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   

Rapid phenotypic evolution with shallow genomic differentiation during early stages of high elevation adaptation in Eurasian Tree Sparrows     

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   

加强教学过程中的实践训练,提高教学质量   总被引：2，自引：2，他引：0  

池进 《高等理科教育》2007,(2):108-110

在教学过程中加强实践训练,由教师单向传授知识转变为教与学双向互动学习是培养学生综合素质的有效途径。文章通过对课堂教学方式的实践训练方法和传统教学方法改革思想的认识,对课堂教学改革与教育创新的关系进行论述,指出实践训练对提高教学质量的作用。  相似文献   

Injectable hybrid inorganic nanoscaffold as rapid stem cell assembly template for cartilage repair     

Shenqiang Wang  Letao Yang  Bolei Cai  Fuwei Liu  Yannan Hou  Hua Zheng  Fang Cheng  Hepeng Zhang  Le Wang  Xiaoyi Wang  Qianxin Lv  Liang Kong  Ki-Bum Lee  Qiuyu Zhang 《国家科学评论(英文版)》2022,9(4)

Cartilage injuries are often devastating and most cannot be cured because of the intrinsically low regenerative capacity of cartilage tissues. Although stem-cell therapy has shown enormous potential for cartilage repair, the therapeutic outcome has been restricted by low survival rates and poor chondrocyte differentiation in vivo. Here, we report an injectable hybrid inorganic (IHI) nanoscaffold that facilitates fast assembly, enhances survival and regulates chondrogenic differentiation of stem cells. IHI nanoscaffolds that strongly bind to extracellular matrix (ECM) proteins assemble stem cells through synergistic 3D cell–cell and cell–matrix interactions, creating a favorable physical microenvironment for stem-cell survival and differentiation in vitro and in vivo. Additionally, chondrogenic factors can be loaded into nanoscaffolds with a high capacity, which allows deep, homogenous drug delivery into assembled 3D stem-cell-derived tissues for effective control over the soluble microenvironment of stem cells. The developed IHI nanoscaffolds that assemble with stem cells are injectable. They also scavenge reactive oxygen species and timely biodegrade for proper integration into injured cartilage tissues. Implantation of stem-cell-assembled IHI nanoscaffolds into injured cartilage results in accelerated tissue regeneration and functional recovery. By establishing our IHI nanoscaffold-templated 3D stem-cell assembly method, we provide a promising approach to better overcoming the inhibitory microenvironment associated with cartilage injuries and to advance current stem-cell-based tissue engineering.  相似文献   

美国智库对中美科技竞争的观点解读及对策建议     

侯冠华 《情报杂志》2021,40(4):33-41

[目的/意义]准确研判美国智库对于中美科技竞争的基本观点,是分析美国对中国进行科技竞争的舆论走向、战略认知与政策取向的重要依据。[方法/过程]选取美国8家主流智库的11份代表性研究成果作为研究样本,发现美国智库主要围绕中国科技实力的发展对美国产生的影响与美国如何同中国展开科技竞争这两个议题进行全面与深入的探讨。总体而言,美国主要智库已就中国科技实力对美国形成重要挑战这一点达成一定的共识,但在美国同中国展开科技竞争应实行的具体政策上存在一定的分歧。[结果/结论]美国智库总体上对中美科技竞争持消极观点,这是美国对中国的战略认知出现转变的结果。这些观点的传播将影响美国政府对华科技政策的取向,影响其他国家同中国展开的科技合作。中国应该在理性与辩证地看待美国主流智库观点的基础上,消除美国智库观点带来的消极影响,管控中美间在科技领域的战略竞争,努力拓展同美国以及其他国家在科技领域的合作空间,增强自主创新能力,化解中国在科技外交上可能面临的不利局面。  相似文献   

谈高等职业教育面临的挑战及对策   总被引：1，自引：0，他引：1  

侯静  王庭宽 《教育与职业》2006,(24):14-15

当前,高校扩招既给高等职业教育的发展带来了机遇,也给它带来了前所未有的影响和冲击。面对机遇和挑战,针对当前高等职业院校办学中暴露出来的问题,文章进行了理性的分析和探讨,试图找出对策,为高等职业教育的生存、发展和壮大提供依据。  相似文献   

绿色农业控制系统创新实践教学平台设计     

王猛  吴建强  李琰  崔振  侯博雅 《中国现代教育装备》2021,(1):26-29

以绿色农业应用为背景,融入现代科技设计创新实践教学平台.系统设计了清洁能源系统、能源储存系统、信息采集系统、智能温室控制系统、中央控制系统、人机交互以及云平台应用系统,实现能源自给自足、环境信息采集与存储、无线区域组网、系统信息显示与预警、智能控制等功能.系统内各功能部分,采用独立的模块化设计,易于组装移植,综合性、开...  相似文献   

论中国共产党长期执政的道德合理性     

黎池 《湖南师范大学社会科学学报》2006,35(3):33-36

巩固中国共产党长期执政的道德基础,解决人心向背问题是关键。新时期中国共产党加强执政能力建设,巩固、扩大党的执政基础,必须从多方面奠定党长期执政的道德合理性基础,必须始终坚持走群众路线。只有全面贯彻马克思列宁主义、毛泽东思想、邓小平理论、“三个代表”重要思想和党的十六届四中、五中全会精神,真正做到“立党为公、执政为民”,不断增强党执政的道德合理性,才能切实提高党的执政能力。  相似文献   

大基础平台下的多特性模块教学改革与实践   总被引：4，自引：0，他引：4  

迟毅林  董为民  刘泓滨  廖丕博  罗德扬 《高等工程教育研究》2006,(1):30-32

面对新世纪社会发展对大机械类人才的需要,昆明理工大学自1996年起,以“厚基础、多特性模块”为前提,把机械电子工程、机械制造工艺及设备、机械设计及制造、热加工工艺及设备等四个窄口径专业整合为“机械工程及自动化”大专业。坚持“方向多样性、动态适应性、师生互动性、国际兼容性”设置多特性模块,遵循三个融合、两个加强、一个突出的原则,三次修订培养方案和教学计划,进行课程体系及配套教材建设,构建了一整套新世纪大机械类人才培养模式。  相似文献   

Molecular design revitalizes the low-cost PTV-polymer for highly efficient organic solar cells     

Junzhen Ren  Pengqing Bi  Jianqi Zhang  Jiao Liu  Jingwen Wang  Ye Xu  Zhixiang Wei  Shaoqing Zhang  Jianhui Hou 《国家科学评论(英文版)》2021,8(8)

Developing photovoltaic materials with simple chemical structures and easy synthesis still remains a major challenge in the industrialization process of organic solar cells (OSCs). Herein, an ester substituted poly(thiophene vinylene) derivative, PTVT-T, was designed and synthesized in very few steps by adopting commercially available raw materials. The ester groups on the thiophene units enable PTVT-T to have a planar and stable conformation. Moreover, PTVT-T presents a wide absorption band and strong aggregation effect in solution, which are the key characteristics needed to realize high performance in non-fullerene-acceptor (NFA)-based OSCs. We then prepared OSCs by blending PTVT-T with three representative fullerene- and NF-based acceptors, PC₇₁BM, IT-4F and BTP-eC9. It was found that PTVT-T can work well with all the acceptors, showing great potential to match new emerging NFAs. Particularly, a remarkable power conversion efficiency of 16.20% is achieved in a PTVT-T:BTP-eC9-based device, which is the highest value among the counterparts based on PTV derivatives. This work demonstrates that PTVT-T shows great potential for the future commercialization of OSCs.  相似文献