Olivine-norite rock detected by the lunar rover Yutu-2 likely crystallized from the SPA-impact melt pool     

Honglei Lin  Zhiping He  Wei Yang  Yangting Lin  Rui Xu  Chi Zhang  Meng-Hua Zhu  Rui Chang  Jinhai Zhang  Chunlai Li  Hongyu Lin  Yang Liu  Sheng Gou  Yong Wei  Sen Hu  Changbin Xue  Jianfeng Yang  Jie Zhong  Xiaohui Fu  Weixing Wan  Yongliao Zou 《国家科学评论(英文版)》2020,7(5):913

Chang’E-4 landed in the South Pole-Aitken (SPA) basin, providing a unique chance to probe the composition of the lunar interior. Its landing site is located on ejecta strips in Von Kármán crater that possibly originate from the neighboring Finsen crater. A surface rock and the lunar regolith at 10 sites along the rover Yutu-2 track were measured by the onboard Visible and Near-Infrared Imaging Spectrometer in the first three lunar days of mission operations. In situ spectra of the regolith have peak band positions at 1 and 2 μm, similar to the spectral data of Finsen ejecta from the Moon Mineralogy Mapper, which confirms that the regolith''s composition of the landing area is mostly similar to that of Finsen ejecta. The rock spectrum shows similar band peak positions, but stronger absorptions, suggesting relatively fresh exposure. The rock may consist of 38.1 ± 5.4% low-Ca pyroxene, 13.9 ± 5.1% olivine and 48.0 ± 3.1% plagioclase, referred to as olivine-norite. The plagioclase-abundant and olivine-poor modal composition of the rock is inconsistent with the origin of the mantle, but representative of the lunar lower crust. Alternatively, the rock crystallized from the impact-derived melt pool formed by the SPA-impact event via mixing the lunar crust and mantle materials. This scenario is consistent with fast-cooling thermal conditions of a shallow melt pool, indicated by the fine to medium-sized texture (<3 mm) of the rock and the SPA-impact melting model [Icarus 2012; 220: 730–43].  相似文献   

Large-scale multiferroic complex oxide epitaxy with magnetically switched polarization enabled by solution processing     

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)/2Fe_yMg_(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 μ_B/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   

SOC中微处理器核的嵌入重用研究     

蒋志迪  姚庆栋  俞国军  王维东  刘鹏  赖莉雅  蔡钟 《科技通报》2006,22(3):400-404

随着集成电路技术发展,系统集成芯片(SOC)由于低功耗、低成本、高性能等特点受到了人们的关注。通用处理器媒体指令扩展技术的发展,使得基于处理器的实时媒体处理算法成为可能。媒体处理器IP核重用成为可编程媒体系统芯片设计的重点和难点。本文围绕媒体处理器IP核在媒体系统芯片中的重用,对数据通路设计及控制信息通信机制进行研究。最后成功开发了一个典型多处理器结构的媒体集成芯片。  相似文献   

网络蠕虫预警与隔离控制方法研究     

于忠  于会 《科技通报》2006,22(4):544-548

针对网络蠕虫的快速传播特性,运用简单流行病学模型和从监控系统获得的非法扫描数据,通过检测非法扫描流量的增长趋势,在蠕虫病毒爆发初期对其进行实时预警,运用数据挖掘技术从扫描数据中自动获取扫描特征,据此特征对蠕虫扫描进行过滤和隔离,阻断蠕虫病毒的传播。  相似文献   

Replication,pathogenicity, and transmission of SARS-CoV-2 in minks     

Lei Shuai  Gongxun Zhong  Quan Yuan  Zhiyuan Wen  Chong Wang  Xijun He  Renqiang Liu  Jinliang Wang  Qinjian Zhao  Yuxiu Liu  Ningning Huo  Junhua Deng  Jingjing Bai  Hongchao Wu  Yuntao Guan  Jianzhong Shi  Kegong Tian  Ningshao Xia  Hualan Chen  Zhigao Bu 《国家科学评论(英文版)》2021,8(3):16-23

Minks are raised in many countries and have transmitted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to humans. However, the biologic properties of SARS-CoV-2 in minks are largely unknown. Here, we investigated and found that SARS-CoV-2 replicates efficiently in both the upper and lower respiratory tracts, and transmits efficiently in minks via respiratory droplets; pulmonary lesions caused by SARS-CoV-2 in minks are similar to those seen in humans with COVID-19. We further found that a spike protein-based subunit vaccine largely prevented SARS-CoV-2 replication and lung damage caused by SARS-CoV-2 infection in minks. Our study indicates that minks are a useful animal model for evaluating the efficacy of drugs or vaccines against COVID-19 and that vaccination is a potential strategy to prevent minks from transmitting SARS-CoV-2.  相似文献   

知识隐喻与教学转型   总被引：16，自引：0，他引：16  

钟启泉 《教育研究》2006,27(5):19-24

从知识隐喻的角度考察知识论历史演进的线索,我们可以看到:一切真正的知识都具有活动的、实践的性质,应当原原本本地看待“认知活动”。不过,这些知识的隐喻尽管凸现了“认知活动”的关系性,但依然没有从近代批判哲学所固有的认识论中解放出来。因此,传统的“客观主义”知识论固然是不可取的,现代的“主观主义”知识轮的局限性也不可轻视。立足于种种知识说给出的若干指标,考察我国的教育改革面临的问题,给予我们的启示是,素质教育的课堂教学需要克服两种片面性:既不能无视儿童已有的知识体系,单向地灌输知识;也不能走向轻视概念性知识、无视知识结构化的体验主义教育。  相似文献   

论课程品质及课程力自增的哲学理据     

钟发全 《中国教育科学(中英文)》2021,(1):91-98

新课程品质及课程力自增,是新课程改革呈旺盛势态的标志。充实哲学理据以接近本质,建议从三个方面着力解决问题:一是理顺新课程改革的结构性问题,能正确理解课程与课程力之间的主体和载体的关系,全面实现自增的旨趣;二是针对课程品质及课程力自增的合理性论证与追述,能着力于内生长与外发展中存在的历史流变,发现不合理存在的原因,从而全...  相似文献   

信息技术与化学教学的整合研究     

黄忠 《基础教育研究》2006,(6):44-45

随着课程教材改革的全面推行,教学手段的现代化已成为当前提高课堂教学效率的一个重要途径。信息技术与学科教学的整合是现代化技术教育的主要手段,即把教学资源和教学要素有机地集合起来．协调教学系统中教师、学生、教育内容和教学媒体等教学诸元素的相互之间的作用关系,使整个教学系统保持协调一致,产生聚集效应。笔者就信息技术与化学教学的整合谈一些见解,与同仁共商讨。  相似文献   

从未成年人权益保护看媒介素养教育的必要性     

钟伟珍 《基础教育研究》2006,(11):9-10

在信息时代,接触媒介已成为未成年人自由时间的主要活动内容。大众媒介在促进社会政治、经济和文化发展的同时,它的负面影响也日益凸显,使未成年人的合法权益遭受侵袭和破坏。文章从维护未成年人权益的角度,阐述实施媒介素养教育的必要性。  相似文献   

作为媒介的博物馆及其在中国的专业化发展方向          下载免费PDF全文

周婧景  钟燕仪 《自然科学博物馆研究》2023,(5):12-22

博物馆是为数不多的、能与受众直接沟通的媒介,虽然小众,但传播内容真实形象、纵观古今,传播方式倡导多感官认知和身体交互,由此在学习、社交和崇拜三方面呈现出不可替代的媒介优势。但目前我国博物馆的这些潜在优势尚未完全释放,究其根源在于专业化程度不高。为此,需要更新认识论以弥补理论和实践的断裂;在整体论视阈下通过关联需求和重组业务提升专业化水平;基于观众立场廓清博物馆学科并提出中国方案。促使博物馆经由专业化发挥其独特的媒介潜能,从根本上帮助破解国人全面发展的难题。  相似文献