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211.
A new sphingolipid, (2S,3R,4E)-1,3-dihydroxy-2-[(nonadecanoyl) amino]-octadec-4-ene (1) along with ubiquitous batyl alcohol is isolated from the gorgonian, Junceella juncea Pallas (Gorgonaceae) of the Indian Ocean. The structure of 1 is determined on the basis of 1H- and 13C-NMR, COSY, FABMS, and GC-EIMS experiments. 相似文献
212.
G.B. Song C.Q. Han J.K. Liang Q.L. Liu F.S. Liu G.H. Rao 《Journal of solid state chemistry》2004,177(7):2394-2403
The subsolidus phase relations of the PrOx-CaO-CuO pseudo-ternary system sintered at 950-1000°C have been investigated by X-ray powder diffraction. In this system, there exist one compound Ca10Pr4Cu24O41, one Ca2Pr2Cu5O10-based solid solution, seven three-phase regions and two two-phase regions. The crystal structures of Ca10Pr4Cu24O41 and Ca2Pr2Cu5O10-based solid solution have been determined. Compound Ca10Pr4Cu24O41 crystallizes in an orthorhombic cell with space group D2h20−Cccm, Z=4. Its lattice parameters are a=11.278(2) Å, b=12.448(3) Å and c=27.486(8) Å. The crystal structure of Ca2Pr2Cu5O10-based solid solution is an incommensurate phase based on the orthorhombic NaCuO2 type subcell. The lattice parameters of the subcell of the Ca2.4Pr1.6Cu5O10 are a0=2.8246(7) Å, b0=6.3693(5) Å, c0=10.679(1) Å, and those of the orthorhombic superstructure are with a=5a0, b=b0, c=5c0. The Ca2.4Pr1.6Cu5O10 structure can also be determined by using a monoclinic supercell with space group C2h5−P21/c, Z=4, a=5a0, b=b0, and β=104.79(1)° or 136.60(1)°, V=5a0b0c0. 相似文献
213.
214.
Summary A volumetric method has been developed for the determination of thorium salts with Titriplex III (disodium EDTA) using a mixture of ferrous salt and cacotheline as indicator. The titration of the thorium salt is carried out in a buffered solution ofph 2.72 in carbon dioxide atmosphere with magnetic stirring until a pink color appears. The reduction of cacotheline to the pink compound occurs only when all the thorium is complexed by EDTA. The end point is sharp and the method has been found to give results accurate to 0.2 to 0.3%. Ferric iron, zirconium and phosphates are found to interfere while ferrous iron does not interfere. Walpole sodium acetate-HCl buffers are to be employed since phosphate-citrate buffers interfere, due to the presence of phosphate and citrate.In conclusion one of us, Mr. V. Narayana Rao, desires to express his grateful thanks to the Ministry of Education, Government of India, for the award of Senior Research Fellowship which has enabled him to take part in this investigation. 相似文献
215.
C.N.R. Rao 《Tetrahedron》1976,32(13):1561-1566
Systematics in the ionization energies corresponding to the different π orbitals of para, meta and ortho-disubstituted benzenes obtained from PES have been investigated. The data have been discussed in terms of correlations with substituents constants and such correlations are shown to provide the basis to differentiate steric from electronic effects in the case of ortho derivatives. Ionization energies from PES corresponding to the lone pair orbitals of substituents in related series of p-disubstituted benzenes are shown to vary systematically with the substituent constants. 相似文献
216.
Lehmler HJ Rama Rao VV Nauduri D Vargo JD Parkin S 《Journal of fluorine chemistry》2007,128(6):595-607
Alkylated perfluorooctanesulfonamides are compounds of environmental concern. To make these compounds available for environmental and toxicological studies, a series of N-alkylated perfluorooctanesulfonamides and structurally related compounds were synthesized by reaction of the corresponding perfluoroalkanesulfonyl fluoride with a suitable primary or secondary amine. Perfluoroalkanesulfonamidoethanols were obtained from the N-alkyl perfluoroalkanesulfonamides either by direct alkylation with bromoethanol or alkylation with acetic acid 2-bromo-ethyl ester followed by hydrolysis of the acetate. N-Alkyl perfluorooctanesulfonamidoacetates were synthesized in an analogous way by alkylation of N-alkyl perfluoroalkanesulfonamides with a bromo acetic acid ester, followed by basic ester hydrolysis. Alternatively, N-alkyl perfluoroalkanesulfonamides can be alkylated with an appropriate alcohol using the Mitsunobu reaction. Perfluorooctanesulfonamide was synthesized from the perfluorooctanesulfonyl fluoride via the azide by reduction with Zn/HCl. All perfluorooctanesulfonamides contained linear as well as branched C8F17 isomers, typically in a 10:1 to 30:1 ratio. The crystal structures of N-ethyl and N,N-diethyl perfluorooctanesulfonamide show that the S-N bond has considerable double bond character. This double bond character results in a significant rotational barrier around the S-N bond (ΔG≠ = 62-71 kJ mol−1) and a preferred solid state and solution conformation in which the N-alkyl groups are oriented opposite to the perfluorooctyl group to minimize steric crowding around the S-N bond. 相似文献
217.
Alkali metal ion—oxygen donor solvent cages as well as coordination compounds, alkali metal oxide glasses and oxyanion salts of alkali metals exhibit low-frequency bands in the infrared spectrum characteristic of the cation—oxygen polyhedra. Similar bands are seen with nitrogen donors. Alkaline earth ions also show such absorption bands due to quantised vibration of cations. These bands not only provide a means of establishing the nature of cation coordination in diverse systems, but also serve as probes to examine ion-solvent interactions. 相似文献
218.
Xiang Pu Hanguang Wang Ping Zou Guangtu Wang Guizhou Yue Kuan Liu Li Cheng Juhua Feng Huixian Zhang Qianming Huang Hanbing Rao 《大学化学》1986,36(1):2002053-0
The crop science of Sichuan Agricultural University is an authorized first-class discipline. As the strategic supporting department for innovative talent cultivation in agriculture and forestry major, we are facing a long-term challenge in reforming the teaching mode for basic course-organic chemistry and cultivating talented students with solid basic knowledge and strong sense of innovation. Herein a thorough survey was performing to establish the executable teaching programs for this course during the "Double-First Class Universities Plan" period. A multidimensional teaching resource library for organic chemistry course was also constructed. The new classroom teaching mode "Interest cultivation-Creative thought development-Autonomous and Cooperative learning", along with a stepwise practice teaching mode "Foundation skills-Integrated application-Innovative trial" was proposed and practiced among thirty-five majors including agriculture, forestry and veterinary, to improve the quality for innovative talent cultivation and support our first-class discipline construction. This research could probably serve as a reference for congeneric agricultural university. 相似文献
219.
[Chemical reaction: See text] We have developed a general, efficient, and inexpensive catalyst system for arylation of amines by using 10 mol % of CuI as the copper source, 20 mol % of diphenyl pyrrolidine-2-phosphonate (DPP) as the ligand, K3PO4 as the base, and DMF containing 2% water (v/v) as the solvent. 相似文献
220.
A simple, sensitive and selective Spectrophotometric method has been developed for the determination of cobalt using indane 1,2,3-trionetrioxime (ITT): The method is based on the colour reaction between ITT and cobalt(II) in sodium acetate-acetic acid buffer (pH 4.5–7.5) medium. The calibration graph for measurement at 320 nm is linear in the range 1.18–23.60g of cobalt per 25 ml, with molar absorptivity of 5.32×1041mol–1 cm–1. The effect of interfering ions has been studied and the method was applied to the determination of cobalt in alloys, with good results. 相似文献