检索结果-南通市图书馆

Theoretical insights into the [4+2]/retro [4+2] cycloaddition approach to the synthesis of biaryls and polycyclic aromatics

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

Science China Chemistry 2013年第5期56卷 633-640页

作者： LI xinyao XU JiaXi State Key Laboratory of Chemical Resource Engineering Department of Organic Chemistry Faculty of Science Beijing University of Chemical Technology

A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder (D-A) reaction acts as the rate-determining step and the consequent [4+2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital (FMO) theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electron-donor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4+2] cycloaddition.

关键词： [4+2]/retro [4+2] cycloaddition biaryls polycyclic aromatics regioselectivity DFT study

中国风湿科临床医生对中医药治疗干燥综合征态度的调查

在线全文

学校读者我要写书评

暂无评论

中国医药导报 2023年第27期20卷 68-72,81页

作者：刘瑞华周新尧郭子琳徐浩东赵子莹唐晓颇中国中医科学院广安门医院风湿科北京100053 南京中医药大学附属苏州市中医医院风湿科江苏南京215002

目的了解中国风湿科临床医生对中医药治疗干燥综合征(SS)的态度,分析中医药应用面临的问题。方法采用匿名问卷调查的形式,调查参加2022年“风云讲坛”的中国风湿科临床医生对中医药治疗SS的态度。结果发放347份调查问卷,回收有效问卷320... 详细信息

目的了解中国风湿科临床医生对中医药治疗干燥综合征(SS)的态度,分析中医药应用面临的问题。方法采用匿名问卷调查的形式,调查参加2022年“风云讲坛”的中国风湿科临床医生对中医药治疗SS的态度。结果发放347份调查问卷,回收有效问卷320份,有效回收率为92.22%。绝大多数医生肯定中医药疗效,希望其缓解SS患者干燥(88.41%)、乏力(68.12%)症状。logistic回归分析显示,具有中医教育背景及工作年限较长者更倾向于推荐中医药治疗SS(P<0.05)。多数医生(65.63%)临床中医药应用比例不足40%,认为与缺乏中医指南、临床研究太少等有关。结论中医药的优势和特色使得中国医生高度关注,但指南缺乏、循证依据不足等问题制约了中医药的应用与发展,亟须制订SS中医诊疗指南,加强中医药研究。

关键词：风湿科临床医生干燥综合征中医药调查

石粉含量对C55机制砂自密实混凝土性能的影响

在线全文

学校读者我要写书评

暂无评论

粉煤灰综合利用 2018年第2期32卷 57-60页

作者：耿权师华周新尧罗思桥尤加林张珂王枭中交第二航务工程局有限公司武汉430040 山西路桥建设集团有限公司太原030006

本文结合某大桥波形钢腹板箱梁混凝土工程,重点研究了石粉含量对C55机制砂自密实混凝土的工作性能、力学性能和耐久性能的影响规律,试验结果表明:石粉含量对C55机制砂自密实混凝土的工作性能、力学性能和耐久性能有显著影响;当石粉含量... 详细信息

本文结合某大桥波形钢腹板箱梁混凝土工程,重点研究了石粉含量对C55机制砂自密实混凝土的工作性能、力学性能和耐久性能的影响规律,试验结果表明:石粉含量对C55机制砂自密实混凝土的工作性能、力学性能和耐久性能有显著影响;当石粉含量为6%~8%时,C55机制砂自密实混凝土各方面性能较优。

关键词：机制砂自密实混凝土石粉含量

Convectively Coupled Equatorial Waves Simulated by CAMS-CSM

在线全文

学校读者我要写书评

暂无评论

Journal of Meteorological Research 2019年第5期33卷 949-959页

作者： Lu WANG Tianjun zhou Jian LI xinyao RONG Haoming CHEN Yufei XIN Jingzhi SU Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environmental Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science&TechnologyNanjing 210044 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

The Chinese Academy of Meteorological Sciences developed a Climate System Model(CAMS-CSM) to participate in the upcoming Coupled Model Intercomparison Project phase 6(CMIP6). In this study, we assessed the model performance in simulating the convectively coupled equatorial waves(CCEWs) by comparing the daily output of precipitation from a 23-yr coupled run with the observational precipitation data from Global Precipitation Climatology Project(GPCP). Four dominant modes of CCEWs including the Kelvin, equatorial Rossby(ER), mixed Rossby–gravity(MRG), tropical depression-type(TD-type) waves, and their annual mean and seasonal cycle characteristics are investigated respectively. It is found that the space–time spectrum characteristics of each wave mode represented by tropical averaged precipitation could be very well simulated by CAMS-CSM, including the magnitudes and the equivalent depths. The zonal distribution of wave associated precipitation is also well simulated, with the maximum centers over the Indian Ocean and the Pacific Ocean. However, the meridional distribution of the wave activities is poorly simulated, with the maximum centers shifted from the Northern Hemisphere to the Southern Hemisphere, especially the Kelvin, MRG, and TD waves. The seasonal cycle of each wave mode is generally captured by the model, but their amplitudes over the Southern Hemisphere during boreal winter are grossly overestimated. The reason for the excessive wave activity over the southern Pacific Ocean in the simulation is discussed.

关键词： CAMS-CSM convectively coupled equatorial waves precipitation seasonal cycle model evaluation

在线全文

学校读者我要写书评

暂无评论

类风湿关节炎骨破坏相关影响因素的研究进展

中国医药导报 2022年第35期19卷 36-39,65页

作者：刘瑞华程增玉徐浩东周新尧唐晓颇中国中医科学院广安门医院风湿科北京100053

类风湿关节炎(RA)是常见的慢性致残性自身免疫病。骨破坏是RA关节受累的最终结局,早期识别其影响因素是有效干预的首要策略。目前国内外已有不少研究和调查关注骨破坏的影响因素,但少有进行系统分析。本文通过检索近年关于RA骨破坏的相... 详细信息

类风湿关节炎(RA)是常见的慢性致残性自身免疫病。骨破坏是RA关节受累的最终结局,早期识别其影响因素是有效干预的首要策略。目前国内外已有不少研究和调查关注骨破坏的影响因素,但少有进行系统分析。本文通过检索近年关于RA骨破坏的相关文献,对其影响因素进行分析,发现女性、发病年龄小、病程长、体重指数低等一般因素,骨髓水肿、骨密度降低等影像学异常,RA相关抗体、细胞因子、急性血清反应物等水平升高及破骨细胞增生、骨保护素下降、维生素D缺乏等实验室检查异常均与骨破坏密切相关,可加速骨破坏进程。这一发现可为临床早期干预提供方向,并为后续研究及预测模型的建立提供参考依据。

关键词：类风湿关节炎骨破坏影响因素

Effect of bubble morphology and behavior on power consumption in non-Newtonian fluids’aeration process

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第1期65卷 243-254页

作者： Xiemin Liu Jing Wan Jinnan Sun Lin Zhang Feng Zhang Zhibing Zhang xinyao Li Zheng zhou Key Laboratory of Mesoscopic Chemistry of Ministry of Education(MOE) School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China Dalian Research Institute of Petroleum and Petrochemicals SINOPECDalian 116045China

Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.

关键词： Non-Newtonian fluids aeration process Power consumption Volumetric mass transfer rate Bubble size

A New Diagnosis Method with Few-shot Learning Based on a Class-rebalance Strategy for Scarce Faults in Industrial Processes

在线全文

学校读者我要写书评

暂无评论

Machine Intelligence Research 2023年第4期20卷 583-594页

作者： xinyao Xu De Xu Fangbo Qin Research Center of Precision Sensing and Control Institute of AutomationChinese Academy of SciencesBeijing100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing100049China

For industrial processes, new scarce faults are usually judged by experts. The lack of instances for these faults causes a severe data imbalance problem for a diagnosis model and leads to low performance. In this article, a new diagnosis method with few-shot learning based on a class-rebalance strategy is proposed to handle the problem. The proposed method is designed to transform instances of the different faults into a feature embedding space. In this way, the fault features can be transformed into separate feature clusters. The fault representations are calculated as the centers of feature clusters. The representations of new faults can also be effectively calculated with few support instances. Therefore, fault diagnosis can be achieved by estimating feature similarity between instances and faults. A cluster loss function is designed to enhance the feature clustering performance. Also, a class-rebalance strategy with data augmentation is designed to imitate potential faults with different reasons and degrees of severity to improve the model’s generalizability. It improves the diagnosis performance of the proposed method. Simulations of fault diagnosis with the proposed method were performed on the Tennessee-Eastman benchmark. The proposed method achieved average diagnosis accuracies ranging from 81.8% to 94.7% for the eight selected faults for the simulation settings of support instances ranging from 3 to 50. The simulation results verify the effectiveness of the proposed method.

关键词： Data augmentation feature clustering class-rebalance strategy few-shot learning fault diagnosis

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

中医临床优势病种探讨——干燥综合征

中国实验方剂学杂志 2023年第8期29卷 73-79页

作者：罗静徐愿周新尧李梦涛侯秀娟王海隆陈华张秦耿研赵金霞赵义赵绵松王伽伯王勇张霄潇陶庆文中日友好医院北京100029 中国中医科学院广安门医院北京100053 中国医学科学院北京协和医院北京100730 北京中医药大学东方医院北京100078 北京中医药大学东直门医院北京100700 首都医科大学附属北京中医医院北京100010 北京大学第一医院北京100034 北京大学第三医院北京100191 首都医科大学北京宣武医院北京100053 首都医科大学北京世纪坛医院北京100038 首都医科大学中医药学院北京100013 北京中医药大学中医学院北京100029 中华中医药学会北京100029

干燥综合征(SS)是常见的风湿免疫病,是中医药治疗的优势病种之一。中华中医药学会组织中医风湿、西医风湿及药学领域专家,深入探讨SS的中医药治疗优势及优选方案。与会专家充分讨论后认为,SS早期诊断率低,缺乏针对性的治疗药物;自身免... 详细信息

干燥综合征(SS)是常见的风湿免疫病,是中医药治疗的优势病种之一。中华中医药学会组织中医风湿、西医风湿及药学领域专家,深入探讨SS的中医药治疗优势及优选方案。与会专家充分讨论后认为,SS早期诊断率低,缺乏针对性的治疗药物;自身免疫异常是SS发病的关键因素,气阴两虚是核心病机;SS的舌象极具特点,可能成为本病早期诊断及中西医结合诊疗的突破口;中医药治疗SS在改善临床症状和系统受累、个体化治疗、缓解睡眠和情志障碍、疾病早期发挥“治未病”功效及中西药联用增效减毒等方面具有优势,在SS不同阶段均有优势点;中药内服、外治、针刺和针刀均是可选的治疗手段;优选方案应在辨证基础上,结合病情阶段、中医药优势综合制订。应深入研究SS的临床特点和生物标记物对本病患者进行分层,探索建立基于循证证据的SS中医精准治疗方案。基于SS舌象的独特表现,建立疾病早期诊断和不良预后识别模型,实现早期防治,改善预后。未来应大力开展中医、中西医结合治疗SS的高质量循证医学研究,制定相关指南,优化和规范当前的诊疗,为说明白、讲清楚中医药治疗SS的优势提供依据。

关键词：干燥综合征优势病种中西医结合专家指导建议

Challenges and opportunities in 2D high-entropy alloy electrocatalysts for sustainable energy conversion

在线全文

学校读者我要写书评

暂无评论

SusMat 2023年第6期3卷 730-748页

作者： Die Lu xinyao Fu Dong Guo Wei Ma Shaohui Sun Gonglei Shao Zhen zhou Interdisciplinary Research Centerfor Sustainable Energy Scienceand Engineering(IRC4SE^(2)) School of Chemical EngineeringZhengzhou UniversityZhengzhouChina

Two-dimensional(2D)high-entropy alloys(HEAs)have emerged as promising electrocatalysts due to the benefits of polymetallic coordination and robust elec-trical ***,the multiple elements in 2D HEAs pose challenges in achieving a uniform composition and maintaining a 2D limit morphology,complicating their structural ***,even minor adjust-ments to the composition can significantly alter the properties of 2D HEAs,underscoring the need for a deeper understanding of their structure-property relationships to advance synthesis and ***,this review crit-ically examines the intrinsic factors influencing synthesis methods and the practical applications of 2D HEAs in electrocatalysis for sustainable energy *** urgency is emphasized for developing new synthesis techniques,enhancing advanced characterization methods,and gaining profound insights into the functional mechanisms of 2D HEAs.

关键词： electrocatalysis high-entropy alloys structure-property relationships synthesis methods two-dimensional materials