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   28篇
  免费   3篇
  国内免费   2篇
化学   31篇
物理学   2篇
  2023年   1篇
  2022年   1篇
  2018年   1篇
  2015年   1篇
  2014年   3篇
  2013年   2篇
  2011年   4篇
  2010年   2篇
  2009年   1篇
  2008年   1篇
  2007年   1篇
  2006年   5篇
  2005年   3篇
  2003年   2篇
  2001年   1篇
  1996年   1篇
  1987年   3篇
排序方式: 共有33条查询结果,搜索用时 0 毫秒
1.
A method of ionic liquid salt aqueous two‐phase extraction coupled with high‐performance liquid chromatography has been developed for the analysis of seven rare ginsenosides including Rg6, F4, 20(S)‐Rg3, 20(R)‐Rg3, Rk3, Rk1, and Rg5 in Xue‐Sai‐Tong injection. The injection was mixed with ionic liquid 1‐butyl‐3‐methylimidazolium bromide aqueous solution, and a mixture was obtained. With the addition of sodium dodecyl sulfate and dipotassium phosphate into the mixture, the aqueous two‐phase mixture was formed after ultrasonic treatment and centrifuged. Rare ginsenosides were extracted into the upper phase. To obtain a high extraction factors, various influences were considered systematically, such as the volume of ionic liquid, the category and amount of salts, the amount of sodium dodecyl sulfate, the pH value of system, and the time of ultrasonic treatment. Under the optimal condition, rare ginsenosides in Xue‐Sai‐Tong injection were enriched and detected, the recoveries of seven rare ginsenosides ranged from 90.05 to 112.55%, while relative standard deviations were lower than 2.50%. The developed method was reliable, rapid and sensitive for the determination of seven rare ginsenosides in the injections.  相似文献   
2.
采用泡沫浮选-固相提取联用法,分离富集三七中的R1,Rg1,Re,Rc,Rb2,Rb3,Rd和Rb1,并用液相色谱法测定其含量,检测灵敏度和选择性都有所提高.对泡沫浮选过程的载气流量、浮选时间、样品溶液pH值和固相提取柱的洗脱条件进行了优化.原人参二醉型皂苷R1,Rc,Rb2,Rb3,Rd和Rb1的回收率在85.0%9...  相似文献   
3.
A high‐efficient and environmental‐friendly method for the preparation of ginsenosides from Radix Ginseng using the method of coupling of ultrasound‐assisted extraction with expanded bed adsorption is described. Based on the optimal extraction conditions screened by surface response methodology, ginsenosides were extracted and adsorbed, then eluted by the two‐step elution protocol. The comparison results between the coupling of ultrasound‐assisted extraction with expanded bed adsorption method and conventional method showed that the former was better than the latter in both process efficiency and greenness. The process efficiency and energy efficiency of the coupling of ultrasound‐assisted extraction with expanded bed adsorption method rapidly increased by 1.4‐fold and 18.5‐fold of the conventional method, while the environmental cost and CO2 emission of the conventional method were 12.9‐fold and 17.0‐fold of the new method. Furthermore, the theoretical model for the extraction of targets was derived. The results revealed that the theoretical model suitably described the process of preparing ginsenosides by the coupling of ultrasound‐assisted extraction with expanded bed adsorption system.  相似文献   
4.
5.
Three new dammarane monodesmosides, named notoginsenosides Ft1 ( 1 ), Ft2 ( 2 ), and Ft3 ( 3 ), together with three known ginsenosides, were obtained from a mild acidic hydrolysis of the saponins from notoginseng (Panax notoginseng (Burk .) F. H. Chen ) leaves. Their structures were elucidated to be (3β,12β,20R)‐12,20‐dihydroxydammar‐24‐en‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 1 ), (3β,12β)‐12,20,25‐trihydroxydammaran‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 2 ), and (3β,12β,24ξ)‐12,20,24‐trihydroxydammar‐25‐en‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 3 ), by means of spectroscopic evidences. The known ginsenosides Rh2 and Rg3 4 – 6 were obtained as the major products from this acidic deglycosylation.  相似文献   
6.
This study compared eight major ginsenosides (Rg1, Rg2, Rf, Re, Rd, Rc, Rb1 and Rb2) between Panax sokpayensis and Panax bipinnatifidus collected from Sikkim Himalaya, India. High-performance liquid chromatographic analysis revealed that all major ginsenosides were present in the rhizomes of P. sokpayensis except ginsenoside Rc, whereas ginsenoside Rf, Rc and Rb2 were not detected in P. bipinnatifidus.  相似文献   
7.
A new extraction method for ginsenosides from ginseng roots, ginseng leaves and ginseng drug preparations by Sep-Pak C18 cartridges has been studied. Ginsenoside extraction by Sep-Pak cartridges is a rapid, efficient, reproducible method. In addition, the extracts were analyzed by high performance thin layer chromatography (HPTLC) and reverse phase high performance liquid chromatography (HPLC). The major components of ginseng saponins were effectively separated using an ODS-120T column.  相似文献   
8.
The Chinese phytomedicinal formulation Sanqi Zongdai Pian, traditionally prepared from crude extracts from roots of Panax notoginseng (Araliaceae), contains highly polar dammarane saponins which were separated at a preparative scale using high-speed counter-current chromatography (HSCCC). In each operation, 283 mg methanolic extract of five tablets was separated and yielded pure 157, 17, 13 and 56 mg of ginsenoside-Rb1, notoginsenoside-R1, ginsenoside-Re and ginsenoside-Rg1, respectively, n-hexane-n-butanol-water (3:4:7, v/v/v) was used for the two-phase solvent system of the HSCCC separation. The chemical structures of three ginsenosides and one notoginsenoside were elaborated by means of electrospray ionization MS-MS and NMR analysis.  相似文献   
9.
Three new dammarane‐type triterpenoid saponins, 1 – 3 , were isolated and identified as (20S)‐20‐O‐[β‐D ‐xylopyranosyl‐(1→6)‐β‐D ‐glucopyranosyl‐(1→6)‐β‐D ‐glucopyranosyl]dammar‐24‐ene‐3β,6α,12β, 20‐tetrol ( 1 ), (20S)‐6‐O‐[(E)‐but‐2‐enoyl‐(1→6)‐β‐D ‐glucopyranosyl]dammar‐24‐ene‐3β,6α,12β,20‐tetrol ( 2 ), and (20S)‐6‐O‐[β‐D ‐xylopyranosyl‐(1→2)‐β‐D ‐xylopyranosyl]dammar‐24‐ene‐3β,6α,12β,20‐tetrol ( 3 ) from the roots of Panax notoginseng (Burkill ) F.H.Chen (Araliaceae). Their structures were elucidated on the basis of spectroscopic analyses, including 1D‐ and 2D‐NMR techniques and HR‐ESI‐MS, as well as by acidic hydrolysis.  相似文献   
10.
Ginseng is a popular herb worldwide and has had varied uses in traditional Asian medicine for thousands of years. There are several different species of the herb, but all share the same constituents. Ginsenosides, the most extensively studied chemical components of ginseng, are generally considered to be one of the most important active ingredients of the plant. In this study, we have developed fast and efficient methodology for isolation of four known ginsenosides Rf, Rd, Re and Rb1 from Ginseng by high performance counter-current chromatography (HPCCC) coupled with evaporative light scattering detection (ELSD). The crude sample for HPCCC was purified firstly from a ginseng extraction using macroporous resin. The enriched saponin fraction (480 mg) was separated by using methylene chloride–methanol–5 mM aqueous ammonium acetate–isopropanol (6:2:4:3, v/v,) as the two-phase solvent system and yielded 10.7 mg of Rf, 11.0 mg of Rd, 13.4 mg of Re and 13.9 mg of Rb1. The purity of these ginsenosides was 99.2%, 88.3%, 93.7% and 91.8%, respectively assessed by HPLC-DAD-ELSD, and their structures were characterized by electrospray ionization mass spectrometry (ESI-MS) and compared with standards. Ammonium acetate was used to shorten the separation time and eliminate emulsification together with a flow step-gradient. The salt can be removed by re-dissolving the sample using acetone.  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