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Species Abundance in a Forest Community in South China：A Case of Poisson Lognormal Distribution

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Journal of Integrative Plant Biology 2005年第7期47卷 801-810页

作者： Zuo-YunYIN HaiREN Qian-MeiZHANG Shao-LinPENG Qin-FengGUO Guo-YiZHOU SouthChinaBotanicalGarden（formerlySouthChinaInstituteofBotany） theChineseAcademyofSciencesGuangzhou510650China／／GuangdongForestResearchInstituteGuangzhou510520China SouthChinaBotanicalGarden（formerlySouthChinaInstituteofBotany） theChineseAcademyofSciencesGuangzhou510650China SouthChinaBotanicalGarden（formerlySouthChinaInstituteofBotany） theChineseAcademyofSciencesGuangzhou510650China／／SchoolofLifeSciencesZhongshanUniversityGuangzhou510275China SouthChinaBotanicalGarden（formerlySouthChinaInstituteofBotany） theChineseAcademyofSciencesGuangzhou510650China／／USGeologicalSurveyJamestownND58401USA

: Case studies on Poisson lognormal distribution of species abundance have been rare, especially in forest communities. We propose a numerical method to fit the Poisson lognormal to the species abundance data at an evergreen mixed forest in the Dinghushan Biosphere Reserve, South China. Plants in the tree, shrub and herb layers in 25 quadrats of 20 m× 20 m, 5 m× 5 m, and 1 m× 1 m were surveyed. Results indicated that: (i) for each layer, the observed species abundance with a similarly small median, mode, and a variance larger than the mean was reverse J-shaped and followed well the zero-truncated Poisson lognormal; (ii) the coefficient of variation, skewness and kurtosis of abundance, and two Poisson lognormal parameters (& and μ) for shrub layer were closer to those for the herb layer than those for the tree layer; and (iii) from the tree to the shrub to the herb layer, the α and the coefficient of variation decreased, whereas diversity increased. We suggest that: (i) the species abundance distributions in the three layers reflects the overall community characteristics; (ii) the Poisson lognormal can describe the species abundance distribution in diverse communities with a few abundant species but many rare species; and (iii) 1/α should be an alternative measure of diversity.

关键词： Dinghushan Biosphere Reserve forest community maximum likelihood estimate (MLE) reverse J-shaped curve species abundance distribution (SAD) value-trying method zero-truncated Poisson lognormal (PLN) distribution

Dihydrochalcones from Symplocos vacciniifolia

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Chinese Chemical Letters 2004年第10期15卷 1182-1184页

作者： TieJunLING LiDongLIN PingWU WenHuaZHOU HuaGuYE MeiFangLIU XiaoYiWEI SouthChinaInstituteofBotany ChineseAcademyofSciencesGuangzhou510650

A new dihydrochalcone glucoside, vacciniifolin, along with confusoside, trilobatin and sieboldin were isolated from the leaves of Symplocos vacciniifolia. By the method of spectral analysis, this new compound was eluc... 详细信息

关键词： Symplocos vacciniifolia Symplocacea dihydrochalcones vacciniifolin.

Synthesis of CO2 Copolymer Based Polyurethane Foams

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Chinese Chemical Letters 2003年第7期14卷 752-754页

作者： BaoHuaLIU LiBanCHEN MinZHANG AiFangYU InstituteofChemistry ChineseAcademyofSciencesBeijing100080；GuangzhouInstituteofChemistryChineseAcademyofSciencesGuangzhou510650 GuangzhouInstituteofChemistry ChineseAcademyofSciencesGuangzhou510650

CO2-copolymer based polyurethane foams were synthesized and characterized in this paper. The foams were found to have higher strength and lower heat of combustion than the conventional polyether polyurethane foams. ... 详细信息

关键词： CO2 epoxides aliphatic polycarbonates polyurethane foams.

"CAGE" VANADYL POLYCARBOXYLATE-THIOUREA COMPLEX FOR THE POLYMERIZATION OF ACRYLONITRILE

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Chinese Journal of Polymer Science 1993年第4期11卷 37-46页

作者：吴锦远杨超雄 Guangzhou Institute of Chemistry Academia Sinica Guangzhou 510650

The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by ' cage ' vanadyl polycarboxylate (P=VO)-thiourea (TU) complex was investigated. The overall rate ofpolymerization isThe relationship between the induction period (τ) and the temperature of polymerization as well as the concentrations of reactants can be expressed as follows :The molecular weight of polyacrylonitrile increases with increasing monomer concentration and decreases with increasing temperature of polymerization and concentrations of vanadyl polycarboxylate and thioureaThe polymerization mechanism was proposed and discussed.

关键词： Cage catalyst Vanadyl polycarboxylate-throurea complex Polymenzation Acrylonitrile.

Spatial distribution of heavy metals of agricultural soils in Dongguan, China

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Journal of Environmental Sciences 2004年第6期16卷 912-918页

作者： XIAYun-sheng LIFang-bai WANHong-fu MAJin YANGGuo-yi ZHANGTian-bin LUOWei GuangdongInstituteofEco-EnvironmentandSoilSciences GuangdongKeyLaboratoryofIntegratedControlofAgrn~EnvironmentGuangzhou510650China.

Distribution and speciation of heavy metals of agricultural soils(85 surface soil samples and 4 soil profiles) in Dongguan were investigated, while total Cr, Cu, Ni, Pb, Zn(abbreviated as Cr, Cu, Ni, Pb, Zn) and available Cu, Zn(Av-Cu, Av-Zn) were analyzed by a flame absorption spectrophotometer(AAS), and total Cd(Cd) was analyzed using graphite furnace AAS. The content of Cd, Cu and Ni was partially much more than the second grade of GB15618-1995 even though the mean contents of all heavy metal were less than the threshold value of the second grade and only the mean content of Pb was more than the value of national background. Results of descriptive statistic showed that the mean content of heavy metals should depend on land utilization and spatial location at some extent. The heavy metal contents were higher in the Southwest and Northwest than in the Central. In addition, the mean contents of Zn and Pb in Dongguan paddy soils were significantly higher than those of Pearl River Delta(PRD) and Taihu Lake region(TLR). Correlation analyses indicated that there existed significant correlation between Cr and Ni in orchard soils, and among Zn, Cd and Cu, between Av-Cu and Cu, between Av-Zn and Cr, Ni, pH value in vegetable soils, and a weak relationship between Cd, Cu and Pb, between Av-Zn and Zn. Principal component analyses(PCA) showed that the order of importance should be Zn>Pb>Cr>Ni>Cu.

关键词： heavy metal spatial distribution agricultural soil Dongguan

DEPENDENCE OF ACRYLONITRILE POLYMERIZATION KINETICS ON THE COMPOSITION OF POLYAMIDOXIME-THIOUREA SYSTEM

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Chinese Journal of Polymer Science 1993年第3期11卷 255-261页

作者：吴锦远杨超雄张广照 Guangzhou Institute of Chemistry Academia Sinica Guangzhou 510650

The polymerization of acrylonitrile (AN) initiated by polypropylene based-polyamidoxime (PPAO)-thiourea (TU) system was investigated at [TU]/[PPAO]>0.5 molar ratio. It shows that the variation of the concentrations of PPAO, thiourea and nitric acid does not exert an observable influence on the reaction rate. The overall rate of polymerization (R_p) isR_p = 2.07e^(-7,800/RT)[ AN]^(2.0)The zero order dependence on PPAO and thiourea concentrations and the lowest value of the collision frequence factor were considered to be a feature of the primary radical termination.

关键词： Acrylonitrile Polymerization Kinetics, Polyamidoxime-thiourea system.

Cumene Liquid Oxidation to Cumene Hydroperoxide over CuO Nanoparticle with Molecular Oxygen under Mild Condition

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Journal of Natural Gas Chemistry 2007年第4期16卷 393-398页

作者： Meiying Zhang Lefu Wang Hongbing Ji Bing Wu Xiaoping Zeng Analytical and Testing Center South China University of Technology Guangzhou 510650 Guangdong China School of Chemical and Energy Engineering South China University of Technology Guangzhou 510650 Guangdong China

CuO nanoparticle was synthesized via wet chemical method and was characterized diffraction （XRD）, nitrogen adsorption-desorption, and scanning electron microscopy （SEM） by X-ray Catalytic oxidation of cumene with molecular oxygen was studied over CuO nanoparticle. The catalysts showed markedly higher activities as compared to CuO prepared by conventional method, CuO/Al2O3, or homogeneous copper catalyst under comparable reaction conditions. The cumene conversion, cumene hydroperoxide （CHP） yield, and selectivity using 0.25 g CuO nanoparticle catalyst and 0.1 mol cumene at 358 K for 7 h were 44.2%, 41.2% and 93.2%, respectively. The catalyst can be recycled. After 6 recycled experiments, no loss of catalytic activity was observed.

关键词： nanoparticle CuO cumene liquid oxidation

Preparation and Characterization of poly (styrene/maleic anhydride)/ kaolin nanocomposites

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Chinese Science Bulletin 2005年第13期50卷 1320-1325页

作者： LIUXuening ZHANGHongtao YANGZhizhong HAChengyong GuangzhouInstituteofChemistry ChineseAcademyofSciencesGuangzhou510650China

The direct exfoliation of in situ intercalative copolymerized styrene/maleic anhydride charge-transfercomplex(PSMA)into the inter lamellar spaces of modified kaolin(Kao-DMSo),which WaS intercalated and surfacemodified by dimethyl sulfoxide (DMSO),WaS *** nano structure of the composites WaS investieated by wide-angle X-ray diffraction (XRD) and transmission elec-tron microscopy(TEM).The interaction between kaolin surface and PSMA chain WaS conformed by FTIR *** XRD results showed that the intercalated polvsty-rene-malelc anhyvdride units were arranged in the flattened *** the 001 diffraction peak of the origlnal kaolin *** TEM image showed that the kaolin WaS exfoliated into nanometer size and dispersed in the polymer *** the thermal stability of the nanocomposites was studied by thermo-gravimetric analysis (TGA),and the resulting thermogram indicated that the thermal stability of the nanocomposites WaS significantly

关键词：聚乙烯高岭土化学合成物技术改进共聚物

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四履带式甘蔗收割机越障性能仿真与试验

农机化研究 2025年第1期47卷 226-233页

作者：李维兴刘庆庭张豪杰华南农业大学南方农业机械与装备关键技术教育部重点实验室广州510642 广东工程职业技术学院广州510650

目前,甘蔗主产地有广西、云南等地区,甘蔗主产区以丘陵山地为主。轮式底盘甘蔗收割机通过性差而无法在狭窄、连绵起伏等复杂坡面作业,需要一种能够适应丘陵山区的甘蔗收割机。为此,设计了一款三角履带式甘蔗收割机,底盘是由前三角履带... 详细信息

目前,甘蔗主产地有广西、云南等地区,甘蔗主产区以丘陵山地为主。轮式底盘甘蔗收割机通过性差而无法在狭窄、连绵起伏等复杂坡面作业,需要一种能够适应丘陵山区的甘蔗收割机。为此,设计了一款三角履带式甘蔗收割机,底盘是由前三角履带轮和后平履带轮构成的4履带行走系统,后履带偏摆转向。同时,对该机的结构参数、履带底盘在翻越垂直壁和跨越壕沟过程中的越障性能进行分析,得出4履带式甘蔗收割机履带底盘越障性能与其结构参数的内在联系;建立了该机的多体动力学模型,在RecurDyn软件中模拟了该机在不同的参数下的动力学性能,并对样机进行越障试验验证。验证试验表明:车辆能够跨越高为18 cm的固体垂直障碍,与仿真数据相比,实际测得的俯仰角、横摆角和翻滚角的幅值变化符合预期,车辆俯仰角波动幅值超过5°,甘蔗收割机的俯仰现象明显;翻滚角变化幅值达到3°,车辆通过障碍时,需要考虑其他因素导致车辆的俯仰角变化;跨越宽为50 cm、高18 cm壕沟时,安全通过壕沟;车辆的翻滚角变化明显,幅值最大相差2°,说明此时车辆左右两边履带的颠簸较为严重,但车辆总体越障稳定性较好。研究成果可为甘蔗收割机结构设计与改进、增强作业安全性提供关键技术支持,具有重要的参考价值。

关键词：甘蔗收割机 RecurDyn动力学底盘参数车辆建模及仿真

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