马齿苋中类黄酮及单宁含量的测定

[目的]为马齿苋的综合开发提供科学依据。[方法]采用乙醇浸提法测定马齿苋中类黄酮含量,并用分光光度法测定马齿苋中单宁的含量。[结果]建立了计算马齿苋中类黄酮含量的线性方程：y=0．1112x-0．0005（y为吸光度;x为芦丁溶液浓度）,相关系数R=0．9991;计算单宁含量的线性方程：y=0．0741x＋0．0033（Y为吸光度;z为单宁酸标准溶液浓度）,相关系数R=0．9995。两者的浓度和吸光度之间都存在极显著的线性关系。并测定出马齿苋中类黄酮及单宁的含量分别为（12．05±0．18）、（10．64±0．26）mg／g。[结论]该结果可为充分利用马齿苋这一植物资源提供参考。     

Carbon respiration and nitrogen dynamics in Corsican pine litter amended with aluminium and tannins

We investigated the carbon (C) mineralisation and nitrogen (N) dynamics in litter from a Corsican pine forest in response to individual and combined additions of aluminium (Al), condensed tannin (extracted from fresh Corsican pine needles) and hydrolysable tannin (commercial tannic acid). Production rates of CO₂, NH₄⁺ and NO₃⁻ concentrations, tannin concentrations and Al speciation were determined at various time intervals during a 28-day incubation experiment. The addition of Al decreased CO₂ production and shut down nitrification. Exchangeable NH₄⁺ strongly increased in the Al-amended litter, likely due to (i) decreased microbial uptake of NH₄⁺, (ii) the inhibition of nitrification and (iii) competition for soil organic matter (SOM) binding sites by Al. Both tannin species affected C mineralisation and/or N dynamics, be it in different ways. Addition of tannic acid led to a strong increase of the C mineralisation rate and microbial uptake of N, caused by rapid degradation of this labile tannin and subsequent increased microbial nutrient demand. Net immobilisation of N occurred as long as one week after addition. Condensed tannin was not consumed but probably strongly bound to (nitrogenous) SOM compounds, forming recalcitrant complexes and decreasing net N mineralisation. Complexation of Al by tannins in solution before addition to the litter mitigated the Al-induced release of exchangeable NH₄⁺. In the case of condensed tannin with complexed Al, this was due to detoxification of Al through complexation. Increased microbial demand for N likely played a major role in decreased NH₄⁺ accumulation in the samples to which tannic acid with complexed Al was added. Nitrification was shut down despite of the complexation of Al by either condensed tannin or tannic acid.     

Dietary mitigation of enteric methane emissions from ruminants: A review of plant tannin mitigation options

Methane gas from livestock production activities is a significant source of greenhouse gas (GHG) emissions which have been shown to influence climate change. New technologies offer a potential to manipulate the rumen biome through genetic selection reducing CH₄ production. Methane production may also be mitigated to varying degrees by various dietary intervention strategies. Strategies to reduce GHG emissions need to be developed which increase ruminant production efficiency whereas reducing production of CH₄ from cattle, sheep, and goats. Methane emissions may be efficiently mitigated by manipulation of natural ruminal microbiota with various dietary interventions and animal production efficiency improved. Although some CH₄ abatement strategies have shown efficacy in vivo, more research is required to make any of these approaches pertinent to modern animal production systems. The objective of this review is to explain how anti-methanogenic compounds (e.g., plant tannins) affect ruminal microbiota, reduce CH₄ emission, and the effects on host responses. Thus, this review provides information relevant to understanding the impact of tannins on methanogenesis, which may provide a cost-effective means to reduce enteric CH₄ production and the influence of ruminant animals on global GHG emissions.     

单宁胶刨花板含水率及浸水时间对吸水厚度膨胀率的影响

本文研究了单宁胶刨花板含水率及浸水时间及吸水厚度膨胀度的影响。     

高粱籽粒果皮和种皮性状与单宁含量的关系

根据直观观察对一些常用高粱品种的籽粒性状基因型做了推测,并将其结果与单宁含量测定结果一起进行了综合分析.试验结果证明,高粱种皮的存在并不必然导致高单宁含量.紫色种皮和深色果皮无种皮的高粱都只含极少量的单宁(分酚).根据这一结果,我们对高粱籽粒分类和高粱品质育种工作中对于籽粒性状的选择提出了一些新的观点,旨在为解决食用、饲用高粱的籽粒品质育种与抗鸟害和病虫害育种之间的矛盾开辟一条新的途径.     

落叶松内酯的化学结构

从落叶松(Larix gmelini)树皮中分离得到一无色片状结晶,其分子式为C_(30)H_(22)O_(10),熔点208—210℃,[α]0°—151°(丙酮,c1.0)。对该化合物及其六乙酰化合物,六甲基化合物,五甲基化合物及其氢化和LiAlH_4还原产物的红外,核磁共振氢谱和碳谱,质谱数据的研究,并最后用X射线结构分析确定其分子结构。该化合物是一种完全新型的螺环二聚黄酮化合物,取名为落叶松内酯。文中还提出了落叶松内酯生物合成途径的设想。     

几种低成本改性酚醛胶及其胶合性能的研究

概述了传统的５１酚醛胶和分别用尿素、落叶松单宁、甲基葡萄糖甙及甲基葡萄糖甙－尿素改性的酚醛胶（分别记为５１ＰＦ、ＴＰＦ、ＰＵＦ、ＭｅＧ－ＰＦ、ＭｅＧ－ＰＵＦ）的基本特性,并研究了分别用上述胶粘剂制成的三层马尾松胶合板在不同处理条件下（Ⅰ干状,Ⅱ冷水浸泡,Ⅲ沸水浸泡,Ⅳ循环煮沸,Ⅴ海水浸泡）的胶合特性。结果表明：１）在相同的涂胶量和热压工艺条件下,各种试件的胶合强度呈现下列下降规律Ⅰ＞Ⅴ＞Ⅱ＞Ⅲ＞Ⅳ。２）各种试件的胶合强度下降程度有显著差异。５１＃ＰＦ强度最高,下降程度最小,其次分别为ＴＰＦ、ＰＵＦ、ＭｅＧ－ＰＵＦ和ＭｅＧ－ＰＦ。ＭｅＧ－ＰＦ胶不能满足Ⅰ类结构胶合板用的要求（ＺＢＢ７０００６－８８或ＪＡＳ结构板标准）;ＭｅＧ－ＰＵＦ适用于条件不太苛刻的室外环境;ＴＰＦ和ＰＵＦ可以替代传统酚醛胶用于室外结构胶合板。对几种改性胶的经济性也进行了分析。     

树木单宁含量可作为对两种星天牛的抗性指标

对８７种常见造林绿化树种的主干树皮，嫩枝和树地的单宁含量进行了测定，并和两种星天牛这些部位相应的刻槽产卵，取食量进行了对比分析。结果表明，抗性树种具有较高单宁含量，而单宁含量较低的树种中有８０％是感虫树种，其余的大多为含有特殊成分的药用树种。     

植物单宁化学与栲胶生产技术新进展

概述近年来国内外在植物单宁化学及栲胶生产技术方面取得的新进展。     

滴定标准曲线法测定核桃青皮中单宁质量分数

利用滴定标准曲线法测定核桃青皮中单宁质量分数,研究结果表明:采用体积分数30%的乙醇作为单宁提取剂,提取效果稳定性好,精密度高,相对标准偏差为1.27%,加标回收率为94.91%。