检索结果-南通市图书馆

Constructing Tertiary Alcohols with Vicinal Stereocenters:Highly Diastereo-and Enantioselective Cyanosilylation of α-Branched Acyclic Ketones and Their Kinetic Resolution

在线全文

学校读者我要写书评

暂无评论

CCS Chemistry 2022年第6期4卷 2140-2152页

作者： Wen-Biao Wu Xin yu jin-sheng yu Xin Wang Wen-Guang Wang Jian Zhou Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesEast China Normal UniversityShanghai 200062 School of Chemistry and Chemical Engineering Shandong UniversityJinan 250100 College of Chemistry Sichuan UniversityChengdu 610064 State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryShanghai 200032

We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent ***,a highly stereoselective cyanosilylation of racemic ketones is developed using our bifunctional cyanating reagent,Me_(2)(CH_(2)Cl)SiCN,giving C^(α)-tetrasubstituted silyl cyanohydrins withtwovicinal stereocenters inupto>20:1 diastereomeric ratio(dr)and 90-98% enantiomeric excess(ee)values,which can undergo various diversification reactions bymanipulating the chloromethyl group.A highly selective kinetic resolution of acyclicα-branched ketones is also developed that allows facile access to acyclic α-alkyl,allyl,and propargyl ketones with good recovery and excellent ee *** synthetic value of this protocol is further demonstrated by the formal synthesis of the anti-obesity agent,taranabant(MK-0364).The activation of Jacobsen’s privileged catalyst(salen)AlCl by a suitable phosphorane plays a crucial role in the reaction.X-ray crystallographic analysis of single crystals of phosphorane-(salen)AlCl complexes and theoretical calculations help provide a working *** present transformation opens a new path for the catalytic stereoselective synthesis of stereochemically complex tertiary alcohols featuring two stereocenters(adjacent or not)from racemic ketones.

关键词： tertiary alcohols with vicinal stereocenters ketone cyanosilylation kinetic resolution

Comments on“Effect of type 2 diabetes mellitus in the prognosis of acute-on-chronic liver failure patients in China”

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2022年第14期28卷 1499-1502页

作者： Wei Wang Chen-Chen Pan Wen-Ying Zhao jin-yu sheng Qi-Qi Wu Si-Si Chen Department of Interventional Oncology Taizhou Municipal HospitalTaizhou 318000Zhejiang ProvinceChina School of Medicine Taizhou University Taizhou 318000Zhejiang ProvinceChina Department of Obstetrics and Gynecology Taizhou Women and Children’s Hospital of Wenzhou Medical UniversityTaizhou 318000Zhejiang ProvinceChina

A study addressing the influence of type 2 diabetes on the prognosis of acute-onchronic liver failure patients was *** statistical deficiencies were found in the reviewed article,and the sample size was too small to s... 详细信息

关键词： Type 2 diabetes mellitus Liver failure Complication Prognosis Age

Heterogeneous engineering of MnSe@NC@ReS_(2) core-shell nanowires for advanced sodium-/potassium-ion batteries

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第8期43卷 3713-3723页

作者： sheng-Jun Lu jin-Yi Lin Cai-Hong Wang yu-Fei Zhang Yi Zhang Hao-Sen Fan College of Materials Science and Metallurgy Engineering Guizhou University Guiyang 550025China School of Energy Science and Engineering Nanjing Tech UniversityNanjing 211816China School of Chemistry and Chemical Engineering Guangzhou UniversityGuangzhou 510006China

Sodium-ion batteries(SIBs) and potassium-ion batteries(PIBs) have been attracting great attentions and widely been exploited due to the abundant sodium/potassium ***,the preparation of high-powered anode materials for SIBs/PIBs plays a decisive role for the commercial applications of SIBs/PIBs in the *** selenides are a class of potential anode materials for SIBs/PIBs because of their small band gap and high electrical *** this work,MnSe and ReS_(2) core-shell nanowires connecting by polydopamine derived carbon nanotube(MnSe@NC@ReS_(2)) have been successfully synthesized from growing ReS_(2) nanosheets array on the surface of MnSe@NC nano wires,which present excellent Na^(+)/K^(+) storage *** applied as SIBs anode,the specific capacity of 300 mAh·g^(-1) was maintwined after 400 cycles at the current density of 1.0 A·g^(-1).Besides,it could also keep 120 mAh·g^(-1) specific capacity after 900 cycles at 1.0 A·g^(-1) for the anode of *** heterogeneous engineering and one-dimensional-two-dimensional(1D-2D) hybrid strategies could provide an ideal strategy for the synthesis of new hetero-structured anode materials with outstanding battery performance for SIBs and PIBs.

关键词： Heterogeneous engineering Core-shell nanowires MnSe@NC@ReS_(2)nanowires Na^(+)batteries K^(+)batteries

A micro-crosslinked amphoteric hydrophobic association copolymer as high temperature-and salt-resistance fluid loss reducer for water-based drilling fluids

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 1980-1991页

作者： Jian Li yu-Xi Ji Xiao-Xiao Ni Kai-He Lv Xian-Bin Huang jin-sheng Sun School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Key Laboratory of Unconventional Oil&Gas Development China University of Petroleum(East China)Qingdao26650ShandongChina Inspection and Testing Center of Huabei Oil Field Company PetroChinaRenqiu062552HebeiChina Drilling Fluid Research Institute CNPC Engineering Technology R&D Company LimitedBeijing102206China

During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a ***,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,DADC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether *** to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the DADC copolymer exhibited outstanding temperature-and *** rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing *** DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling ***,the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)***,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.

关键词： Fluid loss reducer Temperature-and salt-resistance Hydrophobic association Amphoteric Micro-crosslinking

CO_(2)flooding in shale oil reservoir with radial borehole fracturing for CO_(2)storage and enhanced oil recovery

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第1期21卷 519-534页

作者： Jia-Cheng Dai Tian-yu Wang jin-Tao Weng Kang-Jian Tian Li-Ying Zhu Gen-sheng Li State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China China National Oil and Gas Exploration and Development Company Limited Beijing100034China

This study introduces a novel method integrating CO_(2)flooding with radial borehole fracturing for enhanced oil recovery and CO_(2)underground storage,a solution to the limited vertical stimulation reservoir volume in horizontal well fracturing.A numerical model is established to investigate the production rate,reservoir pressure field,and CO_(2)saturation distribution corresponding to changing time of CO_(2)flooding with radial borehole fracturing.A sensitivity analysis on the influence of CO_(2)injection location,layer spacing,pressure difference,borehole number,and hydraulic fractures on oil production and CO_(2)storage is *** CO_(2)flooding process is divided into four *** in layer spacing will significantly improve oil production rate and gas storage ***,serious gas channeling can occur when the spacing is lower than 20 *** the pressure difference between the producer and injector,the borehole number,the hydraulic fracture height,and the fracture width can also increase the oil production rate and gas storage *** analysis shows that layer spacing and fracture height greatly influence gas storage and oil *** outcomes are expected to provide a theoretical basis for the efficient development of shale oil reservoirs in the vertical direction.

关键词： Shale oil Radial borehole fracturing Embedded discrete fracture model Enhanced oil recovery Carbon storage

Demonstration of high-dimensional controlled quantum teleportation for the first time

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 163-164页

作者： yu-Bo sheng Lan Zhou College of Electronic and Optical Engineering and College of Flexible Electronics(Future Technology) Nanjing University of Posts and TelecommunicationsNanjing 210023China College of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China

Controlled quantum teleportation(CQT) [1] is the tripartite version of quantum teleportation and it allows the teleportation of an unknown quantum state under the control of a third party. Compared with low-dimensional counterparts,high-dimensional CQT can exhibit larger information transmission capacity and a higher control power [2,3].

关键词： quantum dimensional high

在线全文

学校读者我要写书评

暂无评论

氢氧涡流燃烧推力器设计方案仿真研究

推进技术 2022年第4期43卷 185-194页

作者：孙得川金盛宇大连理工大学航空航天学院辽宁省空天飞行器前沿技术重点实验室辽宁大连116024 上海空间推进研究所上海空间发动机工程技术研究中心上海201112

涡流燃烧冷壁液体火箭发动机具有燃烧室侧壁温度低的特点,在高空或空间氢氧推力器应用方面很有优势,但是喷管喉部高温限制了它的应用。本文对以气氢气氧为推进剂的涡流燃烧冷壁发动机的设计方案进行了仿真研究,指出涡流工质的选择是燃... 详细信息

涡流燃烧冷壁液体火箭发动机具有燃烧室侧壁温度低的特点,在高空或空间氢氧推力器应用方面很有优势,但是喷管喉部高温限制了它的应用。本文对以气氢气氧为推进剂的涡流燃烧冷壁发动机的设计方案进行了仿真研究,指出涡流工质的选择是燃烧室设计的首要问题,应根据燃烧反应总包方程,以体积流量较大的推进剂作为涡流工质,而并非一定是氧化剂。氢氧涡流燃烧推力器的仿真结果表明,采用氢气作为旋涡工质,可以有效缓解氧气为旋涡工质时喷管壁面温度对混合比的限制,达到较高的比冲和材料容许的较低的喷管内壁温度;半球形头部的燃烧室方案虽然性能较高,但是头部内侧燃气容易聚积、温度过高,不利于长时间工作;采用椭球形头部、平行于轴线的头部氧气喷注形式可以达到较好的性能,并且头部和喷管内壁燃气温度均较低;喉部最高燃气温度随混合比增大而升高,氧化剂与燃料混合比达6时的最高温度为1382K。

关键词：涡流燃烧推力室氧气氢气设计数值模拟

Ability of lactulose breath test results to accurately identify colorectal polyps through the measurement of small intestine bacterial overgrowth

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Surgery 2023年第6期15卷 1138-1148页

作者： Lan Li Xue-yuan Zhang jin-sheng yu Hui-Min Zhou Yan Qin Wen-Rui Xie Wen-jing Ding Xing-Xiang He Department of Gastroenterology The First Affiliated Hospital of Guangdong Pharmaceutical UniversityGuangzhou 510080Guangdong ProvinceChina Washing Microbiota Transplantation Engineering Techniques of Microbiota-Targeted Therapies of Guangdong ProvinceGuangzhou 510080Guangdong ProvinceChina Department of Gastroenterology People's Hospital of Nanxiong CountyNanxiong 512400Guangdong ProvinceChina Department of Genetics Washington University School of MedicineSaint LouisMO 63110United States North America Medical Education Foundation CaliforniaCA 91710United States

BACKGROUND While colorectal polyps are not cancerous,some types of polyps,known as adenomas,can develop into colorectal cancer over *** can often be found and removed by colonoscopy;however,this is an invasive and expensive ***,there is a need for new methods of screening patients at high risk of developing *** To identify a potential association between colorectal polyps and small intestine bacteria overgrowth(SIBO)or other relevant factors in a patient cohort with lactulose breath test(LBT)*** A total of 382 patients who had received an LBT were classified into polyp and non-polyp groups that were confirmed by colonoscopy and *** was diagnosed by measuring LBTderived hydrogen(H)and methane(M)levels according to 2017 North American Consensus *** regression was used to assess the ability of LBT to predict colorectal *** barrier function damage(IBFD)was determined by blood *** H and M levels revealed that the prevalence of SIBO was significantly higher in the polyp group than in the non-polyp group(41%vs 23%,P<0.01;71%vs 59%,P<0.05,respectively).Within 90 min of lactulose ingestion,the peak H values in the adenomatous and inflammatory/hyperplastic polyp patients were significantly higher than those in the non-polyp group(P<0.01,and P=0.03,respectively).In 227 patients with SIBO defined by combining H and M values,the rate of IBFD determined by blood lipopolysaccharide levels was significantly higher among patients with polyps than those without(15%vs 5%,P<0.05).In regression analysis with age and gender adjustment,colorectal polyps were most accurately predicted with models using M peak values or combined H and M values limited by North American Consensus recommendations for *** models had a sensitivity of≥0.67,a specificity of≥0.64,and an accuracy of≥*** The current study made key associations among colorectal polyps,SIBO,and IBFD and demonstrated that LBT ha

关键词： Lactulose breath test Colorectal polyp Small intestine bacteria overgrowth Intestinal barrier function Retrospective study

Flexible nanoimprint lithography enables high-throughput manufacturing of bioinspired microstructures on warped substrates for efficient III-nitride optoelectronic devices

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 Bulletin 2024年第13期69卷 2080-2088页

作者： Siyuan Cui Ke Sun Zhefu Liao Qianxi Zhou Leonard jin Conglong jin Jiahui Hu Kuo-sheng Wen sheng Liu shengjun Zhou Center for Photonics and Semiconductors School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China The Institute of Technological Sciences Wuhan UniversityWuhan 430072China Department of Mechanical and Mechatronics Engineering University of WaterlooWaterloo ONN2L 3G1Canada Jiangxi SMTC Semiconductor Co. Ltd.Nanchang 330096China

III-nitride materials are of great importance in the development of modern optoelectronics,but they have been limited over years by low light utilization rate and high dislocation densities in heteroepitaxial films grown on foreign substrate with limited refractive index contrast and large lattice ***,we demonstrate a paradigm of high-throughput manufacturing bioinspired microstructures on warped substrates by flexible nanoimprint lithography for promoting the light extraction *** design a flexible nanoimprinting mold of copolymer and a two-step etching process that enable high-efficiency fabrication of nanoimprinted compound-eye-like Al2O3 microstructure(NCAM)and nanoimprinted compound-eye-like SiO_(2)microstructure(NCSM)template,achieving a 6.4-fold increase in throughput and 25%savings in economic costs over stepper projection *** to NCAM template,we find that the NCSM template can not only improve the light extraction capability,but also modulate the morphology of AlN nucleation layer and reduce the formation of misoriented GaN grains on the inclined sidewall of microstructures,which suppresses the dislocations generated during coalescence,resulting in 40%reduction in dislocation *** study provides a low-cost,high-quality,and high-throughput solution for manufacturing microstructures on warped surfaces of III-nitride optoelectronic devices.

关键词： Flexible nanoimprint lithography Bioinspired Micro-and nano-manufacturing III-nitride epitaxy Optoelectronic devices