检索结果-南通市图书馆

Ground State Solutions for a Class of Choquard Equations Involving Doubly Critical Exponents

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

Acta Mathematicae Applicatae Sinica 2021年第4期37卷 820-840页

作者： Yong-yong li gui-dong li Chun-lei TANG School of Mathematics and Statistics Southwest UniversityChongqing400715China College of Mathematics and Statistics Northwest Normal UniversityLanzhou730070China

In this paper,we are concerned with the autonomous Choquard equation−Δu+u=(Iα∗|u|^(α/N+1))|u|^(α/N−1)u+|u|^(2∗−2)u+f(u)inR^(N),where N≥3,Iαdenotes the Riesz potential of orderα∈(0,N),the exponentsα/N+1 and 2^(∗)=2N/(N−2)are critical with respect to the Hardy-littlewood-Sobolev inequality and Sobolev embedding,*** on the variational methods,by using the minimax principles and the Pohožaev manifold method,we prove the existence of ground state solution under some suitable assumptions on the perturbation f.

关键词： choquard equation doubly critical exponents ground state solution

Evolution of a Long-lived Sunspot Group and Its Associated Solar-terrestrial Events

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2005年第1期5卷 77-86页

作者： gui-QingZhang li-RongTian NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012

A long-lived sunspot group (AR9604) on the south hemisphere that lasted five solar rotations and produced some strong bursts is analyzed. The focus is on its evolving features. Its whole life was successfully maintained by four Emerging Flux Regions (EFRs). Apart from the one that lasted only a short time and did not produce any bursts, the other three EFRs have the following common features: (1) A positive writhe of magnetic flux tubes and a twist of the field lines of the same sign, indicating kink instability. (2) A clockwise rotation and a high tilt because the writhe was right-handed. (3) A compact 'island δ' structure of the sunspot group indicating concentrated kink instability. Since magnetic reconnection easily occurs at the kinked point of a very kink-unstable flux tube, these features should be the inducement of the strong bursts.

关键词： Sun - active region evolution

Jasmonic acid alleviates cadmium toxicity in Arabidopsis via suppression of cadmium uptake and translocation

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2020年第2期62卷 218-227页

作者： gui Jie Lei li Sun Ying Sun Xiao Fang Zhu gui Xin li Shao Jian Zheng State Key Laboratory of Plant Physiology and Biochemistry College of Life SciencesZhejiang UniversityHangzhou 310058China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China College of Agronomy and Biotechnology Zhejiang UniversityHangzhou 310058China

Jasmonic acid(JA)is thought to be involved in plant responses to cadmium(Cd)stress,but the underlying molecular mechanisms are poorly ***,we show that Cd treatment rapidly induces the expression of genes promoting endogenous JA synthesis,and subsequently increases the JA concentration in Arabidopsis ***,exogenous methyl jasmonate(MeJA)alleviates Cd-generated chlorosis of new leaves by decreasing the Cd concentration in root cell sap and shoot,and decreasing the expression of the AtIRT1,AtHMA2 and AtHMA4 genes promoting Cd uptake and long-distance translocation,*** contrast,mutation of a key JA synthesis gene,At AOS,greatly enhances the expression of AtIRT1,AtHMA2 and AtHMA4,increases Cd concentration in both roots and shoots,and confers increased sensitivity to *** Me JA recovers the enhanced Cd-sensitivity of the ataos mutant,but not of atcoi1,a JA receptor *** addition,exogenous Me JA reduces NO levels in Cd-stressed Arabidopsis root *** together,our results suggest that Cd-induced JA acts via the JA signaling pathway and its effects on NO levels to positively restrict Cd accumulation and alleviates Cd toxicity in Arabidopsis via suppression of the expression of genes promoting Cd uptake and long-distance translocation.

关键词： Jasmonic acid cadmium uptake translocation

Effect of printing parameters on properties of 3D printing sand samples

在线全文

学校读者我要写书评

暂无评论

China Foundry 2023年第6期20卷 553-562页

作者： De-quan Shi Yin-yu Hou gui-li Gao School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China School of Mechanical and Energy Engineering Shanghai Technical Institute of Electronics and InformationShanghai 201411China

Three-dimensional sand printing(3DSP)is widely applied in sand mold *** this study,the effects of printing parameters including the resolution of printehead holes,activator content,layer thickness,and recoating speed on the tensile and bending strengths,gas evolution,and loss-on-ignition(LOI)of 3DSP samples were investigated by changing single parameter,and the dimension deviation was also *** the resolution increases,the tensile strength,bending strength,gas evolution,LOI,and deviations at X-and Y-axis directions decrease gradually while the deviation at Z-axis direction firstly increases and then *** gas evolution and LOI drops by 13.02%and 8.13%respectively,but the strength only reduces by 2.2% when the resolution increases from 0.08 mm to 0.09 *** strengths of samples rise at first and then decline while the gas evolution and LOI rise gradually with the increasing activator content or recoating *** activator content is found to have little effect on the gas evolution as the activator increases from 0.14%to 0.34%,the gas evolution is increased by 7.3%which is far less than the LOI increment of 24.1%.As the layer thickness increases,the tensile and bending strengths firstly rise and then drop while gas evolution and LOI *** the optimal printing parameters of 0.09 mm resolution,0.18%activator,0.28 mm layer thickness and 160 mm·s^(-1) recoating speed,the tensile strengths for X-sample and Y-sample are 1.48 MPa and 1.37 MPa,the bending strengths are 1.84 MPa and 1.75 MPa,the gas evolution and LOI are 9.62 mL·g^(-1) and 1.92%,respectively.

关键词： three-dimensional sand printing printing parameters mechanical properties LOI

Continuous Flow Reactor for Hydroxylation of Benzene to Phenol by Hydrogen Peroxide

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2012年第5期25卷 585-591,I0004页

作者： li Zhang Hui-hui liu gui-ying li Chang-wei Hu Key Laboratory of Green Chemlstry and Technology Ministry of Education College of Chemlstry Sichuan University Chengdu 610064 China

The direct hydroxylation of benzene to phenol catalyzed by activated carbon-supported Fe （Fe/AC） in acetonitrile using H2O2 as the oxidant was studied in a continuous flow reactor. Results showed that the continuous operation could obtain high phenol yield of 28.1%, coupled with the turnover frequency of 3 h^-1, and high selectivity of 98% under mild condition. The catalyst was characterized by N2 adsorption/desorption, Boehm titration, X-ray photoelectron spectra, and Fourier transform infrared spectroscopy. It was observed that iron may interact with the carboxyl group forming iron-carboxylate like species, which act as the active phase. The apparent activation energy obtained by fitting an Arrhenius model to the experimental data was 13.4 kJ/mol. The reaction order was calculated to be about i, 0.2 for benzene and 0.7 for H202.

关键词： Continuous flow reactor Hydroxylation Activated carbon Iron-carboxylate Active phase Activation energy

Effect of arc sprayed coatings on tensile properties of a type 316 steel

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

中国有色金属学会会刊：英文版 2004年第Z1期14卷 95-99页

作者： liU gui-min MA li-li K.J.Kurzydlowski Faculty of Materials Science and Engineering Academy of Armored Force EngineeringBeijing 100072 China Faculty of Materials Science and Engineering Academy of Armored Force EngineeringBeijing 100072 China Faculty of Materials Science and Engineering Warsaw University of Technology Warsaw Poland

The effect of Al- and AlSiRE-coatings obtained by arc spray (AS) and high velocity arc spray (HVAS) technologies, on the tensile properties of type 316 steel specimens strained at elevated temperatures in air and vacuum has been systematically investigated. It is found that both temperature and environment play an important role in determining the mechanical properties of the coated 316 steel specimens strained at elevated temperatures. And the quantitative changes of surface roughness of coatings before and after straining correspond to the mechanical properties of the 316 steel substrate.

关键词： type 316 steel arc spray high velocity arc spray coating tensile property

Dynamic and Static Recrystallization Behaviour of Coarse-grained Austenite in a Nb-V-Ti Microalloyed Steel

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

Journal of Iron and Steel Research International 2014年第2期21卷 233-239页

作者： Qing-yun SHA Da-hang li gui-yan li Technology Center Angang Steel Company Limited

The dynamic recrystallization （DRX） and static recrystallization （SRX） behaviour of coarse-grained aus- tenite in a Nb-V-Ti microalloyed steel were studied by using a Gleeble thermomechanical simulator. Continuous and interrupted compression tests of coarse-grained austenite were performed in the temperature range of 1000-1 150 ℃ at a strain rate of 0. 1- 5 s 1. The peak and critical strains for the onset of DRX were identified with strain hardening rate analysis, and the ratio of critical strain to peak strain was found to be consistent with the one reported for fine- grained austenite. An equation of the time for 50% softening was proposed by considering the activation energy of steel without microalloying elements and the solute drag effect of microalloying elements. Strain-induced precipitation may not take place at the deformation temperature above 1000 ℃, which indicates that SRX of coarse-grained aus- tenite is mainly retarded by coarse grain size and Nb in solution during rough rolling.

关键词： coarse-grained austenite dynamic recrystallization static recrystallization critical strain time for 50%softening

Effect of pipe material and low level disinfectants on biofilm development in a simulated drinking water distribution system

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 725-731页

作者： ling-ling ZHOU Yong-ji ZHANG gui-bai li School of Municipal Environmental Engineering Harbin Institute of Technology Harbin 150090 China State Key Laboratory of Pollution Control and Resources Reuse Tongji University Shanghai 200092 China

The efficiency of chlorine and chloramines disinfection on biofilm development in a simulated drinking water distribution system was investigated by using heterotrophic bacterial spread plate technique. The experiments were carried out with four annular reactors (ARs) with stainless steel (SS) or copper (Cu) material slides. The results showed that there were fewer bacteria attached to Cu slides without a disinfectant compared with those attached to SS slides. When the water was disinfected with chloramines, the heterotrophic plate counts (HPCs) on the biofilm attached to the Cu slides were significantly lower (by 3.46 log CFU/cm2) than those attached to the SS slides. likewise, the biofilm HPC numbers on the Cu slides were slightly lower (by 1.19 log CFU/cm2) than those on the SS slides disinfected with chlorine. In a quasi-steady state, the HPC levels on Cu slides can be reduced to 3.0 log CFU/cm2 with chlorine and to about 0.9 log CFU/cm2 with chloramines. The addition of chloramines resulted in a more efficient reduction of biofilm heterotrophic bacteria than did chlorine. We concluded that the chlorine and chloramines levels usually employed in water distribution system were not sufficient to prevent the growth and development of microbial biofilm. The combination of copper pipe slides and chloramines as the disinfectant was the most efficient combination to bring about diminished bacterial levels.

关键词： Copper (Cu) Stainless steel (SS) Biofilm Heterotrophic plate counts (HPCs) Chlorine Chloramines

Microbes as a production host to produce natural active compounds from mushrooms:biosynthetic pathway elucidation and metabolic engineering

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2021年第8期19卷 580-590页

作者： YANG li-Yang GONG Qiang GUO Jian-Quan li gui-Lan School of Basic Medical Sciences Shanxi University of Chinese MedicineJinzhong 030619China School of Public Health Shanxi Medical UniversityTaiyuan 030001China

Mushrooms are abundant in bioactive natural *** to strict growth conditions and long fermentation-time,microbe as a production host is an alternative and sustainable approach for the production of natural *** review focuses on the biosynthetic pathways of mushroom originated natural compounds and microbes as the production host for the production of the above natural compounds.

关键词： Mushroom Natural compound Microbes Synthetic biology Metabolic engineering