(Light emitting diode,发光二极管 )照明的过渡，主要的光源制造商正在加强和 LED制造商的联合… 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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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
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 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