首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   24篇
  免费   0篇
化学   10篇
物理学   2篇
综合类   12篇
  2022年   4篇
  2020年   2篇
  2019年   2篇
  2017年   2篇
  2016年   1篇
  2015年   2篇
  2010年   1篇
  2007年   1篇
  2006年   1篇
  2005年   2篇
  1998年   1篇
  1997年   1篇
  1995年   1篇
  1994年   1篇
  1991年   2篇
排序方式: 共有24条查询结果,搜索用时 15 毫秒
1.
The importance of monitoring key aroma compounds as food characteristics to solve sample classification and authentication is increasing. The rhizome of Polygonatum sibiricum (PR, Huangjing in Chinese) has great potential to serve as an ingredient of functional foods owing to its tonic effect and flavor properties. In this study, we aimed to characterize and classify PR samples obtained from different processing levels through their volatile profiles and flavor properties by using electronic nose, electronic tongue, and headspace gas chromatography-mass spectrometry. Nine flavor indicators (four odor indicators and five taste indicators) had a strong influence on the classification ability, and a total of 54 volatile compounds were identified in all samples. The traditional Chinese processing method significantly decreased the contents of aldehydes and alkanes, while more ketones, nitrogen heterocycles, alcohols, terpenoids, sulfides, and furans/pyrans were generated in the processing cycle. The results confirmed the potential applicability of volatile profiles and flavor properties for classification of PR samples, and this study provided new insights for determining the processing level in food and pharmaceutical industries based on samples with specific flavor characteristics.  相似文献   
2.
Reinvestigating the chemical constituents of the roots of Xanthium sibiricum led to the isolation of a new naphthoquinone (1), together with 13 known compounds (214). Their structures were elucidated by using spectroscopic analyses, including HR-ESI-MS, 1D and 2D NMR, and by comparing their NMR data with those of related compounds. Compound 1 showed moderate antibacterial activity against Escherichia coli, Bacillus subtilis, Micrococcus tetragenus and Staphylococcus aureus, while 6 and 12 showed stronger antibacterial activity than the positive control ciprofloxacin against E. coli, with minimum inhibitory concentration values of 0.17 and 0.35 μg/mL, respectively.  相似文献   
3.
The essential oil from Filifolium sibiricum (L.) Kitam were extracted using hydrodistillation and GC-MS was used to analyse the essential oil. The main components were espatulenol (8.55%), geranyl acetate (8.03%), caryophyllene oxide (5.47%), calamenene (4.79%), geraniol (4.28%), calamenene (4.53%), geraniol (4.06%), cedrene epoxide (3.23%), myrtenol (3.18%), transgeranylgeranio (3.13%), etc. The essential oil showed intensive inhibitory effects against MCF-7 with IC50 level of 0.78 mg/mL, HepG-2 with IC50 level of 0.44 mg/mL, SKOV-3 with IC50 level of 0.27 mg/mL, BGC-823 with IC50 level of 0.34 mg/mL. In the antibacterial test, the essential oil showed the significant antibacterial activities. The MIC and MBC values were 5.20 and 5.20 mg/mL against Staphylococcus aureus.  相似文献   
4.
用聚丙烯酰胺凝胶电泳对内蒙古常见禾本科牧草羽茅(Achnatherum sibiricum(L.)Keng)在6个不同地理及生态环境下的种群进行了过氧化酶同工酶研究,通过对酶谱的比较分析,结果表明:羽茅的种内变异很小,各样点间的同工酶谱十分相近,酶谱不随地理、生态环境的改变而发生相应的变化,说明其体内遗传资源的相对稳定性。  相似文献   
5.
二维1H NMR研究双藁本内酯结构   总被引:1,自引:0,他引:1  
双叶本内酯(z,z'-6,61,7,3a1-diligustilide)构型复杂,采用1D-NMR技术难以明确指定。本文使用400 MHz H-H COSY和H-H NOESY对标题化合物的构型进行研究,其结果有助于此类化合物的结构和构型确定。  相似文献   
6.
Target biomolecule-immobilized magnetic beads could be used as a powerful tool for screening active compounds present in natural products. Low damage rates of the target proteins, associated with the availability of diverse automated online approaches for analysis, make it a valuable tool for affinity studies. RAW264.7 cells (a kind of murine macrophage cell line) were used in this study. These cellular membranes were immobilized onto the surface of MBs and were used for screening the active compounds of Polygonatum sibiricum. Combining this technique with HPLC led to the identification of an active compound and its biological activity was confirmed. This is the first report establishing the use of RAW264.7 cellular membrane-coated magnetic bead fishing followed by HPLC analysis for screening active compounds from natural products.  相似文献   
7.
Chemical investigation of the rhizomes of Polygonatum sibiricum Red. led to the identification of 27 constituents. Among them, a total of 16 compounds were obtained from Polygonatum for the first time, in which, 3 and 4 were also firstly isolated as natural products. Anti-inflammatory activity studies on 13 isolated compounds showed that β-carboline constituents, especially compounds 1 and 2, significantly inhibited the expression of NO, TNF-α, IL-6 and IL-1β in lipopolysaccharide (LPS)-treated RAW264.7 macrophage cells. Moreover, western blotting analysis demonstrated that compound 1 significantly inhibited the expression of COX-2, iNOS and the activation of NF-κB, suggesting that β-carboline structures may play an important role in inhibition of NF-κB signaling pathway, which thereby inhibits the production of inflammatory factors. The present research may not only help further elucidation of the anti-inflammatory mechanism of P. sibiricum Red., but also provide the potential bioactive molecules for inflammatory diseases research.  相似文献   
8.
选用不同离子组合的低共熔溶剂提取黄精多糖,筛选确定尿素-氯化胆碱低共熔溶剂提取黄精多糖效果最好,随后在单因素考察的基础上,采用响应面分析法优化尿素-氯化胆碱低共熔溶剂提取黄精多糖的工艺条件,并进行了低共熔溶剂重复利用对多糖提取率和含量的影响研究。通过测定总抗氧化能力、超氧阴离子(O-2)自由基和1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率考察黄精多糖体外抗氧化活性。结果表明:低共熔溶剂提取黄精多糖的优化工艺参数为温度70℃、尿素-氯化胆碱物质的量比1.19、时间42.30min、液料比20.75mL/g,此条件下的多糖提取率为18.55%,较预测值相对误差为2.69%,比传统的热水浸提法增加了139.97%。低共熔溶剂重复利用不仅对黄精多糖提取率没有影响,在重复利用第3次时提取率最高,较新鲜溶剂提高了83.9%;而且黄精多糖含量随重复次数增加呈不断增加后趋于稳定的趋势,重复利用4、5次后多糖含量基本趋于稳定,达到63.48%、64.12%,说明其纯度不断提高。黄精多糖的O-2自由基清除能力、DPPH自由基清除能力、总抗氧化能力随质量浓度的增加而增加;在测定的质量浓度范围内,清除O-2自由基和DPPH自由基的IC50分别为0.524、0.951mg/mL,总抗氧化能力最高为241.2μg/mL。因此,低共熔溶剂法是一种效率高、清洁环保的新型黄精多糖提取方法。  相似文献   
9.
10.
苍耳不同溶剂提取物对粘虫和蚜虫的杀虫活性研究   总被引:7,自引:0,他引:7  
通过苍耳不同溶剂提取物对蚜虫和粘虫的杀虫活性测定,证明不同提取溶剂所得苍耳提取物杀虫活性差异显著.各作用方式的杀虫结果表明:苍耳各提取物对粘虫具有很强的拒食活性,对蚜虫的活性较低;同时表明,苍耳的氯仿提取物杀虫活性最好.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号