检索结果-南通市图书馆

Ab Initio Prediction of ^(29)Si-NMR Chemical Shifts

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of Qingdao 2002年第1期1卷 63-65页

作者： CHU Shidong li yingxia SONG Ni GUAN Huashi Institute of Marine Drugs Ocean University of QingdaoQingdao 266003P.R.China

The ability of several ab initio models to predict experimental 29Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allyltrimethylsilane (C) are calculated by GIAO , CSGT and IGAIM methods, using HF/6-31G*, B3LYP/6-31G*, HF/6-311+G **, B3LYP/6-311+G ** and MPW1PW91/6-311+G ** models respectively. The 29Si chemical shifts calculated by GIAO method using HF/6-311+G ** model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical shifts in all cases studied, suggesting that the models are of practical value.

关键词： Si-NMR Chemical Shift ab initio prediction Density Functional Theory

Novel Pt-Ni Bimetallic Catalysts Pt(Ni)-LaFeO_3/SiO_2 via Lattice Atomic-Confined Reduction for Highly Efficient Isobutane Dehydrogenation

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2019年第3期25卷 245-257页

作者： Xiao Yang Guilong liu yingxia li lihong Zhang Xitao Wang Yuan liu School of Chemical Engineering and Technology Tianjin University College of Chemistry and Chemical Engineering Luoyang Normal University

In this study, a series of novel Pt-Ni bimetallic catalysts supported on LaFeO_3/SiO_2 with different amounts of Ni were prepared by the lattice atomic-confined reduction of LaFe_(1-x)(Ni, Pt)_xO_3/SiO_2 perovskite precursors and applied in isobutane dehydrogenation to isobutene reaction. The catalysts were characterized by X-ray diffraction, H_2-temperature-programmed reduction, Brunauer-Emmett-Teller analysis, transmission electron microscopy, energy dispersive X-ray, CO chemisorption, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The as-synthesized Pt-Ni bimetallic catalysts possessed smaller most probable particle size with tunable Pt-Ni interaction, depending on the Ni content. The catalyst with Ni content of 3.0 wt% showed excellent activity and stability(the isobutane conversion and isobutene selectivity remained at about 38% and 92%, respectively, after 310 min) for the isobutane dehydrogenation reaction. It also provided approximately six times turnover frequency of the catalyst without Ni. The excellent activity and stability of the 3.0 wt% Ni-containing catalyst can be attributed to its small metal nanoparticles with high dispersion and suitable Pt-Ni interaction. Moreover, the Pt(Ni)-LaFeO_3/SiO_2 catalyst with Ni content of 3.0 wt% had been run for more than 35 h without obvious loss of activity,indicating its long-term stability, and the decrease in the Pt-Ni interaction that accompanied the formation of the FeNi alloy phase was thought to be responsible for the slight decrease in activity.

关键词： Perovskite Isobutane dehydrogenation Isobutene Pt-Ni interaction Silica

Application of plasma-activated water for Escherichia coli decontamination and shelf-life extension of kale

在线全文

学校读者我要写书评

暂无评论

Food Quality and Safety 2022年第3期6卷 416-426页

作者： Hexiang Wang yingxia li Qian Xi Rongwei Han Patrick J.Cullen Qijing Du Yongxin Yang Fereidoun Forghani Jiacheng Zhang Jun Wang College ofFood Science and Engineering Qingdao Agricultural UniversityQingdaoChina College of Food Science and Engineering Tarim UniversityAlarChina School of Chemical and Biomolecular Engineering University of SydneySydneyNSWAustralia Molecular Epidemiology Inc.15300 Bothell Way NELake Forest ParkWAUSA Shandong Engineering Technology Research Center of Food Quality and Safety Control QingdaoChina Qingdao Engineering Research Centerof Food Quality and Safety Risk Assessment QingdaoChina

The aim of this study was to examine the effectiveness of plasma-activated water(PAW)for inactivating Escherichia coli(***)and retention of key quality factors for *** plasma discharge times(1,2,3,4,5,and 10 min)and different exposure times(2,4,6,8,10,and 15 min)were used to investigate the inactivation effect of *** spot-inoculated on *** influence of different exposure times on the pH,hardness and color of kale was studied *** addition,the effects of PAW on the shelf-life of kale over 12 d of storage at 4℃ were *** results showed that after the treatment of 5-PAW-8(8 min treatment by PAW generated by 5 min plasma discharge),the population of *** on kale was reduced by approximately 1.55 log colony-forming units(CFU)/g and the changes in pH,hardness and color of kale were not significant(P>0.05).During the storage period after 5-PAW-8 treatment,the hardness,weight loss,color,surface morphology and ascorbic acid were found to be better than those of the two control groups(P0.05).It is indicated that PAW treatment is a promising methodfor improving microbiological safety and extending the shelf-life of kale.

关键词： Plasma-activated water kale Escherichia coli shelf-life quality

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

氢化可的松氨基糖衍生物的合成

有机化学 2003年第4期23卷 361-367页

作者：曲峰李英霞宋妮中国海洋大学海洋药物与食品研究所青岛266003

描述了一条简单有效的合成氢化可的松氨基糖衍生物的合成路线 .实验中首先将氢化可的松转化为琥珀酸酯衍生物 2 ,葡萄糖、2 乙酰氨基葡萄糖、半乳糖、乳糖及氨基葡萄糖盐酸盐转化成为相应的氨基糖 7a～ 7d和 12 ,然后 2与 7a～ 7d和 12... 详细信息

描述了一条简单有效的合成氢化可的松氨基糖衍生物的合成路线 .实验中首先将氢化可的松转化为琥珀酸酯衍生物 2 ,葡萄糖、2 乙酰氨基葡萄糖、半乳糖、乳糖及氨基葡萄糖盐酸盐转化成为相应的氨基糖 7a～ 7d和 12 ,然后 2与 7a～ 7d和 12在DCC的作用下通过酰胺键进行偶联 ,得到一系列氢化可的松糖氨基糖衍生物 13a～ 13e .上述目标化合物均为新化合物 ,其结构分别通过红外光谱 (IR)、核磁共振波谱 ( 1HNMR ,13 CNMR)及HMRS进行了确证 .

关键词：氢化可的松氨基糖衍生物合成甾醇皮质激素类药物

Molecular characterization and structure basis of a malonyltransferase with both substrate promiscuity and catalytic regiospecificity from Cistanche tubulosa

在线全文

学校读者我要写书评

暂无评论

Acta Pharmaceutica Sinica B 2024年第5期14卷 2333-2348页

作者： Xiao liu Yuyu liu Xiping Xu Wenqian Huang Yaru Yan yingxia Wang Weisheng Tian Ting Mo Xiaoxue Cui Jun li She-Po Shi Pengfei Tu Modern Research Center for Traditional Chinese Medicine Beijing Research Institute of Chinese MedicineBeijing University of Chinese MedicineBeijing 100029China Modern Research Center for Traditional Chinese Medicine School of Chinese Materia MedicaBeijing University of Chinese MedicineBeijing 100029China

Enzymatic malonylation of natural glycosides provides a promising alternative method for drug-like malonylated glycosides ***,the catalytic potential and structural basis of plant malonyltransferase are far from being fully *** work identified a new malonyltransferase CtMaT1 from Cistanche *** displayed unprecedented mono-and/or di-malonylation activity toward diverse glucosides with different aglycons.A“one-pot”system by CtMaT1 and a malonyl-CoA synthetase was established to biosynthesize nine new malonylated *** investigations revealed that CtMaT1 possesses an adequately spacious acyl-acceptor pocket capable of accommodating diverse ***,it recognizes malonyl-CoA through strong electrotactic and hydrogen ***/MM calculation revealed the H167-mediated SN2 reaction mechanism of CtMaT1,while dynamic simulations detected the formation of stable hydrogen bonds between the glucose-6-OH group and H167,resulting in its high malonylation *** energy profiles of two isomeric glycosides highlighted lower reaction energy barriers towards glucoside substrates,emphasizing CtMaT1's preference for ***,a mutant CtMaT1H36A with notably increased di-malonylation activity was *** underlying molecular mechanism was illuminated through MM/GBSA binding free energy *** study significantly advances the understanding of plant acyltransferases from both functional and protein structural perspectives,while also providing a versatile tool for enzymatic malonylation applications in pharmacology.

关键词： Plant acyltransferase Malonyltransferase Malonylated glycosides Enzymatic catalysis Enzyme promiscuity

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

护理缺失研究进展

护士进修杂志 2024年第4期39卷 421-425,430页

作者：李文明左燕雨戴兵李英霞河南省南阳市中心医院河南南阳473000

护理缺失是指护理行为的缺失,其存在必然导致护理质量降低,影响患者安全。本文就护理缺失的概念、理论模型、主要缺失内容、测评工具、不良影响及相关干预措施进行阐述,并对未来研究提出建议和展望,以期引起国内护理工作者和管理者的重... 详细信息

护理缺失是指护理行为的缺失,其存在必然导致护理质量降低,影响患者安全。本文就护理缺失的概念、理论模型、主要缺失内容、测评工具、不良影响及相关干预措施进行阐述,并对未来研究提出建议和展望,以期引起国内护理工作者和管理者的重视,为相关研究的开展提供借鉴和参考。

关键词：护理缺失患者安全护理质量测评工具干预措施综述

维普期刊数据库博看期刊

磷改性MCM-22分子筛上苯与1-十二烯烷基化合成十二烷基苯

在线全文

学校读者我要写书评

暂无评论

催化学报 2008年第9期29卷 889-894页

作者：田玲李建伟李英霞陈标华北京化工大学化工资源有效利用国家重点实验室北京100029

采用浸渍法制备了一系列用于苯和1-十二烯烷基化合成十二烷基苯的磷改性MCM-22分子筛,以X射线衍射(XRD)和固体27Al3、1P核磁共振,N2吸附,氨程序升温脱附(NH3-TPD),热重(TG)和红外光谱(FT-IR)等表征技术,结合固定床连续流动反应器中的性... 详细信息

采用浸渍法制备了一系列用于苯和1-十二烯烷基化合成十二烷基苯的磷改性MCM-22分子筛,以X射线衍射(XRD)和固体27Al3、1P核磁共振,N2吸附,氨程序升温脱附(NH3-TPD),热重(TG)和红外光谱(FT-IR)等表征技术,结合固定床连续流动反应器中的性能评价,较为系统地研究了磷改性对MCM-22分子筛的结构、表面酸性及其烷基化催化性能的影响.结果表明,用磷改性MCM-22分子筛虽然不会影响分子筛的晶体结构,但是会破坏分子筛上的Si-O-Al键,使部分四配位铝转化为六配位铝.由于聚合态的磷酸盐可能与Al发生键合,多聚态磷酸盐数量随着磷含量的增加而增多,从而改变了分子筛的孔道大小和酸性,使得强酸减少,弱酸增多,酸强度降低,总酸量和B酸中心数随着磷含量的增加呈现先增后减的规律,L酸减少.适当的磷含量有利于提高MCM-22分子筛对苯与1-十二烯烷基化反应的催化选择性和稳定性,改性磷含量为0.5%左右时产物2-十二烷基苯收率最高.

关键词： MCM-22分子筛磷改性苯 1-十二烯烷基化

Early and Sensitive Detection of Pathogens for Public Health and Biosafety:An Example of Surveillance and Genotyping of SARS-CoV-2 in Sewage Water by Cas12a-Facilitated Portable Plasmonic Biosensor

在线全文

学校读者我要写书评

暂无评论

Research 2024年第2期2023卷 259-272页

作者： Tianzhong li Yuzhi Chen Zhi Chen Yuan Hao Minyi liang yingxia liu Guanyong Ou Huanian Zhang Yuxuan Tang Yabing Hao Swelm Wageh Omar AAl-Hartomy Abul Kalam Bin Zhang Xin Shi Xuejin li Han Zhang College of Physics and Optoelectronic Engineering Institute of Translational MedicineDepartment of OtolaryngologyShenzhen Second People's HospitalFirst Affiliated Hospital of Shenzhen UniversityHealth Science CenterShenzhen UniversityShenzhen 518060China Shenzhen Key Laboratory of Sensor Technology Shenzhen 518060China The Sixth Affiliated Hospital of Guangzhou Medical University Qingyuan People's HospitalQingyuan 511518China Shenzhen Key Laboratory of Pathogen and Immunity National Clinical Research Center for Infectious DiseaseState Key Discipline of Infectious DiseaseShenzhen Third People's HospitalSecond Hospital Affiliated to Southern University of Science and TechnologyShenzhen 518112China School of Medicine Southern University of Science and TechnologyShenzhen 518055China School of Physics and Optoelectronic Engineering Shandong University of TechnologyZibo 255049China Department of Physics Faculty of ScienceKing Abdulaziz University Jeddah 21589Saudi Arabia Research Center for Advanced Materials Science(RCAMS) King Khalid UniversityP.0.Box 9004Abha 61413Saudi Arabia Department of Chemistry College of ScienceKing Khalid UniversityP.0.Box9004Abha 61413 Saudi Arabia Health Sciences Institute China Medical UniversityShenyang 110000China The Chinese University of Hong Kong Shenzhen 518060China

Infectious diseases severely threaten public health and global *** addition to transmission through the air,pathogenic microorganisms have also been detected in environmental liquid samples,such as sewage *** biochemical detection methodologies are time-consuming and cost-ineffective,and their detection limits hinder early *** the present study,ultrafine plasmonic fiber probes with a diameter of 125μm are fabricated for clustered regularly interspaced short palindromic repeats/CRISPR-associated protein(CRISPR/Cas)-12a-mediated sensing of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Single-stranded DNA exposed on the fiber surface is trans-cleaved by the Cas12a enzyme to release gold nanoparticles that are immobilized onto the fiber surface,causing a sharp reduction in the surface plasmon resonance(SPR)*** proposed fiber probe is virus-specific with the limit of detection of~2,300 copies/ml,and genomic copy numbers can be reflected as shifts in wavelengths.A total of 21 sewage water samples have been examined,and the data obtained are consistent with those of quantitative polymerase chain reaction(qPCR).In addition,the Omicron variant and its mutation sites have been fast detected using S gene-specific *** study provides an accurate and convenient approach for the real-time surveillance of microbial contamination in sewage water.

关键词： fiber consuming hinder

Evidence of Robust Participation by equatorial 4-O group in glycosylation on a 2-Azido-2-deoxy-glucopyranosyl Donor

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

Evidence of Robust Participation by equatorial 4-O group in ...