四种不同年份普洱茶中茶多酚与咖啡碱成分的分析

分别用紫外分光光度和高效液相色谱法对存储7年、5年、3年、1年的普洱茶中茶多酚与咖啡碱进行了定量分析。结果表明：普洱茶中茶多酚与存储年限呈负相关．第五年时茶多酚急剧下降;四种茶叶中咖啡碱与存储年限也呈负相关,但是咖啡碱的含量随储存年限的下降不明显。经过感官测试,年份越久远的普洱茶的颜色和香味越好,其原因是普洱茶在储存过程中茶多酚与咖啡碱可能转化为起色物质和增香物质,但是普洱茶储存过程中化学、生物的转化等还需要进一步研究。     

腐乳品质改善的研究进展

腐乳是通过微生物发酵而成的一种滋味鲜美,营养丰富的佐餐食品,具有独特的风味以及良好的生理保健功能.结合国内外对腐乳的研究,主要对腐乳的生产工艺、微生物种类、风味物质、后发酵期的缩短以及腐乳生产和安全性控制进行了综述.相信随着人们健康意识的提高以及现代科学技术的应用,腐乳将具有更为广阔的发展前景.     

Effects of nitrite levels,endpoint temperature and storage on pink color development in turkey rolls

The objective of this research was to determine the relationship between minimum nitrite level, endpoint temperature and storage period on pink discoloration of turkey rolls. Rolls were prepared with 0, 3 or 5 parts per million (ppm) NO₂^–, cooked to an endpoint temperature of 75 °C or 85 °C and stored at 4 °C. During the 13-day storage period, on the 0th, 4th, 8th and 13th days cured pigment, total pigment, residual nitrite and color parameters were measured and sensory color was evaluated. At each endpoint temperature, addition of 3 ppm or 5 ppm NO₂^– significantly increased cured pigment and total pigment levels. Cured pigment levels of turkey rolls cooked to 75 °C were higher than rolls cooked to 85 °C, regardless of the NO₂^– level. There was a significant decrease in cured pigment levels at the end of the storage period (13th day). Analysis of residual NO₂^– in all treatment groups showed no detectable amounts. Endpoint temperature and addition of NO₂^– affected L* values: rolls cooked to the 75 °C endpoint had higher L* values. The additon of nitrite with the 75 °C endpoint temperature resulted in higher a* values. a* values also increased during the storage. The higher endpoint temperature (85 °C) resulted in lower a* values. Yellowness was not affected by final cooking temperature. Both the addition of NO₂^– and storage decreased b* values. The panel found no differences in pinkness intensity between the two levels of added nitrite (3 and 5 ppm). Sensory pinkness intensity in nitrite-added samples increased with increasing storage.     

雍正时期宫廷器物中的荷莲纹样剖析

荷莲纹样的样式和使用频率在雍正朝达到历史上的高峰。本文试图从社会政治背景、经济实力、文化氛围的角度,分析雍正朝宫廷器物中荷莲纹样的内容、布局、造型和装饰寓意在特定时代的成因。     

Diets during far-off and close-up dry periods affect periparturient metabolism and lactation in multiparous cows

The objectives of this study were to determine the effects of far-off and close-up diets on prepartum metabolism, postpartum metabolism, and postpartum performance of multiparous Holstein cows. From dry-off to −25 d relative to expected parturition (far-off dry period), cows were fed a control diet to meet National Research Council (NRC) recommendations for net energy for lactation (NE_L) at ad libitum intake (100NRC; n = 25) or a higher nutrient density diet, which was fed for either ad libitum intake to provide at least 150% of calculated NE_L requirement (150NRC; n = 25) or at restricted intake to provide 80% of calculated NE_L requirements (80NRC; n = 24). From −24 d relative to expected parturition until parturition (close-up period), cows were fed a diet that met or exceeded NRC nutrient recommendations at either ad libitum intake (n = 38) or restricted intake (n = 36) to provide 80% of the calculated NE_L requirement. After parturition, all cows were fed a lactation diet and measurements were made through 56 d in milk (DIM). Prepartum metabolism was consistent with the plane of nutrition. During the first 10 DIM, far-off treatments had significant carryover effects on dry matter intake, energy balance, serum nonesterified fatty acid (NEFA) concentration, and serum β-hydroxybutyrate concentration. Cows with the lower energy balance during the far-off period (100NRC and 80NRC) had higher dry matter intake and energy balance and lower serum NEFA and β-hydroxybutyrate during the first 10 DIM. There were no effects of close-up diet and no interactions of far-off and close-up treatments. During the first 56 DIM, there were no residual effects of far-off or close-up diets on dry matter intake, milk yield or composition, body weight, body condition score, serum glucose and insulin concentrations, or muscle lipid concentration. Serum NEFA was higher for 150NRC than 80NRC; 100NRC was intermediate. Thus, the effects of far-off and close-up treatments on postpartum variables diminished as lactation progressed. Overfeeding during the far-off period had a greater negative impact on peripartum metabolism than did differences in close-up period nutrition.     

中国画表现形式在连环画创作中的应用探究

中国连环画作品充实着人们的文化生活,它不仅是青少年的重要课外读物,也是许多成年人文化娱乐的重要内容。连环画作品大多以手绘的形式出现,所涉及的题材也较为广泛。除了宣传教育方面的题材以外,连环画的创作者们还将各种古典小说、历史、传说故事等传统文化介绍给广大人民群众。中国连环画艺术发展于20世纪二三十年代,到1970年代,发展到了顶峰。那时,从事这项工作的几乎都是顶尖、一流画家,创造了中国连环画史上无与伦比的艺术表现形式高峰。     

Increasing dietary sugar concentration may improve dry matter intake, ruminal fermentation, and productivity of dairy cows in the postpartum phase of the transition period

The current study was undertaken to investigate the effect of feeding diets varying in sugar concentration to postpartum transition cows on productivity, ruminal fermentation, and nutrient digestibility. We hypothesized that the high-sugar diet would increase dry matter intake and lactation performance. The secondary objective was to characterize changes in ruminal fermentation and nutrient digestibility over the first 4 wk of lactation. Fifty-two Holstein cows, including 28 primiparous and 24 multiparous cows, 10 of which were previously fitted with a ruminal cannula, were assigned to the experimental diets containing either high sugar (HS = 8.4%) or low sugar (LS = 4.7%) immediately after calving, based on their expected calving date. Data and samples were collected on d 5.2 ± 0.3, 12.2 ± 0.3, 19.2 ± 0.3, and 26.1 ± 0.3 relative to parturition for wk 1, 2, 3, and 4 respectively. Cows fed HS had increased dry matter intake compared with those fed LS (18.3. vs. 17.2 kg/d). Further, cows fed HS sorted for particles retained on the pan of the Penn State Particle Size Separator to a greater extent than cows fed LS. Feeding HS tended to increase nadir (5.62 vs. 5.42), mean (6.21 vs. 6.06), and maximum pH (6.83 vs. 6.65). The duration (h/d) and area (pH × min/d) that ruminal pH was below pH 5.8 were not affected by treatment. Ruminal volatile fatty acid concentration and molar proportions of individual volatile fatty acids were not affected by treatment. The digestibility of dry matter, organic matter, neutral detergent fiber, and starch were not affected by treatment, averaging 63.3, 65.2, 43.2, and 93.5%, respectively. Feeding HS decreased plasma glucose concentration compared with feeding LS (51.3 vs. 54.0 mg/dL), but concentration of plasma insulin was not affected by treatment, averaging 4.17 μIU/mL. Cows fed HS had higher concentrations of plasma β-hydroxybutrate (17.5 vs. 10.5 mg/dL) and nonesterified fatty acids (344 vs. 280 μEq/L). Milk yield and milk composition were not affected by treatment, but a tendency for increased milk fat yield was observed for cows fed HS compared with LS (1.44 vs. 1.35 kg/d). The results of the current study imply that replacing cracked corn grain with sucrose may improve dry matter intake, ruminal pH status, and lactation performance.     

严寒地区深水桥梁施工组织设计探讨

以同江跨境铁路桥为例,结合项目所处地区严寒的气候特点,对如何安排深水桥梁施工组织进行了介绍,并对工期的确定方法进行了详细阐述,为今后类似桥梁施工组织设计提供了参考依据。     

论建设工程缺陷责任期

缺陷责任期由起始时间和持续时间决定,其长度由合同双方约定,最长不超过24个月。它具有法定特征、自然特征、约定特征等特征。缺陷责任期设置的目的之一,就是缺陷责任期届满应当结清质量保证金,故缺陷责任期与质量保证金密切相关。     

合成纤维水泥稳定土抗裂性试验研究

为提高道路半刚性基层的抗裂性,以合成纤维半刚性材料为研究对象,通过室内抗弯拉试验,分析合成纤维的掺量及试件养护龄期等对合成纤维水泥稳定土抗弯拉强度的影响。结果表明,随着纤维掺量的增加、长径比的增大,水泥稳定土的抗裂性亦逐渐增强;合成纤维水泥稳定土的抗裂性随着养护龄期的增长逐渐增大。