共查询到20条相似文献,搜索用时 15 毫秒
1.
A novel oligosaccharide was isolated and purified from the mucus of the loach, Misgurnus anguillicaudatus. Its was identified by several qualitative tests and characterized by elementary analysis,UV and IR spectrum. Its average molecular weight(Mw=1539.4) was determined by gel permeation chromatography. The major structural monomers of Misgurnus anguillicaudatus oligosaccharide were identified to be D-galactose and L-fucose by paper chromatography and gas chromatography. 相似文献
2.
Xinhe BAO Alexis T. BELL Yide XU 《天然气化学杂志》2006,15(1):I0001-I0001
It has been 15 years that the Journal of Natural Gas Chemistry, an international, academic Journal focusing on the publication of worldwide research in the field of natural gas chemistry, has been published. Five years ago, the Editorial Board of the Journal was reorganized and moved to the Dalian Institute of Chemistry Physics, Chinese Academy of Sciences. The Journal has concentrated on the reporting of fundamental research and development information in the field of natural gas 相似文献
3.
A synthetic approach to the C1–C19 polyketide fragment of the phorboxazoles is disclosed here. While an initial two-directional approach was efficient, it did not proceed in a high enough yield to justify moving forward. A subsequent successful strategy for the generation of the C11–C15 pyrans of both of the phorboxazoles was achieved, and the installation of the C9 stereocenter was able to be demonstrated. Furthermore, an efficient route for the preparation of the C1–C8 fragment with suitable functionality to allow for elaboration into the complete C1–C19 fragment, with the capricious C2–C3 Z-geometry installed, was also achieved. 相似文献
4.
A six-step approach to the tetracyclic core of merrilactone A is described that uses an intramolecular Paterno-Büchi photoaddition to install the key oxetane ring. Irradiation of bicyclic enone 16, constructed through cyclopentenone alkylation followed by a domino oxy-/carbopalladation reaction, produces the tetracyclic oxetane 17 in excellent yield, having the core carbon skeleton of the target compound merrilactone A. [reaction: see text] 相似文献
5.
Gui Hong YAN Da XING* Shi Ci TAN Institute of Laser Life Science South China Normal University Guangzhou 《中国化学快报》2004,15(1):101-104
Electrochemiluminescence (ECL), like other chemiluminescence technique, offers high signal-to-noise ratio. Furthermore, it has the advantage over other chemiluminescence techniques of being initiated by a voltage potential. Thus, it provides a better-controlled luminescence. This technique has been used in measuring many kinds of organic and inorganic matters, and analyzing many kinds of antigen, antibody and hapten, such as carcinoembryonic antigen and alpha-fetoprotein, etc1-6. The ele… 相似文献
6.
Ömer Taspinar Tobias Wilczek Julian Erver Dr. Martin Breugst Dr. Jörg-Martin Neudörfl Prof. Dr. Hans-Günther Schmalz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4256-4260
We report the first chemical synthesis of eurysterol A, a cytotoxic and antifungal marine steroidal sulfate with a unique C8−C19 oxy-bridged cholestane skeleton. After C19 hydroxylation of cholesteryl acetate, used as an inexpensive commercial starting material, the challenging oxidative functionalization of ring B was achieved by two different routes to set up a 5α-hydroxy-7-en-6-one moiety. As a key step, an intramolecular oxa-Michael addition was exploited to close the oxy-bridge (8β,19-epoxy unit). DFT calculations show this reversible transformation being exergonic by about −30 kJ mol−1. Along the optimized (scalable) synthetic sequence, the target natural product was obtained in only 11 steps in 5 % overall yield. In addition, an access to (isomeric) 7β,19-epoxy steroids with a previously unknown pentacyclic ring system was discovered. 相似文献
7.
We have performed intensive computer simulations of the irreversible annihilation reaction: A + A → C + C and of the trapping reaction: A + B → C + B for a variety of three-dimensional fluids composed of identical spherical particles. We have found a significant difference in the asymptotic behavior of the rate coefficients for these reactions. Both the rate coefficients converge to the same value with time t going to infinity but the convergence rate is different: the O(t(-1/2)) term for the annihilation reaction is higher than the corresponding term for the trapping reaction. The simulation results suggest that ratio of the terms is a universal quantity with the value equal to 2 or slightly above. A model for the annihilation reaction based on the superposition approximation predicts the difference in the O(t(-1/2)) terms, but overestimates the value for the annihilation reaction by about 30%. We have also performed simulations for the dimerization process: A + A → E, where E stands for a dimer. The dimerization decreases the reaction rate due to the decrease in the diffusion constant for A. The effect is successfully predicted by a simple model. 相似文献
8.
Arulmozhiraja S Coote ML Kitahara Y Juhász M Fujii T 《The journal of physical chemistry. A》2011,115(19):4874-4881
An unknown species has been detected in the analysis of the products in a pyrolysis of polycarbonate using Li(+) ion-attachment mass spectrometry (IAMS). The mass spectra exhibited a Li(+) adduct peak at m/z 233 that was tentatively assigned to bisphenol A (BPA) biradical. Experimentally, this assignment was supported by the observation that the production rate increased under an inert nitrogen atmosphere. To further confirm the assignment, the stability of the BPA biradical to intramolecular rearrangement reactions as well as unimolecular decomposition has been analyzed via density functional theory calculations [B3LYP/6-311+G(3df,2p)]. The results show that the bisphenol A biradical is an open-shell biradical singlet that is stable to unimolecular decomposition. Although some of the proposed intramolecular rearrangement products have lower energies than those of the BPA diradical, these pathways have large reaction barriers and the kinetic lifetime of the radical is expected to be of the order of hours under the conditions of the experiment. The calculations also reveal that the bisphenol A diradical has large Li(+) affinities supporting the fact that these Li(+) complexes could be detected in the Li(+) ion attachment mass spectrometry. On the basis of these results the Li(+) adduct peak at m/z 233 detected in the pyrolysis of polycarbonate is assigned to the bisphenol A biradical. 相似文献
9.
A remark on the “Theory of the dielectric dispersion due to the interfacial polarization” 总被引:1,自引:0,他引:1
Tetsuya Hanai 《Colloid and polymer science》1961,175(1):61-62
10.
Abstract Phase diagram results and high resolution adiabatic scanning calorimetric data are presented for several binary mixtures of 4-cyanocyclohexyl-4'-n-butyl-cyclohexane and 1 amino-9-fluorenone showing smectic A1 and smectic à phases at low temperatures. Contrary to present theoretical expectations and experimental evidence for other systems, we find strongly first order nematic to smectic A1 transitions with a latent heat of about 2 kJ/mol for all the mixtures investigated. The enthalpy change related to the smectic A1 to smectic à transitions is two orders of magnitude smaller and corresponds most likely to a fluctuation induced first order transition. 相似文献
11.
《合成化学》2004,(Z1)
The alkyl polyglycosides (APG) is new type the surfactants that is made by regeneration resource of the starch and the grease, since the nineties of 20th century it is energetically exploited in international extent. APG not only good in surface activity,but also plenty on bubble, thin greasy and stabilization, there are good decontamination, compatibility, innocuity, not incitation and unique function that organism decomposition of swiftness and downrightness, and so on. APG is to get produ… 相似文献
12.
A New Ceramide from the Ascomycete Tuber indicum 总被引:4,自引:0,他引:4
A new C-18 phytosphingosine derivative (1) was isolated from the fruiting bodies of Tuber indicum. Its structure was established as (2S,3S,4R,2′R)-2-N-(2′-hydroxytricosanoyl)-octadecan-1,3,4-triol by spectral and chemical methods. 相似文献
13.
14.
Xiao Hua XU* Chang Jian LIN Jian Hua LU Guang Min YAO Yan Ming LI Institute of Elemento-Organic Chemistry Nankai University Tianjin 《中国化学快报》2002,13(10)
The alga Caloglossa leprieurii is a chinese traditional drug having been used as anthelmintic, from the alga Caloglossa leprieurii, we had isolated two novel metabolites and three known compounds1-2. Further efforts to study this genus systematically made us to obtain a novel bromo-sesquiterpene 1 from Caloglossa leprieurii collected from the XiSha islands in south China sea. The EtOH extract of the alga Caloglossa leprieuri was partitioned between EtOAc and H2O, and the resulted organi… 相似文献
15.
A New Ceramide from the Basidiomycetes Armillaria mellea 总被引:2,自引:0,他引:2
Jin Ming GAO Ze Jun DONG Ji Kai LIU* Kunming Institute of Botany Chinese Academy of Sciences Kunming Northwest Sci. 《中国化学快报》2001,(2)
As one part of our study on the bioactive metabolites of the higher fungi in Yunnan Province, the chemical constituents of Armillaria mellea (Tricholomataceae) collected at Zhong Dian in Yunnan Province have been investigated. The present report deals with the structural elucidation of a new ceramide 1, named armillaramide, isolated from the AcOEt extract of the fruiting bodies of this fungus.Figure 1 The structure of armillaramide 1Compound 1, white amorphous powder, mp 113(117(C, [(] + … 相似文献
16.
A new disaccharide,digobiose 1, was isolated from the rhizomes of Macrothelypteris digophlebia (Bak.) Ching var. Elegans (koidz.). Its structure which is very similar with that of sucrose was identified as a -D-glucopyranosyl (1(r) 2¢ )-b -D-sorbopyranoside by spectroscopic analysis. 相似文献
17.
A New Triterpene from the Orchid Pholidota yunnanensis 总被引:2,自引:0,他引:2
ZhiMingBI ZhengTaoWANG LuoShanXU 《中国化学快报》2004,15(10):1179-1181
A new triterpene, 25-methylenecyclopholidonyl p-hydroxy-trans-cinnamate, was isolated from a orchid Pholidota yunnanensis. The structure elucidation and ^1H, ^13C-NMR assignments were achieved by spectral and chemical method. 相似文献
18.
A New Asterosaponin from the Starfish Culcita novaeguineae 总被引:1,自引:0,他引:1
HaiFengTANG YangHuaYI LingLI PengSUN DaZhengZHOU BaoShuLIU 《中国化学快报》2005,16(5):619-622
A new asterosaponin named novaeguinoside A, along with a known saponin, asteronyl pentaglycoside sulfate, was isolated from the starfish Culcita novaeguineae. The new compound was identitied to be sodium 6α-O-{β-D-fucopyranosyl-(1→2)-β-D-fucopyranosyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-[β-D-quinovopyranosyl}-5α-pregn-9(11)-en-20-one-3β-yl-sulfate by extensive spectral analysis and chemical evidence. 相似文献
19.
Potassiumselenatedborohydride(KBHZSe3),sodiumselenatedborohydride(NaBHZSe3)werepreparedfirstbyLalancetteetall.However,sincethen,therehavebeenlittlereportabouttheirapplication.Wehaveusedpotassiumselenatedborohydrideinformamidetoreducearomaticnitrocompounds,andsuccessfullyobtainedthecorrespondinganilines2.Inaddition,wehavealsoreportedthereductionofarylsulfonylchloridestothecorrespondingdisulfidesbysodiumselenatedborohydriderefluxinginCH,CN'.Fromourresearchwork,KBHZSe3andNaBHZSe3werefou… 相似文献