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催化光度法测定痕量锰屡见报道,但方法的灵敏度大多不超过10-9g/mL。在氨性溶液中,痕量Mn(Ⅱ)对H_2O_2氧化溴邻苯三酚红的反应有强烈的催化作用,以α,α′-联吡啶为活化剂,采用固定时间法,非催化反应与催化反应产物的吸光度之比的对数值1g(A_0/A)与Mn(Ⅱ)的浓度在一定范围内呈线性关系,由此建立了催化退色光度法测定痕量Mn(Ⅱ)的新方法。本方法的检出灵敏度可达8×10-(10)g/mL,与文献相当,测定范围为0～0.5ug/25mL,测定费时少,重现性好,有一定的选择性。 1.主要仪器及试剂 721型分光光度计,超级恒温水浴(±0.1K)。 相似文献
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本文研究了Zn~(2+)—PAN—OP乳化剂光度法,测定痕量锌的反应条件。在O—15μg/50ml范围内符合比尔定律,表观摩尔吸光系数为3.68×10~4。方法应用于人参中痕量锌的测定,结果满意。 相似文献
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柠檬酸铁铵分光光度法测定茶多酚 总被引：1，自引：0，他引：1
利用茶多酚与柠檬酸铁铵生成深红色络合物进行分光光度法测定茶多酚。结果表明:在pH>10的碱性介质中络合物的最大吸收峰在550nm处,比色液茶多酚浓度在0～200μg/ml范围内遵从朗伯——比耳(Lambert-Beer)定律。考察了氨试剂、柠糠酸铁铵、羧甲基纤维素钠试剂对测定结果的影响,呈色物质的时间稳定性结果表明:茶汤待测液茶多酚浓度为2.4mg/ml时最适测定条件,低粘度羧甲基纤维素钠试剂用量5ml,柠檬酸铁铵试剂0.5ml,氨试剂0.5ml,蒸馏水定容至25ml,回收率98.3％～101.8％。本方法的缺点主要是低粘度羧甲基纤维素钠试剂需大、中型离心机离心,粘度大,如果没有压吸式移液管,移液较困难。 相似文献
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棉子壳是食用菌栽培的主要原料 ,迄今为止 ,人们对 Bt棉棉子对平菇生长的影响认识不一。利用液体培养基中加入棉子成分的方法 ,进一步探索了 Bt棉棉子对平菇菌丝生长的影响。1材料和方法Bt蛋白提取液稀释 Bt蛋白 ( 1 0 0μg· ml-1)至3μg·ml-1,即为 Bt蛋白液。 1 0 g棉子 ,粉碎 ,加入蒸馏水 1 0 0 ml,搅拌 1 h;提取液 0 .2 μm过滤 ,用蒸馏水补足至 1 0 0 ml,即为棉子提取液。双倍 PD(双倍 PD培养基 ) :马铃薯浸粉 0 .2 5 g,葡萄糖 1 .0 g,蒸馏水 2 5 ml;1 2 1℃、 1 5 min。特殊 PD(特殊 PD培养基 ) :蒸馏水 2 0 ml,其余与双倍 PD… 相似文献
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氢化物发生-原子荧光法测定大豆色拉油中的痕量砷 总被引：7，自引：0，他引：7
研究利用干灰化法消解大豆色拉油 ,用氢化物发生 -原子荧光法测定其中的痕量砷 ,对消化方法、样液介质及酸度、还原剂 (KBH4)浓度、干扰离子、还原掩蔽剂等影响因素进行了探讨、得出试验的最佳条件。试验结果准确 ,灵敏度高 ,重现性好 ,方法简便、快速 ,适合于植物油中痕量砷的测定 ,方法的回收率在 86 .9%～ 98.0 %之间 ;线性范围为 0～ 2 0 0ng ml;检出限为 0 .19ng ml。 相似文献
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用RP-HPLC法测定人参茎叶皂苷粉中人参皂苷Re含量 总被引：2，自引：0，他引：2
过去对人参茎叶皂苷含量的测定只限于总皂苷的含量测定 ,对单体皂苷含量测定较少。本文用反相HPLC法测定了人参茎叶皂苷粉中人参皂苷Re的含量。色谱柱为Shim -packclc-ODS柱 (0 1 5m× 6 0mm ,,5μm)。流动相为 0 0 5 %磷酸 :乙腈 (4∶1 ) ,检测波长 2 0 3nm ,流速 1 2ml/min ,柱温 38℃。测得人参茎叶皂苷粉中人参皂苷Re含量为1 6 85 %。 相似文献
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我国部分大米含硒量分析及生物硒肥对籽粒硒水平的影响 总被引：20，自引：0，他引：20
用原子荧光分光光度法测定了江苏省 5 2个不同品种大米样品、全国部分省市 30个大米样品以及两种用不同硒生物肥生产的富硒大米的含硒量 ,研究了生物硒肥对大米含硒量及硒形态的影响。结果表明 ,江苏省的大米含硒量为 0 .0 15～ 0 .0 5 6 mg/kg,平均为 0 .0 35 mg/kg± 0 .0 0 9mg/kg;全国部分地区的大米含硒量为 0 .0 11～ 0 .0 5 5 mg/kg,平均为 0 .0 2 5mg/kg± 0 .0 11mg/kg,湖北恩施的大米含硒量达 0 .2 6 2 mg/kg。依据中国营养学会推荐的谷物食品摄入量 ,推算江苏省和其他地区居民从大米中摄入的硒分别为 10 .5～ 17.5 μg/(d·人 )和 7.5～ 12 .5 μg/(d·人 )。在水稻齐穗期喷施硒 2 0 g/hm2 ,大米含硒量由普通大米的 0 .0 71mg/kg分别提高到 0 .4 71mg/kg和 0 .6 4 0 mg/kg,有机硒比例分别由普通大米的 78.38%提高到 87.11%和 89.0 8%。外源硒能显著提高大米的含硒量和有机硒含量及比例 相似文献
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Joseph E. Laferriere Charles W. Weber Edwin A. Kohlhepp 《Plant foods for human nutrition (Dordrecht, Netherlands)》1991,41(3):277-282
Teas of plant origin traditionally consumed by the Mountain Pima of Chihuahua, Mexico, were analyzed for mineral nutritional content. Fe, Cu, Zn, Ca, and Mg composition was determined for native teas made from shoots ofTagetes lucida, T. filifolia, Elytraria imbricata, andHolodiscus dumosus, and from root xylem ofCeanothus depressus andPhaseolus ritensis. Native uses of these teas are also described. 相似文献
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Lakshman Lal 《Potato Research》1987,30(2):329-334
Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong
(1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage,
sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over
45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield
of a subsequent crop. 相似文献
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《Journal of Crop Improvement》2013,27(2):81-114
Summary The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices. 相似文献
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Tatiana G. Polotow Sandra C. Poppe Cristina V. Vardaris Douglas Ganini Maísa Guariroba Rita Mattei Elaine Hatanaka Maria F. Martins Eduardo F. Bondan Marcelo P. Barros 《Marine drugs》2015,13(10):6117-6137
Health authorities worldwide have consistently recommended the regular consumption of marine fishes and seafood to preserve memory, sustain cognitive functions, and prevent neurodegenerative processes in humans. Shrimp, crabs, lobster, and salmon are of particular interest in the human diet due to their substantial provision of omega-3 fatty acids (n-3/PUFAs) and the antioxidant carotenoid astaxanthin (ASTA). However, the optimal ratio between these nutraceuticals in natural sources is apparently the key factor for maximum protection against most neuro-motor disorders. Therefore, we aimed here to investigate the effects of a long-term supplementation with (n-3)/PUFAs-rich fish oil, ASTA-rich algal biomass, the combination of them, or krill oil (a natural combination of both nutrients) on baseline redox balance and neuro-inflammation indexes in cerebellum and motor cortex of Wistar rats. Significant changes in redox metabolism were only observed upon ASTA supplementation, which reinforce its antioxidant properties with a putative mitochondrial-centered action in rat brain. Krill oil imposed mild astrocyte activation in motor cortex of Wistar rats, although no redox or inflammatory index was concomitantly altered. In summary, there is no experimental evidence that krill oil, fish oil, oralgal biomass (minor variation), drastically change the baseline oxidative conditions or the neuro-inflammatory scenario in neuromotor-associated rat brain regions. 相似文献
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Youna Hemery Ulla Holopainen Anna-Maija Lampi Pekka Lehtinen Tanja Nurmi Vieno Piironen Minnamari Edelmann Xavier Rouau 《Journal of Cereal Science》2011
Wheat bran is a composite material made of several layers, such as pericarp, testa and aleurone. It could be fractionated into purified fractions, which might either be used as food ingredients, or serve as a starting material for extraction of bioactive compounds. The aim of this work was to evaluate the potential of using electrostatic separation as a way to obtain purified fractions from wheat bran. Ultrafine-ground bran obtained either by cryogenic grinding or by grinding at ambient temperature was used as starting material. The ultrafine bran was then charged by tribo-electrification and introduced in a chamber containing two high voltage electrodes, where bran particles were separated depending on their acquired charge, allowing positively and negatively charged fractions to be collected separately. The particle size distribution, microstructure and biochemical composition of the obtained fractions were studied. The charge of the particles was influenced by their biochemical composition: particles rich in highly branched and cross-linked arabinoxylans (pericarp) were separated from particles rich in β-glucan, ferulic acid and para-coumaric acid (aleurone cell walls). The testa and the intracellular compounds from aleurone were not highly charged, neither positively nor negatively. The most positively charged fraction represented 34% of the initial bran, and contained 62% of the ferulic acid present in the initial bran. The yield of the separation process was good (5.4% loss), and could be further increased. 相似文献
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M. I. Siri P. Villanueva M. J. Pianzzola L. Franco Fraguas G. Galván M. Acosta F. Ferreira 《Potato Research》2004,47(3-4):127-138
Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results
for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin
presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear
relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins
and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds. 相似文献
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Alexander N. Shikov Elena V. Flisyuk Ekaterina D. Obluchinskaya Olga N. Pozharitskaya 《Marine drugs》2020,18(11)
Marine organisms represent an excellent source of innovative compounds that have the potential for the development of new drugs. The pharmacokinetics of marine drugs has attracted increasing interest in recent decades due to its effective and potential contribution to the selection of rational dosage recommendations and the optimal use of the therapeutic arsenal. In general, pharmacokinetics studies how drugs change after administration via the processes of absorption, distribution, metabolism, and excretion (ADME). This review provides a summary of the pharmacokinetics studies of marine-derived active compounds, with a particular focus on their ADME. The pharmacokinetics of compounds derived from algae, crustaceans, sea cucumber, fungus, sea urchins, sponges, mollusks, tunicate, and bryozoan is discussed, and the pharmacokinetics data in human experiments are analyzed. In-depth characterization using pharmacokinetics is useful for obtaining information for understanding the molecular basis of pharmacological activity, for correct doses and treatment schemes selection, and for more effective drug application. Thus, an increase in pharmacokinetic research on marine-derived compounds is expected in the near future. 相似文献
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Novel food and non-food uses for sorghum and millets 总被引：4，自引：3，他引：4
Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity. 相似文献