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1.
对电感耦合等离子体发射光谱法(ICP-OES)测定土壤有效锌含量的不确定度进行评定,分析了整个检测过程产生不确定度的来源,对称样量、浸提液体积、标准系列溶液配制、线性标准曲线拟合、测量重复性等产生的不确定度分量进行计算,量化给出扩展不确定度。待测土壤中有效锌含量最终结果表示:w(Zn)=(1.12±0.10)mg/kg,包含因子k=2,置信概率为95%。测量过程中,标准溶液制备所产生的不确定度最大。因此,在ICP-OES法测定土壤样品有效锌时应足够重视标准溶液制备与曲线拟合过程,以减小测量不确定度。本文研究结果为控制ICP-OES法测定土壤有效锌数据质量提供了理论依据。 相似文献
2.
采用高效液相色谱法对水溶肥料中植物生长调节剂2,4-二氯苯氧乙酸(2,4-D)的含量进行测定,对测量结果进行不确定度评定。分析检测过程中产生不确定度的来源,包括试样称样、试样定容、标准溶液配制、标准曲线拟合、实验重复性、回收率及仪器精度等分量,计算了各分量的相对标准不确定度,量化给出扩展不确定度。待测肥料样品中最终结果表示:X(2,4-D)=(391.0±29.4) μg/g,包含因子k=2,置信概率为95%。本次测量结果不确定度主要来源于标准溶液制备、标准曲线的拟合和重复性测定。 相似文献
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《农产品质量与安全》2017,(4)
采用微波消解-原子荧光光谱法测定了蔗渣中的汞含量,对其测定结果的不确定度来源进行了分析,依据JJF1059.1-2012《测量不确定度评定与表示》,量化了各不确定度分量,计算合成不确定度,最终得出测定结果的扩展不确定度。结果表明,测定结果的不确定度主要来源为校准曲线拟合、标准溶液配制、测量重复性,样品消解液定容和样品称量对最终不确定度结果影响不大。测定结果的扩展不确定度为0.013 mg/kg(k=2),蔗渣中汞含量的测定结果表示为(0.340±0.013)mg/kg(k=2,P=95%)。 相似文献
4.
以电感耦合等离子体质谱法(ICP-MS)测定富硒木耳中的硒含量,对其测量结果进行了不确定度评估。根据GB5009.268-2016 《食品安全国家标准食品中多元素的测定》方法,分析探讨了影响测量结果不确定度的来源因素,依据JJF1059.1-2012 《测量不确定度评定与表示》对各不确定度分量进行合成并扩展,并通过公式计算测量结果的扩展不确定度。评估结果明确了标准曲线配制是产生测量结果不确定度的主要因素,重复性、拟合曲线和仪器校准有一定的不确定度引入,试样制备引入的不确定度可以忽略不计。当包含因子k=2时,测量结果的扩展不确定度为0.43 mg/kg,样品的测量结果表示为(8.48±0.43) mg/kg,同时与原子荧光法测定硒的不确定度评定予以比较。 相似文献
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盆栽选取四川、重庆典型的砂岩黄壤、灰岩黄壤、酸性紫色土为供试土壤,田间选取在砂岩黄壤上生长了25年的茶园,连续5年研究了施用钾肥(硫酸钾)对茶园土壤钾库及钾素平衡的影响。结果表明:施用钾肥能显著提高土壤钾库的各类钾素,但其绝对含量都呈逐年下降的趋势。土壤中各类钾素的变化因土壤类型而异,土壤各类钾素的增量均为灰岩黄壤砂岩黄壤酸性紫色土。不施钾肥(CK)的盆栽茶树、田间茶树分别每年从土壤取走钾素0.10.g/kg。盆栽三种土壤的钾素年平均流失量分则别为0.18.g/kg(灰岩黄壤)、0.09.g/kg(砂岩黄壤)、0.07g/kg(酸性紫色土),可见种植茶树施用K肥很有必要。 相似文献
7.
采用冷消解-原子荧光光谱法测定土壤中汞含量,对其结果的不确定度来源进行了分析,对各种不确定度分量进行了量化,计算测定结果的扩展不确定度。结果表明,不确定度主要由校准曲线绘制、标准溶液配制、重复测量次数产生的不确定度组成;样品定容和样品称量对最终不确定度结果影响较小可忽略不计。 相似文献
8.
通过比较不同前处理方式对饲料标准物质中总砷(As)、铅(Pb)、镉(Cd)的提取效果,建立了微波消解-ICP-MS测定饲料中重金属元素的方法。研究结果表明,饲料标准物质中总砷、铅、镉的回收率为89.4%～111%, RSD为1.8%～2.7%,准确度、精密度均满足检测需求。同时通过元素含量计算公式,对试验过程中引入的不确定度进行分析,并对影响试验结果的不确定度分量进行计算评定。评定结果显示,饲料标准物质中总砷、铅、镉的测量结果分别表示为As(2.94±0.43) mg/kg, Pb (4.04±0.48) mg/kg, Cd (0.379±0.063) mg/kg,包含因子k=2。 相似文献
9.
对原子荧光光度法测定土壤中总汞含量的不确定度进行了评定。按GB/T 22105.1—2008,对土壤样品进行检测,建立数学模型,系统分析和量化不确定度各分量,求得其扩展不确定度。分析结果表明,影响土壤中总汞测定的不确定度主要来源于试样的重复测定,而样品稀释和样品称重产生的不确定度很小。其中,在试样的重复测定所产生的不确定度因素中,又以最小二乘法拟合标准曲线所产生的不确定度最大,样品多次重复测试过程中随机误差次之,而仪器校准和标准物质所产生的不确定度较以上小很多。 相似文献
10.
《农产品质量与安全》2016,(5)
铜是饲料中重要的营养元素。本文探讨了火焰原子吸收光谱法测定饲料中铜含量的不确定度评价方法,分析了整个测定过程中不确定度的来源,并对各不确定度分别进行了计算,求得扩展不确定度为1.4 mg/kg,检测结果表示为(55.3±1.4)mg/kg,为饲料中铜元素以及相同方法测定的其他微量元素含量的测量不确定度评定提供了参考。 相似文献
11.
Leila Shekari Maryam Mozafariyan Mirza Hasanuzzaman Farshad Sadeghi 《Journal of plant nutrition》2017,40(6):761-772
Selenium (Se) is an essential element for humans but is not considered as essential for plants. However, its beneficial role in improving plant growth and stress tolerances is well established. In order to study the role of Se in cadmium (Cd) toxicity in pepper (Capsicum frutescens cv. Suryankhi Cluster), this experiment was carried out in greenhouse conditions. Treatments comprised Cd [0, 0.25, and 0.5 mM cadmium chloride (CdCl2)] and Se [0, 3, and 7 µM sodium selenite (Na2SeO3)] with three replications. The result showed that Cd decreased chlorophyll a, chlorophyll b, and carotenoids, whereas Se supplementation diminished Cd toxicity on photosynthetic pigment. Selenium at 7 µM significantly increased the leaf area in the plants grown at 0.25 mM Cd. The application of Se at 3 µM with 0.25 mM Cd and Se at 3 µM and Se at 7 µM with 0.5 mM Cd increased the activity of catalase (CAT). Selenium at 7 µM decreased the proline content of pepper leaves exposed to Cd at 0.5 mM (30%). Selenium significantly enhanced the antioxidant activity of leaves, which was diminished by Cd toxicity. In general, Se has a beneficial effect on plant growth and is an antioxidant enzyme of pepper cv. Suryankhi Cluster under Cd stress and non-stress conditions. 相似文献
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M. Kaplan 《Journal of plant nutrition》2013,36(2):237-244
Copper (Cu)‐containing fertilizers, fungicides, and bactericides has been used extensively in the greenhouses in the Antalya province in recent decades with the use of such materials tending to increase year by year. The level of DTPA‐extractable Cu was determined in 210 soils (0–20 and 20–40 cm depth) and 105 leaf samples obtained from 105 tomato greenhouses. The DTPA‐extractable Cu contents of the soils taken from the 0–20 depth ranged between 0.76 and 88.03 mg kg‐1 (mean 7.79 mg kg‐1). The percentage of soils containing DTPA‐extractable Cu greater than the critical toxicity level (20 mg kg‐1) was 8.1. The Cu content of tomato leaf samples ranged between 2.4 and 1,490 mg kg‐1 (mean 166.5 mg kg‐1). The Cu concentration in leaf samples was very high due to the intensive use of foliar applied Cu‐containing chemicals. As a consequence, 24.8% of the leaf tomato samples analyzed contained over 200 mg Cu kg‐1, the maximum accepted tolerance level. Therefore, it may be necessary to reduce the use of Cu‐containing pesticides and fertilizers, or at least reduce the amount of Cu‐containing fertilizers being used in those greenhouses where Cu‐containing pesticides have been or are being used. 相似文献
13.
Sandro Froehner Karina Scurupa Machado Elisa Stefen Marcelo Nolasco 《Water, air, and soil pollution》2011,219(1-4):591-599
The presence of sexual hormones (female estrogens) was assessed in sediments of a mangrove located in the urban region of southern Brazil. The estrogens are involved in human sexual reproduction. They act as the chemical messengers, and they are classified as natural and synthetic. The estrogens inputs in the environment are from treated and untreated sewage. The presence of estrogens in sewage is excretion from the female due to natural production and use of contraceptives (synthetic estrogens). With the indiscriminate release of sewage into the environment, estrogens can be found in rivers, lakes, and even in oceans. In this work, the presence of estrone (E1), 17-??-estradiol (E2), and 17-??-ethynilestradiol (EE2) in eight sedimentary stations in Itacorubi mangrove located on Santa Catarina Island, south Brazil, was investigated. Historically, the Itacorubi mangrove has been impacted by anthropogenic activities because the mangrove is inserted in the urban area of the Florianopolis. The estrogen EE2, used as contraceptive, had the highest concentration in mangrove sediment, 129.75?±?3.89 ng/g. E2 was also found, with its concentration ranging from 0.90?±?0.03 to 39.77?±?1.19 ng/g. Following the mechanism, under aerobic or anaerobic conditions, E2 will first be oxidized to E1, which is further oxidized to unknown metabolites and finally to CO2 and water (mineralized). EE2 is oxidized to unknown metabolites and also finally mineralized. Theoretically, under anaerobic conditions, EE2 can be reduced to E1 even in environments such as mangrove which is essentially anaerobic. 相似文献
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红壤区不同肥力水稻土根际硝化作用特征 总被引：3，自引：1，他引：2
通过根际培养箱(三室)——速冻切片技术研究了红壤地区高、低两种肥力下水稻苗期根表、根际和土体土壤矿质态氮含量和硝化强度,以及水稻生长、氮素积累的差异。结果表明,肥力水平对水稻根表和根际土壤铵态氮(NH4+-N)含量无显著影响,但高肥力显著提高土体土壤NH4+-N含量,以及根表、根际和土体土壤硝态氮(NO3--N)含量及硝化强度。两种肥力水稻土硝化强度最大值均出现在距根表2 mm处,分别为0.20和0.31μmol kg-1 h-1。土体土壤硝化强度随距根表距离增加而降低,低肥力土壤在距根表10～40mm处时硝化强度接近本底值,而高肥力土壤在距根表20～40 mm处时接近本底值。与不种水稻的CK相比,种植水稻显著提高根际土壤硝化强度。高肥力能显著改善水稻生长,增加植株氮素积累量,尤其显著促进根系生长及通气组织发育。由于红壤稻田肥力水平的差异造成水稻根际硝化强度以及水稻吸收NO3-的差异,导致高肥条件下水稻显示出更强的生长势和氮素吸收利用能力。因此,合理提高红壤稻田肥力水平对改善红壤区水稻根际土壤硝化作用及水稻氮素营养具有重要意义。 相似文献
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自由基在鸡肾病发生中的作用研究 总被引：2，自引：2，他引：0
肾病即急性肾小管坏死.鸡肾病在养鸡生产中极为常见,尤其近年来,鸡肾病的发生日益增多,由于其发生机制不清楚,临床治疗鸡肾病的依据不足,致使治疗效果不佳,为此,提出本研究以探讨鸡肾病的发生机制,为本病防治提供理论依据. 相似文献
16.
Ohnishi H Iwanaga S Kawazoe K Ishizawa K Orino S Tomita S Tsuchiya K Kanematsu Y Harada N Mori K Tsuchihashi T Ishikawa Y Tamaki T 《Journal of agricultural and food chemistry》2008,56(21):10092-10098
This study investigated whether reducing agents such as quercetin and iron(II) facilitate formation of nitric oxide (NO) gas from orally ingested nitrite in an vivo study. When 3 mg/kg Na (15)NO2 was orally administered to rats with or without iron(II) or quercetin, Hb (15)NO, which is indicative of systemic (15)NO, was detected in the blood, with the maximum blood concentration of Hb (15)NO at 15 min after nitrite or nitrite plus quercetin treatment, whereas after administration of nitrite plus iron(II) or nitrite plus iron(II) and quercetin, the time was shortened to 10 min. Interestingly, iron(II), quercetin, or iron(II) plus quercetin did not affect the total amount of Hb (15)NO generated from orally administered Na (15)NO2. However, the systemic nitrite concentration was significantly decreased in the presence of iron(II) or iron(II) plus quercetin. These results may indicate that iron(II) is critical to the generation of NO gas from nitrite, whereas quercetin contributed little under the in vivo experimental conditions. 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(15):1948-1959
Brazil is the largest producer of oranges (Citrus sinensis) in the world. The nutrient management of tree orchards is designed from experiments with a limited number of varieties. This knowledge is transferred to other varieties by diagnosing tissue nutrient composition and tree demand. Compositional data analysis has been first applied to tissue analysis of agricultural crops using centered log ratios with compositional nutrient diagnosis (CND-clr). The isometric log ratio (ilr) transformation is a new approach based on binary nutrient ratios and the principle of orthogonality (CND-ilr). We analyzed eleven nutrients: nitrogen (N), sulfur (S), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) in leaf tissue samples across 108 commercial plots (thirty-one grow Valencia, twenty-two Hamlim, twenty Pera, and thirty-five Natal). Nutrients were partitioned between macro- and micronutrients as well as anionic and cationic species. The effect size of varieties over Valencia was quantified by the mean and standard deviation of ilr values across ilr coordinates. Specific varietal nutrient profiles and ilr norms were defined. The nutrient profile of orange varieties could be classified into homogeneous groups to take advantage of fertilizer trials conducted on varieties of the same group. The Aitchison distance and a perturbation vector could be instrumental for diagnostic purposes and nutrient management. 相似文献
19.
Role of aldehyde oxidase in the hepatic in vitro metabolism of 3-methylindole in pigs 总被引：2，自引：0，他引：2
The metabolism of 3-hydroxy-3-methylindolenine (HMI), a recently discovered metabolite of 3-methylindole (3MI, skatole) produced by porcine liver microsomes, was investigated in vitro using porcine liver cytosol. HMI was rapidly metabolized to a single product, 3-hydroxy-3-methyloxindole (HMOI), by porcine cytosol. By the use of the selective inhibitors menadione and quinacrine, it was shown that the enzyme responsible for the oxidation of HMI into HMOI was aldehyde oxidase (AO; aldehyde:oxygen oxidoreductase, EC 1.2.3.1). The activity of AO in the conversion of HMI to HMOI was measured in a population of pigs (n = 30) with a wide range of 3MI levels in back fat (0.07-0.30 mg/kg). AO activity was found to be negatively correlated (r = -0.70; P < 0.001) with the level of 3MI in fat. The results of the present study suggest that AO plays an important role in the metabolism of 3MI in the pig and that its catalytic activity is related to an adequate 3MI clearance. 相似文献
20.
Vélez G Fernández MA Muñoz J Williams PA English RJ 《Journal of agricultural and food chemistry》2003,51(1):265-269
The influence of guar gum and xanthan gum on the creaming of 10% oil in water emulsions has been investigated. The presence of very low concentrations of the polysaccharides (typically < approximately 0.075%) was found to induce depletion flocculation of the emulsion droplets and increased the rate of creaming. However, at higher polysaccharide concentrations (typically > approximately 0.1%) the creaming rate was reduced due to the increased viscosity of the aqueous phase. For most systems a delay period was noted before creaming started, which was found to be dependent on the zero shear viscosity of the continuous phase and independent of polysaccharide type. The delay period increased significantly at zero shear viscosities approaching 1 Pa s. A mathematical model has been used to fit the creaming rate profiles and a simple exponential relationship obtained between delay time and polysaccharide concentration. 相似文献