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金钟山亚热带森林林窗特征与木本植物多样性的关系

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生态学杂志 2024年第3期43卷 675-681页

作者：杨元征蒙洲菊苏宏新王嘉丽蔡文华杨健俎佳星南宁师范大学北部湾环境演变与资源利用教育部重点实验室南宁530001 南宁师范大学广西地表过程与智能模拟重点实验室南宁530001 南宁师范大学地理科学与规划学院南宁530001

开展林窗空间格局与林下木本植物多样性关系的研究,对于认识森林物种共存、生物多样性维持以及生态系统可持续发展具有重要意义。本研究以广西金钟山自然保护区24 hm^(2)永久森林动态监测样地为对象,采用机载激光雷达获取样地点云数据,... 详细信息

开展林窗空间格局与林下木本植物多样性关系的研究,对于认识森林物种共存、生物多样性维持以及生态系统可持续发展具有重要意义。本研究以广西金钟山自然保护区24 hm^(2)永久森林动态监测样地为对象,采用机载激光雷达获取样地点云数据,通过R语言提取林窗并计算各林窗的形状复杂指数,利用相关分析量化林窗特征与林下木本植物多样性的关系。结果表明:该研究区林窗空隙率为6.16%,密度为15.5个·hm^(-2),平均面积为39.72 m^(2),整体以微小和中型林窗为主;林窗空间分布格局存在地形分异特征,多分布于低海拔和缓坡区域;林窗形状复杂指数与香农指数、物种丰富度指数均呈正相关,且在低海拔和陡坡处表现更加明显。本研究揭示了亚热带森林林窗植被更新特征,对区域生物多样性保护具有一定指导作用。

关键词：激光雷达亚热带森林林窗分布格局生物多样性

公共服务促进农民农村共同富裕:作用机理、现实差距与实践路径

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宁夏党校学报 2024年第3期26卷 64-72页

作者：杨园争杜志雄中国社会科学院农村发展研究所北京100732

共同富裕是中国特色社会主义的本质要求。公共服务的高效供给既是共同富裕的重要内容,也是实现共同富裕的重要手段。基于公共服务与农民农村共同富裕的密切关系,需要针对城乡间、区域间及不同群体间基本公共服务水平的差距,厘清以优化... 详细信息

共同富裕是中国特色社会主义的本质要求。公共服务的高效供给既是共同富裕的重要内容,也是实现共同富裕的重要手段。基于公共服务与农民农村共同富裕的密切关系,需要针对城乡间、区域间及不同群体间基本公共服务水平的差距,厘清以优化提升农村基本公共服务促进农民农村共同富裕的机理。宏观层面上,探索以城乡一体化消解公共服务二元分异、以县乡村一体化推动农村基本公共服务均等化、以基本公共服务标准化加速均等化实现、以数字化提升农村基本公共服务可及性的战略路径。微观层面上,要用好提高弱势群体保障水平、创建和评选公共服务一体化示范县、统筹布局城乡“新基建”、加快公共服务数字化转型等实践抓手,提高公共服务供给效率,实现农民农村共同富裕。

关键词：公共服务共同富裕一体化均等化数字化

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Influence of Milling Conditions on the Mechanical Alloying of Fe-B Powders

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Journal of Materials Science & Technology 1999年第2期15卷 137-142页

作者： yang, yuanzheng Li, Qiaoshen Zhu, Youlan Ma, Xueming Dong, Yuanda Guangdong Univ Technol Dept Mat Sci & Engn Guangzhou 510090 Peoples R China Shanghai Univ Dept Mat Sci & Engn Shanghai 200072 Peoples R China

Amorphous and nanostructural Fe-B alloys made by mechanical alloying of elemental Fe and amorphous B powders have been studied using X-ray diffraction, differential scanning calorimetry and Mossbauer spectroscopy. It has been shown that the milling conditions have a strong effect on the alloying. The single phase amorphous alloy, which is limited at nominal composition of Fe//6//0B//4//0, has been produced only by milling in Ar atmosphere and in other composition range the mixture of nanostructure Fe-like phase and Fe//2B compound with a little amorphous phase were obtained. While by milling in air atmosphere the introduction of oxygen in air may suppress the formation of amorphous phase, thus the compounds Fe//2B may be synthesized with no trace of amorphous phase. The crystallization temperatures of amorphous phase in the resultant products are higher than those of a single amorphous alloy Fe//6//0B//4//0, and hardly independent of the milling conditions and the composition. In addition, it is revealed that detectable B content in the final products is lower than the nominal composition of all the initial samples, which indicates that some B atoms may be located in the disordered interfacial regions of the nano-structural alloyed mixtures. (Edited author abstract) 12 Refs.

关键词： Iron alloys

Effects of rare-earth elements on the glass-forming ability and mechanical properties of Cu_(46)Zr_(47-x)Al_7M_x(M = Ce,Pr,Tb,and Gd) bulk metallic glasses

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Rare Metals 2010年第5期29卷 444-450页

作者： XIE Zhiwei ZHANG Yongzhang yang yuanzheng CHEN Xianzhao TAO Pingjun Faculty of Material and Energy Guangdong University of Technology Guangzhou 510006 China

Cu46Zr47-xA17Mx （M = Ce, Pr, Tb, and Gd） bulk metallic glassy （BMG） alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability （GFA）, thermal stability, and mechanical properties of Cu46Zr47-xA17Mx were investigated. The GFA of Cu46Zr47-xA17Mx （M = Ce, Pr） alloys is dependent on the content of Ce and Pr, and the optimal content is 4 at.%. Cu46Zr47-xA17Thx（X = 2, 4, and 5） amorphous alloys with a diameter of 5 mm can be prepared. The GFA of Cu46Zr47-xA17Gdx（x = 2, 4, and 5） increases with increasing Gd. Tx and Tp of all decrease. Tg is dependent on the rare-earth element and its content. ATx for most of these alloys decreases except the Cu46Zra2Al7Gd5 alloy. The activation energies △Eg, △Ex, and △Ep for the Cu46Zr42A17Gd5 BMG alloy with Kissinger equations are 340.7, 211.3, and 211.3 kJ/mol, respectively. These values with Ozawa equations are 334.8, 210.3, and 210.3 kJ/mol, respec- tively. The Cu46Zr45Al7Tb2 alloy presents the highest microhardness, Hv 590, while the Cu46Zr43A17Pr4 alloy presents the least, Hv 479. The compressive strength （at.f.） of the Cu46Zra3A17Gd4 BMG alloy is higher than that of the Cu46Zr43Al7Tb4 BMG alloy.

关键词： amorphous materials metallic glass rare-earth elements suction casting glass-forming ability mechanical property

A Mssbauer Study on the Mechanically Alloyed Cu-Sn Alloys

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Journal of Materials Science & Technology 1998年第6期14卷 551-554页

作者： yuanzheng yang Youlan ZHU and Qiaoshen LI(Dept. of Materials Science and Engineering, Guangdong University of Technology, Guangzhou 510090, China)Xueming MA and Yuanda DONG(Dept. of Materials Science and Engineering, Shanghai University, Shanghai 200072, Dept. of Materials Science and Engineering Guangdong University of Technology Guangzhou 510090 China Dept. of Materials Science and Engineering Shanghai University Shanghai 200072 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

Nanocrystalline E and η electron compounds and supersaturated solid solution of the Cu-Sn system have been prepared by mechanical alloying of elemental Cu and Sn powders. The atomie alloying and microstructure of the resultant alloys have been investigated by XRD, DSC and 119Sn Mossbauer spectroscopy. A little amount of SnO2 was detected by Mossbauer spectroscopy, although no trace of diffiaction peaks occurred in the XRD pattern. Thus the spectra for all the milled samples should be fitted using two quadrupole-splitting doublets: one corre sponding to SnO2, the other corresponding to the resultant alloys. The composition dependence of the hyperfine parameters has been eXtensively discussed and explained well with respect to oxidation, sudece effect resulting from grain refinement, coordination environment asymmetry and distortion caused or/and induced by mechanical alloying.

关键词： Sn A M ssbauer Study on the Mechanically Alloyed Cu-Sn Alloys Cu

脓毒症ICU获得性衰弱发病机制及诊疗研究进展

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临床急诊杂志 2024年第6期25卷 318-324页

作者：郭同武赵明锐冼丽娜杨远征海南医学院急诊创伤学院海口570100 海南医学院第二附属医院重症医学科海南医学院第一附属医院重症医学科海南医学院第一附属医院TICU

ICU获得性衰弱(intensive care unit acquired weakness,ICU-AW)作为重症监护室脓毒症患者的常见并发症,多累及骨骼肌、呼吸肌及平滑肌等,会导致脱机困难、住院时间延长、医疗费用剧增,并严重影响患者远期生活质量。但脓毒症ICU-AW的发... 详细信息

ICU获得性衰弱(intensive care unit acquired weakness,ICU-AW)作为重症监护室脓毒症患者的常见并发症,多累及骨骼肌、呼吸肌及平滑肌等,会导致脱机困难、住院时间延长、医疗费用剧增,并严重影响患者远期生活质量。但脓毒症ICU-AW的发病机制尚不明确、诊断评估标准缺乏统一、治疗时机和方案选择仍无具体标准。鉴于该病发病机制和诊疗选择存在争议,本文结合国内外文献资料,对脓毒症患者ICU-AW的发病机制及诊疗措施相关研究进展进行综述,以期加深临床多学科对该病的认知并针对性提高疾病的早期认识、诊断及诊疗协作能力。

关键词：脓毒症 ICU获得性衰弱肌无力发病机制诊断评估

Super-plasticity of Zr_(64.80)Cu_(14.85)Ni_(10.35)Al_(10) bulk metallic glass at room temperature

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Chinese Science Bulletin 2008年第3期53卷 465-468页

作者： TAO PingJun yang yuanzheng BAI XiaoJun XIE ZhiWei CHEN XianCao DONG ZhenJiang Wen JianGuo Faculty of Materials and Energy Guangdong University of Technology Guangzhou 510006 China College of Materials Science and Engineering Shenzhen University Shenzhen 518060 China

Generally,bulk metallic glasses(BMGs)exhibit a very limited plastic deformation under a compression load at room temperature,often less than 2% before *** this letter,through an appropriate choice of BMGs' composition,an amorphous rod of Zr64.80Cu14.85Ni10.35Al10 with a diameter of 2 mm was prepared by using copper mold suction casting.X-ray diffraction and differential scanning calorimetry were utilized to determine its structure and thermal stability,and the uniaxial compression test was adopted to study its plastic deformation behavior at room temperature *** results showed that the glass transition temperature and onset temperature of the exothermic reaction of the amorphous rod were 646 and 750 K,respectively,and its micro-hardness was 594.7 *** com-pression,when the engineering strain and engineering stress arrived at 9.05% and 1732 MPa,respec-tively,i.e.,the true strain and true stress reached 9.42% and 1560 MPa,respectively,the amorphous rod started to *** yielding,with the increase of load,the strain increased and the glass rod ulti-mately were compressed into flake-like *** the maximum engineering strain was larger than 70%,i.e.,the maximum true strain exceeded by 120%,the amorphous specimen was not fractured,indicating that it has super-plasticity at room *** the appropriate choice of compo-sition and optimization of the technological process,flexible BMG with super-plasticity at room tem-perature could be produced.

关键词：大体积金属玻璃单轴向压力试验超塑性锌铜镍铝合金

基于时间序列的广西桉树人工林识别及时空变化分析

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中国科技论文 2024年第1期19卷 123-130页

作者：黄秋霞蔡文华王嘉丽俎佳星杨元征广西民族师范学院历史文化与旅游学院广西崇左532200 北部湾环境演变与资源利用教育部重点实验室(南宁师范大学) 南宁530001 广西地表过程与智能模拟重点实验室(南宁师范大学) 南宁530001

高效且准确地长时间监测桉树人工林面积及其时空动态变化是保持生态系统稳定及维持桉树长期稳定可持续的重要前提。基于Google Earth Engine(GEE)云平台,以Landsat系列遥感影像为数据源,采用时间序列分析方法提取广西2000-2020年桉树人... 详细信息

高效且准确地长时间监测桉树人工林面积及其时空动态变化是保持生态系统稳定及维持桉树长期稳定可持续的重要前提。基于Google Earth Engine(GEE)云平台,以Landsat系列遥感影像为数据源,采用时间序列分析方法提取广西2000-2020年桉树人工林,并分析其时空分布格局变化。结果表明:2007、2010、2015、2020年识别结果的总体精度均高于85%,分类精度较高,识别效果较好,基于时间序列分析的桉树人工林识别方法具有较高的准确性;2000—2020年广西桉树人工林面积快速增长,2000-2015年桉树人工林面积逐年增长,2015年之后呈现平缓波动变化趋势;广西桉树人工林种植范围不断扩张,各个地级市桉树人工林面积均呈现上升趋势,北回归线以南地区尤为显著。在地形分布方面,桉树人工林主要分布于斜坡区域。研究结果可为区域制定合理可持续的桉树人工林种植措施提供参考依据。

关键词：广西桉树林识别 Google Earth Engine 空间格局

微量氮元素添加对Zr基非晶合金力学性能影响的研究

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材料研究与应用 2024年第1期18卷 166-171页

作者：何华杰陶平均温盛华黄圣楷龙紫云杨元政广东工业大学广东广州510006 东莞市逸昊金属材料科技有限公司广东东莞523731 广东省科学院新材料研究所广东广州510650

采用铜模吸铸法,成功地制备了直径3 mm的(Zr_(55)Cu_(30)Al_(10)Ni_(5))_(100-x)N_(x)(x=0、0.5、1.0、1.5、2.0)非晶合金棒材。利用氮氧分析仪、X射线衍射仪、差示扫描量热仪、万能试验机、显微硬度计和扫描电镜等手段,系统地研究了氮... 详细信息

采用铜模吸铸法,成功地制备了直径3 mm的(Zr_(55)Cu_(30)Al_(10)Ni_(5))_(100-x)N_(x)(x=0、0.5、1.0、1.5、2.0)非晶合金棒材。利用氮氧分析仪、X射线衍射仪、差示扫描量热仪、万能试验机、显微硬度计和扫描电镜等手段,系统地研究了氮含量对(Zr_(55)Cu_(30)Al_(10)Ni_(5))_(100-x)N_(x)非晶合金的力学性能的影响。同时,对氮元素添加时非晶合金体系的剪切带与断口形貌进行了分析讨论。结果表明:不同氮含量的(Zr_(55)Cu_(30)Al_(10)Ni_(5))_(100-x)N_(x)合金中,氮含量(原子百分数)分别为0.08%、0.49%、1.18%、1.48%、1.73%;在添加微量氮元素前后,块体合金(Zr_(55)Cu_(30)Al_(10)Ni_(5))_(100-x)N_(x)均呈现完全非晶结构;原始Zr_(55)Cu_(30)Al_(10)Ni_(5)非晶合金的显微硬度值为478.62 HV,添加氮元素后显微硬度随氮含量增加而递增,显微硬度最高为519.16 HV;添加氮元素前,Zr_(55)Cu_(30)Al_(10)Ni_(5)合金的抗压强度为1738 MPa、塑性形变量为2.1%;当x=0.5时,抗压强度降至1719 MPa、塑性形变量降至1.0%;当x≥1.0时,抗压强度持续下降且塑性较差。

关键词： Zr基非晶合金 N元素力学性能铜模吸铸法非晶结构断口形貌显微硬度机理

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