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71.
戚琦 《理化检验(化学分册)》2007,43(3):211-212
研究了电感耦合等离子体原子发射光谱法(ICP-AES)的仪器工作参数,溶液提升速率为2.4 mL.min-1,雾室压力为2.07×105Pa,观测高度为16 mm。用浓硝酸1 mL作样品的消化剂。用此方法测定杨树叶标准物质(GBW 07604)中铜、锌、铅、镍,相对误差在0.54%~9.3%之间,加标回收率在97.9%~101.0%之间。 相似文献
72.
基于反射光谱的温室黄瓜叶片磷素含量分析与预测 总被引:10,自引:1,他引:9
以温室栽培黄瓜作物为对象,分析了叶片反射光谱与叶片磷素含量之间的相关关系,并建立了预测模型。首先利用便携式光谱辐射仪测量了自然光照条件下温室黄瓜叶片的光谱反射率,并计算了反射率光谱的一次微分光谱。相关分析表明反射率光谱与叶片含P量之间具有一定的相关性,但线性相关不显著。利用微分光谱可以部分消除系统误差、背景噪声等的影响,明显提高了相关系数,但预测模型精度仍然达不到实用程度。在理论分析的基础上,选取978,920,737和458 nm等4个波长作为特征波长,分别利用人工神经网络和支持向量机建立了黄瓜叶片P素含量对应于微分光谱特性的非线性预测模型,结果表明两种算法都获得了较好的预测效果,支持向量机模型的预测能力(Rv=0.754)优于人工神经网络模型(Rv=0.712)。 相似文献
73.
Dr. Chanchal Kumar Roy Syed Shaheen Shah Akter H. Reaz Sharmin Sultana Dr. Al-Nakib Chowdhury Dr. Shakhawat H. Firoz Dr. Md. Hasan Zahir Dr. Mohammed Ameen Ahmed Qasem Dr. Md. Abdul Aziz 《化学:亚洲杂志》2021,16(4):296-308
We demonstrate a facile efficient way to fabricate activated carbon nanosheets (ACNSs) consisting of hierarchical porous carbon materials. Simply heating banana leaves with K2CO3 produce ACNSs having a unique combination of macro-, meso- and micropores with a high specific surface area of ∼1459 m2 g−1. The effects of different electrolytes on the electrochemical supercapacitor performance and stability of the ACNSs are tested using a two-electrode system. The specific capacitance (Csp) values are 55, 114, and 190 F g−1 in aqueous 0.5 M sodium sulfate, organic 1 M tetraethylammonium tetrafluoroborate in acetonitrile, and pure ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) electrolytes, respectively. The ACNSs also shows the largest potential window of 3.0 V, the highest specific energy (59 Wh kg−1) and specific power (750 W kg−1) in [BMIM][PF6]. A mini-prototype device is prepared to demonstrate the practicality of the ACNSs. 相似文献
74.
稀土矿区茶叶中稀土元素ICP-AES测定 总被引:5,自引:0,他引:5
本文用ICP-AES测定稀土矿区茶叶中稀土元素,并用干扰系数法校正茶叶中的无机元素及其他稀土元素对待测稀土元素的光谱干扰。在最佳工作条件下,测定了茶叶样品中的稀土元素含量。 相似文献
75.
The hyperspherical harmonics expansion method has been used to solve the trinucleon system where the nucleons interact through
Reid soft core potential. The binding energy of triton, both for extreme adiabatic approximation and uncoupled adiabatic approximation,
and theS-state,S′-state andD-state probabilities are calculated and compared with the results by the Faddeev method. 相似文献
76.
Antonietta Cerulli Angela Mari Anna Balato Rosanna Filosa Serena Lembo 《Natural product research》2018,32(10):1170-1175
The phytochemical investigation of the methanol extract of the leaves of Castanea sativa Mill., source of the Italian PGI (Protected Geographical Indication) product ‘Marrone di Roccadaspide’ (Campania region) afforded as main compounds crenatin (1), chestanin (2), gallic acid (3), cretanin (4), 5-O-p-coumaroylquinic acid (5), p-methylgallic acid (6) and quercetin-3-O-glucoside (7). To quantify the isolated compounds a LC-ESI(QqQ)MS method working with a very sensitive and selective mass tandem experiment called Multiple Reaction Monitoring (MRM) has been developed. Moreover the antioxidant capacity by TEAC assay and the ability of compounds 1–7 to protect HaCaT human keratinocytes from UVB-induced damage has been investigated. 相似文献
77.
Roger Remy Dresch Maria Terezinha Kreinecker Dresch Renata Biegelmeyer Débora Fretes Argenta Ricardo Fagundes da Rocha Helder Ferreira Teixeira 《Natural product research》2018,32(4):486-492
The aim of the present study was to develop a phytocosmetic using Vitis waste by-products, for use as a topical formulation for skin protection against ultraviolet radiation damage. The study also evaluates the free radical scavenger activity of the crude extracts of dried leaves of Vitis vinifera and Vitis labrusca, as well as the anthocyanins, flavonoid fraction and isolated compounds. Next, release and permeation studies of hydrogels were performed using Franz-type diffusion cells. Flavonoid acted more intensively in TRAP and conjugated dienes antioxidant assays, whereas anthocyanins had higher antioxidant activity in hydroxyl and nitric oxide assay. Only quercetin-3-O-glucuronide (5) was released from hydrogels, and the flavonoid retention in porcine ear skin after eight hours of permeation was below of limit of quantification for this compound. The polyphenols present in Vitis are capable of absorbing UV and visible light, justifying their potential as sunscreens for the development of a phytocosmetic. 相似文献
78.
《Journal of separation science》2018,41(2):571-577
An effective high‐speed countercurrent chromatography method was successfully established by using ionic liquids as the modifier of the two‐phase solvent system. Adding a small amount of ionic liquids significantly shortens the separation time and improves the separation efficiency. The conditions of ionic‐liquid‐modified high‐speed countercurrent chromatography including solvent systems, types and content of added ionic liquids, and ionic liquids posttreatment were investigated. The established method was successfully applied to separate alkaloids from lotus leaves using a two‐phase solvent system composed of petroleum ether/ethyl acetate/methanol/water/[C4mim][BF4] (1:5:1:5:0.15, v/v/v/v/v). Four alkaloids pronuciferine (1.7 mg), N‐nornuciferine (4.3 mg), nuciferine (3.1 mg), and roemerine (2.1 mg) were obtained with the purities of 90.53, 92.25, 99.86, and 98.63%, respectively, from 100 mg crude extract of lotus leaves. The results indicated that the ionic‐liquid‐modified high‐speed countercurrent chromatography method was suitable for alkaloid separation from lotus leaves and would be a promising method for the separation of alkaloids from other natural products. 相似文献
79.
80.
Mohammad Abul Hossain Mikio Kumita Yoshimasa Michigami Shigeru Mori 《Adsorption》2005,11(5-6):561-568
Dynamic characteristics of Cr(VI) sorption on used black tea leaves (UBTLs) as a low-cost adsorbent are studied. Batch experiments
were conducted to evaluate the effects of Cr(VI) concentration, solution pH and temperature on the removal process. Both of
adsorption and reduction, involved in the process, are affected by the processing parameters. The adsorption kinetics is described
successfully using pseudo-second order rate equation and the rate constant decreases with increasing the initial concentration
of Cr(VI) up to 150 mg/L (for 0.1 g/L UBTLs) then becomes slow. Experimental and calculated kinetic data for equilibrium are
well expressed by Langmuir isotherm. The solution pH has a profound effect on the adsorption rate. The rate constant increases
linearly with an increase in temperature, and the low value of activation energy of adsorption, 16.3 kJ/mol, indicates that
Cr(VI) is easily adsorbed on UBTLs. The maximum Cr(VI) adsorptive conditions, with a minimum reduction, were achieved from
the dynamics of operational parameters: the initial Cr(VI) concentration < 150 mg/L (for 0.1 g/L UBTLs); the initial solution
pH = 1.54–2.00 and the processing temperature < 50 ∘C, for the possibility of its practical application. 相似文献