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为了推广激光雷达技术在森林蓄积量估测计量方面的应用,本研究以东北林区云冷杉林、落叶松林、红松林和樟子松林4种典型针叶林为对象,基于机载激光雷达获取的点云数据提取特征变量,结合800块地面样地数据,采用逐步回归方法和偏最小二乘方法,建立4种针叶林的蓄积量模型.结果 表明:偏最小二乘法建立的模型精度优于逐步回归方法(ΔR2...  相似文献   

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空气负离子(NAI)作为评价大气环境质量的重要指标,以往研究侧重于野外观测试验,关于控制条件下的NAI研究甚少.本研究于2018年9-10月在浙江钱江源森林生态站杭州虎山试验基地人工气候室内控制相同气候条件下,对枫香和红豆杉不同植株数量的NAI浓度进行连续定位监测;在其他条件一致的情况下,分别设置空气温度和相对湿度的不同梯度,监测NAI浓度变化,旨在为探究森林植被和气象因子对NAI作用机理提供理论依据.结果表明: 两种植物显著提高NAI浓度.植株数量与NAI浓度呈极显著正相关,二者在0~50株范围内最符合二次函数关系,枫香、红豆杉的NAI浓度与株数的拟合方程分别为y=-0.0484x2+4.7005x+345.7(R2=0.62)、y=-0.0207x2+1.9189x+365.91(R2=0.34).NAI浓度与空气温度在5~30 ℃范围内呈极显著正相关,拟合方程为y=0.4139x2-9.2229x+89.919(R2=0.92).NAI浓度与空气相对湿度在56%~87%范围内呈极显著正相关,拟合方程为y=3.6508e0.0526x(R2=0.94).  相似文献   

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利用光谱反射率测量的光化学植被指数(PRI)估算植被光合作用的光能利用效率(LUE),能够更好地为生态系统总初级生产力的估算及尺度扩展提供重要的技术支撑.本研究以中国通量网(ChinaFLUX)千烟洲通量观测站为研究区域,2013年9月和12月在通量塔上测量了中亚热带人工针叶林的植被反射光谱,并获取了通量塔上同步观测的气象数据和涡度相关通量数据,对两者进行回归分析.结果表明: PRI-LUE相关关系(R2=0.20,P<0.001)优于NDVI LUE.在整个观测期内,土壤水分含量(SWC)与PRI组合的二元回归模型能够提高LUE的估算精度(日间观测R2=0.29,P<0.001;正午观测R2=0.30,P<0.01),而在秋季,饱和水汽压差(VPD)与PRI组合的二元回归模型能较好地估算正午LUE(R2=0.448, P<0.001),表明环境因子SWC和VPD是影响PRI-LUE关系的重要因素,不同季节的二元回归模型所选择的最佳环境变量有所不同.  相似文献   

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Tri-1-alkynyltin compounds [R2Sn(CCR1)3 (1), R2 = Me, R1 = Me (a), nBu (b), tBu (c), Me3Si (d), 1-(1-cyclohexenyl) (e); R2 = Et, R1 = Me (a(Et)), nBu (b(Et)), tBu (c(Et)), SiMe3 (d(Et)); R2 = nBu, R1 = Me (a(Bu)), nBu (b(Bu))] were prepared, and their reactivity towards trialkylboranes Et3B (2) and iPr3B (3) in 1,1-organoboration reactions was studied. The first step in each reaction is an intermolecular 1,1-alkytoboration. Afterwards, intramolecular 1,1-vinyloboration or 1,1-alkyloboration compete with further intermolecular 1,1-alkyloboration. Various triorganotin cations (4-7), stabilized by intramolecular side-on coordination to the CC bond of an alkynylborate moiety, were detected as highly fluxional intermediates prior to rearrangement into heterocyclic systems such as stannoles (9-11), 1-stanna-4-bora-2, 5-cyclohexadienes (8, 12). The reactions between 1a or 1a(Bu) and an excess of Et3B (2) afford the tris(alkenyl)tin compounds 13 via threefold intermolecular 1, 1-ethyloboration. 13 rearrange to the 3-stannolenes (14a or 14a(Bu)). The intermediates and final products were characterized by multinuclear one- and two-dimensional 1H, 11B, 13C, 29Si and 119Sn NMR.  相似文献   

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初小静  韩广轩 《生态学杂志》2015,26(10):2978-2990
湿地由于具有较高的初级生产力以及较低的有机质降解速率而成为缓解全球变暖的潜在有效碳汇.虽然近年来中国湿地生态系统CO2交换过程及其影响机制研究取得了一系列进展,但尚缺乏对数据进行系统性整合分析.基于29篇文献的数据,对中国21个典型湿地植被净生态系统CO2交换(NEE)、生态系统呼吸(Reco)、总初级生产力(GPP)、NEE的光响应参数以及Reco的温度响应参数进行整合分析,并探讨了这些指标对温度与降雨的响应.结果表明: 年尺度上,气温和降雨量对NEE(R2=50%,R2=57% )、GPP(R2=60%,R2=50%)和Reco(R2=44%,R2=50%)均有显著影响(P<0.05).生长季尺度上,NEE (R2=50%)、GPP (R2=36%)和Reco(R2=19%)与气温呈显著相关(P<0.05);同时NEE(R2=33%)和GPP(R2=25%)也与降雨量呈显著相关(P<0.05),但Reco与降雨量的相关关系不显著(P>0.05).生长季降雨量与最大光合速率(Amax)之间呈显著相关 (P<0.01),但与表观量子产率(α)、白天生态系统呼吸速率(Reco,day)无显著相关(P>0.05).生长季气温对α、Amax和Reco, day均无显著影响(P>0.05).生态系统基础呼吸速率(Rref)与降雨量无显著相关(P>0.05),但是生态系统呼吸的温度敏感系数(Q10)与降雨量呈显著的线性负相关(P<0.05),同时气温对Q10(R2=0.35)、Rref(R2=0.46)均产生显著影响(P<0.05).  相似文献   

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湿地由于具有较高的初级生产力以及较低的有机质降解速率而成为缓解全球变暖的潜在有效碳汇.虽然近年来中国湿地生态系统CO2交换过程及其影响机制研究取得了一系列进展,但尚缺乏对数据进行系统性整合分析.基于29篇文献的数据,对中国21个典型湿地植被净生态系统CO2交换(NEE)、生态系统呼吸(Reco)、总初级生产力(GPP)、NEE的光响应参数以及Reco的温度响应参数进行整合分析,并探讨了这些指标对温度与降雨的响应.结果表明: 年尺度上,气温和降雨量对NEE(R2=50%,R2=57% )、GPP(R2=60%,R2=50%)和Reco(R2=44%,R2=50%)均有显著影响(P<0.05).生长季尺度上,NEE (R2=50%)、GPP (R2=36%)和Reco(R2=19%)与气温呈显著相关(P<0.05);同时NEE(R2=33%)和GPP(R2=25%)也与降雨量呈显著相关(P<0.05),但Reco与降雨量的相关关系不显著(P>0.05).生长季降雨量与最大光合速率(Amax)之间呈显著相关 (P<0.01),但与表观量子产率(α)、白天生态系统呼吸速率(Reco,day)无显著相关(P>0.05).生长季气温对α、Amax和Reco, day均无显著影响(P>0.05).生态系统基础呼吸速率(Rref)与降雨量无显著相关(P>0.05),但是生态系统呼吸的温度敏感系数(Q10)与降雨量呈显著的线性负相关(P<0.05),同时气温对Q10(R2=0.35)、Rref(R2=0.46)均产生显著影响(P<0.05).  相似文献   

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光照强度对筛豆龟蝽生长发育及繁殖的影响   总被引:1,自引:0,他引:1  
许喆  崔娟  毕锐  高宇  史树森 《昆虫学报》2019,62(5):645-652
【目的】为明确光照强度对筛豆龟蝽 Megacopta cribraria 种群生长发育及生殖力的影响,进一步探索筛豆龟蝽对光环境的适应规律。【方法】在温度24±1℃,相对湿度60%±10%,光周期 16L ∶8D 条件下,通过测定寄主植物大豆上筛豆龟蝽在不同光照强度(500, 2 500, 4 500, 6 500, 8 500 和10 500 lx)下的生长发育及繁殖指标,包括各虫态发育历期、成虫寿命、存活率、若虫期营养积累效率等;利用生命表方法进一步分析光照强度对种群趋势变化的影响。【结果】光照强度对筛豆龟蝽各虫态发育历期、存活率以及成虫生殖力等均产生显著影响。各阶段的发育历期有随光照强度增加而缩短的趋势,其发育速率和若虫期营养积累效率均与光照强度呈显著正相关。各阶段发育速率与光照强度的关系模型分别为:卵期 V 1= 0.129968exp(0.011310 L I)(R^2=0.610, P <0.0001),若虫期 V 2=0.000767LI^0.014182 ( R^2 =0.980, P <0.0001),雌虫产卵前期 V 3=0.019000 L 0.418000 I ( R^2 =0.837, P <0.0001);若虫期营养积累效率与光照强度之间符合三次函数模型 y =0.0004 x^3-0.0064 x^2+0.0361 x +0.0660 ( R^2 =0.983, P <0.0001);筛豆龟蝽种群趋势指数 I 随光照强度增加而显著增大,光照强度低于2 500 lx时,其种群不能完成生殖过程。【结论】光照强度可显著影响筛豆龟蝽种群生长发育及生殖力。较高的光照强度(10 500 lx)更有利于其种群数量增长,而较低的光照强度(≤2 500 lx)将导致种群逐渐消亡。  相似文献   

9.
陈万超  张俊峰  吴迪  张忠  李文  汪雯翰  王琨  杨焱 《菌物学报》2021,40(9):2364-2375
本研究对38个不同批次和菌龄的椴木栽培鲍姆桑黄孔菌Sanghuangporus baumii子实体醇提物进行了高效液相色谱(HPLC)分析,建立了S. baumii醇提物HPLC指纹图谱,提取得到27个共有峰信息(P1-P27);同时,对38个样品醇提取的Trolox等价抗氧化能力(TEAC)进行分析,基于正交偏最小二乘(OPLS)回归建立了抗氧化活性预测模型,潜变量数为3,交互验证所得累积模型预测参数(Q2)为0.803,变量累积解释指标(R2X)和(R2Y)分别为0.574和0.954,相关系数平方(R2)为0.954,经验证模型可以获得良好的预测效果,可以准确反映谱峰与活性之间相关关系;利用模型变量投影重要性(VIP)指标筛选得到14个共有峰对抗氧化活性具有显著贡献。研究获得的鲍姆桑黄孔菌抗氧化谱效关系模型为桑黄原料活性的预测提供了有效的方法,可辅助指导鲍姆桑黄孔菌活性化合物的分离纯化,也为鲍姆桑黄孔菌栽培子实体的品质控制提供了技术手段。  相似文献   

10.
基于安徽省大别山区马鬃岭林场杉木人工林30块样地1087组数据,选用7个常用树高-胸径(H-D)模型(线性模型、Chapman-Richards模型、Logistic模型等),采用最小二乘法拟合并选出最优基础模型(式11,只含D变量的Chapman-Richards模型),然后基于该模型构建含林分变量优势木平均高度、密度的H-D模型(式12),同时考虑样地水平的随机效应,分别基于式11、12构建混合模型(式13、14),并用幂函数、指数函数消除误差异方差,利用决定系数(R2)、均方根误差(RMSE)、平均绝对误差(MAE)和平均相对误差绝对值(MAPE)等指标来评价模型的拟合与预测能力,最终获取最优树高预测模型.结果表明:含林分变量的模型的拟合精度(式12,R2=0.863、RMSE=1.381、MAE=0.971)优于基础模型(式11,R2=0.827、RMSE=1.554、MAE=0.101).对于误差方差,幂函数、指数函数均能较好地消除异方差,但幂函数相对最好.混合模型的拟合与预测能力均优于式11、12,但混合模型(式13、14)之间的拟合与预测精度相差不大.基于混合效应的H-D模型(式13)能够较好地描述不同林分间H-D关系的差异,实际运用中可选用该模型来预测杉木树高,具有较高的预测精度.  相似文献   

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微囊藻和栅列藻的垂直迁移及生态学意义   总被引:4,自引:0,他引:4  
吴生才  陈伟民 《生态科学》2004,23(3):244-248
本研究在自制沉降柱中,检测铜绿微囊藻(Microcystis aeroginosa)和斜生栅列藻(Scenedesmus obliquus)不同生长时期的细胞群体在不同光照条件下的垂直迁移。本文首次提出藻密度衰减系数(K)的概念、拟合方法和生态学意义,并根据等细胞密度沉降面的沉降速率来计算细胞沉降速率(Vc),以这两个参数来衡量细胞的沉降特性,对细胞垂直迁移研究的方法进行了的探索。结果表明,两种藻细胞群体在三个生长时期和四种光照条件的沉降特性表现已定的差异。栅列藻细胞密度的衰减系数(K)最小值为-0.0021cm-1(上浮),最大值为0.0065cm-1(下沉);微囊藻的K最小值为-0.0029cm-1(上浮),最大值为0.0036cm-1(下沉)。两种藻沉降曲线的指数拟合的R2大多在0.6以上,说明K值是一个较好的衡量细胞群体沉降特性的参数,细胞密度与深度的关系较好地服从指数规律。细胞沉降速度V的最大值(4.681cm·h-1,下沉)出现在栅列藻的指数期,最大上浮速率-1.790cm·h-1,出现在微囊藻的稳定期。本文得到的活体藻细胞群体的垂直迁移特性差异的实验数据,说明该实验方法的适用性和两种藻沉降特性差异的可检测性。本文讨论了水华优势种形成与藻细胞群体迁移特性之间的关系。  相似文献   

12.
It is commonly assumed that variation in abiotic site conditions influences the number of niches, which in turn affects the potential species richness in an area. Based on theoretical considerations, abiotic variation is often used as an estimator of species richness at broad scales, while at finer landscape scales the diversity of habitat types is used. However, habitat estimators assume the landscape to be composed of discrete, homogeneous patches with sharp boundaries, and such a concept is hard to apply in gradient-dominated landscapes. The aim of this study was therefore to investigate the influence of topographic variability (TV) on species richness at the landscape level (gamma (γ) diversity) and on its components (alpha (α) and beta (β) diversity) at microsite and habitat group levels. Using floristic data from 12 "landscapes" of 1 km2 we investigated the influence on diversity components of two simple and one complex measures of TV. While the standard deviation (SD) of altitude explained a high proportion of the variation in γ diversity (linear regression model, R2=0.63), the complex measure, SD of solar radiation explained it even better (R2=0.82). There were strong effects of TV on α and β diversity components at the microsite level, but only marginal increases of the diversity components at the habitat level. Further analyses revealed that the missing increase of the habitat level components was caused by differences between habitat groups and that only grassland diversity components increased significantly with TV. We conclude that TV at a landscape scale has strong effects on niche or microsite diversity and is an appropriate estimator of relative species richness in landscapes that are topographically heterogeneous and gradient dominated.  相似文献   

13.
1. We empirically modelled profundal macroinvertebrate biomass (PMB) from collections of macroinvertebrates and a suite of trophic, water chemistry and morphometric variables from 26 lakes located within the Boreal Mixedwood and Boreal Subarctic ecoregions of Alberta, Canada.
2. Hypolimnetic dissolved oxygen (DO) concentrations (mg L−1) explained 37% of the variance in PMB ((g m−2)0.1) as a quadratic function, whereas water temperature (°C) explained 23% of variance in a linear relationship.
3. In contrast with other studies based on oligotrophic systems, indirect indicators of food availability (i.e. chlorophyll a and total phosphorus concentrations and Secchi depth) were not significant predictors of PMB in this study.
4. The predictive power of our models may be improved by obtaining more frequent (seasonal) estimates of PMB and hypolimnetic DO concentration and by quantifying biotic factors such as competition, predation, life history phenologies and recruitment success.  相似文献   

14.
Vibeke Holter 《Ecography》1984,7(2):165-170
Nitrogen fixation activity was determined for Lotus tenuis. Medicago lupulina and Trifolium pratense . The three species grew in clones in grassland in an area reclaimed from brackish water in the 1940s. The N2[C2H2]-fixation was measured in soil cores throughout 1974 and 1975. From cores taken in dense and uniform stands of the species, the yearly N2[C2H2]-fixation at maximum cover was estimated. L. tenuis fixed about 4 g N m−2 yr−1 (area with max. cover 130%), i.e. 30–56% of its requirement. Both M. lupulina and T. pratense fixed about 7 g N m−2 yr−1 (maximum cover 37% and 80%) i.e. 67% of their N-requirement. Average N2[C2H2]-fixation for the whole area was 0.4 g N m−2 yr−1, considerably less than the N-addition through rainfall.  相似文献   

15.
为研究长江口鮻矢耳石形态特征及其质量与年龄的关系,2017年2—6月从长江口水域采集鮻358尾,解剖并提取耳石324对,并对其形态学参数进行测量分析.结果表明:鮻矢耳石具有基叶和翼叶,中央听沟明显,矢耳石的大小和形状随个体生长变化明显,矢耳石由边缘规则的圆润瓜子状渐变为褊窄的叶片状,边缘波浪状突起逐渐变多.矢耳石平均密度为1.52 mg·mm-2,平均矩形趋近率为0.68,耳石长占其体长的0.021%~0.047%,耳石宽占其体长的0.009%~0.021%,耳石质量占其体质量的0.045‰~0.731‰.鮻矢耳石长(OL)、宽(OW)、质量(OM)均与体长呈显著相关,耳石宽与耳石质量函数关系式的决定系数(R^2)最高(0.928).耳石质量与体长(BL)最佳拟合方程为幂函数:OM=0.0009BL1.8737(R2=0.967);耳石质量与年龄(A)以及体长与年龄的最佳拟合方程为多项式:OM=2.9262A^2+4.8437A+2.1894(R^2=0.847);BL=-3.2248A^2+102.54A+38.373(R^2=0.858),矢耳石质量与年龄呈显著线性相关,用耳石质量与年龄关系估算的年龄与从耳石上直接读取的年龄无显著差异,矢耳石质量可以作为鉴定鮻年龄的有效辅助手段.  相似文献   

16.
R. LEMA-KISOKA, N. HAYEZ, I. LANGER, P. ROBBERECHT, E. SARIBAN AND C. DELPORTE. Characterization of functional VIP/PACAP receptors in the human erythroleukemic HEL cell line. PEPTIDES. The presence of VIP/PACAP receptors was investigated on the human erythroleukemic cell line HEL. Specific binding of [125I]-PACAP or [125I]-VIP on HEL cells or membranes was very low and did not allow to perform competition curves. At 37°C PACAP transiently increased cAMP levels in the presence of the non-specific phosphodiesterase inhibitor IBMX, suggesting rapid desensitization. Kinetic studies revealed that optimal conditions to measure the EC50 of PACAP(1–27) were 10 min at 20°C. Under those conditions, PACAP-related peptides increased cAMP levels with EC50 in agreement with the pharmacological profile of the VPAC1 receptor subtype: PACAP = VIP > [K15, R16, L27]VIP(1–7)/GRF(8–27) = [R16]ChSn (two VPAC1 agonists) HELODERMIN = secretin. RO 25–1553, a selective activator of VPAC2 receptor was inactive at 1 μM. Dose-response curves of VPAC1 agonist molecules (PACAP, VIP, [K15, R16, L27]VIP(1–7)/GRF(8–27), [R16]ChSn) were shifted to the right by the VPAC1 receptor antagonist [AcHis1, D-Phe2, Lys15, Leu17]VIP(3–7)/GRF(8–27), with a Ki of 3 ± 1 nM (n = 3). The presence of VPAC1 receptor mRNA was confirmed by RT-PCR. Preincubation with PACAP or PMA showed that VPAC1 receptors underwent homologous and heterologous desensitization.

This study provides the first evidence for the expression of functional VPAC1 receptors undergoing rapid desensitization in HEL cells.  相似文献   


17.
Spinach plants ( Spinacia oleracea L. cv. Subito) were grown in a complete nutrient solution under ample light intensity (14 h day−1 at 660 μmol m−2 s−1) before being transferred either to a minus-N solution (experiment 1), or to limiting light conditions (6 h day−1 at 220 μmol m−2 s−1; experiment 2). Shoot growth in experiment 1 decreased significantly from 0.24 day−1 to 0.07 day−1 after the fourth day of transfer. Root relative growth rate increased after 1 day from 0.25 to 0.31 day−1, but decreased on the fifth day after transfer to 0.11 day−1. Shoot growth in experiment 2 decreased significantly from 0.25 to 0.17 day−1 after the fourth day of transfer, while root growth decreased to half of its original level (0.25 day−1) already on the second day. Growth substrate levels in the plants (free sugars, free amino acids) and starch levels depended on the plant age, the moment in the diurnal cycle, and the imposed treatment. Fluctuations in shoot growth or root growth resulting from the light or N limitation could not be explained by a correspondent increase or decrease in the levels of growth substrates. The hypotheses underlying the functional equilibrium theory, assuming shoot and root growth to be controlled by N- and C-containing substrates respectively, and several other growth and partitioning models are therefore questioned. A neglect of the osmotic role of the free sugars in these models might be the explanation for this.  相似文献   

18.
Abstract .1. The pine sawfly, Neodiprion autumnalis , infests ponderosa pine, Pinus ponderosa , growing at low densities near the bottom of an altitudinal gradient in Arizona, U.S.A. The relative importance of host-plant quality vs. natural-enemy effects in determining the spatial distribution of this sawfly was examined over a 3-year period.
2. Field and laboratory bioassays were conducted on all life stages of N. autumnalis at two forest stand densities (high ≥ 23 m2 ha–1, low ≤ 7 m2 ha–1) and at two elevations (bottom slope = 2390 m, top slope = 2540 m). These experiments were used for constructing life tables of N. autumnalis that compared the effects of host-plant quality on oviposition preference and progeny performance with the effects of natural enemies at different tree densities and elevations.
3. Life-table analyses determined that mortality attributed to host-plant effects during the egg and larval stages had the largest impact on fitness between tree densities and elevations.
4. Natural enemies caused a significant reduction in progeny survival, but their effects were similar across all tree densities and elevations during egg and larval life stages. However, cocoon-stage survival did vary between tree densities and elevations due to natural-enemy effects.
5. It was concluded that the observed oviposition preference for, and higher progeny performance on, trees at low densities and bottom slope elevations were caused primarily by host-plant effects.
6. These results further the argument that heterogeneity at the resource level (i.e. bottom-up forces) determines potential outcomes of multitrophic level interactions.  相似文献   

19.
王海波  辛颖  赵雨森 《植物研究》2015,35(4):618-622
以2011年的Landsat TM为主要遥感数据,借助于RS和GIS技术完成对俄罗斯大果沙棘人工林生物量进行估侧。结果表明:植被指数和生物量的一元线性回归分析模型中,比值植被指数(RVI)和归一化植被指数(NDVI)与俄罗斯大果沙棘具有较高的相关性,相关系数(R2)分别为0.908 6和0.868 5;基于植被指数和生物量的多元线性回归分析模型中,相关系数(R2)为0.909,经过模型检验,多元回归遥感植被指数模型的精度要高于一元遥感植被指数的精度,但是基于遥感指数模型预测生物量值比理论生物量值偏高。  相似文献   

20.
The Emerson-Trinder reaction has been optimized in this work using an initial rate spectrophotometric method and response surface methodology (RSM). In this investigation, the variation range of critical variables along with the fixed parameters were selected based on a preliminary 'one at a time' (OVAT) procedure for the subsequent RSM chemometric analysis as follows: pH (6-10), buffer concentration (50-250 mM), 4-aminoantipyrine (4-AAP) concentration (1-5 mM), temperature (25-45°C). The optimum values of fixed parameters were: 4-fluorophenol (4-FP, 30 mM), horseradish peroxidase (HRP) enzyme activity (0.12 U mL-1), and the fixed concentration of the H2O2 in the chemometric experiments was 11.4 µM. The non-linear nature of the experimental response of the reaction system was explained by a second-order polynomial equation, which revealed the impact of the experimental factors, their interactions and also their optimum values. The results of the reported RSM analysis proved to be quite appropriate for the design and optimization of this reaction, as illustrated by the relatively high value of the determination coefficient (R2=96.7%) for the fitting of quadratic model, along with the satisfactory results generated by the analysis of variance (ANOVA). All the evaluated analytical characteristics of this method: typical reaction progress curves, resulting linear calibration curve, within-day precisions at low and at high levels, and the upper and lower detection limits were, also, reported. In addition, to check the quality of the optimization and validity of the model, the assay of H2O2, in pooled serum matrix and in cosmetic samples, was performed.  相似文献   

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