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排序方式: 共有313条查询结果,搜索用时 31 毫秒
91.
92.
Lars Ovesen Torben Leth Kirsten Hansen 《Journal of the American Oil Chemists' Society》1998,75(9):1079-1083
This study examined trans monounsaturated fatty acid contents in all margarines and shortenings marketed in Denmark, and in frying fats used by the
fast-food restaurants Burger King and McDonald’s. Trans C18:1 content was 4.1±3.8% (g per 100 g fatty acids) in hard margarines, significantly higher than the content in soft margarines
of 0.4±0.8%. Shortenings had an even higher content of trans C18:1, 6.7±2.3%, than the hard margarines. Margarines and shortenings with high contents of long-chain fatty acids had about 20%
total trans monoenoic of which close to 50% were made up of trans long-chain fatty acids. Both fast-food frying fats contained large amounts of trans C18:1, 21.9±2.9% in Burger King and 16.6±0.4% in McDonald’s. In Denmark the per capita supply of trans C18:1 from margarines and shortenings and frying fats has decreased steadily during recent years. The supply of trans C18:1 from margarines and shortenings in the Danish diet is now 1.1 g per day. 相似文献
93.
In recent years some research towards developing forecasting models for wind power or energy has been carried out. In order to evaluate the prediction ability of these models, the forecasts are usually compared with those of the persistence forecast model. As shown in this article, however, it is not reasonable to use the persistence model when the forecast length is more than a few hours. Instead, a new statistical reference for predicting wind power, which basically is a weighting between the persistence and the mean of the power, is proposed. This reference forecast model is adequate for all forecast lengths and, like the persistence model, requires only measured time series as input. Copyright © 1998 John Wiley & Sons, Ltd. 相似文献
94.
Akerstedt M Forsbäck L Larsen T Svennersten-Sjaunja K 《The Journal of dairy research》2011,78(1):88-96
Dairy herds are expanding and, with increasing numbers of animals in each herd, there is a need for automatic recording of indicators in milk in order to detect mastitis, inflammation of the udder. A number of biomarkers for mastitis have been suggested over the years. Mastitis usually occurs in one of the four udder quarters and since it is now possible to milk each udder quarter separately in automated milking systems, it is important to evaluate the normal variation in the biomarkers at udder quarter level. This study evaluated the normal variations between milkings for some biomarkers in clinically healthy cows, determined by repeated somatic cell count and bacteriological analysis. The biomarkers studied were serum amyloid A (SAA), haptoglobin (Hp), lactate dehydrogenase (LDH), N-acetyl-β-D-glucosaminidase (NAGase) and alkaline phosphatase (AP), parameters that have been suggested as markers for mastitis. Ten cows were monitored on 42 consecutive milking occasions through collection of udder quarter milk samples and representative cow composite milk samples, giving a total of 2100 individual milk samples. Each cow had its individual profile for the concentrations and variations in the parameters analysed. Although there was relatively large variation between cows for the biomarkers analysed, the variation between milkings in clinically healthy quarters within cows was often below 10%. The biomarker with the lowest variation in this study was LDH. The results suggest that comparing quarters within an individual cow can identify deviations from the natural variations between milkings. This could be a valuable tool instead of, or in combination with, a cut-off value for each parameter in order to detect changes in the milk indicating mastitis. 相似文献
95.
Axel Nørlund Christensen Torben R. Jensen Nicola V. Y. Scarlett Ian C. Madsen Jonathan C. Hanson 《Journal of the American Ceramic Society》2004,87(8):1488-1493
The hydrolysis of pure and sodium-substituted calcium aluminates and cement clinker phases was investigated in situ in the temperature range 25°–170°C, using the angle dispersive powder synchrotron powder X-ray diffraction technique. The final hydrolysis product in all cases was Ca3 Al2 (OH)12 . The intermediate phase Ca4 Al2 O7 ·19H2 O was formed from the pure calcium aluminates, and the intermediate phases Ca4 Al2 O7 · x H2 O, x = 11, 13, or 19, were formed from the cement clinker phases. 相似文献
96.
Octanol-water partition coefficients (K ow s) of substituted polycyclic aromatic compounds (PACs), anthracene-, pyrene- and quinoline-derivatives, have been determined using HPLC. The determined K ow s have been compared with results from theoretical fragment methods, developed by Rekker and Mannhold [1] and by Hansch and Leo [2]. The results showed that if these theoretical methods are to be useful with simple substituted PAHs they must be applied differently than normally supposed, due to intramolecular steric conditions. Comparison of the determined K ow s with measured K oc values showed that the relationship between K oc and K ow is not straightforward, and that prediction of K oc from K ow alone will not give results applicable for substituted polycyclic aromatic compounds. 相似文献
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100.
Martin Sndergaard Erik Jeppesen Jens Peder Jensen Torben Lauridsen 《Lakes & Reservoirs: Research and Management》2000,5(3):151-159
Lake restoration in Denmark has involved the use of several different restoration techniques, all aiming to improve lake water quality and establishing clear‐water conditions. The most frequently used method, now used in more than 20 lakes, is the reduction of zooplanktivorous and benthivorous fish (especially roach (Rutilus rutilus) and bream (Abramis brama)) with the objective of improving the growth conditions for piscivores, large‐sized zooplankton species, benthic algae and submerged macrophytes. Piscivore stocking (mainly Esox lucius (pike)), aiming especially at reducing the abundance of young‐of‐the‐year fish, has been used in more than 10 lakes and frequently as a supplement to fish removal. Hypolimnetic oxidation, with oxygen and nitrate, has been undertaken in a few stratified lakes and sediment dredging, with the purpose of diminishing the internal phosphorus loading, has been experimented with in one large, shallow lake. Submerged macrophyte implantation has been conducted in some of the biomanipulated lakes to increase macrophyte abundance and distribution. Overall, the results from lake restoration projects, in the mainly shallow Danish lakes, show that external nutrient loading must be reduced to a level below 0.05–0.1 mg P L–1 under equilibrium conditions to gain permanent effects on lake water quality. By using fish removal, at least 80% of the fish stock should be removed over a period of not more than 1–2 years to obtain a substantial effect on lower trophic levels and to avoid regrowth of the remaining fish stock. Stocking of piscivores requires high densities (>0.1 individuals m–2) if an impact on the plankton level is to be obtained and stocking should be repeated yearly until a stable clear‐water state is reached. The experiments with hypolimnetic oxygenation and sediment dredging confirm that internal phosphorus loading can be reduced. Experience from macrophyte implantation experiments indicates that protection against grazing by herbivorous waterfowl may be useful in the early phase of recolonization. 相似文献