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用眼和手去发现的切赫
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作者 增年 《小学生导读》 2011年第5期6-8,共3页
任何重大的科学发现,都可能会带来一场科学的革命。但这种发现是来之不易的。关于生命起源的发现,就是一个例证。
关键词 《用眼和手去发现的切赫 小学生 语文学习 阅读
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生物科学史上的“意外”收获
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作者 冯建婕 《中学生物学》 2007年第2期3-4,共2页
在生物科学史上,有许多重要的发现其实是科学家们“无心插柳”的结果,如米歇尔发现核酸,格里菲思发现转化因子,巴斯德研制出鸡霍乱疫苗,切赫发现RNA具有催化活性等,但偶然背后也隐藏着必然的因素。
关键词 生物科学史 米歇尔 格里菲思 巴斯德 切赫
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坦克手 还在场上
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作者 欧阳大哥 《新体育》 2018年第2期104-104,共1页
偶然看到一条新闻,说切赫即将迎来他的英超第二百场零封,恍惚了一下,这老头怎么还存踢?后来想想,比他大4岁的布冯还在,卡西也比他大1岁。
关键词 足球 体育运动 运动员 切赫
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Realization of band-pass and low-pass filters on a single chip in terahertz regime 被引量:2
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作者 王蕾 耿照新 +3 位作者 贺训军 曹亚鹏 杨玉平 陈宏达 《Optoelectronics Letters》 EI 2015年第1期33-35,共3页
In this paper, we present the design, simulation, fabrication and characterization of a terahertz(THz) filter based on metamaterial consisting of the periodical double symmetric splits ring resonator(DS-SRR) array. We... In this paper, we present the design, simulation, fabrication and characterization of a terahertz(THz) filter based on metamaterial consisting of the periodical double symmetric splits ring resonator(DS-SRR) array. We can observe that the metamaterial-based filter possesses a band-pass transmission when the electrical field is along y direction, and it possesses a low-pass transmission when the electrical field is along x direction. Our results demonstrate that the proposed filter can realize the switching between band-pass effect and low-pass effect by only changing the polarization direction of the incident electromagnetic wave. Moreover, the calculated surface current distributions are also used to analyze the switchable mechanism of the THz metamatrial filter. Therefore, the proposed THz wave filter has a potential application in THz wave communication systems. 展开更多
关键词 pumped gains neodymium pumping varied operate adjusting mirror resonator attractive
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Single-/dual-wavelength switchable and tunable compound-cavity erbium-doped fiber laser with super-narrow linewidth 被引量:2
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作者 冯亭 延凤平 刘硕 《Optoelectronics Letters》 EI 2016年第2期119-123,共5页
A single-/dual-wavelength switchable and tunable erbium-doped fiber laser(EDFL) with super-narrow linewidth has been proposed and experimentally demonstrated at room temperature. The fiber laser is based on a compound... A single-/dual-wavelength switchable and tunable erbium-doped fiber laser(EDFL) with super-narrow linewidth has been proposed and experimentally demonstrated at room temperature. The fiber laser is based on a compound cavity simply composed of a ring main cavity and a two-ring subring cavity(TR-SC). Regardless of single- or dual-wavelength operation, the EDFL could always work well in single-longitudinal-mode(SLM) state at every oscillating wavelength. In dual-wavelength operation, the spacing could be tuned from 0 nm to 4.83 nm. In single-wavelength operation, the EDFL could lase at a fixed wavelength of 1 543.65 nm or another wavelength with a tunable range of 4.83 nm. The super-narrow linewidths of 550 Hz and 600 Hz for two wavelengths are obtained. The proposed EDFL has potential applications in microwave/terahertz-wave generation and high-precision distributed fiber optical sensing. 展开更多
关键词 tunable narrow spacing longitudinal terahertz lasing microwave tuned simply tuning
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