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Science China Chemistry 2024年第7期67卷 2306-2313页

作者： Dong-yue Cai Weiming Shi Zhao-Hui Jin zhi-xiang yu Jin-Xin Zhao Jian-Min yue State Key Laboratory of Drug Research Shanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203China University of Chinese Academy of Sciences Beijing 100049China Beijing National Laboratory for Molecular Sciences(BNLMS) Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking UniversityBeijing 100871China

Mimicking biosynthetic pathways of hongkonoids led to the development of a new Cu(Ⅰ)-catalyzed[3+2]cycloaddition ofα-hydroxyketone andβ-keto enol ethers,affording tetrahydrofuran acetals in a highly diastereoselective manner and 100%atom *** studies on the mechanism disclosed a concerted but asynchronous Michael addition/aldol *** the same importance,this methodology provides a practical biomimetic approach for one-step construction of the dibenzylbutyrolactol lignan backbone starting from two phenyl propane derivatives,opening up a powerful new approach for lignan synthesis,which is showcased by succinct total syntheses of two biologically important aryltetralin-type lignans,β-apopicropodophyllin and *** the mild and operationally simple conditions,the developed chemistry might have a promising prospect in potential industrial applications.

关键词： [3+2]cycloaddition transition-metal catalysis tetrahydrofuran lignans natural products

一氧化碳参与的过渡金属催化的插羰环加成反应研究进展

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有机化学 2024年第4期44卷 1045-1068页

作者：李晨龙余志祥北京大学化学与分子工程学院、北京分子科学国家研究中心、生物有机与分子工程教育部重点实验室北京100871

作为一种高效构建环状分子的方法,环加成反应一直以来备受合成化学家的青睐.一氧化碳(CO)气体是一种商业易得且廉价的原料,常作为“一碳”组分参与各种过渡金属催化的环加成反应.近几十年来,得益于金属有机化学的深入研究,CO气体参与的... 详细信息

作为一种高效构建环状分子的方法,环加成反应一直以来备受合成化学家的青睐.一氧化碳(CO)气体是一种商业易得且廉价的原料,常作为“一碳”组分参与各种过渡金属催化的环加成反应.近几十年来,得益于金属有机化学的深入研究,CO气体参与的过渡金属催化的环加成反应得到了迅速发展.此类插羰环加成反应之所以成为有机化学的研究前沿,是因为它们不仅可以用于构建复杂的环状骨架,还可以引入具有广泛衍生化能力的羰基官能团.这篇文章旨在详细介绍CO气体参与的过渡金属催化的插羰环加成反应,并按照不同反应类型进行梳理和总结.

关键词：环状分子一氧化碳(CO)气体过渡金属催化插羰反应环加成反应

Robust object tracking with RGBD-based sparse learning

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Frontiers of Information Technology & Electronic Engineering 2017年第7期18卷 989-1001页

作者： Zi-ang MA zhi-yu xiang College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China Zhejiang Provincial Key Laboratory of lnformation Network Technology Hangzhou 310027 China

Robust object tracking has been an important and challenging research area in the field of computer vision for decades. With the increasing popularity of affordable depth sensors, range data is widely used in visual tracking for its ability to provide robustness to varying illumination and occlusions. In this paper, a novel RGBD and sparse learning based tracker is proposed. The range data is integrated into the sparse learning framework in three respects. First, an extra depth view is added to the color image based visual features as an independent view for robust appearance modeling. Then, a special occlusion template set is designed to replenish the existing dictionary for handling various occlusion conditions. Finally, a depth-based occlusion detection method is proposed to efficiently determine an accurate time for the template update. Extensive experiments on both KITTI and Princeton data sets demonstrate that the proposed tracker outperforms the state-of-the-art tracking algorithms, including both sparse learning and RGBD based methods.

关键词： Object tracking Sparse learning Depth view Occlusion templates Occlusion detection

Robust water hazard detection for autonomous off-road navigation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 786-793页

作者： Tuo-zhong YAO zhi-yu xiang Ji-lin LIU Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

Existing water hazard detection methods usually fail when the features of water surfaces are greatly changed by the surroundings, e.g., by a change in illumination. This paper proposes a novel algorithm to robustly detect different kinds of water hazards for autonomous navigation. Our algorithm combines traditional machine learning and image segmentation and uses only digital cameras, which are usually affordable, as the visual sensors. Active learning is used for automatically dealing with problems caused by the selection, labeling and classification of large numbers of training sets. Mean-shift based image segmentation is used to refine the final classification. Our experimental results show that our new algorithm can accurately detect not only ‘common’ water hazards, which usually have the features of both high brightness and low texture, but also ‘special’ water hazards that may have lots of ripples or low brightness.

关键词： Water hazard detection Active leaming Adaboost Mean-shift

Vision based terrain reconstruction for planet rover using a special binocular bundle adjustment

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第10期9卷 1341-1350页

作者： Min-yi SHEN zhi-yu xiang Ji-lin LIU Institute of Information and Communication Engineering Zhejiang University Hangzhou 310027 China Zhejiang Provincial Key Laboratory of Information Network Technology Zhejiang University Hangzhou 310027 China

This paper presents a pure vision based technique for 3D reconstruction of planet terrain. The reconstruction accuracy depends ultimately on an optimization technique known as 'bundle adjustment'. In vision techniques, the translation is only known up to a scale factor, and a single scale factor is assumed for the whole sequence of images if only one camera is used. If an extra camera is available, stereo vision based reconstruction can be obtained by binocular views. If the baseline of the stereo setup is known, the scale factor problem is solved. We found that direct application of classical bundle adjustment on the constraints inherent between the binocular views has not been tested. Our method incorporated this constraint into the conventional bundle adjustment method. This special binocular bundle adjustment has been performed on image sequences similar to planet terrain circumstances. Experimental results show that our special method enhances not only the localization accuracy, but also the terrain mapping quality.

关键词： 3D reconstruction Binocular bundle adjustment (BBA) Scale-invariant feature transform (SIFT) Re-projectionerror RANSAC

Synergy of activating substrate and introducing C–H…O interaction to achieve Rh2(II)-catalyzed asymmetric cycloisomerization of 1,n-enynes

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Science China Chemistry 2020年第9期63卷 1230-1239页

作者： Rui Wu Kai Chen Jun Ma zhi-xiang yu Shifa Zhu Key Lab of Functional Molecular Engineering of Guangdong Province School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou 510640China College of Chemistry and Chemical Engineering Central South UniversityChangsha 410083China Beijing National Laboratory for Molecular Sciences(BNLMS) Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking UniversityBeijing 100871China

We report the first Rh2(II)-catalyzed asymmetric cycloisomerization of activated enynes to provide cyclopropane-fused tetrahydropyridines in good yields and excellent enantioselectivities under mild *** activated group,CHZ(Z is electronwithdrawing group(EWG)),in the enyne substrates exerts two synergetic roles,one is to activate alkyne for the cyclopropanation reaction;the other is to introduce the C–H…O interaction between substrate and catalyst(reducing the energy barrier of the reaction).This double-mode activation was supported by both density functional theory(DFT)calculations and experimental *** strategy was also extended to other CH2 Z(Z can be OH,OMe,F)as activating groups that made the CH2 more acidic so that the substrates could also form increased C–H…O interaction with the catalyst.

关键词： asymmetric cycloisomerization chiral cyclopropane dirhodium catalysis carbene

“钢结构设计原理”课程教学新模式的探索与实践

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教育教学论坛 2024年第15期 81-84页

作者：余志祥陈景鑫张明西南交通大学土木工程学院四川成都610031

为响应《关于深化本科教育教学改革全面提高人才培养质量的意见》,提高本科教学质量,教学课题组探索了“钢结构设计原理”课程教学的新模式,即以线下教学为主,结合线上直播授课、网络教学平台以及QQ交流群内讨论答疑的方式开展课程教学... 详细信息

为响应《关于深化本科教育教学改革全面提高人才培养质量的意见》,提高本科教学质量,教学课题组探索了“钢结构设计原理”课程教学的新模式,即以线下教学为主,结合线上直播授课、网络教学平台以及QQ交流群内讨论答疑的方式开展课程教学,在尽可能给予学生最好的课堂学习体验的同时,也为他们提供优质的课后学习资料。线上与线下并行、理论与实践结合是该新模式探索的关键。此外,引入钢结构工程中蕴含的丰富的思政元素,综合提升学生的专业知识与思想品德素养。

关键词：本科教学新模式钢结构设计原理线上与线下并行教学网络教学平台 QQ交流群

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ANSYS辅助土木工程专业课程教学的思考

教育教学论坛 2024年第23期 9-12页

作者：余志祥刘楠枫张明西南交通大学土木工程学院四川成都610031

土木工程专业课程涉及面广,专业度高,其主要内容分为专业基础课和专业核心课两大类,涉及的专业术语多,前后课程关联性强,并要求学生在学习中能够将具体工程问题抽象为典型工程模型进行分析计算。ANSYS是一款集建模求解能力、非线性分析... 详细信息

土木工程专业课程涉及面广,专业度高,其主要内容分为专业基础课和专业核心课两大类,涉及的专业术语多,前后课程关联性强,并要求学生在学习中能够将具体工程问题抽象为典型工程模型进行分析计算。ANSYS是一款集建模求解能力、非线性分析能力、网格划分及优化能力、耦合分析能力为一体的有限元分析软件,在土木工程中被广泛运用。在土木工程专业课程中,利用ANSYS辅助分析工程问题,能使抽象模型直观化、复杂信息有序化、分析结果形象化,能够提高学生的学习兴趣和自主实践能力。

关键词： ANSYS 土木工程专业课程课程教学

Stereo vision based SLAM using Rao-Blackwellised particle filter

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 500-509页

作者： Er-yong WU Gong-yan LI zhi-yu xiang Ji-lin LIU Department of lnformation Science and Electrical Engineering Zhejiang University Hangzhou 310027 China National Laboratory of Pattern Recognition Institute of Automation CAS Beijing 100080 China

We present an algorithm which can realize mobile robot in unknown outdoor environments, which 3D stereo vision simultaneous localization and mapping （SLAM） for means the 6-DOF motion and a sparse but persistent map of natural landmarks be constructed online only with a stereo camera. In mobile robotics research, we extend FastSLAM 2.0 like stereo vision SLAM with ＂pure vision＂ domain to outdoor environments. Unlike popular stochastic motion model used in conventional monocular vision SLAM, we utilize the ideas of structure from motion （SFM） for initial motion estimation, which is more suitable for the robot moving in large-scale outdoor, and textured environments. SIFT features are used as natural landmarks, and its 3D positions are constructed directly through triangulation. Considering the computational complexity and memory consumption, Bkd-tree and Best-Bin-First （BBF） search strategy are utilized for SIFT feature descriptor matching. Results show high accuracy of our algorithm, even in the circumstance of large translation and large rotation movements.

关键词： Robot Vision based SLAM SIFT Feature management

Provocation Test-Confirmed Chlorhexidine-Induced Anaphylaxis in Dental Procedure

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Chinese Medical Journal 2018年第23期131卷 2893-2894页

作者： Jian-Qing Gu Shuang Liu yu-xiang zhi Department of Allergy Peking Union Medical College HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100730China Institute of Clinical Medicine Peking Union Medical College HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100730China

To the Editor:Chlorhexidine (CHL)is a widely used broad-spectrum antiseptic and *** used as a topical antimicrobial agent,CHL is now available in different forms and is present in various settings.[1] CHL has the potential to cause Type I and Type IV hypersensitivity reactions,varying from mild cutaneous reactions to anaphylaxis.[2] An increased recognition of CHL-induced hypersensitivity parallels the increased use of CHL in medical care and the increased awareness of allergy.[3]

关键词： Anaphylaxis Dental Procedure