检索结果-南通市图书馆

Bifunctional organocatalyst-catalyzed dynamic kinetic resolution of hemiketals for synthesis of chiral ketals via hydrogen bonding control

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2025年第1期36卷 248-252页

作者： Meng shan Yongmei yu Mengli sun Shuping Yang Mengqi Wang Bo Zhu Junbiao Chang State Key Laboratory of Antiviral Drugs Pingyuan LaboratoryNMPA Key Laboratory for Research and Evaluation of Innovative DrugSchool of Chemistry and Chemical EngineeringHenan Normal UniversityXinxiang 453007China

Herein,we report the dynamic kinetic resolution asymmetric acylation ofγ-hydroxy-γ-perfluoroalkyl butenolides/phthalides catalyzed by amino acid-derived bifunctional organocatalysts,and a series of ketals were obtained in high yields(up to 95%)and excellent enantioselectivities(up to 99%).In terms of synthetic utility,the reaction can be performed on a gram scale,and the product can be converted into potential biological nucleoside analog.

关键词： Bifunctional organocatalyst Dynamic kinetic resolution Hemiketal Chiral ketals Hydrogen bonding

New Taub-NUT black holes with massive spin-2 hair

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第2期68卷 51-58页

作者： yu-Qi Chen Hai-shan Liu Center for Joint Quantum Studies and Department of Physics School of ScienceTianjin UniversityTianjin 300350China

We consider Einstein gravity extended with quadratic curvature invariants,within which the well-known Ricci-flat Taub-NUT black hole remains a *** analysis of the unstable Lichnerowicz modes in the Taub-NUT background enables us to identify the mass and NUT parameters(m,n)where new Taub-NUT black holes can *** then adopt numerical techniques to construct these new Taub-NUT black holes,which bifurcate away from the Ricci-flat *** the Ricci-flat Taub-NUT,there can exist two new black holes for an appropriate given temperature,making it a total of three if we include the Ricci-flat one.

关键词： higher derivative gravity black hole solution Taub-NUT spacetime

A Case Study in Teaching Pipes-and-filters and Batch Sequential Software Architectures

在线全文

学校读者我要写书评

暂无评论

计算机教育 2012年第10期 18-22页

作者： sun yu-shan DING Jian-rui School of Software Harbin Institute of Technology Weihai 264209 China

In this paper,a case study is carried out in comparison of pipes-and-filters architecture and batch sequential *** on a data flow system and the two mentioned architectures are presented.A Java template class design in implementing the "pipes" and "filters" in the pipes-and-filters architecture is given at the design ***,this paper uses a concrete example to show how to use Java to implement the pipesand-filters *** varied amount of data from text files,performance and memory usage of the two architectures are illustrated.

关键词： Software architecture data flow system pipes-and-filters architecture batch sequential architecture

在线全文

学校读者我要写书评

暂无评论

血乳酸在判断新生儿败血症预后中的临床价值

中国当代儿科杂志 2019年第7期21卷 629-634页

作者：孙玉姗余加林重庆医科大学附属儿童医院儿科研究所/儿童发育疾病研究教育部重点实验室/儿童发育重大疾病国家国际科技合作基地/儿科学重庆市重点实验室

目的探讨动脉血乳酸水平在判断新生儿败血症预后中的临床价值.方法收集301例败血症新生儿的临床资料,主要包括入院时血乳酸、C反应蛋白、降钙素原等生化指标.通过ROC曲线分析,评估入院时血乳酸水平对判断新生儿败血症预后的价值.结果足... 详细信息

目的探讨动脉血乳酸水平在判断新生儿败血症预后中的临床价值.方法收集301例败血症新生儿的临床资料,主要包括入院时血乳酸、C反应蛋白、降钙素原等生化指标.通过ROC曲线分析,评估入院时血乳酸水平对判断新生儿败血症预后的价值.结果足月儿血乳酸重度升高组病死率(26.1%)较轻度升高组(3.1%)和乳酸正常组(0%)明显升高(P<0.017).预后不良组入院时血乳酸水平(6.5±5.1 mmol/L)较预后良好组(3.6±1.7 mmol/L)明显升高(P<0.05).入院时血乳酸水平(临界值为6.15 mmol/L)对判断新生儿败血症预后的敏感性和特异性分别为0.545、0.919.结论早期血乳酸水平可作为判断新生儿败血症预后的生化指标,特异性高,但敏感性较低.

关键词：败血症乳酸预后新生儿

An integrated GPS /DR navigation system for AUV

在线全文

学校读者我要写书评

暂无评论

Journal of Marine Science and Application 2006年第4期5卷 8-13页

作者： PANG Yong-jie sun yu-shan GAN Yong WAN Lei College of Shipbuilding Engineering Harbin Engineering University Harbin 150001 China

GPS/Dead-reckoning navigation system for autonomous underwater vehicle (AUV) is introduced, which includes navigation overall architecture, hardware and software structure. Dead-reckoning theory is presented in details. And the strong tracking Kalman filter and Singer model are applied to handle the imprecise navigation mode, which can improve the navigation system’s precision and reliability. Finally, the sea experiments which include autonomous search mission in an unknown area and long distance motion are conducted to demonstrate the reliability and feasibility of the navigation system.

关键词： AUV GPS dead-reckoning strong tracking Kalman filter (STKF)

Design of novel sliding-mode controller for high-velocity AUV with consideration of residual dead load

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2018年第1期25卷 121-130页

作者： JIANG Chun-meng WAN Lei sun yu-shan LI yue-ming Science and Technology on Underwater Vehicle Laboratory Harbin Engineering University

This work focuses on motion control of high-velocity autonomous underwater vehicle(AUV).Conventional methods are effective solutions to motion control of low-and-medium-velocity *** not taken into consideration in the control model,the residual dead load and damping force which vary with the AUV’s velocity tend to result in difficulties in motion control or even failure in convergence in the case of high-velocity *** full consideration given to the influence of residual dead load and changing damping force upon AUV motion control,a novel sliding-mode controller(SMC)is proposed in this *** stability analysis of the proposed controller is carried out on the basis of Lyapunov *** sea trials results proved the superiority of the sliding-mode controller over sigmoid-function-based controller(SFC).The novel controller demonstrated its effectiveness by achieving admirable control results in the case of high-velocity movement.

关键词： autonomous underwater vehicle sliding-mode control stability analysis residual dead load sigmoid-function-based control

High-temperature calcination dramatically promotes the activity of Cs/Co/Ce-Sn catalyst for soot oxidation

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2025年第1期36卷 534-538页

作者： Meng Wang Yan Zhang yunbo yu Wenpo shan Hong He Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control Ningbo Urban Environment Observation and Research StationInstitute of Urban EnvironmentChinese Academy of SciencesNingbo 315800China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Catalytic oxidation of soot is of great importance for emission control on diesel *** this work,a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation,and it was unexpectedly found that high-temperature calcination greatly improved the activity of the *** the calcination temperature was increased from 500℃ to 750℃,T_(50) decreased from 456.9℃ to 389.8℃ in a NO/O_(2)/H_(2)O/N_(2) *** results revealed that high-temperature calcination can promote the ability to transfer negative charge density from Cs to other metal cations in Cs/Co/Ce-Sn,which will facilitate the production of more oxygen defects and the generation of more surface-active oxygen *** oxygen species are beneficial to the oxidation of NO to NO_(2),leading to the high yield of NO_(2) ***,the Cs/Co/Ce-Sn catalyst calcined at 750℃ demonstrated higher activity than that calcined at 500℃.This work provides a pathway to prepare high efficiency catalysts for the removal of soot and significant insight into the effects of calcination on soot oxidation catalysts.

关键词： Soot oxidation Calcination Surface defects Surface-active oxygen species NO_(2)

Output Consensus of Heterogeneous Linear MASs via Adaptive Event-Triggered Feedback Combination Control

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2025年第1期12卷 285-287页

作者： Shuo yuan Chengpu yu Jian sun the School of Automation Beijing Institute of Technology the Beijing Institute of Technology Chongqing Innovation Center

Dear Editor,This letter studies output consensus problem of heterogeneous linear multiagent systems over directed graphs. A novel adaptive dynamic event-triggered controller is presented based only on the feedback combination of the agent's own state and neighbors' output,which can achieve exponential output consensus through intermittent communication. The controller is obtained by solving two linear matrix equations, and Zeno behavior is excluded.

关键词： Directed graphs

Acute and chronic excitotoxicity in ischemic stroke and late-onset Alzheimer's disease

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第7期20卷 1981-1988页

作者： shan Ping yu Emily Choi Michael QJiang Ling Wei Department of Anesthesiology Emory University School of MedicineAtlantaGAUSA Center for Visual and Neurocognitive Rehabilitation Atlanta Veterans Affairs Medical CenterDecaturGAUSA

Stroke and Alzheimer's disease are common neurological disorders and often occur in the same *** comorbidity of the two neurological disorders represents a grave health threat to older *** review presents a brief background of the development of novel concepts and their clinical *** activity of glutamatergic N-methyl-D-aspartate receptors and N-methyl-D-aspartate receptor-mediated Ca^(2+)influx is critical for neuronal *** ischemic insult induces prompt and excessive glutamate release and drastic increases of intracellular Ca^(2+)mainly via N-methyl-D-aspartate receptors,particularly of those at the extrasynaptic *** Ca^(2+)-evoked neuronal cell death in the ischemic core is dominated by necrosis within a few hours and days known as acute ***,mild but sustained Ca^(2+)increases under neurodegenerative conditions such as in the distant penumbra of the ischemic brain and early stages of Alzheimer's disease are not immediately toxic,but gradually set off deteriorating Ca^(2+)-dependent signals and neuronal cell loss mostly because of activation of programmed cell death *** on the Ca^(2+)hypothesis of Alzheimer's disease and recent advances,this Ca^(2+)-activated“silent”degenerative excitotoxicity evolves from years to decades and is recognized as a unique slow and chronic *** N-methyl-D-aspartate receptor subunit GluN3A,primarily at the extrasynaptic site,serves as a gatekeeper for the N-methyl-D-aspartate receptor activity and is neuroprotective against both acute and chronic *** stroke and Alzheimer's disease,therefore,share an N-methyl-D-aspartate receptor-and Ca^(2+)-mediated mechanism,although with much different time *** is thus proposed that early interventions to control Ca^(2+)homeostasis at the preclinical stage are pivotal for individuals who are susceptible to sporadic late-onset Alzheimer's disease and Alzheimer's disease-related

关键词： Ca^(2+)hypothesis cognitive deficits hyperactivity late-onset Alzheimer's disease neurodegeneration N-methyl-D-aspartate receptors N-methyl-D-aspartate receptor subunits pathogenesis preventive treatment