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1.
Effects of different forms and origins of oilseeds on dynamics of ruminal biohydrogenation of long‐chain fatty acids in vitro 下载免费PDF全文
A. Hoffmann H. Steingass M. Schollenberger H. Terry K. Hartung E. Weiss R. Mosenthin 《Journal of animal physiology and animal nutrition》2015,99(6):1031-1038
Dietary unsaturated fatty acids (FA) are intensively hydrogenated in the rumen, resulting in reduced amount of poly‐unsaturated fatty acids (PUFA) and accumulation of several biohydrogenation (BH) products. In this study, BH of PUFA originating from different oilseeds (linseed, soya beans, sunflower seed and rapeseed) present in crushed oilseeds or their free oils were assessed in vitro. The assay substrates were incubated in buffered rumen fluid for 0, 6, 12 and 24 h. After incubation, the FA pattern of the incubated samples was analysed using gas chromatography. Biohydrogenation is defined as disappearance of double bonds (DB) calculated from the contents of unsaturated FA. After 24‐h incubation, the DB contents of all oilseeds were reduced (p < 0.001) by 40–60%. The reduction was higher (p < 0.001) for the crushed form compared with the oil form. In addition, linseed and sunflower seed known as oilseeds with high contents of linolenic acid C18:3 c9,12,15 (LNA) and linoleic acid C18:2 c9,12 (LA), respectively, showed a higher (p < 0.001) accumulation of the BH intermediates conjugated linoleic acid (CLA, isomer C18:2 c9t11) and vaccenic acid (C18:1 t11) for the crushed form, when compared with the oil. These results suggest an inherent effect of the physical form of the assay oilseeds on in vitro BH. Changes in FA pattern during BH in vitro can be attributed to both source and physical form of the assay oilseeds. However, further investigations are warranted to ensure whether the observed in vitro effects on ruminal BH can be confirmed in vivo. 相似文献
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Cao Jin-zhen Yu Li-li You Xiao-di Kamdem D. Pascal 《中国林学(英文版)》2007,9(4):239-245
In order to clarify the interaction between copper and wood substances in wood treated with copper containing water-borne wood preservatives, the dielectric constant ε′ and dielectric loss factor ε″ of untreated wood and wood treated with four concentration levels of copper-ethanolamine (Cu-EA) solutions were determined within a temperature range from –100 to 40°C and a frequency range from 100 to 1 MHz. Three dielectric relaxation processes were observed in the ε″ spectrum; among them R-I is based on the reorientation of methylol groups in the amorphous region of wood cell walls and R-II is related to wood extractives. R-III appeared in Cu-EA treated wood, and its magnitude decreases with the concentration of Cu-EA solutions used in this experiment. This relaxation process was considered to be based on the reorientation of copper-ethanolamine-wood complexes in wood cell walls. At low copper retention, the hydrogen in the complex can form hydrogen bonding with adjacent hydroxyl groups, which results in a strong bonding state between copper and wood; at high copper retention, the numerous copper-ethanolamine complexes not only hinder them from forming hydrogen bonding with adjacent wood molecules due to steric hindrance, but also weaken the interaction between wood molecules themselves, which corresponds to reducing ε″ values of both R-I and R-III processes. The results explain the fact of in-creasing copper leaching in wood treated with high concentration copper-based water-borne preservatives. 相似文献
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含铜氮配键腰果酚醛缩聚物的特性及表征 总被引:1,自引:0,他引:1
腰果酚醛树脂中含有较活泼的酚羟基,略显酸性,易受碱的腐蚀。先由共缩聚法得到以苯胺改性的腰果酚醛缩聚物,再使之与CuCl2反应,合成含铜一氮配键腰果酚醛缩聚物。用IR、动态粘弹谱(DMTA)、TG和其他手段对产物的结构和理化性能进行表征。结果表明,金属铜离子与苯胺分子中氮原子形成配位健,增大了涂膜内部的交联度,使分子链间形成更大的网状结构。因此,含铜-氮配键腰果酚醛涂膜的物理机械性能、热稳定性、耐化学介质尤其是耐碱性能得到很大的改善。 相似文献
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本文研究了不同N源对落叶松苗木干物重、养分吸收及离子平衡的影响。结果表明:施铵态N的苗木干物重小于对照处理;施硝铵态N的苗木生长与对照和施硝态N的苗木差别不大,但较施铵态N的苗木生长要好。铵态N与硝铵态N处理苗木地上部的阳离子总浓度受N水平的影响很小,而硝态N处理时则阳离子浓度增加;各处理对地上部阴离子浓度的影响均不大。在根部除硫酸根与钙离子外,阳离子与阴离子浓度均变化不大。硝态N处理的苗木具有较高的C-A值;△(C-A)/△Norg值在硝态N处理的苗木中随N供应量的增加而略有变化,但铵态N处理则明显下降;硝铵态N处理苗木的△(C-A)/△Norg值界于铵态N处理与硝态N处理之间。 相似文献
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The effects of reduced headspace pressure on the development of gluten network in doughs made from both high-protein flour (HPF) and low-protein flour (LPF) were investigated. The effect of vacuum mixing was found to be dependent on both flour-type and mixing-time. A significant increase in dough extensibility was observed when the HPF dough was mixed under moderate vacuum of −0.04 MPa for 3 min as compared to the one mixed under atmospheric pressure for the same duration. This was attributed to the formation of a more extensive gluten network associated with an increased disulphide bond density and a significantly higher β-sheet to β-turn ratio. On the other hand, over-mixing was observed in the LPF dough that was mixed for 5 min under atmospheric pressure. Applying moderate vacuum of −0.04 MPa allowed the LPF dough to withstand longer mixing time, as indicated by its increased disulphide bond density and biaxial extensibility compared to the control dough mixed under atmospheric pressure. Results of this study suggest the potential of applying vacuum to reduce the mixing time required for high protein flour and to prevent the over-mixing of low protein flour. 相似文献
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在系统梳理绿色债券相关理论基础上,以16个二级行业为研究对象,运用事件分析法分析林业企业上市公司发行绿色债券与股价相关性、林业企业发行绿色债券的市场价值,探索发行绿色债券的林业企业市场效应。结果表明:绿色债券融资对提升公司长短期的市场价值具有重大影响,绿色债券融资是经济实体发展绿色经济的表现,是符合经济趋势和其自身发展趋势的行为。林业企业对绿色债券的发行,持积极股价效应,提升公司市场价值;由于其项目投融资的绿色性,对市场效应有更好的显著性和持续性,对绿色债券的发行表现出积极市场效应,提升企业市场价值。依据绿色债券理论和实践,并结合林业企业自身的生态特性,从林业企业发行绿色债券的政策制度、融资优势、自身特征三个方面,在详细阐述林业企业发行绿色债券可行性基础上,提出林业企业推动绿色债券发行相关建议:构建林业企业绿色债券制度规范、增强林业企业绿色债券融资意识、提高林业企业绿色债券运营能力、加强林业企业绿色债券人才建设。 相似文献
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汽车上将蓄电池负极与车身的金属部分相连接的导线通常称为搭铁线。搭铁线虽小,在汽车电路中却起着重要的作用。着重介绍了汽车搭铁线的类型、作用、故障诊断,为正确检修提供参考。 相似文献