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41.
H H Chang J W De Vries W E Hobbs 《Journal of the Association of Official Analytical Chemists》1979,62(6):1281-1284
The difference between the CB and Best Foods methods in extracting aflatoxins from peanut products has been studied. The CB method yields 60, 121, 35, and 22% higher results for aflatoxins B1, B2, G1, and G2, respectively for 4 samples of peanut meal and 6 samples of peanut butter studied. Both reverse phase liquid chromatography and thin layer chromatography were used to quantitate the extracted aflatoxins. 相似文献
42.
The chemistry of humic and fulvic acids extracted from argentine soils—I. Analytical characteristics
Five humic and three fulvic acids were extracted from Argentine Chestnut, Brunizem, Solod and Solonetz soils and analysed by electrometric, spectroscopic and spectrometric methods. There were great similarities in elementary analysis, functional group content, absorption characteristics in the visible region and in the IR, and in the ESR measurements between the humic acids and, similarly, between the fulvic acids. There were distinct differences between the humic and fulvic acids in C, H, N and O content, distribution of oxygen in functional groups, E4/E6 ratios and free radical content. 相似文献
43.
44.
D. P. De Vries 《Euphytica》1965,14(1):78-82
In 9–13 year old cherry seedling populations, totalling 1,033 individuals, a preliminary selection was made in 1963, for field resistance to bacterial canker (Pseudomonas syringae
van Hall).The field resistance of the three cherry species used, P. avium, P. cerasus and P. avium × P. cerasus, has shown to be low, high and very high, respectively. 相似文献
45.
Consumer perception versus scientific evidence of farmed and wild fish: exploratory insights from Belgium 总被引:2,自引:2,他引:0
Wim Verbeke Isabelle Sioen Karen Brunsø Stefaan De Henauw John Van Camp 《Aquaculture International》2007,15(2):121-136
The increasing number of marketable fish being supplied from aquaculture is a response to the increasing demand for healthy
food and is filling the gap left by depleting natural fish stocks. Little is known about the awareness and perception of the
consumer in terms of farmed fish versus fish from capture fisheries. The consumer's subjective point of view is of overriding
importance for the production system and product acceptance as well as for future market success. In this paper consumer perception
in Belgium is explored and compared against scientific evidence of farmed versus wild fish. Primary data were collected through
a consumer survey (April 2003) and focus group discussions (May 2004) with Belgian consumers. The majority of the consumer
sample reported no perceived differences between farmed versus wild fish. However, mean perception scores were slightly in
favour of wild fish on the attributes taste, health and nutritious value, in particular among consumers aged 55 years and
older. The availability of farmed fish was perceived to be better than that of wild fish, while the consumer's perception
of safety did not differ between farmed and wild fish. The focus group discussions indicated that consumers’ opinions and
beliefs about farmed fish are mainly based on emotion and image transfer from intensive terrestrial livestock production rather
than on awareness and factual knowledge of aquaculture.
相似文献
John Van CampEmail: |
46.
47.
本文介绍了1种利用智能型、高精度脉宽调制发生器SA4828和单片机结合构成的风电逆变器,并给出了SA4828与单片机相结合的控制方法及初始参数的选定。实验表明逆变器的硬件和软件设计合理,工作可靠性高。 相似文献
48.
49.
毒死蜱微囊悬浮剂的制备及微囊化条件的优化 总被引:7,自引:4,他引:3
以脲醛树脂为壁材,采用原位聚合法制备了20%毒死蜱微囊悬浮剂,探讨了影响微囊粒径大小及分布的因素,优化了微囊化条件,并就其与毒死蜱乳油对韭菜迟眼蕈蚊Bradysia odoriphaga幼虫的毒力进行了对比。结果表明,选用苯乙烯-马来酸酐共聚乳液(SMA)为分散剂(质量分数为总体系的2.5%),乳化条件为1 500 r/min搅拌30 min,60 min内调节体系pH值至2.5,反应后期升温至45℃,在此条件下制备的毒死蜱微胶囊外形较好,平均粒径为8.9 μm,分散系数为0.182 6,包封率高达99.54%。毒力测定结果表明,乳油和微胶囊对韭菜迟眼蕈蚊幼虫的初始LC50值分别为2.05和 3.02 μg/mL;而在自然环境中放置32 d后,乳油对该虫的毒力下降较快,LC50值为100.23 μg/mL,而微囊悬浮剂毒力仍保持较高水平,LC50值为15.63 μg/mL。表明毒死蜱微囊悬浮剂兼具速效性高和持效期长的优点。 相似文献
50.
When quinoa, Chenopodium quinoa Willd., is cultivated in South America outside of its Andean origin, the heteropterans Liorhyssus hyalinus (Fabricius) and Nysius simulans Stål may emerge as important pests. Here we studied the development and reproduction of both species at different constant temperatures in the laboratory. Egg and nymphal development were investigated at 18, 22, 26, 30, 34, and 36°C. For both species, egg incubation time significantly decreased as the temperature increased. Nymphs did not successfully develop at 18°C and the total nymphal time significantly decreased as the temperature increased from 22 to 36°C. Based on a linear day-degree (DD) model, the lower developmental threshold (LDT) temperatures for eggs and nymphs were estimated to be 16.0 and 17.9°C for L. hyalinus, and 16.1 and 19.7°C for N. simulans, respectively. Thermal requirements for egg and nymphal development were 68.6 and 114.8 DD for L. hyalinus, and 77.7 and 190.3 DD for N. simulans, respectively. Reproduction and adult longevity were studied at 22, 26, 30, and 34°C. For both species preoviposition time decreased as temperature increased, and the oviposition period was longest at 26°C. The highest fecundity and egg viability were observed at 30°C, whereas longevities were higher at 22–26°C than at 30–34°C. As the lowest tested temperatures were not suitable to both heteropterans and 30°C was found to be the optimal temperature for development and reproduction, peak densities are expected in warm areas and seasons. 相似文献