检索结果-南通市图书馆

Rhodium-catalyzed coupling-cyclization reaction of isocyanides and 2-azidophenyloxyacrylates:synthesis of N-(3-substituted benzo[d]oxazol-2(3H)-ylidene)amines and dihydrobenzo[d]oxazoles

在线全文

学校读者我要写书评

暂无评论

Organic Chemistry Frontiers 2022年第2期9卷 407-412页

作者： Ming Yang xue-Cen xu yue Gong yu-long Zhao Jilin Province Key Laboratory of Organic Functional Molecular Design&Synthesis Department of ChemistryNortheast Normal UniversityChangchun 130024China

A rhodium-catalyzed coupling cyclization of isocyanides with 2-azidophenyloxyacrylates has been developed for the first *** reaction allows divergent syntheses of two significant N-heterocycles,fivemembered N-(3-substituted benzo[d]oxazol-2(3H)-ylidene)amines and dihydrobenzo[d]oxazoles,from readily available starting materials in a single step.

关键词： substituted catalyzed amines

Optimizing luminescence sensitivity and moisture stability of porous coordination frameworks by varying ligand side groups

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 2019年第3期62卷 341-346页

作者： Jia-Wen Ye xu-yu Li Hao-long Zhou Jie-Peng Zhang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry School of Chemistry Sun Yat-Sen University

Hydrophobic ethyl, butyl or hexyl groups were introduced into the dicarboxylate ligand in the fluorescent porous coordination framework [Zn_2(fda)_2(bpy)](LMOF-202, H_2fda=9H-fluorene-2,7-dicarboxylic acid, bpy=4,4′-bipyridine) for improving water stability and tuning oxygen sensitivity. The long hexyl groups gave satisfactory water stability but its oxygen sensitivity is low(70.8% fluorescence quenched at 1 bar O_2(1 bar=105 Pa)). In contrast, the shorter side groups gave high oxygen sensitivity(93.9% fluorescence quenched at 1 bar O_2) and low water stability. The derivation of the Stern-Volmer curves of the O_2 luminescence quenching data from the linear form can be used for detecting trace impurities in the luminescent framework, being much more sensitive than conventional methods such as powder X-ray diffraction. Mixing the ethyl and hexyl groups in the solid-solution manner brought high oxygen sensitivity(96.4% fluorescence quenched at 1 bar O_2) and high water stability simultaneously in the same coordination framework.

关键词： metal-organic framework water stability oxygen fluorescence sensor

Enhanced permeation performance of polyether-polyamide block copolymer membranes through incorporating ZIF-8 nanocrystals

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2017年第7期25卷 882-891页

作者： longwei xu long Xiang Chongqing Wang Jian yu Lixiong Zhang Yichang Pan State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 210009China

Membrane-based CO_2 separation is a promising alternative in terms of energy and environmental issues to other conventional techniques. Polyether-polyamide block copolymer(Pebax) membranes are promising for CO_2 separation because of their excellent selectivity, but limited by their moderate gas permeability. In this study,fresh-prepared zeolitic imidazolate framework-8(ZIF-8) nanocrystals were integrated into the Pebax?1657matrices to form mixed matrix membranes. The resulting membrane exhibits significantly improved CO_2permeability(as high as 300% increase), without the sacrifice of the selectivity, to the pristine polymer membrane. Several physical characterization techniques were employed to confirm the good interfacial interaction between ZIF-8 fillers and Pebax matrices. The effect of added ZIF-8 fillers on the transport mechanism through MMMs is also explored. Mixed-gas permeation for both CO_2/N_2 and CO_2/CH_4 was also evaluated. The separation performance for CO_2/CH_4 mixtures on the ZIF-8/Pebax MMMs is very close to the Roberson upper bound, and thus is technologically attractive for purification of natural gas.

关键词： Membrane Separation Carbon dioxide Mixed matrix membrane Metal-organic framework

Synthesis and characterization of Li_4Ti_5O_(12) via a hydrolysis process from TiCl_4 aqueous solution

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2014年第4期33卷 459-465页

作者： xuan-yu Wang yun-Jiao Li Cang xu long Kong Lin Li School of Metallurgical Science and Engineering Central South University

Spinel-type lithium and titanium composite oxide Li4TisO12 was successfully synthesized via a novel hydrolysis method followed by calcination using titanium tetrachloride （TIC14） and lithium hydroxide （LiOH.H2O） as raw materials. Three major factors, including LiOH con- centration, LiOH dosage, and hydrolysis temperature were studied for optimizing the synthetic conditions to obtain a phase-pure Li4Ti5012. The physical and electrochemical properties of samples were characterized by X-ray dif- fraction （XRD）, thermogravimetric analysis （TGA）, fourier transform infrared spectroscopy （FT-IR）, scanning electron microscopy （SEM）, and constant current discharge-charge test. The FT-IR results indicate the presence of [TiO6] octahedra. The SEM images show that the Li4Ti5O12 pre- cursor obtained is an amorphous solid with an irregular and rough morphology. It is revealed that the phase-pure spinel Li4Ti5O12 powders with well crystallization and regular morphology can be obtained by calcining the precursor at 800 ℃ for 6 h. The constant current discharge-charge tests indicate that the Li4TisO12 material delivers an excellent cycling ability, maintaining 93.8 % of its initial specific capacity after 60 cycles at a current density of 0.5C.

关键词： Lithium ion battery Titanium tetrachloride Li4Ti5O12 Synthesis Hydrolysis method

Effects of mesoscale gravity waves on sporadic E simulated by a one-dimensional dynamic model

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2025年第1期9卷 1-9页

作者： xu Zhou ZeZhong Li XinAn yue LiBo Liu Key Laboratory of Earth and Planetary Physics/Heilongjiang Mohe National Geophysical Observatory/Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences(CAS)Beijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China CAS Center for Excellence in Comparative Planetology/CAS Key Laboratory of Geospace Environment/Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China

In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively *** this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high *** by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower *** effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the *** mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their *** addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.

关键词： sporadic E ion tidal layer gravity waves numerical simulation

n-Nonane hydroisomerization over hierarchical SAPO-11-based catalysts with sodium dodecylbenzene sulfonate as a dispersant

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2021年第2期18卷 654-666页

作者： Cheng-long Wen Jun-Dong xu xue-Man Wang yu Fan State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249People’s Republic of China

To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane ***,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane *** n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)***,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional *** n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous *** results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon *** these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.

关键词： SAPO-11 molecular sieve n-Nonane hydroisomerization External surface area External Brønsted acid centers Selectivity to di-branched isomers

Magnetic resonance cholangiography in assessing biliary anatomy in living donors:A meta-analysis

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2013年第45期19卷 8427-8434页

作者： yu-Biao xu yu-long Bai Zhi-Gang Min Shan-yu Qin Department of General Surgery Jiangbin Hospital of Guangxi Zhuang Autonomous Region the First Affiliated Hospital of Guangxi Medical University Department of Radiology the First Affiliated Hospital of Xi’an Jiaotong University

AIM:To establish the role of magnetic resonance cholangiography(MRC)in diagnosis of biliary anatomy in living-donor liver transplantation(LDLT)***:A systematic review was performed by searching electronic bibliographic databases prior to March *** with diagnostic results and fulfilled inclusion criteria were *** methodological quality of the studies was ***,specificity and other measures of the accuracy of MRC for diagnosis of biliary anatomy in LDLT donors were summarized using a random-effects model or a fixed-effects *** receiver operating characteristic(SROC)curves were used to summarize overall test *** bias was assessed using Deek’s funnel plot asymmetry *** analysis was adopted to explore the potential sources of ***:Twelve studies involving 869 subjects were eligible to the *** scores of Quality Assessment of Diagnostic Accuracy Studies for the included studies ranged from 11 to *** summary estimates of sensitivity,specificity,positive likelihood ratio,negative likelihood ratio,diagnostic OR of MRC in diagnosis of biliary anatomy in LDLT donor were 0.88(95%CI:0.84-0.92),0.95(95%CI:0.93-0.97),15.33(95%CI:10.70-21.95),0.15(95%CI:0.11-0.20)and 130.77(95%CI:75.91-225.27),*** significant heterogeneity was detected in all the above four *** under SROC curve was *** publication bias was noted across the studies(P=0.557).Sensitivity analysis excluding a study with possible heterogeneity got a similar overall result,which suggested the little influence of this study on the overall ***:Our results suggest that MRC is a high specificity but moderate sensitivity technique in diagnosis of biliary anatomy in LDLT donors.

关键词： Magnetic resonance imaging Cholangiography Biliary Anatomy Living donors

Highly stable Eu-coordination polymer exhibiting the highest quantum yield

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 2023年第5期66卷 1400-1405页

作者： Ming-yu Ye Ming-xuan Zhang Qiao-Fei xu Han xu La-Sheng long Lan-Sun Zheng State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry College of Chemistry and Chemical EngineeringXiamenUniversityXiamen361005China

Lanthanide luminescent materials with high quantum yield and thermal stability are of key importance for their practical *** we report crystal structures and luminescent properties of[Eu(pfbz)_(2)(phen)Cl](1)and[Tb(pfbz)2(phen)Cl](2)(pfbz=Pentafluorobenzoate).Single-crystal analysis reveals that both 1 and 2 crystallize in a polar space group of *** on their luminescent properties indicates that the solid-state quantum yields of 1 and 2 are 97.7%and 90.7%,respectively,while their efficiency of the sensitization process is as high as 100%,revealing that polar structures are more favorable to obtain high quantum *** analysis reveals that both 1 and 2 can be stable up to 240℃.More importantly,temperature-dependent luminescent spectra of 1 indicate its luminescent intensity at 612 nm only decreased by 5%from room temperature to 373 K,whereas at 373 K,its luminescent intensity remains almost constant for 36 *** that1 represents the highest quantum yield among known Eu-coordination polymers and its performance as the LED material is better than that of commercially widely used luminescent materials of(Sr,Ca)Al Si N3:Eu(630 nm)and(Sr,Ca)Al Si N3:Eu(640 nm),the present work provides an excellent substitute for commercial LED materials.

关键词： lanthanide coordination polymers luminescence LED materials

Characterization of condensed phase nitric acid particles formed in the gas phase

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2011年第3期23卷 412-418页

作者： long Jia Yongfu xu State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The formation of nitric acid hydrates has been observed in a chamber during the dark reaction of NO2 with O3 in the presence of air. The size of condensed phase nitric acid was measured to be 40-100 nm and 20-65 nm at relative humidity （RH） ≤ 5% and RH = 67% under our experimental conditions, respectively. The nitric acid particles were collected on the glass fiber membrane and their chemical compositions were analyzed by infrared spectrum. The main components of nitric acid hydrates in particles are HNO3.3H2O and NO3-.xH2O （x≥ 4） at low RH, whereas at high RH HNO3.H2O, HNO3-2H2O, HNO3.3H2O and NO3--xH20 （x≥ 4） all exist in the condensed phase. At high RH ***2O （x ≤3） collected on the glass fiber membrane is greatly increased, while NO3-.xH2O （x ≥ 4） decreased, compared with low RH. To the best of our knowledge, this is the first time to report that condensed phase nitric acid can be generated in the gas phase at room temperature.

关键词： nitric acid particles relative humidity chamber