检索结果-南通市图书馆

Modular assembly of complex C-alkyl glycoside enabled via cooperative NHC and photoredox catalysis

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年

作者： Rui-Qiang Jiao Ming Li Xi Chen Mei-Ze Xu Tian Ding xiao-Ping Gong Zhuo-Mei Li Xue-Yuan Liu yong-Min Liang State Key Laboratory of Applied Organic Chemistry Lanzhou University College of Chemistry and Chemical Engineering Northwest Normal University

C-Alkyl glycosides are found in natural products and are indispensable in drug development programs,owing to their diverse range of medicinal ***-component reactions involving glycosyl radical addition are well documented and proved efficient for the C-alkyl glycosides ***,multicomponent reactions for the rapid and controllable construction of structurally diversified C-alkyl glycosides in a single step remains a significant challenge due to the issues associated with balancing reactivity,compatibility,and ***,we report an NHC and photoredox co-catalyzed three-component method to access complex and valuable C-alkyl *** protocol exhibits broad substrate scope and excellent chemoand ***,nine types of sugars are compatible with this *** addition,the generality of this catalytic strategy was further highlighted by the potential for scalable production,the feasibility of further modifications of the products and its successful application in the late-stage functionalization of pharmaceutical skeletons.

关键词：

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

喷印金属微滴撞击粗糙表面的分子动力学模拟

原子与分子物理学报 2025年第4期42卷 73-80页

作者：苏仁健陈小勇游自浩桂林电子科技大学机电工程学院桂林541004 广西制造系统与先进制造技术重点实验室桂林541004

研究金属微滴撞击固体表面的行为对预测微滴形态和实现高精度的喷印制造具有重要的意义.然而,由于微纳尺度下金属微滴撞击实验的难以开展,目前涉及金属微滴撞击粗糙表面的形态变化和热毛细效应机理尚不清楚.本文采用分子动力学模拟研究... 详细信息

研究金属微滴撞击固体表面的行为对预测微滴形态和实现高精度的喷印制造具有重要的意义.然而,由于微纳尺度下金属微滴撞击实验的难以开展,目前涉及金属微滴撞击粗糙表面的形态变化和热毛细效应机理尚不清楚.本文采用分子动力学模拟研究了镓铟微滴撞击粗糙表面的动态行为,定量分析了撞击速度、粗糙结构和不同温度对微滴撞击行为的影响.结果表明:随着撞击速度的提高,微滴先后呈现沉积、弹跳和破碎飞溅三种模式,且微滴的最大铺展因子与韦伯数呈幂函数关系.此外,通过修饰基底粗糙结构发现,结构间距或高度的变化对微滴的弹跳行为存在不同的影响机制,可以有效促使或抑制微滴的弹跳行为.最后,分析得出随着温度的提高,微滴的铺展直径会变大,产生的黏性耗散也会增大.研究结果对金属微滴撞击行为的有效预测提供了理论基础.

关键词：金属微滴撞击粗糙基底分子动力学

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

基于线性扩散板的高光抑制方法研究

液晶与显示 2016年第9期31卷 897-901页

作者：孙永建孙晓明刘云起王武超王刘阳李泊洋哈尔滨理工大学测控技术与仪器黑龙江省高校重点实验室黑龙江哈尔滨150080

陶瓷、金属等光滑表面的强反射性质,会使图像饱和产生高光现象,导致测量精度大幅下降。针对这一问题,本文利用扩散板对光的扩散作用,设计了基于线性扩散板的高光抑制系统。首先从理论上研究线性扩散板的扩散原理,并利用高光点反射辐射... 详细信息

陶瓷、金属等光滑表面的强反射性质,会使图像饱和产生高光现象,导致测量精度大幅下降。针对这一问题,本文利用扩散板对光的扩散作用,设计了基于线性扩散板的高光抑制系统。首先从理论上研究线性扩散板的扩散原理,并利用高光点反射辐射亮度分析线性扩散板对高光的抑制作用。然后搭建系统平台,完成相机标定、投影仪标定等系统搭建工作。最后对陶瓷盘子和大理石罐等具有强反射表面的物体进行三维测量,实验结果表明,线性扩散板能够实现三维测量中强反射表面的高光抑制,其中大理石罐、陶瓷盘子、花盆、杯子的高光点数目相比未加扩散板时分别减少了19.6倍、5.6倍、4.4倍与3.9倍。扩散板能够减弱高光点的反射辐射亮度,对高光具有一定的抑制作用,三维重构结果中高光区域明显缩小。

关键词：三维视觉检测高光抑制结构光线性扩散板

Numerical investigation of an advanced aircraft model during pitching motion at high incidence

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第2期59卷 276-288页

作者： LIU jian SUN HaiSheng HUANG yong jianG yong xiao ZhiXiang School of Aerospace Engineering Tsinghua University Beijing 100084 China China Aerodynamics Research and Development Center Mianyang 621000 China

An unsteady Reynolds averaged Navier–Stokes(URANS) method combined with a rigid dynamic mesh technique was developed to simulate unsteady flows around complex configurations during pitching motion. First, a test case with the NACA0012 airfoil was selected to validate the numerical methods and our in-house codes. Then, we evaluated the unsteady flows around an advanced aircraft model during harmonic pitching motion at high incidence. The effects of pitching motion on the hysteresis of aerodynamic force, the evolution of the leading-edge vortex, and the distribution of pressure on the model's surface were analyzed in detail. The roles of several significant parameters such as the reduced frequency and pitching amplitude were revealed. Several conclusions were found: pitching motion would delay the initiation of the leading-edge vortex, strengthen the vorticity, postpone the occurrence of vortex breakdown, and weaken the massively separated flows, thus causing additional aerodynamic force. Two categories of critical reduced frequency have been found, which divide the influence of reduced frequency on aerodynamic force into three stages, called the linear increasing range, slowly increasing range, and constant range. The first-order phase lag between the aerodynamic force and the incidence is a constant that is independent of the amplitude when the reduced frequency is sufficiently high. A scaled maximum value of C_L is proposed; it depends only on the reduced frequency(instead of the amplitude), and increases linearly when the reduced frequency is sufficiently low.

关键词： pitching motion hysteresis critical reduced frequency phase lag scaled maximum of CL

在线全文

学校读者我要写书评

暂无评论

总体国家安全观视阈下科技安全概念诠释

北京理工大学学报(社会科学版) 2025年第1期27卷 162-173页

作者：肖君拥杨勇北京理工大学　法学院北京100081

科技安全是国家安全的重要组成部分。理论概念的研究是分析和解决科技领域实践问题的基本方式，科技安全概念奠定了相关研究的理论基础、方法基础和范式基础，直接影响实践的具体方向。从科技安全的概念出发，梳理科技安全概念的理论嬗... 详细信息

科技安全是国家安全的重要组成部分。理论概念的研究是分析和解决科技领域实践问题的基本方式，科技安全概念奠定了相关研究的理论基础、方法基础和范式基础，直接影响实践的具体方向。从科技安全的概念出发，梳理科技安全概念的理论嬗变过程。同时，进行简要评析，阐明科技安全相关实践。研究发现：通说概念采用与国家安全相关概念一致的定义方式，将科技安全的特性通过科技体系、技术要求、外部威胁、保障能力等方面具体化。此概念具有一定的合理性与必要性，但仍然存在对技术类型和国家利益的保障范围限缩化、对科技面临的威胁判断片面化、对保障科技安全状态的能力总结单一化等问题。在总体国家安全观视阈下准确定义科技安全概念，需要对通说概念进行必要修正，并从整体上理解科技安全概念的性质、前提与相关术语。

关键词：科技安全科技体系国家安全总体国家安全观国家利益

Identification of a dual functional betulinic acid analog for the treatment of osteoarthritis by phenotypic screening

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Life Sciences 2025年第1期 300-302页

作者： Ze-Min Lin Mai Xiang Wen-Hui Wei Shu-Hui Fan Li Chen Jie Wang xiao-Qian Yang Chun-Hao Yang Shi-Jun He jian-Ping Zuo Laboratory of Immunopharmacology State Key Laboratory of Drug ResearchShanghai Institute of Materia MedicaChinese Academy of Sciences School of Pharmacy University of Chinese Academy of Sciences School of Pharmacy Nanjing University of Chinese Medicine State Key Laboratory of Drug Research Department of Medicinal ChemistryShanghai Institute of Materia MedicaChinese Academy of Sciences Innovation Research Institute of Traditional Chinese Medicine Shanghai University of Traditional Chinese Medicine Experiment Center for Science and Technology Shanghai University of Traditional Chinese Medicine

Dear Editor, Phenotypic drug discovery, which observes compound effects on physiology,has given way to targeting specific molecules, but has revived by using modern methods to find drugs based on therapeutic outcomes in disease models(Vincent et al., 2022). Osteoarthritis(OA) is a prevalent chronic joint disorder, primarily affecting knee joints, with osteoclast activation due to low-grade inflammation resulting in increased bone resorption and structural changes in the joint(Katz et al.,2021).

关键词：

同方期刊数据库

Influence of coating and dew point on hearth roll pickup

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2019年第6期26卷 647-652页

作者： xiao-fei Zheng yong-lin Kang jian Zhou School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Shougang Jingtang Iron and Steel United Co. Ltd. Tangshan 063200 Hebei China

Thermal spray coatings have been widely used on hearth rolls in a continuous annealing line to improve steel sheet quality and prolong the roll service life. One of the common defects formed on a working hearth roll is the oxide pickup. The most common cause of the pickup formation is that the active Mn oxide reacts with coating. The potentials of two different coatings, CoCrAlYTa-Al2O3 (No. 1) and CoCrYNi-Y2O3 (No. 2), to duplicate pickups by reacting with Fe and Mn oxides were studied. There are three stages during pickup producing and growing. No. 2 coating effectively reduced the corrosion of Mn oxide. The characterization and modification of the surface oxide formed can be changed with different dew points. The results indicate that the dew point from — 53 to — 10 ℃ can change the depth of Mn oxide, such that an alteration can prevent the first stage and second stage and is good for preventing the pickup growing.

关键词： Pickup Coating Dew point Surface oxide Hearth roll

新质生产力的运行机理、生成逻辑与模式建构——基于生产力与生产关系辩证统一的视角

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

新疆师范大学学报（哲学社会科学版） 2025年第1期46卷 89-97页

作者：李勇坚张海汝中国社会科学院财经战略研究院北京100005 浙江财经大学浙江杭州310018 江苏省社会科学院经济研究所江苏南京210004

新质生产力是创新发挥主导作用,摆脱传统经济增长方式、生产力发展路径,具有高科技、高效能、高质量特征,符合新发展理念的先进生产力质态。纵观三次科技革命变革生产力的历程,新质生产力的产生和发展是生产力与生产关系相互作用的结果... 详细信息

新质生产力是创新发挥主导作用,摆脱传统经济增长方式、生产力发展路径,具有高科技、高效能、高质量特征,符合新发展理念的先进生产力质态。纵观三次科技革命变革生产力的历程,新质生产力的产生和发展是生产力与生产关系相互作用的结果,具有生产力与生产关系的双重内涵和发展要求。新质生产力以新型劳动者、新型劳动资料、新型劳动对象及其组合模式和新型生产关系为架构要素与发展基础,其生成逻辑与运行机理是由技术革命性突破引发,在催生新型生产力要素、新型要素组合模式的基础上促使与新质生产力相适应的新型生产关系变革形成,新型生产关系的反作用促进新质生产力进一步生成的过程。发展新质生产力要以实施创新驱动战略、加快产业深度转型、构建要素生态系统和全面深化改革为基本模式和关键路径。亟须加快实现高水平科技自立自强,加快技术革命性创新;促进产业深度转型,构建现代化产业体系;促进生产要素创新配置,构建新质生产要素系统;全面深化改革,加快建立健全与新质生产力相适应的新型生产关系,促进新质生产力加快形成发展。

关键词：新质生产力新型生产关系技术革命性突破全面深化改革

DVB-S2 inner receiver design for broadcasting mode

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第1期8卷 28-35页

作者： YANG jian-xiao WANG Kuang ZOU Zhi-yong Institute of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China Guoxin Co Ltd Hangzhou 310027 China

This paper details on the design of DVB-S2 receivers which is compliant with the broadcasting mode. Special at-tention is paid to the specific receiver functions necessary to demodulate the received signal. To show the system performance we consider the design of a complete receiver consisting of timing recovery unit, frame synchronization unit, frequency recovery unit and phase recovery unit. The system is easier to hardware implementation comparing with that provided in (ETSI, 2005; Sun et al., 2004). After the performance of the algorithms is analyzed and a quantitative result is given, this allows us to draw conclusions concerning the achievable system performance under realistic complexity assumptions.

关键词： DVB-S2 Timing recovery Frame synchronization Frequency recovery Phase recovery