排序方式: 共有60条查询结果,搜索用时 15 毫秒
31.
Guangyin Wang Junzeng Zhang Marianna Kulka Fujiang Guo Yiming Li 《Helvetica chimica acta》2014,97(7):985-991
Three new eremophilane glucosides, namely, petasitosides A–C, and seven known eremophilane‐type sesquiterpenoids were isolated from the roots of Petasites japonicus. Their structures were elucidated by spectroscopic techniques including 1D‐ and 2D‐NMR spectroscopy and mass spectrometry. This is the first report on eremophilane glycosides from the genus Petasites. 相似文献
32.
通过克隆刺参杀菌通透性增强蛋白(Bactericidal Permeability-increasing Protein, BPI)N末端的cDNA序列并进行原核表达, 获得了N端活性片段体外重组蛋白, 分析其抑菌谱. 结果表明: 刺参BPI蛋白N末端cDNA全长642bp, 编码214个氨基酸; 体外表达获得了分子量为30kDa的重组蛋白, 该蛋白对副溶血弧菌、哈维氏弧菌和藤黄微球菌均具有明显的杀菌作用, 其中对副溶血弧菌活性最强, 抑菌圈直径达2.5cm. 相似文献
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利用高效液相色谱法建立了仿刺参皂苷类成分的指纹图谱,为仿刺参的质量控制提供了新的方法。采用固相萃取制备供试品溶液,选用Zorbox SB-C18色谱柱(250 mm×4.6 mm, 5 μm),以乙腈-0.1%磷酸水溶液为流动相进行梯度洗脱,检测波长为205 nm,柱温30 ℃。分析了不同产地的10批仿刺参样品,采用国家药典委员会推荐的“中药色谱指纹图谱相似度评价系统(2004 A版)”处理谱图,确定了6个共有峰。计算了10个样本间的指纹图谱相似度,所得相似度计算结果均大于0.97。该方法具有良好的稳定性和重现性,可用于仿刺参的质量控制。 相似文献
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仿刺参是具有极高经济价值的水产资源,是海水养殖产业的重要组成部分,研发出一种灵活、稳定、高效的仿刺参产地溯源方法对于水产养殖产业具有极强的现实意义。仿刺参主要有三种养殖方式,分别是底播增殖、圈养养殖和筏式养殖。不同产地采用不同的养殖方式,仿刺参的营养价值、药用价值和经济价值都存在着明显差异。不同产地初级生产者的构成不同,作为初级生产者的不同藻类与浮游生物体内的脂肪酸特征也各不相同,通过食物链的传递,不同产地的仿刺参具有了不同的脂肪酸特征。气相色谱指纹图谱法是一种快速准确地食品产地溯源技术,碳稳定同位素质谱法不仅可以鉴别产地还可以区分出食品的营养价值。采集9个最具代表性产地的仿刺参样品,先利用Folch法对样品进行总脂提取,再通过气相色谱仪测定出各种脂肪酸的种类及其相对含量;最后使用稳定同位素质谱仪测定出每种脂肪酸各自的碳稳定同位素组成数据。使用单因素方差分析法对脂肪酸相对含量和脂肪酸碳稳定同位素组成数据进行显著性检验,各筛选出17种脂肪酸数据作为两个模型的输入。主成分分析(PCA)法可以降低数据的维度,聚合不同种脂肪酸数据的溯源特征,提高产地溯源的精度。支持向量机(SVM)是一种以结构化风险最小为目标的分类识别算法,具有优秀的泛化能力。研究结果表明,不同产地仿刺参的脂肪酸相对含量和脂肪酸碳稳定同位素组成数据存在明显差异。通过主成分变换后,脂肪酸数据的聚类特征更加明显,运用随机交叉验证法确定前6个主成分作为两个支持向量机分类器的输入。采用基于遗传交叉因子改进的粒子群优化算法(GPSO),以粒子不同K值各100次交叉验证的平均准确率作为其适应度,寻找支持向量机分类器模型的最优参数组合。最终计算得到脂肪酸相对含量产地溯源模型的最优参数组合为σ=6.247 599和C=14.313 042,平均准确率为79.49%;脂肪酸碳稳定同位素组成产地溯源模型的最优参数组合为σ=7.626 194和C=2.193 410,平均准确率为98.33%。对比交叉验证的结果,脂肪酸碳稳定同位素组成产地溯源模型具有更高的准确率和更强的泛化性能。在两个模型的识别结果不一致时,采用脂肪酸碳稳定同位素组成模型的识别结果。将实验室检测与互联网技术进行整合,构建了仿刺参产地溯源在线系统。实现了“互联网+产地溯源”的一体化溯源模式,为进一步开展食品产地溯源研究提供了科学依据和技术支撑。 相似文献
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近红外漫反射光谱法测定麦冬的多糖含量 总被引:3,自引:0,他引:3
采用近红外光谱分析技术对麦冬多糖进行定量分析.对麦冬的原始漫反射光谱采用了一阶导数、二阶导数、平滑、散射校正等多种光谱解析手段,初步选择了建模波段,并结合偏最小二乘回归法对麦冬多糖进行了定标建模分析.结果表明,光谱经过一阶导数+标准乘性散射校正(MSC)+SG平滑处理,选取4 000~4 900,5 100~6 900,7 050~10 000 cm-1波段建模得到的定标模型效果最佳,分析结果精度较高,R2,RMSEC,R2CV,RMSECV,主因子数分别为0.996,0.237,0.973,0.583,6.模型经过验证样品集检验,预测相关系数达到0.968 8. 相似文献
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37.
尖海龙与日本海马脂肪的提取和分析 总被引:29,自引:3,他引:29
本采用快速脂肪提取法取代索氏提取法,提取时间仅需45min提取率98.8%以上,并利用50m×0.35mmi.d,PEG-20M玻璃毛细管柱,分析了山东黄海海域尖海龙与日本海马脂肪中的脂肪酸,其中,尖海龙分离出59个峰,鉴定了42个,日本海马分离出52个峰,鉴定了41个,分别占脂肪酸总量的97.3%和98.0%,测得尖海龙脂肪中的EPA+DHA占31.0%,日本海马为14.1%。 相似文献
38.
《Biomedical chromatography : BMC》2018,32(5)
Polyphenols from ethyl acetate extracts from the leaves, stems and roots of Korean Humulus japonicus were comprehensively profiled using liquid chromatography–electrospray ionization–tandem mass spectrometry. A total of 36 polyphenols were detected, of which 26 were structurally characterized based on their [M − H]− peak, tandem mass spectrometry fragmentation pattern, UV–vis absorption and published data. Validation data provided satisfactory results for the evaluated parameters. The determination coefficients were ≥0.9812. The limits of detection and quantification were 0.017–0.573 and 0.056–1.834 mg/L, respectively, indicating good performance limits. The accuracy (expressed as percentage recovery) at 50 and 100 mg/L was 71.4–99.7 and 75.1–105.1%, with precisions (expressed as relative standard deviation) of 1.5–7.3 and 0.8–4.1%, respectively, indicating acceptable accuracy and precision values. The leaves were rich in total polyphenols (3089.9 ± 6.4 mg/kg of fresh sample) followed by the stems (1313.9 ± 6.4 mg/kg of fresh sample) and roots (655.2 ± 2.7 mg/kg of fresh sample). Antioxidant activity, determined by α,α‐diphenyl‐β‐picrylhydrazyl, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) scavenging activity and ferric reducing antioxidant power assay, revealed the lowest EC50 value for the leaf extracts, indicating a higher scavenging activity in this tissue followed by the roots and stems. Overall, the results indicated that H. japonicus is rich in polyphenols and could be a potential alternative to Humulus lupulus (hop plant) in the brewery industry. 相似文献
39.
Rui‐Jie Hou Fu‐Lin Yan Hai‐Yang Zhang Yi‐Xiao Bai Ming‐Ming Ding 《Helvetica chimica acta》2012,95(7):1175-1180
Two new ent‐kaurene diterpenoids, 15α,20‐dihydroxy‐6,7‐seco‐entkaur‐16‐ene‐7,1α(6,11α)‐diolide ( 1 ), 6β‐butyroxy‐3β‐hydroxy‐6,7‐seco‐6,20‐epoxy‐7,1α‐olide‐entkaur‐16‐en‐15‐one ( 2 ), together with 25 known compounds, 3 – 27 , were isolated from the leaves of Isodon japonicus. Their structures were established by spectroscopic methods, including 2D‐NMR techniques. 相似文献
40.
Huan Yan Xu‐Hong Li Xue‐Fang Zheng Chang‐Li Sun Hai‐Yang Liu 《Helvetica chimica acta》2013,96(7):1386-1391
Reinvestigation of the AcOEt‐soluble part of the EtOH extract of whole plants of Chloranthus japonicus afforded four new lindenane‐type sesquiterpenoid lactones, chlojaponilactones B–E ( 1 – 4 , resp.), together with nine known sesquiterpenoids. Their structures and relative configurations were established on the basis of extensive spectroscopic data and by comparison with the relevant literature. 相似文献