罗威纳犬(2)

一、罗威纳犬的起源 罗威纳犬的起源众说纷纭.有人认为是一个引入犬种,古罗马军队通过阿尔卑斯山关隘入侵北欧的途中,随军带了一种体型高大,黑棕黄色的犬,通过黑森林地带时,它们一直吵个不停,被遗漏于此地.经德国的繁育员们花了比古罗马时代还要长的时间来培育它们,形成了今天的罗威纳犬;也有人坚信罗威纳犬与罗特威勒地名存在着必然的联系.     

设施农业在推广中的问题及对策

在简述发展设施农业重要意义的基础上,详细分析了目前设施农业发展中存在的主要问题,讨论提出了相应的对策建议,为推广设施农业提供了参考依据。     

浅谈城市园林绿化的生态功能和社会功能

城市是人类社会活动的主要空间,随着城市化进程的加快,环境问题愈来愈受到关注和重视,园林绿化在城市生态环境的改善中发挥着重要的作用.城市园林绿化既有生态功能又有社会功能.     

Effects of dietary neutral detergent fibre on production performance, nutrient utilization, caecum fermentation and fibrolytic activity in 2- to 3-month-old New Zealand rabbits

An experiment was conducted to determine the effects of different dietary neutral detergent fibre (NDF) levels on growth performance, nutrient utilization, caecum development, caecal fermentation, slaughter performance, immune organ and fibrolytic activity in 2- to 3-month-old New Zealand meat rabbits. Eighty 2-month-old rabbits were allocated in individual cages for five treatments in which they were fed each diet with NDF at 240, 270, 300, 330 and 360 g/kg respectively. The results are as follows: the average daily gain of 300 g/kg NDF group was the highest (30.09 g/day) and higher than that of 240 g/kg NDF group (p < 0.05). The feed/gain ratio of 300 g/kg NDF group was the lowest (4.27) and lower than those of 240 and 360 g/kg NDF groups (p < 0.05). The coefficient of total tract apparent digestibility (CTTAD) of energy, crude protein, crude fibre and ether extract decreased when dietary NDF increased (p < 0.05); CTTAD of NDF increased when dietary NDF increased (p < 0.01). Digestible nitrogen and retained nitrogen of 240, 270, 300 and 330 g/kg NDF groups were higher than that of 360 g/kg NDF group (p < 0.05). The caecum weight, the proportion of caecum weight to body weight and the acetic acid ratio of volatile fatty acid rose when dietary NDF concentration increased (p < 0.05). The NH(3)-N concentration of caecum dropped when dietary NDF increased (p < 0.05). The fibrolytic activity increased when the dietary NDF increased (p < 0.01).     

Correlations between the amounts of free asparagine and saccharides present in commercial cereal flours in the United Kingdom and the generation of acrylamide during cooking

A range of commercially available cereals (mainly rye and wheat) used to manufacture U.K. bakery products were obtained, and the levels of free amino acids and sugars were measured. Selected samples were cooked as flours and doughs to generate acrylamide and the data compared with those obtained from a model system using dough samples that had been additionally fortified with asparagine (Asn) and sugars (glucose, fructose, maltose, and sucrose). In cooked flours and doughs, Asn was the key determinant of acrylamide generation. A significant finding for biscuit and rye flours was that levels of Asn were correlated with fructose and glucose. The results suggest that for these commercial cereals, selection based on low fructose and glucose contents, and hence low asparagine, could be beneficial in reducing acrylamide in products (e.g., crackers and crispbreads) that have no added sugars.     

乡村旅游概念辨析

从国内外学者对乡村旅游概念多角度界定的层面进行总结评述,并对与乡村旅游易混淆概念进行辨析,分析探索乡村旅游的内涵。     

粉胶比对沥青混合料路用性能影响的试验研究

合理的粉胶比有利于提高沥青混合料的路用性能。试验在不同粉胶比条件下,通过车辙试验、低温弯曲试验、浸水马歇尔和冻融劈裂试验,分析沥青混合料的高温性能、低温性能和水稳性的变化,以确定合理的粉胶比范围。试验结果表明：粉胶比的增大,动稳定度增大,在粉胶比为1.2时出现峰值,随后开始下降;弯拉应变随粉胶比的增大而增大,粉胶比在1.0-1.1之间达到峰值,之后开始减小;劲度模量先减小后增大,呈凹形曲线,粉胶比为1.0时达到最小值;残留稳定度随粉胶比变化呈现增加后减小变化,最大值出现在粉胶比为1.0左右;冻融劈裂强度比先增大后减小,最大值在1.0-1.2范围内。综合考虑,在进行沥青混合料配合比设计时,粉胶比宜控制在0.9-1.2范围内。