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Theoretical Investigation on Regioselectivities of Diels-Alder Reactions by Conjugated Effect

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Chinese Journal of Chemistry 2020年第12期38卷 1696-1702页

作者： Zhen-Zhen Xu Jian zhao dong-xia zhao Zhong-Zhi Yang Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution and School of Chemistry Biology and Materials ScienceEast China University of TechnologyNonchangJiangxi 330013China School of Chemistry and Chemical Engineering Liaoning Normal UniversityDalianLiaoning 116029China

of main observation and conclusion The regioselectivities of 76 Diels-Alder reactions between unsymmetrical dienes and dienophiles were investigated by local softness and generalized local softness at atomic and chemical bond view,respectively,where the reactivity descriptors were calculated by finite difference approximation and ABEEMan *** on local HSAB principle and matching criterion of local softness,reasonable explanation and prediction on regioselectivities of all reactions through ABEEMan model have been obtained,which are in agreement with the experimental ***,at n-bond level,while the 1-substituents of dienes were NH2/NMe2,and NEt2/because of the p-R conjugated effect between the lone pairs of Natom and the conjugated n-bond of the four double-bonded carbon atoms in diene,it made the dienophile not easy to approach diene by Manner A,hence,Manner B can forecast the ortho regioisomer as main product well,and Manner A *** to the other reactions,both Manner A and Manner B can predict their *** can be seen that the ABEEMan model can take the effect of the chemical environment on the reaction reactivity into account richly,especially the system includes n-bond and lone ***,the results through the finite difference approximation are not reasonable.

关键词： reactivity conjugated approximation

Rationalization of regioselectivity of electrophilic substitution reaction for cyclic compounds in terms of D_(pb) values

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Chinese Chemical Letters 2015年第5期26卷 553-556页

作者： Yang Liu Zhong-Zhi Yang dong-xia zhao School of Chemistry and Chemical Engineering Liaoning Normal University

Accepted theories predict that substitution reactions are controlled by the electronic nature of the attacked site for electrophilic aromatic substitution. Here it is shown that in addition the bond strength of the broken bond may also influence the regioselectivity of the substitution reaction, and that the Dpb is a good indicator of the strength of a chemical bond. The Dpb denotes the depth of the potential acting on one electron in a molecule at the bond center （bc）. In this letter, the values of Dpb along the C-H and N-H bonds have been investigated, and it is demonstrated that for aromatic compounds, the regioselectivity of the electrophilic substitution can well be rationalized in terms of Dpb values.

关键词： Dpb Substitution reaction Regioselectivity Bond strength

An investigation of crambin and BPTI based on ABEEM/MM model

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Chinese Chemical Letters 2007年第12期18卷 1554-1556页

作者： Qing Mei Guan dong xia zhao Zhong Zhi Yang Department of Chemistry Liaoning Normal University Dalian 116029 China

Molecular dynamics simulation studies on crambin, BPTI （298 K, in vacuo） have been performed by ABEEM/MM method. Some structural properties were discussed. The results show fair consistency with those from X-ray exp... 详细信息

关键词： ABEEM/MM method Crambin BPTI Molecular dynamics simulations

Theoretical investigation of the stereoselectivity of some Diels-Alder reactions involving cyclopentadiene

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Chinese Chemical Letters 2008年第9期19卷 1135-1138页

作者： dong xia zhao Zhen Zhen Xu Zhong Zhi Yang College of Chemistry and Chemical Engineering Liaoning Normal University Dalian 116029 China

The stereoselectivity of some Diels-Alder reactions was investigated by means of ABEEM-oTr model. Combined with local hard-soft and acid-base （HSAB） principle, we made reasonable explanation by calculating local sof... 详细信息

关键词： ABEEM-σπ model Diels--Alder reaction Stereoselectivity Local softness

Exponential Stability of a Coupled Heat-ODE System

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Exponential Stability of a Coupled Heat-ODE System

Experimental study on asphaltene precipitation induced by CO_2 flooding

第25届中国控制与决策会议

作者： dong-xia zhao Jun-Min Wang the Department of Mathematics Beijing Institute of Technology the Department of Mathematics North University of China the Department of Mathematics Beijing Institute of Technology

ISBN: (纸本)9781467355339

This paper addresses the feedback stabilization of an interconnected Heat-ODE system with the Dirichlet interconnection. The "interconnection" between the heat equation and the ODE are bi-directional, in which the Dirichlet boundary observation of the heat equation is fed into the ODE, and the velocity of ODE is flowed into the boundary of the heat equation. The semigroup approach is adopted in investigation. By a detailed analysis, we obtain the asymptotic expressions of eigenvalues and eigenfunctions. It is shown that there is a sequence of generalized eigenfunctions, which forms a Riesz basis for the Hilbert state space. This deduces the spectrumdetermined growth condition for the C0-semigroup, and as a consequence, the exponential stability of the system is then followed. Numerical simulations are presented.

关键词： Heat equation Dirichlet interconnection Riesz basis Exponential stability

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Petroleum Science 2014年第1期11卷 174-180页

作者： dong zhao-xia WANG Jun LIU Gang LIN Mei-qin LI Ming-yuan Enhanced Oil Recovery Research Institute China University of Petroleum Beijing Key Laboratory for Greenhouse Gas Storage and Enhanced Oil Recovery Key Laboratory of Enhanced Oil Recovery CNPC

The effects of CO2 pressure,temperature and concentration on asphaltene precipitation induced by CO2 were studied using a high-pressure vessel,interfacial tensiometer,Fourier transform infrared （FTIR） and drill core displacement experimental *** results indicated that the content of asphaltene in crude oil decreased,and the interfacial tension between a model oil and distilled water increased,with an increase of CO2 pressure,decrease of temperature and increase of molar ratio of CO2 to crude oil when CO2 contacted crude oil in the high pressure *** content of asphaltene in sweepout oil and the permeability of test cores both also decreased with an increase of CO2 flooding *** main reason for changes in content of asphaltene in crude oil,in interfacial tension between model oil and distilled water and in the permeability of the test core is the precipitation of asphaltene which is an interfacially active substance in crude *** of asphaltene also blocks pores in the drill core which decreases the permeability.

关键词： CO2 flooding asphaltene precipitation oil-water interfacial tension core permeability

Influence of dissolved oxygen content on oxidative stability of linked polymer solution

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Petroleum Science 2009年第4期6卷 421-425页

作者： zhao-xia dong Mei-qin Lin Jian Xin Ming-yuan Li China Univ Petr Enhanced Oil Recovery Res Ctr Beijing 102249 Peoples R China

The influence of dissolved oxygen content on the oxidative stability of a linked polymer solution (LPS) was studied by micro-filtration, dynamic light scattering and viscosity measurements. The results showed that at the same temperature, the degree of the oxidative degradation of the LPS increased and the rapidity of the oxidative degradation was accelerated with the increase of the dissolved oxygen content. Consequently, the size of linked polymer coils (LPCs) of the LPS became small, and the plugging capability of the LPS decreased. At a fixed content of dissolved oxygen, with increasing degradation temperature, almost the same results were observed, namely, an increased degree of oxidative degradation, accelerated rapidity of the oxidative degradation and decreased plugging capacity, with decreased oxidative stability of LPS. At 90 °C, in the presence of oxygen, LPS lost its plugging capability after having been degraded for a period of time. But at 40 °C, LPS with low dissolved oxygen content could be stable for a long time. The decreased plugging ability of LPS after oxidative degradation is mainly caused by the decreased size and number of the LPCs due to the breaking of hydrolyzed polyacrylamide (HPAM) molecule segments and the structural changing of HPAM molecules.

关键词： Linked polymer solution HPAM content of dissolved oxygen degradation stability

Protein-mimicking nanoparticle(Protmin)-based nanosensor for intracellular analysis of metal ions

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Nuclear Science and Techniques 2018年第1期29卷 82-89页

作者： Dan Zhu dong-xia zhao Jia-Xuan Huang Jiang Li xiao-Lei Zuo Li-Hua Wang Chun-Hai Fan Division of Physical Biology and Bioimaging Center Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of Sciences Key Laboratory for Organic Electronics and Information Displays Institute of Advanced Materials (IAM) Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM) Jiangsu Key Laboratory for BiosensorNanjing University of Posts and Telecommunications

In this study, we designed and applied proteinmimicking nanoparticles(Protmin) as an intracellular nanosensor for in vivo detection of lead ions(Pb^(2+)).Monodispersed gold nanoparticles(Au NPs) of 13 nm in diameter were modified using poly-adenine-tailed Pb^(2+)-specific 8–17 DNAzyme to form a spherical and functional Protmin. Substrate strands modified with a fluorophore at the 50 end and a quencher at the 30 end were bound to DNAzyme. Pb^(2+) facilitated cleavage of DNAzyme to release the fluorophore-modified short strands to generate fluorescence. We observed rapid kinetics of the Protmin nanosensor, for which the typical assay time was 10 ***, we demonstrated the Protmin nanosensor could readily enter living cells and respond to Pb^(2+) in the intracellular environment. The broad of range of Protmindesigns will be useful for advancing biological and medical applications.

关键词： Protmin Nanosensor Poly-adenine Lead ion Intracellular detection

Tissue Doppler imaging study of right ventricular myocardial systolic activation in subjects with pulmonary arterial hypertension

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Chinese Medical Journal 2007年第13期120卷 1172-1175页

作者： YOU xiang-dong PU zhao-xia PENG xian-jing ZHENG Sheng-zhou Department of Ultrasound Second Affiliated Hospital Zhejiang University College of Medicine Hangzhou 310009 China

Background Tissue Doppler imaging （TDI） has provided an objective means to quantify global and regional left ventricular （LV） and right ventricular （RV） function with improved accuracy and greater reproducibility than conventional echocardiography. This study was conducted to assess RV myocardial systolic activation by TDI in subjects with pulmonary arterial hypertension （PAH）. Methods A total of 30 patients with PAH and 30 healthy volunteers, all comparable in age and sex, underwent standard Doppler echo and TDI. Using pulsed Doppler echocardiography combined with TDI, the following regional parameters were evaluated in three different myocardial segments （RV basal lateral wall, basal septal, and LV basal lateral） on apical 4-chamber view： systolic （Sm）, early- and late-diastolic （Em and Am） peak velocities. RV myocardial systolic activation delay was defined as the difference in time to peak TDI systolic velocities between the RV basal lateral wall and basal septal. In addition, RV end-diastolic and end-systolic areas were measured to calculate RV fractional area change from the same apical 4-chamber view. Results Compared with the control group, patients with PAH showed increased RA and RV end-diastolic diameter （RA：（4.5±1.2）cm vs （3.0±0.8）cm, P〈0.05 and RV：（4.8±1.9）cm vs （3.4±0.5）cm, P〈0.05） and reduced RV fractional area change; （35±14）% vs （56±9）%, P〈0.05. These PAH patients showed lower myocardial peak velocities and a significant activation delay compared with controls （P〈0.05）. Moreover, a strong correlation between RV myocardial systolic activation delay and RV fractional area change was shown in patients with pulmonary arterial hypertension （r = -0.82）. Conclusions In PAH, RV myocardial systolic activation was markedly delayed, which was directly related to the RV fractional area change. RV myocardial systolic activation delay assessed by TDI could offer a unique approach to predict RV dysfunction.

关键词： tissue Doppler imaging pulmonary arterial hypertension right ventricular dysfunction