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   25篇
  免费   3篇
  2021年   2篇
  2018年   1篇
  2015年   3篇
  2014年   1篇
  2011年   4篇
  2009年   4篇
  2007年   1篇
  2006年   3篇
  2005年   1篇
  2003年   1篇
  1999年   1篇
  1981年   1篇
  1980年   1篇
  1978年   1篇
  1977年   2篇
  1972年   1篇
排序方式: 共有28条查询结果,搜索用时 0 毫秒
21.
Manilkara huberi is a timber species, found and intensely exploited in the Amazonian forest. Twelve highly polymorphic microsatellite loci were developed from a genomic library enriched for AG/TC repeats. Levels of polymorphism were evaluated using a total of 12 adult trees from a natural population. An average of 6.43 alleles per locus were detected, and expected heterozygosity ranged from 0.721 to 0.862. These loci represent a powerful tool in investigating the mating system, gene flow, parentage and population dynamics in natural populations of M. huberi, all of which are needed to implement sound management.  相似文献   
22.
Three new triterpenoid saponins, elucidated as 3-O-β-d-glucopyranosyloleanolic acid 28-O-β-d-xylopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→2)-β-d-xylopyranoside (parkioside A, 1), 3-O-[β-d-apifuranosyl-(1→3)-β-d-glucopyranosyl]oleanolic acid 28-O-[β-d-apifuranosyl-(1→3)-β-d-xylopyranosyl-(1→4)-[α-l-rhamnopyranosyl-(1→3)]-α-l-rhamnopyranosyl-(1→2)β-d-xylopyranoside (parkioside B, 2) and 3-O-β-d-glucuronopyranosyl-16α-hydroxyprotobassic acid 28-O-α-l-rhamnopyranosyl-(1→3)-β-d-xylopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→2)-β-d-xylopyranoside (parkioside C, 3), were isolated from the n-BuOH extract of the root bark of Butyrospermum parkii, along with the known 3-O-β-d-glucopyranosyloleanolic acid (androseptoside A). The structures of the isolated compounds were established on the basis of chemical and spectroscopic methods, mainly 1D and 2D NMR data and mass spectrometry. The new compounds were tested for both radical scavenging and cytotoxic activities. Compound 2 showed cytotoxic activity against A375 and T98G cell lines, with IC50 values of 2.74 and 2.93 μM, respectively. Furthermore, it showed an antioxidant activity comparable to that of Trolox or butylated hydroxytoluene (BHT), used as controls, against 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), oxygen and nitric oxide radicals.  相似文献   
23.
Nine saponins were isolated from the seeds of Mimusops laurifolia. Their structures were established using one- and two-dimensional NMR spectroscopy and mass spectrometry. Three of them are identified as: 3-O-(beta-d-apiofuranosyl-(1-->3)-beta-d-glucuronopyranosyl)-28-O-(alpha-l-rhamnopyranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl)-16alpha-hydroxyprotobassic acid, 3-O-(beta-d-glucopyranosyl-(1-->3)-beta-d-glucopyranosyl)-28-O-(alpha-l-rhamnopyranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl)-16alpha-hydroxyprotobassic acid and 3-O-(beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranosyl)-28-O-(alpha-l-rhamnopyranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl)-16alpha-hydroxyprotobassic acid.  相似文献   
24.
The sterol fraction of Argan seed oil (Argania spinosa) contains two main compounds, 5α-stigmast-7-en-3β-ol (schottenol) and 5α-stigmast-7,22(E)-dien-3β-ol (spinasterol).  相似文献   
25.
Four triterpenoid glycosides, possessing protobassic acid as common aglycon, together with 16 known compounds were isolated from the leaves of Planchonella obovata. They are 6β-hydroxy-conyzasaponin G (2), 3‴-O-de-β-d-apiofuranosylisoarganin F (3), isoarganin F (4), and 6β-hydroxy-conyzasaponin N (5). The structures of these glycosides were elucidated based on spectroscopic analysis, in particular using 1D TOCSY to confirm the 1H NMR assignment of each sugar residue. The absolute configuration of each monosaccharide in the glycon part was determined by GC-FID. Compound 5, Mi-saponin A (8), and ursolic acid (10) showed moderate inhibitory activities against HL-60 leukemia cell line with the IC50 values of 16.88, 15.50, and 12.68 μM, respectively.  相似文献   
26.
An organometallic complex of nickel has been isolated from nickel-accumulating plants of New Caledonia and has been identified by a combination of infrared spectroscopy, high-voltage paper electrophoresis, gas-liquid chromatography and mass spectrometry. Most of the nickel in Sebertia acuminata, Homalium francii, Homalium guillainii, Homalium kanaliense, Hybanthus austrocaledonicus and Hybanthus caledonicus is found as a negatively-charged citratonickelate (II) complex with Ni(H2O)62+ as the major cationic constituent.  相似文献   
27.
28.
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