排序方式: 共有20条查询结果,搜索用时 15 毫秒
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S. A. G. F. Angelino H. P. M. van Laarhoven J. J. M. van Westerop B. M. Broekhuijse H. C. M. Mocking 《Journal of the Institute of Brewing》1997,103(1):41-46
It was demonstrated that the Dumas method is suitable to analyse single kernel barley samples for their total nitrogen content directly without milling. The method was compared to the nitrogen analysis in milled samples over a range of 1.5-3.0%N. These samples consisted of kernel size grading fractions from barley cultivated at different N-dressings and using a shading regime. A good correlation was found between milled and whole barley kernels (r2=0.852). The method was used to determine the nitrogen content of individual kernels in the barley grading fractions. The nitrogen content in these fractions decreased with increasing kernel size depending on growth conditions. A large variation in nitrogen content between individual kernels was found for all grading fractions. In a study of barley main spikes the variation in kernel nitrogen content within spikes was smaller than the variation between spikes, especially when the barley was grown at a 60% light reduction regime during the kernel filling period. The average kernel total nitrogen content under the latter condition was about two times as high as in the control experiment. The kernel position along the spike did not clearly affect its nitrogen content. Acid and SDS polyacrylamide gel electrophoresis (PAGE) revealed similar banding patterns for proteins from kernels at different positions of both low and high N barley spikes. The single kernel method for nitrogen may be used by the breeder as a quality criterion for new barley varieties to test their spike development at different cultivation conditions. It can suit the maltster to screen rapidly the homogeneity in nitrogen (protein) content of barley batches. 相似文献
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杜马斯燃烧法测定牛奶中的蛋白质含量 总被引:2,自引:1,他引:1
目的通过对杜马斯燃烧法和凯氏定氮法测定牛奶中的蛋白质含量的比较,建立杜马斯燃烧法测定牛奶中蛋白质的方法。方法杜马斯燃烧法检测条件:称样量100 mg,通氧量80 m L/min,通氧时间80 s;结果选用合适的燃烧条件用杜马斯燃烧法可以准确测定牛奶中的蛋白质含量。结论此方法具有结果准确、精密度高、易于操作的优点,适用于大批量牛奶样品的检测。 相似文献
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氮含量是钒氮合金质量的重要技术指标之一,目前国内主要采用湿法分析氮,结果可靠但效率低,因此有必要建立快速测定钒氮合金中氮含量的方法。实验探讨了采用杜马斯燃烧法测定钒氮合金中氮的方法,对样品粒径、称样量、燃烧时间、助熔剂用量进行了优化。实验选定条件为:样品粒径不大于0.074mm,称样量0.040 0~0.060 0g,燃烧时间270s,采用0.1g纯镍和0.1g纯钨作助熔剂。结果表明:在优化实验条件下,氮含量为13.14%~16.64%(质量分数,下同),氮的质量分数与对应的峰面积呈线性关系,校准曲线的线性相关系数r为0.999 6。按照实验方法测定钒氮合金有证标准物质中氮,测定值与标准值的相对误差为0.21%~0.38%。方法用于实际样品中13.55%~15.56%氮的测定,结果的相对标准偏差(RSD,n=10)为0.42%~0.50%。 相似文献
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Comparison of combustion and Kjeldahl methods for determination of nitrogen in oilseeds 总被引:1,自引:0,他引:1
James K. Daun Douglas R. DeClercq 《Journal of the American Oil Chemists' Society》1994,71(10):1069-1072
The recent development of combustion-type nitrogen analyzers capable of handling relatively large samples with semi automatic
operation offers a potential replacement for the Kjeldahl method for direct determination of nitrogen. Nitrogen analyses for
canola seed, flaxseed, sunflower seed, mustard seed and soybeans on a LECO (St. Joseph, MI) FP-428 Nitrogen Analyzer were
evaluated against results from the Grain Research Laboratory's (GRL) Kjeldahl system. The nitrogen analyzer gave significantly
higher values than the Kjeldahl method, resulting in a correction of low values in the GRL Kjeldahl, caused by the inability
to use mercury as catalyst. The standard error for results from the analyzer was comparable to that for the Kjeldahl method.
The nitrogen analyzer also was faster than the Kjeldahl method and had less environmental impact. The combustion method has
replaced the Kjeldahl method for routine nitrogen determinations in oilseed surveys conducted by the GRL.
Presented at the 84th AOCS Annual Meeting & Expo, April 27, 1993, Anaheim, California. 相似文献
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采用杜马斯燃烧法,利用氮分析仪对煤炭中的氮含量进行测定。试样在一个分析周期中分为3个阶段:冲洗、燃烧和分析。结果表明,用杜马斯燃烧法测定煤炭中氮含量与传统湿法分析相比,操作方法简便容易掌握,快速分析的同时确保了准确性,符合工业生产与试验分析的要求。 相似文献
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Jerry Suchy Odean M Lukow Bin X Fu 《Journal of the science of food and agriculture》2003,83(10):1083-1090
Wheat protein composition is important for understanding the biochemical basis of wheat quality. The objective of this study was to design a simple protein fractionation protocol with low cross‐contamination and to show that these protein fractions were associated with wheat quality. The protocol consists of three sequential extractions from 100 mg of flour with 7.5% propan‐1‐ol and 0.3 M sodium iodide (monomeric‐rich protein), 50% propan‐1‐ol (soluble glutenin‐rich protein) and 40% propan‐1‐ol and 0.2% dithiothreitol (insoluble glutenin‐rich protein). Nitrogen content of protein solubility groups was determined from dry residues using an automated combustion nitrogen analyser. About 90% of the total protein in the flour was solubilised. Cross‐contamination of protein fractions was evaluated by SDS‐PAGE, SE‐HPLC and RP‐HPLC. Variation in nitrogen content of the protein solubility fractions was lowest for monomeric‐rich protein (<2%) and insoluble glutenin‐rich protein (<4%). Three wheats with similar high‐molecular‐weight (HMW) glutenin subunit composition, Alpha 16, Glenlea and Roblin, varied significantly (P ≤ 0.05) in the proportion of monomeric‐rich and insoluble glutenin‐rich protein in the flour. Dough rheological properties were directly related to the proportion of insoluble glutenin‐rich protein and inversely related to the proportion of monomeric‐rich protein. The protocol was validated using an expanded set of 11 wheats which also showed that inter‐cultivar differences in the proportion of monomeric‐rich, insoluble glutenin‐rich protein and glutenin‐to‐gliadin ratio in the flour governed dough rheological properties such as mixograph, farinograph and microextension tests. The protocol has merit for quality screening in wheat‐breeding programmes when the sample size is too small or when time constraints limit the ability to perform traditional rheological tests. For the Department of Agriculture and Agri‐Food, Government of Canada, Copyright © Minister of Public Works and Government Services Canada 2003. Published for SCI by John Wiley & Sons, Ltd. 相似文献
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At the beginning of the 20th century, Alfred Binet sought teaching positions at the Colfte de France and the Sorbonne. Binet wanted to develop experimental psychology in France, but the strong psychopathological orientation of French psychology blocked his ambition. The 1st part of this article relates the history of the introduction of psychology, via Théodule Ribot, to the Sorbonne and the Coll6ge de France. Ribot's premature retirement from the Collège de France in 1901 triggered a battle that led to Binet's repeated failure to gain access to these institutions of higher education and the success in 1902 of Ribot's students: Pierre Janet at the Colfte de France and Georges Dumas at the Sorbonne. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献