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Chinese Physics B 2012年第5期21卷 6-10页

作者：王肖肖孙现亭张美玲韩月林贾利群 School of Science Jiangnan University School of Electric and Information Engineering Pingdingshan University

The mei symmetry and the mei conserved quantity of Appell equations in a dynamical system of relative motion with non-Chetaev nonholonomic constraints are *** differential equations of motion of the Appell equation for the system,the definition and the criterion of the mei symmetry,and the expression of the mei conserved quantity deduced directly from the mei symmetry for the system are *** example is given to illustrate the application of the results.

关键词： non-Chetaev nonholonomic constrained system dynamics of relative motion Appell equation mei conserved quantity

Crystal Structure of a 4-Methyl-phenylacetylide-bridged Pt^(II)Cu^_(2)^(I) Heterotrinuclear Organometallic Complex

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Chinese Journal of Structural Chemistry 2004年第10期23卷 1103-1106页

作者： WU mei-mei CHEN Zhong-Ning State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterThe Chinese Academy of SciencesFuzhouFujian 350002China Graduate School of the Chinese Academy of Sciences Beijing 100039China

The heterotrinuclear complex [PtCu2(m-dppm)2(dmbpy)2(m-h1,h2 C CPhCH3-4)2] (ClO4)21.5CH2Cl2 1 (dmbpy = 4,4-dimethyl-2,2?bipyridine, dppm = bis(diphenylphosphino)meth- ane) has been prepared and characterized by X-ray crystallography. The complex crystallizes in the triclinic system, space group P with a = 12.9359(3), b = 14.3908(2), c = 15.2121(3) ? α = 107.370(1), β = 93.539(1), γ = 108.207(1), V = 2529.59(8) ?, Mr = 2015.96, Z = 1, Dc = 1.323 g/cm3, F(000) = 1019, m(MoKa) = 2.042 mm-1, the final R = 0.0604 and wR = 0.1529 for 8002 observed reflections with I > 2σ(I). The 4-methylphenylacetylides are bonded to the PtII and CuI centers in η1 (s) and η2 (p) coordination modes, respectively. The PtII atom is linked by one dppm bridge to adopt a square planar environment and CuI by one alkynyl ligand to assume a distorted tetrahedral geometry.

关键词： copper crystal structure 4,4'dimethyl-2,2'bipyridine 4-methyl-phenylacetylene platinum

Impact of the Return Flow on Heavy Pollution in Winter over the Beijing–Tianjin–Hebei Region

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Journal of Meteorological Research 2023年第3期37卷 370-386页

作者： mei mei Yihui DING Zunya WANG Chinese Academy of Meteorological Sciences China Meteorological Administration(CMA)Beijing 100081 University of Chinese Academy of Sciences Beijing 100049 Laboratory for Climate Studies/CMA–NJU Joint Laboratory for Climate Prediction Studies National Climate CentreChina Meteorological AdministrationBeijing 100081 National Climate Centre China Meteorological AdministrationBeijing 100081

In North China,the return flow(RF)refers to the airflow at the rear of an inshore high pressure,bringing southerly wind to the Beijing–Tianjin–Hebei(BTH)region when the high pressure pushes deeper from coast into the *** studies have pointed out the significant contribution of southerly anomalies to the transport and accumulation of pollutants in the BTH ***,the relationship between RF and heavy pollution episodes(HPEs)in the BTH region requires more in-depth analysis,and this study will focus on this *** objectively identifying RFs and HPEs based on the ERA5 reanalysis data and observed hourly PM_(2.5)concentration data during 9 winters of 2012–2020,it is found that almost two-thirds of the HPEs in the BTH region coincide with the occurrence of *** northward transport of warm and humid air is stronger in the HPEs under RF conditions,whereas the sinking motion and the decrease in boundary layer height dominate the HPEs without any *** then classify the RFs into north and south types by a demarcation line of 32°*** types of RFs are featured with a zonal circulation pattern,stable atmosphere,and southerly airflow favoring the development of HPEs,but the south type RFs bring warmer and wetter air masses to the BTH region,forming a more stable and thicker inversion layer and causing more severe *** occurrences of the RF,low-level winds are observed to accelerate,and the ageostrophic wind components contribute mainly to this *** the presence of RFs,the kinetic energy generation at the high level decreases,and the weakened downward transport results in weak low-level northerly winds,weak turbulence,and a shallow boundary layer,thus hindering the diffusion of atmospheric pollutants in the BTH region.

关键词： the Beijing-Tianjin-Hebei region return flow heavy pollution episode PM2.5

Hierarchical hesitant fuzzy K-means clustering algorithm

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Applied Mathematics(A Journal of Chinese Universities) 2014年第1期29卷 1-17页

作者： CHEN Na XU Ze-shui XIA mei-mei School of Economics and Management Southeast University School of Applied Mathematics Nanjing University of Finance and Economics Business School Sichuan University School of Economics and Management Tsinghua University

Due to the limitation and hesitation in one＇s knowledge, the membership degree of an element to a given set usually has a few different values, in which the conventional fuzzy sets are invalid. Hesitant fuzzy sets are a powerful tool to treat this case. The present paper focuses on investigating the clustering technique for hesitant fuzzy sets based on the K-means clustering algorithm which takes the results of hierarchical clustering as the initial clusters. Finally, two examples demonstrate the validity of our algorithm.

关键词： 90B50 68T10 62H30 Hesitant fuzzy set hierarchical clustering K-means clustering intuitionisitc fuzzy set

An automated method for glacial lake mapping in High Mountain Asia using Landsat 8 imagery

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Journal of Mountain Science 2018年第1期15卷 13-24页

作者： ZHANG mei-mei CHEN Fang TIAN Bang-sen Key Laboratory of Digital Earth Science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences No. 9 Dengzhuang South Road Beijing 100094 China University of Chinese Academy of Sciences Beijing 100049 China Hainan Key Laboratory of Earth Observation Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Sanya 572029 China

Glacial lakes in the High Mountain Asia(HMA)are sensitive to global warming and can result in much more severe flood disasters than some largesized *** accurate and robust method for the extraction of glacial lakes is critical to effective management of these natural water *** methods often have limitations in terms of low spectral contrast and heterogeneous backgrounds in an *** study presents a robust and automated method for the yearly mapping of glacial lake over a large scale,which took advantage of the complementarity between the modified normalized difference water index(MNDWI)and the nonlocal active contour model,required only local homogeneity in reflectance features of *** cloud computing approach with the Google Earth Engine(GEE)platform was used to process the intensive amount of Landsat 8 images from 2015 (344 path/rows and approximately 7504 scenes).The experimental results were validated by very high resolution images from Chinese GaoFen-1 (GF-1) panchromatic multi-spectral(PMS)and appeared a general good *** is the first time that information regarding the spatial distribution of glacial lakes over the HMA has been derived automatically within quite a short period of *** integrating it with the relevant indices,it can also be applied to detect other land cover types such as snow or vegetation with improved accuracy.

关键词： Glacial lake Landsat 8 Modified Normalized Difference Water Index Nonlocal active contour

Oxidative stress and DNA damages induced by cadmium accumulation

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Journal of Environmental Sciences 2007年第5期19卷 596-602页

作者： LIN Ai-jun ZHANG Xu-hong CHEN mei-mei CAO Qing Department of Environmental Science and Engineering Beijing University of Chemical Technology Beijing 100029 China Department of Soil Environmental Sciences Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Beijing City University Beijing 100083 China

Experimental evidence shows that cadmium （Cd） could induce oxidative stress and then causes DNA damage in animal cells, however, whether such effect exists in plants is still unclear. In the present study, Vicia faba plants was exposed to 5 and 10 mg/L Cd for 4 d to investigate the distribution of Cd in plant, the metal effects on the cell lipids, antioxidative enzymes and DNA damages in leaves. Cd induced an increase in Cd concentrations in plants. An enhanced level of lipid peroxidation in leaves and an enhanced concentration of H2O2 in root tissues suggested that Cd caused oxidative stress in Vicia faba. Compared with control, Cd-induced enhancement in superoxide dismutase activity was significant at 5 mg/L than at 10 mg/kg in leaves, by contrast, catalase and peroxidaseactivities were significantly suppressed by Cd addition. DNA damage was detected by neutral/neutral, alkaline/neutral and alkaline/alkaline Comet assay. Increased levels of DNA damages induced by Cd occurred with reference to oxidative stress in leaves, therefore, oxidative stress induced by Cd accumulation in plants contributed to DNA damages and was possibly an important mechanism of Cd-phytotoxicity in Vicia faba plants.

关键词： Cd Vicia faba oxidative stress DNA damage

Aromatic Polyimides with Tertbutyl-substituted and Pendent Naphthalene Units:Synthesis and Soluble,Transparent Properties

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Chinese Journal of Polymer Science 2015年第8期33卷 1074-1085页

作者： Chan-juan Liu mei mei Xiang-lin Pei 黄孝华 Chun Wei Key Laboratory of New Processing Technology for Nonferrous Metal & Materials Ministry of Educationand School of Material Science and EngineeringGuilin University of Technology Ministry of Education Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources School of Chemistry and Pharmaceutical ScienceGuangxi Normal University

A novel non-coplanar aromatic diamine monomer, 3,3＇-ditertbutyl-4,4＇-diaminodiphenyl-4＂-naphthylmethane （TAPN） was synthesized by a condensation reaction of 2-tertbutylaniline and 1-naphthaldehyde under catalyst hydrochloric acid. The structure of the monomer was confirmed by FTIR, NMR, elementary analysis and mass spectrometry. A series of aromatic polyimides （PIs） were synthesized via conventional one-step polycondensation from TAPN and various commercial aromatic dianhydrides. All of the PIs exhibit excellent solubility in common organic solvents, even in low boiling point solvents such as chloroform （CHC13）, tetrahydrofuran （THF） and acetone. The PIs present outstanding thermal stability with the glass transition temperature （Tg） ranged from 299 ℃ to 350 ℃, and the temperature at 10% weight loss ranged from 490 ℃ to 504 ℃, and high optical transparency with the cutoff wavelengths of 306-356 nm. Moreover, the flexible and tough PI films have prominent mechanical properties with tensile strengths in the range of 77.6-90.5 MPa, tensile modulus in the range of 1.8-2.4 GPa and elongation at break in the range of 6.3%-9.5%, as well as lower dielectric constant （2.89-3.12 at 1 MHz） and lower moisture absorption （0.35%-0.66%）.

关键词： Polyimides Solubility Dielectric constant Tertbutyl Naphthyl.

Electrohydrodynamic behaviors of droplet under a uniform direct current electric field

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Chinese Physics B 2020年第3期29卷 312-317页

作者： Zi-Long Deng mei-mei Sun Cheng Yu Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Department of Mechanical Engineering University of Hawaii at ManoaHonolulu 96822USA

The electrohydrodynamic behaviors and evolution processes of silicone oil droplet in castor oil under uniform direct current(DC)electric field are visually observed based on a high-speed microscopic ***,the effects of different working conditions,such as electric field strength,droplet size,etc.,on droplet behaviors are roundly *** can be found that there are four droplet behavior modes,including Taylor deformation,typical oblique rotation,periodic oscillation,and fracture,which change with the increase of electric field *** is also demonstrated that the degree of flat ellipse deformation gets larger under a stronger electric ***,both of the stronger electric field and smaller droplet size lead to an increase in the rotation angle of the droplet.

关键词： DC electric field droplet deformation rotation

Clay-Supported Molybdenum-Based Catalysts for Higher Alcohol Synthesis from Syngas

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： Gai-mei Wu Ji-long Zhou mei-mei Lv Wei Xie Song Sun Chen Gao Wen-dong Wang Department of Chemical Physics University of Science and Technology of China Hefei 230026China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

A kind of clay-supported K-Co-Mo catalyst was prepared by a sol-gel method combined with incipient wetness impregnation. The catalyst structure was characterized by X-ray diffraction, N2 adsorption-desorption, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy techniques and its catalytic performance for higher alcohol synthesis from syngas was investigated. The active components has a high dispersion on the clay support surface. The increase of the Mo loading promoted reduction of Mo6+ but had no significant influence on the reduction of Mo4+ and Co2+ species. After reduction, a kind of lower state Moδ+ (1<δ<4) species was observed on the surface. Compared with the unsupported catalyst, the clay supported K-Co-Mo catalysts showed much higher catalytic performance for alcohol formation. The reason can be explained that the supported catalyst have a high active surface area and the mesoporous structure prolonged the residence time of intermediates for alcohol formation to some extent, which promoted the formation of higher alcohols. The high activity of the catalyst reduced at 773 K may be attributed to the high content of Moδ+ (1<δ<4) species on the surface, which was regarded as the active site for the adsorption of nondissociative CO and responsible for the alcohol formation.

关键词： Higher alcohol synthesis Clay support K-Co-Mo catalyst Syngas

Identification and Expression of Floral Organ Homeotic Genes from Alpinia oblongifolia (Zingiberaceae)

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Journal of Integrative Plant Biology 2009年第2期51卷 155-166页

作者： Yong-mei Xia Xue-mei Gao Qing-Jun Li Xishuangbanna Tropical Botanical Garden the Chinese Academy of Sciences Menglun Mengla Yunnan 666303 China

Current understanding of the classical ABC model of floral development has provided a new set of characters to evaluate floral evolution. However, what is still lacking is a clear assessment of this genetic program across monocots. Here, to investigate the evolution of members of class A and B genes in monocots, we report the sequence characteristic and transcript expression of three new MADS-box genes in Alpinia oblongifolia Hayata. Sequence and phylogenetic analysis reveals that these genes are FUL-like and AP3-1ike. Therefore, they were termed AoFL1, AoFL2 and AoAP3. AoFL1 contains the FUL motif, but AoFL2 lacks this motif. Their expression revealed by in situ hybridization may reflect the ancestral function of FUL-like genes in the specification of inflorescence and floral meristems. The AoAP3 gene contains two conserved motifs, the PI-derived and paleoAP3 motifs. The AoAP3 transcripts located to the corolla and stamen, and hybridization signals were detected in the central whorl. These expression patterns suggest that the functions of homologous organ identity genes are diversified in A. oblongifolia. The implications of these findings on the conservation of homologous gene function are discussed.

关键词： ABC model floral organ identity in situ hybridization MADS-box genes phylogenetic analysis.