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Projectively Flat Singular Square Metrics with Constant Flag Curvature

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Acta Mathematica Sinica,English Series 2020年第6期36卷 638-650页

作者： guang Zu CHEN xin Yue CHENG School of Science East China Jiao Tong UniversityNanchang 330013P.R.China School of Mathematical Sciences Chongqing Normal UniversityChongqing 401331P.R.China

In this paper,we study and characterize locally projectively flat singular square metrics with constant flag ***,we obtain the sufficient and necessary conditions that singular square metrics are locally pro jectively... 详细信息

关键词： Singular square metric projectively flat metric flag curvature

Spatiotemporal dynamics of the social structure of Indo-Pacific humpback dolphins(Sousa chinensis)in Xiamen waters from 2007 to 2019

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Zoological Research 2024年第2期45卷 439-450页

作者： Yi Lu xin-Rong Xu Bing-Yao Chen Thomas A Jefferson Holly Fearnbach guang yang Jiangsu Key Laboratory for Biodiversity and Biotechnology College of Life SciencesNanjing Normal UniversityNanjingJiangsu 210023China Clymene Enterprises LakesideCalifornia 92040USA Marine Mammal Research SR3SeaLife ResponseRehabilitation and ResearchWA 98275USA Southern Marine Science and Engineering guangdong Laboratory(guangzhou) No.1119Haibin RoadNansha DistrictGuangzhouGuangdong 511458China

As highly social animals,Indo-Pacific humpback dolphins(Sousa chinensis)exhibit community ***,our understanding of the external and internal factors influencing these dynamics,as well as their spatiotemporal variations,is still *** the present study,variations in the social structure of an endangered Indo-Pacific humpback dolphin population in Xiamen Bay,China,were monitored over two distinct periods(2007–2010 and 2017–2019)to analyze the effects of habitat utilization and the composition of individuals within the *** both periods,the population demonstrated a strikingly similar pattern of social differentiation,characterized by the division of individuals into two main clusters and one small ***,the two primary clusters occupied the eastern and western waters,respectively,although the core distribution area of the eastern cluster shifted further eastward between the two *** this distribution shift,the temporal stability of the social structure and inter-associations within the eastern cluster remained unaffected.A subset of 16individuals observed in both periods,comprising 51.6%and 43.2%of the population in each respective period,emerged as a foundational element of the social structure and may be responsible for sustaining social structure stability,especially during the 2007–2010 *** observations suggest that the composition of dominant individuals,an internal factor,had a more substantial influence on the formation of the social network than changes in habitat use,an external ***,the study proposes distinct conservation measures tailored to each of the two main clusters.

关键词： Social differentiation Social structure Sousa chinensis Dynamics Conservation

年龄相关性白内障术后泪膜稳定性变化早期临床研究

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国际眼科杂志 2005年第4期5卷 677-680页

作者：李颖王从毅吴利安倪伟张林杨新光中国陕西省西安市第四医院眼科 710004 西安交通大学第一医院眼科中国陕西省西安市710061

目的:评价白内障术后不同时间泪膜稳定性的变化,探讨泪膜稳定性的变化与手术方式之间的关系。方法:设计自身配对研究。选择2003/2004期间在我院住院的年龄相关性白内障患者(随机检查110例120眼)。透明角膜切口超声乳化白内障及折叠式后... 详细信息

目的:评价白内障术后不同时间泪膜稳定性的变化,探讨泪膜稳定性的变化与手术方式之间的关系。方法:设计自身配对研究。选择2003/2004期间在我院住院的年龄相关性白内障患者(随机检查110例120眼)。透明角膜切口超声乳化白内障及折叠式后房型人工晶状体植入组:80例(90眼);白内障囊外摘除联合后房型人工晶状体植入组:30例(30眼)。所有患者分别于术前、术后1,7d;1,3mo依次行SIt、BUT、角结膜荧光素染色并对其泪膜稳定性的变化进行分析。结果:术前两组SIt、B U T测定及角膜荧光染色无明显差异(P>0.05);与术前相比,两组术后1-2d,B U T测定明显缩短(P0.05);术后7d,两组SIt测定恢复到术前水平,差异无显著意义;两组恢复程度亦无明显差异SIt(P>0.05);术后1moBUT测定基本恢复到术前水平,差异无显著意义;两组恢复的程度亦无显著意义(P>0.05)。术后1d超声乳化组角膜荧光素染色为(+),伤口处角膜水肿,囊外组角膜荧光素染色为(+～++)。术后1mo,角结膜荧光素染色及伤口处角膜水肿基本恢复到术前水平。结论:年龄相关性白内障两种手术方式均影响泪膜稳定性,手术切口越大,影响泪膜稳定性越明显;但两种手术方式术后泪膜稳定性恢复程度却无显著性差异。

关键词：年龄相关性白内障术后泪膜稳定性角膜荧光素手术切口手术治疗

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传统结肠镜检查法的应用现状

现代生物医学进展 2017年第6期17卷 1180-1182页

作者：李姗姗张慧超徐丹张广鑫杨幼林哈尔滨医科大学附属第一医院黑龙江哈尔滨150001

自20世纪六十年代末结肠镜检査术问世以来,无论是其操作手法还是器械改革均得到飞速发展,并广泛应用于临床,使直视病灶、实现活检及治疗成为可能。虽然,结肠镜检查为结直肠疾病的诊断及治疗带来了巨大的帮助并成为结直肠癌诊断的金标准... 详细信息

自20世纪六十年代末结肠镜检査术问世以来,无论是其操作手法还是器械改革均得到飞速发展,并广泛应用于临床,使直视病灶、实现活检及治疗成为可能。虽然,结肠镜检查为结直肠疾病的诊断及治疗带来了巨大的帮助并成为结直肠癌诊断的金标准,但其局限性也日渐明显。作为一种侵入性操作,结肠镜检查无法避免的腹部疼痛、难以预知的并发症、无法保证的成功率以及可能存在的漏诊率限制了其临床应用不仅在一定程度上降低了患者的依从性,增加了操作的困难度,且使一部分具有操作指征的患者错失早期诊断及治疗的最佳时机。本文简要阐述了传统注气式结肠镜检查法的一般特点并总结了其应用现状,以期为今后传统注气式结肠镜检查法的合理化应用提供一定的参考依据。

关键词：注气式结肠镜结直肠疾病现状局限性

A molecular insight into coke formation process of vacuum residue in thermal cracking reaction

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Petroleum Science 2024年第3期21卷 2130-2138页

作者： Ji-guang Li xin Guo Huan-Di Hou Heavy Oil Processing Department Sinopec Research Institute of Petroleum Processing Co.LtdBeijing100083China

Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with various reaction time were performed to evaluate the coke formation *** total yields of ideal components including naphtha,atmospheric gas oil(AGO)and vacuum gas oil(VGO)of thermal cracking reactions increased from 10.89%to 40.81%,and the conversion ratios increased from8.05%to 43.33%with increasing the reaction time from 10 to 70 *** asphaltene content increased from 12.14%to a maximum of 22.39%and then decreased,and this maximum of asphaltene content occurred at the end of the coking induction *** asphaltenes during the coking induction period,at the end and after coking induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for coke formation process,and the coke formation pathways were discussed to reveal the coke formation process at molecular level.

关键词： Vacuum residue Thermal cracking Asphaltene Coking induction period Sulfur Nitrogen

Stabilize and Reinforce Hydrogen-Bonded Polymer Complex Elastic Fiber by Catechol Chemistry and Coordination

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Chinese Journal of Polymer Science 2023年第12期41卷 1846-1855,I0006页

作者： Ze-xin Liu De-Zhong Liu Cai-Hong Zhang Wei-Jie Wang Hao Huang Shu-guang yang State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Center for Advanced Low-Dimension MaterialsCollege of Materials Science and EngineeringDonghua UniversityShanghai 201620China

Hydrogen-bonded polymer complex fiber of poly(ethylene oxide)(PEO)and poly(acrylic acid)(PAA)shows rubber elasticity in ambient environment,but the fiber has relatively low strength and weak *** apply the catechol chemistry and metal coordination to stabilize and strengthen the PEO/PAA *** is grafted with dopamine(Dopa),and then combines with PEO to prepare ***-Dopa in the fiber is crosslinked through oxidation induced dismutation and the metal ions are introduced through *** cross-linking and coordination greatly improve the stability of the fiber against the erosion of alkaline *** four different metal coordination fibers,PEO/PAA-Dopa/Cu fiber keeps the excellent extensibility(~1000%)and presents much higher initial modulus(~7 MPa),ultimate strength(~20 MPa),and toughness(~60 MJ/m^(3))than its precursor PEO/PAA *** addition,PEO/PAA-Dopa/Cu fiber shows quick recovery and large energy dissipation ratio compared with the PEO/PAA *** distinct mechanical properties enhancement of the hydrogen-bonded complex fiber is attributed to the synergy of hydrogen bonds,coordination and covalent bond cross-linking.

关键词： Elastic fiber Hydrogen-bonded complexation Catechol chemistry Coordination Elastomer

Doping effect on thermoelectric properties of nonstoichiometric AgSbTe_2 compounds

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 352-356页

作者： Sheng-nan Zhang guang-yu Jiang Tie-jun Zhu xin-bing Zhao Sheng-hui yang State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Northwest Institute of Non-Ferrous Metal Research Xi＇an 710016 China

Nonstoichiometric ternary thermoelectric materials Ag0.84Sb1.15M0.01Te2.16 （M=Ce, Yb, Cu） were prepared by a direct melt-quench and hot press process. The carrier concentration of all the samples increased after doping. Thermoelectric properties, namely electrical con-ductivity, Seebeck coefficient, and thermal conductivity, were measured from 300 to 673 K. The phase transition occurring at about 418 K representing the phase transition from b-Ag2Te to a-Ag2Te influenced the electrical transport properties. The electrical conductivities of Ce and Yb doped samples increased after doping from 1.9×104 to 2.5×104 and 2.3×104 S·m-1, respectively, at 673 K. Also, at room temperature, the Seebeck coefficient of the Ce doped sample relatively increased corresponding to the high carrier concentration due to the changes in the band structure. However, all the thermal conductivities increased after doping at low temperature. Because of the higher thermal conductivity, the dimensionless figure of merit ZT of these doped samples has not been improved.

关键词： thermoelectric materials rare earth elements doping silver antimony telluride

Ultrathin self-assembly MXene/Co-based bimetallic oxide heterostructures as superior and modulated microwave absorber

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Journal of Materials Science & Technology 2023年第3期134卷 132-141页

作者： Hui-Ya Wang Xiao-Bo Sun Yue xin Shu-Hao yang Peng-Fei Hu guang-Sheng Wang School of Chemistry Beihang UniversityBeijing 102206China Research Institute of Aero-Engine Beihang UniversityBeijing 102206China

Lightweight and high-efficiency absorbing materials equipped with tunable electromagnetic properties are the foremost important factors for driving applications of 5 G smart era and military ***-ulated by the remarkable merits of heterogeneous interface engineering,a series of unique flower-like Co-based multiphases nanostructures were successfully synthesized through identical hydrothermal method,and subsequently anchored on the Ti_(3)C_(2)T_(x)*** suitable metal ion modulation is feasible to regulate the components,heterogeneous interfaces and defects for tailoring the electromag-netic parameters and microwave absorption(MA)***,the permittivity decreases of CMOT(CoO/MCo_(2)O_(4)/Ti_(3)C_(2)T_(x),M=Fe,Cu,Zn)composites proceed gradually in the order of Fe^(2+),Cu^(2+),Zn^(2+),while the MA performance with tunable absorption peak could be modulated *** asobtained CFOT-12(10 wt%),CCOT-15(10 wt%)and CZOT-15(15 wt%)exhibit excellent MA capacity with a minimum reflection loss(RL_(min))of-41.06,-52.67,-52.52 dB and corresponding effective absorption bandwidth(EAB)of 3.68,4.48,3.92 GHz at 2.10,1.90,1.80 mm,*** work expands a novel approach to construct multicomponent heterostructure for tuning the EM parameters and absorbing property,as well as realize the high efficient and light weight.

关键词： Heterogeneous interface Modulation MXene High-efficiency absorbing materials Lightweight

Supernova neutrinos in a strangeon star model

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Research in Astronomy and Astrophysics 2017年第9期17卷 39-50页

作者： Mao Yuan Ji-guang Lu Zhi-Liang yang Xiao-Yu Lai Ren-xin Xu Department of Astronomy Beijing Normal UniversityBeijing 100875China School of Physics Peking UniversityBeijing 100871China School of Physics and Engineering Hubei University of EducationWuhan 430205China Kavli Institute for Astronomy and Astrophysics at Peking University Beijing 100871China

The neutrino burst detected during supernova SN 1987A is explained in a strangeon star model, in which it is proposed that a pulsar-like compact object is composed of strangeons （strangeon： an abbreviation for ＂strange nucleon＂）. A nascent strangeon star＇s initial internal energy is calculated, with the inclusion of pion excitation （energy around 1053 erg, comparable to the gravitational binding energy of a collapsed core）. A liquid-solid phase transition at temperature - 1 - 2 MeV may occur only a few tens of seconds after core collapse, and the thermal evolution of a strangeon star is then modeled. It is found that the neutrino burst observed from SN 1987A can be reproduced in such a cooling model.

关键词： stars neutron -- supernovae individual (SN 1987A)- neutrinos