检索结果-南通市图书馆

Theoretical Mechanistic Studies of Rh-Catalyzed c(sp^3)-H Amination:A Comparison with Co Analogue and Metal Effects

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2020年第12期38卷 1526-1532页

作者： yang Yu Gen Luo jimin yang Yi Luo State Key Laboratory of Fine Chemicals School of Chemical EngineeringDalian University of TechnologyDalianLiaoning 116024China Institutes of Physical Science and Information Technology Anhui UniversityHefeiAnhui 230601China

of main observation and conclusion The mechanism of Rh-catalyzed C(sp^3)—H amination has been computationally *** reaction mechanism mainly involves sequential C(sp^3)—H activation,decarboxylation,nitrene migration insertion,and protonation *** concerted metalation deprotonation(CMD)and external base assisted deprotonation(EBAD)pathways are found for the involved C(sp^3)—H activation in both Rh and Co analogous *** is different from the previously reported C(sp^2)—H activation,where the CMD is *** key mechanistic difference between the two systems is found to be in the C(sp^3)—H activation *** comparison with Rh species,the lower activity of Co complex toward the C(sp^3)—H activation could be ascribed to smaller atomic size of Co and thus larger steric repulsion between ancillary ligand and substrate along with the CMD *** view of the EBAD pathway,however,the lower activity of Co species could be imputed to the triplet nature of Co center,which is against the electron transfer from the electron-rich carbon atom of the deprotonating C(sp^3)—H bond to the Co *** to the subsequent decarboxylation and nitrene insertion steps,compared with the Co system,the relatively lower reactivity of Rh species is partially due to the stronger Rh—N bond,and the higher Ti(Rh—N)and n^*(Rh—N)orbital energies of the corresponding transition state structure.

关键词： structure. activation steps

Isomeric fluorescence sensors for wide range detection of ionizing radiations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第4期34卷 247-257页

作者： jimin Han Tianyu yang Li yang Yuanjian Li State Key Laboratory of Explosion Science and Technology of China Beijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401120China

In order to achieve a wider range of ionizing radiations detection,novel fluorescence sensing materials have been developed that utilize the fluorescence enhancement phenomenon caused by the intramolecular photoinduced electron transfer(PET)*** perylene diimide isomers PDI-P and PDI-B were designed and synthesized,and their molecular structures were characterized by high-resolution Fourier transform mass spectrometry(HRMS),nuclear magnetic resonance hydrogen and carbon spectroscopy(~1H and~(13)C NMR).The interaction between ionizing radiation and fluorescent molecules was simulated by HCl *** results show that combining PDIs and HCl can improve fluorescence through the retro-PET *** the similarities in chemical structures,the fluorescent enhancement multiple of PDI-B with aromatic amine as electron donor is much higher than that of PDI-P with alkyl *** the direct irradiation experiments of ionizing radiation,the emission enhancement multiples of PDI-P and PDI-B are 2.01 and 45.4,***,density functional theory(DFT)and time-dependent density functional theory(TDDFT)calculations indicate that the HOMO and HOMO-1 energy ranges of PDI-P and PDI-B are 0.54 e V and 1.13 e V,respectively.A wider energy range has a stronger driving force on electrons,which is conducive to fluorescence *** femtosecond transient absorption spectroscopy(fs-TAS)and transient fluorescence spectroscopy(TFS)tests show that PDI-B has shorter charge separation lifetime and higher electron transfer rate *** both isomers can significantly reduce LOD during PET process,PDI-B with aromatic amine has a wider detection range of 0.118—240 Gy due to its larger emission enhancement,which is a leap of three orders of *** breaks through the detection range of gamma radiation reported in existing studies,and provides theoretical support for the further study of sensitive and effective new materials for ionizing radiation dete

关键词： Perylene imide Intramolecular PET Ionizing radiation detection Fluorescence sensor Isomers

维普期刊数据库

Mn^(2+)-doped ZrO_(2)@PDA nanocomposite for multimodal imaging-guided chemo-photothermal combination therapy

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2021年第8期32卷 2405-2410页

作者： Ning Chen Wenhui Fu Jie Zhou Linqiang Mei jimin yang yang Tian Qiang Wang Wenyan Yin Laboratory for Micro-sized Functional Materials Department of Chemistry and College of Elementary EducationCapital Normal UniversityBeijing 100048China CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety CAS-HKU Joint Laboratory of Metallomics on Health and EnvironmentBeijing Metallomics FacilityNational Consortium for Excellence in MetallomicsInstitute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Chemistry and Chemical Engineering Linyi UniversityLinyi 276005China Laboratory of Nano-Bio Interface Suzhou Institute of NanoTech and Nano-BionicsChinese Academy of SciencesSuzhou 215123China

Developing low toxicity and multifunctional theranostic nanoplatform is the key for precise cancer diagnosis and ***,an inorganic-organic hybrid nanocomposite is designed by modifying zirconium dioxide(ZrO_(2)) with polydopamine(PDA) followed by doping Mn^(2+) ions and functionalizing with Tween 20(Tween-ZrO_(2)@PDA-Mn2+) for multimodal imaging and chemo-photothermal combination *** as-prepared nanocomposite exhibits good biocompatibility in vitro and in ***,it can be employed as a multifunctional platform not only for computed tomography(CT)imaging and T1-weighted magnetic resonance(MR) imaging,but also for efficient chemotherapeutic drug doxorubicin hydrochloride(DOX) ***,because of the pronounced photothermal conversion performance and controllable DOX release ability triggered by the near-infrared(NIR)irradiation and acidic pH,the synergistic effect between photothermal the rapy and chemotherapy results in an enhanced cancer treatment efficacy in *** work provides a high-performance inorganicorganic hybrid nanotheranostic platform for chemo-photothermal cancer therapy guided by CT and MR imaging.

关键词： ZrO_(2)nanoparticles Polydopamine Multimodal imaging Chemo-photothermal therapy

维普期刊数据库

在线全文

学校读者我要写书评

暂无评论

低聚木糖的提取方法及其在食品工业中的应用

中国果菜 2024年第9期44卷 30-35页

作者：杨继敏张振中肖林王新明山东哈维药业有限公司山东菏泽274000 山东龙力生物科技股份有限公司山东德州251200

低聚木糖是一类具有益生元活性的功能性低聚糖,无毒副作用,稳定性好,来源广泛。本文结合国内外关于低聚木糖的研究进展,总结了低聚木糖的生物学特性和提取方法(物理法、化学法、生物酶法等),并对其在果蔬饮料、乳制品、焙烤制品等食品... 详细信息

低聚木糖是一类具有益生元活性的功能性低聚糖,无毒副作用,稳定性好,来源广泛。本文结合国内外关于低聚木糖的研究进展,总结了低聚木糖的生物学特性和提取方法(物理法、化学法、生物酶法等),并对其在果蔬饮料、乳制品、焙烤制品等食品工业方面的应用进行了综述,以期提高低聚木糖工业化生产效益及拓宽其在市场上的应用。

关键词：低聚木糖提取方法生物学特性食品工业

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

克弗尔压片糖果工艺研究

中国果菜 2024年第8期44卷 20-24,31页

作者：杨继敏王宪文王新明肖林山东哈维药业有限公司山东菏泽274000 山东龙力生物科技股份有限公司山东禹城251200

为丰富压片糖果产品类型,提高食品的健康和功能性,本文以克弗尔果味粉、木糖醇、微晶纤维素、麦芽糊精和硬脂酸镁为原料,采用湿法制粒压片方式,研发克弗尔压片糖果,并通过单因素和正交试验优化产品配方和工艺参数。结果表明,克弗尔压片... 详细信息

为丰富压片糖果产品类型,提高食品的健康和功能性,本文以克弗尔果味粉、木糖醇、微晶纤维素、麦芽糊精和硬脂酸镁为原料,采用湿法制粒压片方式,研发克弗尔压片糖果,并通过单因素和正交试验优化产品配方和工艺参数。结果表明,克弗尔压片糖果的最佳配方为微晶纤维素和麦芽糊精添加量54.6%(质量比为2∶1)、克弗尔果味粉添加量30%、木糖醇添加量15%和硬脂酸镁添加量0.4%,制得的压片糖果口感较好。经检测,片剂的平均硬度11.46 kg,脆碎度0.25%±0.016%,片剂质量差异0.73~0.77 g;各项指标均符合标准要求。

关键词：克弗尔压片糖果配方优化正交试验

维普期刊数据库博看期刊

Diboron-mediated palladium-catalyzed asymmetric transfer hydrogenation using the proton of alcohols as hydrogen source

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2021年第10期64卷 1743-1749页

作者： Bo Wu jimin yang Shu-Bo Hu Chang-Bin Yu Zi-Biao Zhao Yi Luo Yong-Gui Zhou Dalian Institute of Chemical Physics Chinese Academy of SciencesDalian 116023China State Key Laboratory of Fine Chemicals School of Chemical EngineeringDalian University of TechnologyDalian 116024China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

The developments of hydrogen sources stand at the forefront of asymmetric reduction. In contrast to the well-studied alcohols as hydrogen sources via β-hydride elimination, the direct utilization of the proton of alcohols as a hydrogen source for activatormediated asymmetric reduction is rarely explored. Herein we report the proton of alcohols as a hydrogen source in diboronmediated palladium-catalyzed asymmetric transfer hydrogenation of 1,3-diketones and indoles, providing a series of chiral β-hydroxy ketones and indolines with excellent yields and enantioselectivities. This strategy would be useful for the synthesis of chiral deuterium-labelled compounds due to the ready availability of deuterium-labelled alcohols. Mechanistic investigations and DFT calculations revealed that active chiral Pd-H species was generated from the proton of alcohols by activating of tetrahydroxydiboron, hydrogen transfer was the rate-determining step, and the reaction preferred Pd(0)-catalyzed mechanism.

关键词： proton of alcohols hydrogen source asymmetric reduction

维普期刊数据库

Role of temperature in tribolayers in fretting wear ofγ-TiAl alloy

在线全文

学校读者我要写书评

暂无评论

Friction 2024年第5期12卷 939-953页

作者： Yulei yang Hongfei SHANG Huiping PEI jimin XU Yi LIANG Minghui PAN School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing100084China Institute of Tribology Hefei University of TechnologyHefei230009China

The formation of tribolayers may play significant influences on fretting *** elevated temperature,the adhesion among wear debris and the increased diffusion rate facilitate the formation of ***,the intensification of oxidation at elevated temperature and the low diffusion rate in oxides may play an adverse *** present study aims to investigate the role of temperature in tribolayers in fretting wear using aγ-TiAl *** electron microscope,energy dispersive spectrometer,Raman spectrometer,transmission electron microscope and nanoindentation were utilized to investigate the wear debris,tribolayers,and wear *** fretting tests showed that,compared with that at room temperature(RT)and 350℃,significant reduction in wear rate and decrease in the fluctuation of friction coefficient occurred at 550 and 750℃.It was further revealed that when temperature raised from room temperature(RT)to 750℃,the oxidation of the wear debris increased slightly and the diffusion coefficients increased prominently,which facilities the formation of well tribo-sintered *** well tribo-sintered tribolayers presented homogenous structure,nanocrystalline grains with excellent mechanical properties,and resulted in the improvement in the fretting wear resistance of theγ-TiAl alloy at 550 and 750℃.

关键词： tribolayer temperature fretting wear γ-TiAl alloy

Engineering the future cereal crops with big biological data:toward intelligence-driven breeding by design

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Genetics and Genomics 2024年第8期51卷 781-789页

作者： Lei Liu jimin Zhan Jianbing Yan National Key Laboratory of Crop Genetic Improvement Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei 430070China

How to feed 10 billion human populations is one of the challenges that need to be addressed in the following decades,especially under an unpredicted climate *** breeding,initiating from the phenotype-based selection by local farmers and developing into current biotechnology-based breeding,has played a critical role in securing the global food ***,regarding the changing environment and ever-increasing human population,can we breed outstanding crop varieties fast enough to achieve high productivity,good quality,and widespread adaptability?This review outlines the recent achievements in understanding cereal crop breeding,including the current knowledge about crop agronomic traits,newly developed techniques,crop big biological data research,and the possibility of integrating them for intelligence-driven breeding by design,which ushers in a new era of crop breeding practice and shapes the novel architecture of future *** review focuses on the major cereal crops,including rice,maize,and wheat,to explain how intelligence-driven breeding by design is becoming a reality.

关键词： Crop Big biological data Multi-omic Artificial intelligence Crop design breeding

Control of electromechanical performance in 3D printing latticestructured BaTiO_(3) piezoelectric ceramics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第7期13卷 987-1001页

作者： Zhujun Jiang Yinghong Sun jimin Chen Yong Zeng Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing 100124China Beijing Engineering Research Center of 3D Printing for Digital Medical Health Beijing University of TechnologyBeijing 100124China

Barium titanate(BaTiO_(3))piezoelectric ceramics with triply periodic minimal surface(TPMS)structures have been frequently used in filters,engines,artificial bones,and other fields due to their high specific surface area,high thermal stability,and good heat ***,only a limited number of studies have analyzed the effect of various parameters,such as different wall thicknesses and porosities of TPMS structures,on ceramic electromechanical *** this study,we first employed vat photopolymerization(VPP)three-dimensional(3D)printing technology to fabricate high-performance BaTiO_(3) *** investigated the slurry composition design and forming process and designed a stepwise sintering postprocessing technique to achieve a density of 96.3%and a compressive strength of 250±25 MPa,with the piezoelectric coefficient(d33)reaching 263 pC/***,we explored the influence of three TPMS structures,namely,diamond,gyroid,and Schwarz P,on the piezoelectric and mechanical properties of BaTiO_(3) ceramics,with the gyroid structure identified as exhibiting optimal ***,we examined the piezoelectric and mechanical properties of BaTiO_(3) ceramics with the gyroid structure of varying wall thicknesses and porosities,thus enabling the modulation of ceramic electromechanical performance.

关键词： three-dimensional(3D)printing piezoelectric ceramics porous structure mechanical properties electrical properties