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Wei Ren Tang Li Qiuzhi Qu Bin Wang Lin Li Desheng Lü Weibiao Chen Liang Liu 《国家科学评论(英文版)》2020,7(12):1828
Atomic clocks with cold atoms play important roles in the field of fundamental physics as well as primary frequency standards. Operating such cold atom clocks in space paves the way for further exploration in fundamental physics, for example dark matter and general relativity. We developed a space cold atom clock (SCAC), which was launched into orbit with the Space Lab TG-2 in 2016. Before it deorbited with TG-2 in 2019, the SCAC had been working continuously for almost 3 years. During the period in orbit, many scientific experiments and engineering tests were performed. In this article, we summarize the principle, development and in-orbit results. These works provide the basis for construction of a space-borne time-frequency system in deep space. 相似文献
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Yanhua Qu Chunhai Chen Ying Xiong Huishang She Yong E Zhang Yalin Cheng Shane DuBay Dongming Li Per G P Ericson Yan Hao Hongyuan Wang Hongfeng Zhao Gang Song Hailin Zhang Ting Yang Chi Zhang Liping Liang Tianyu Wu Jinyang Zhao Qiang Gao Weiwei Zhai Fumin Lei 《国家科学评论(英文版)》2020,7(1):113
Known as the ‘third polar region’, the Qinghai-Tibet Plateau represents one of the harshest highland environments in the world and yet a number of organisms thrive there. Previous studies of birds, animals and humans have focused on well-differentiated populations in later stages of phenotypic divergence. The adaptive processes during the initial phase of highland adaptation remain poorly understood. We studied a human commensal, the Eurasian Tree Sparrow, which has followed human agriculture to the Qinghai-Tibet Plateau. Despite strong phenotypic differentiation at multiple levels, in particular in muscle-related phenotypes, highland and lowland populations show shallow genomic divergence and the colonization event occurred within the past few thousand years. In a one-month acclimation experiment investigating phenotypic plasticity, we exposed adult lowland tree sparrows to a hypoxic environment and did not observe muscle changes. Through population genetic analyses, we identified a signature of polygenic adaptation, whereby shifts in allele frequencies are spread across multiple loci, many of which are associated with muscle-related processes. Our results reveal a case of positive selection in which polygenic adaptation appears to drive rapid phenotypic evolution, shedding light on early stages of adaptive evolution to a novel environment. 相似文献
44.
Cong Liu Feng An Paria S M Gharavi Qinwen Lu Junkun Zha Chao Chen Liming Wang Xiaozhi Zhan Zedong Xu Yuan Zhang Ke Qu Junxiang Yao Yun Ou Zhiming Zhao Xiangli Zhong Dongwen Zhang Nagarajan Valanoor Lang Chen Tao Zhu Deyang Chen Xiaofang Zhai Peng Gao Tingting Jia Shuhong Xie Gaokuo Zhong Jiangyu Li 《国家科学评论(英文版)》2020,7(1):84
Complex oxides with tunable structures have many fascinating properties, though high-quality complex oxide epitaxy with precisely controlled composition is still out of reach. Here we have successfully developed solution-based single-crystalline epitaxy for multiferroic (1-x)BiTi(1-y)/2FeyMg(1-y)/2O3–(x)CaTiO3 (BTFM–CTO) solid solution in large area, confirming its ferroelectricity at the atomic scale with strong spontaneous polarization. Careful compositional tuning leads to a bulk magnetization of 0.07 ± 0.035 μB/Fe at room temperature, enabling magnetically induced polarization switching exhibiting a large magnetoelectric coefficient of 2.7–3.0 × 10−7 s/m. This work demonstrates the great potential of solution processing in large-scale complex oxide epitaxy and establishes novel room-temperature magnetoelectric coupling in epitaxial BTFM–CTO film, making it possible to explore a much wider space of composition, phase, and structure that can be easily scaled up for industrial applications. 相似文献
45.
网络时代的大众阅读——"网络阅读"研究综述 总被引:6,自引:0,他引:6
网络阅读是一种新型的阅读形式,它也对当今大众阅读习惯和阅读文化带来了种种影响.文章对我国近年来研究"网络阅读"这一主题的文献进行了归纳,综合了若干主流观点,对网络阅读的优劣势进行了详细阐述,同时分析了网络阅读对传统阅读的冲击,较为全面地总结了网络阅读的特点以及发展趋势. 相似文献
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根据《技术创新》课程的性质及功能,提出了课题研讨式课内教学和技术创新实践式课外教学交叉配合的《技术创新》课程教学模式。在转变教育观念的基础上,提出了《技术创新》课程全程多方位成绩考核模式。 相似文献
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基于网络的教学管理实践与思考 总被引:1,自引:1,他引:0
基于网络的教学管理具有涉及人员广泛、影响深刻、易于实践与检验的特点,因而可以做为建设数字化校园的突破口。本文以青岛大学教务在线的实践为例,探讨了高等学校实现在线教务管理的步骤、方法及应注意的问题,通过实践效果肯定了在线教务管理对教学管理工作的积极影响,指出了深化数字化校园建设中应进一步解决的问题。 相似文献
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Jiang Keyu 《中外文化交流(英文版)》2014,(7):42-43
Despite opposition by her family, gifted dancer Jiang Keyu decided to go to Africa and devoted her youthful years to the National Dance Company of Cameroon. She has not only made contribution to China-Cameroon cultural exchange but also found her Mr. Right. 相似文献
50.
以延安市城区中小学啦啦操运动项目的发展情况为研究对象,通过文献资料法、问卷调查法、专家访谈法、数理统计法和逻辑分析法等研究方法,从啦啦操运动员、教练员以及啦啦操的开展现状等方面进行研究分析,对延安市城区中小学啦啦操运动项目开展的状况以及发展中存在的问题进行了比较全面的掌握和分析,为啦啦操在延安市中小学校园中的更好、更快、更健康的发展提供合理化的建议,并在此基础上提出延安市中小学啦啦操运动发展的相应对策. 相似文献