Chemical conversions of salvianolic acid B by decoction in aqueous solution

Salvianolic acid B (Sal B) is the most abundant phenolic compound in Salvia miltiorrhiza, which has been widely used for the treatment of cardiovascular diseases in Oriental medicine. To elucidate structure of the converted compounds of Sal B by decoction in aqueous solution, Sal B (200mg) was decocted in an aqueous solution (200mL) at pH 4.9 and the decocted solution was purified by Sephadex LH-20 column chromatography and preparative HPLC. The 13 converted compounds were isolated and the chemical structures were determined by NMR and MS. In addition to the 4 compounds previously reported as conversion products of Sal B by decoction, 9 compounds were first reported with the complete structure of compounds isolated from decocted Sal B solution and three of the compounds were determined to be novel compounds. In addition, a conversion mechanism of compounds converted by decoction was proposed on the basis of kinetics studies, which reasonably supported the conversion mechanism of Sal B. The 13 compounds seemed to be produced by the hydrolysis of an ester bond, decarboxylation, retro oxa-Michael reaction, hydration, and radical reaction during decoction in aqueous solution.     

罗曼蛋鸡饲粮养分转化率的研究

对合肥市蜀山种鸡场 2 0 0只 40～ 44周龄罗曼蛋鸡日采食饲粮量及养分量和日产蛋成分量等进行了 3 4d的实测 ,在此基础上 ,测算了鸡对饲粮主要养分的转化率 ;并考察了温、湿度因子对其影响。结果表明 :温度对产蛋率、DM、CP、EE、Sac、Ash、Ca、P、Lys、Met、Trp、Thr、Val、Phe、Ile、Arg、His转化率影响显著 (P <0 .0 5 )或极显著 (P <0 .0 1) ;对只日采食饲粮、料蛋比、Leu转化率影响不显著 (P >0 .0 5 ) ;湿度对上述指标观测值的影响均不显著 (P >0 .0 5 )。     

Biomass expansion factors for Sitka spruce (<Emphasis Type="Italic">Picea sitchensis</Emphasis> (Bong.) Carr.) in Ireland

The assessment of a forest resource in national inventories provides a firm basis for the calculation of biomass and carbon (C) stocks of forests. Biomass expansion factors (BEFs) and conversion factors provide a robust and simple method of converting from forest tree stem volume to total forest biomass. These factors should be constructed on the basis of nationally specific data in order to take account of regional differences in growth rates, management practices, etc. The objective of this study is to improve the accuracy of biomass estimation by calculating a range of age-dependant BEFs from representative data that more accurately describe the allometry of present forests. The results from this study show that the allocation of biomass to compartments in forest stands and throughout a rotation varies considerably, and that the use of BEFs for the calculation of C stocks in forests of sub-timber dimensions is highly impractical.

农牧变迁与科尔沁蒙古族农民的节水灌溉技术选择

文章以内蒙古通辽市白村为个案,主要从农牧变迁的视角对科尔沁蒙古族乡村地区节水灌溉技术推广困难的问题进行探究.研究发现,在科尔沁蒙古族乡村社会由半农半牧向纯农耕文明的转变过程中,由于特殊的社会文化传统和生计模式,从而形成独特的技术需求,造成节水灌溉技术推广困难.因此,在一个灌溉历史并不长的蒙古族聚居地区,需要寻找到现代农业技术与本土知识体系的最佳结合点.     

城市边缘区土地利用与土地覆被变化特点研究——以济南市长清区为例

在Arcview3.3和Fragstats3.3的支持下,分别探讨了土地利用的用途转移变化特点;运用景观生态学的原理和方法,对济南市长清区土地利用景观格局的变化特点进行了分析,二者结合研究,可以更好地反映城市边缘区的土地利用特点。结果表明,长清区土地利用的变化较大,整体上突出表现为林地、耕地面积增加,未利用土地迅速减少;景观整体的多样性相对较小,平均斑块分维数和优势度有所增加,景观聚合度增强,有单一化的趋势,结构有待于进一步优化。     

苜蓿中华根瘤菌电转条件的优化

为了研究苜蓿中华根瘤菌电转化的条件,通过对不同的细胞生长周期、复苏缓冲液、电转缓冲液、电场强度和电阻对电转率影响程度来作出变化曲线,以确定电转化的最优条件,从而提高苜蓿中华根瘤菌电转化率.结果表明细胞的对数生长初期、复苏缓冲液Ⅴ、电转缓冲液Ⅳ、23 kv/cm和200Ω适合作为苜蓿中华根瘤菌电转的条件.     

不同光照日周期对肉用仔鸡生产性能影响的研究

本试验利用3126只美·爱拔益加AA肉用仔鸡,在自行设计的间歇光照制的环境中,观测不同光照日周期及光照强度对21～56日龄肉用仔鸡生产性能的影响。试验结果表明:在存活率,饲料利用率及出栏群平均个体重三方面,采用间歇光照制及光照强度为5勒克司的第一、二试验组优于连续24小时光照日周期及光照强度2。勒克司的对照组。其中,采用光照日周期为1L:3D,5勒克司光照管理程序的第一试验组优于光照日周期为1L:1.5D、5勒克司光照管理程序的第二组。     

关于粮食主产区(吉林省)玉米转化与利用探讨

论述了饲料工业、玉米深加工工业和食品工业是玉米转化的主要方向,通过对吉林省玉米产业发展现状、转化潜力和增值分析,提出玉米转化途径的重点选择以及发展玉米经济的战略对策。     

恒压供水水泵机组简易系统

介绍了典型的一用一备机组管路系统及其工作原理，分析了系统中各组件随外界供水量变化的运行逻辑关系，解决了进口负压水泵的脱水空转，进口倒灌水泵浸泡锈蚀两个问题。     

氰在土壤中的吸附与转化

氰(C2N2)是一种具有替代溴甲烷潜力的新熏蒸剂,明确C2N2在土壤中的吸附与转化行为对C2N2的安全应用具有重要的意义.利用静态法研究了C2N2在土壤中的吸附与转化过程,土壤对C2N2的吸附速率与土壤的理化性质有关,受环境温度、土壤含水量和土壤生物的影响较少,与熏蒸浓度无关.采用气相色谱(GC)和流动注射分析仪(FIA)测定了土壤对C2N2的吸附率和C2N2在土壤中的可能转化产物.结果表明,土壤对C2N2的吸附能力很强,熏蒸2h吸附率在75％以上,熏蒸24 h吸附率在98％以上,并可快速转化为HCN、NH4+和NO3-.其中,大约20％的C2N2转化为NH4+和NO3-,13％的C2N2转化为HCN.熏蒸48 h未检测到NO2-.HCN在土壤中不稳定,可进一步转化为其他含氮化合物.