A pair of epimers were isolated from Celastrus flagellaris Rupr,for the first time,their chemical structures were elucidatcd as 1α,6β,8α,13-tetraacetoxy-9α-benzoyloxy-β-dihydroagarofuran(1) and lα,6β,8α,13-tetraacetoxy-9β-benzoyloxy-β-dihydroagarofuran(2) mainly by ¹H-¹H COSY,¹³C-¹H COSY,NOESY and HMBC spectra.Compound 1 is a new compound named as Celastrine.

This paper reports the experimental results of localized MRS using STEAM of MRI,in which the water signal in VOI is suppressed by presaturation radiation using shaped r.f pulses with two unequal widths in perpendicular phases.This water-suppression method is more effective than the dephasing method by gradient pulses.Among the threc kinds of common shaped pulses,the GAUSS shaped pulse is the best

Structures of crosslinks produeed in benzophenone-photoinitiated crosslinking of low density polycthylene(LDPE) have been studied for the firet time by solution-state ¹³C NMR spedroscopy.The H-links and Y-type long branches have been observed and identified.The concentrations of H-and Y-type crosslinks are estimated to be 5.7-16-9 and 7.6-21.6 structure units pcr 10000 carbon atonis with the LDPE samples UV-irradiated for 5-10 seconds in the melt,respectively.

²⁷AI NMR spectra of the synthetic samples cemented by kaolinite and goethite shows that their cementation nature is to form hydrogen bonds between kaolinite and goethite.

Sonme samples of crude oil without preliminary treatment from Xinjiang,Shengli and Huabei oilfield have been determined diredly by¹³C and ¹H NMR spectrometry.From the resulting spectra,a series of average structural parameters has been derived.On the basis of those results,parameters fa,Hm,Cz,m_A,m_N,m_P have been proposed as the fingerprints of crude oil,which allow various oils to be characterized.The method can provide a quick but rough guide to the cvaluation and dassification of the crude oil.

The mechanism of the lactone ring opening of Crystal Voilet Lactone was investigated by means of ¹³C NMR.The structure of triphenylcarbenium ion and its stability were analyzed.The equilibrium constant between the lactone form and carboxyl form was obtained from ¹³C NMR data.The machanisms of opening and closing of the lactone ring in different conditions wcre discussed.

The adsorption of oxygen molecules on the CoO-MgO as a kind of heterogeneous oxygen carrier has been studicd from 77 to 300K by ESR,It was observed that Co²⁺ ions on the surface of CoO-MgO could combine with oxygen reversibly at low temperature of 77-150K and generate a cobalt-oxygen radical adduct Co³⁺-O₂^- which is responsible for the appearanee of hyperfine stnlctural lines in ESR spectrum.On increasing the temperature O₂^- radical in cobalt-oxygen adduct would be transferred and stabillzed on Mg²⁺ ions,and fomied a new Mg²⁺-O₂^- radical adduct at room temperature,In this paper the electronic structure of the cobalt-oxygen adduct and their bonding nature were discussed by the analysis of ESR spectra.Both the spin polarintion due to σ-л bond interaction and the electron delocalization had been suggested to account for the origin of the hyperfine lines in ESR spectra.

Two powder samples of copper(Ⅱ) benzo-15-crown-5(Cu(Ⅱ) B15C5) coniplexes with 3d_Z²-ground state doublet doped in different substrathe were prepared.The ESR measurements demonstrate that H₂O molecules are the azial ligands of Cu(Ⅱ) B15C5 complex doped in B15C5 substrate,whereas ClO₄^- ions are the ones in Mg(Ⅱ) B15C5 substrate,The line shape of ESR spectra are found to be strongly affected by the axial ligands.The copper(Ⅱ)-ligand bonding parameters are estimated from the ESR parameters by means of Bleaney formula and the bonding nature is discussed and compared.

The photoinduced electron transfer and photocatalytic reaction processes of fivc kinds of amides at the surfaee of silver-modified titanium dioxide(Ag-TiO₂) particles have been studied by ESR method.The used amides include fo formamide(FA),dimethylformamide(DMFA),acetamide(AA),dimethylacetamide(DMAA) and propionamide(PA).Results show that the photocatalysis ability of Ag-TiO₂ particles is much greater than that of the unmodified TiO₂.As without TiO₂,the ESR signal of the adduct[DMPO-CONH₂] was observcd only in photolysis of formamide system,and no ESR signal was detected for other four kinds of amides.However,the clear ESR signals could be observed for five kinds of amides in the presence of TiO₂ particles.Two kinds of carbon centered radicals and hydroxyl radical were detected.ESR signals were obviously enhanced by silver-modified TiO₂ particles.At the same condition,the enhancing effect of Ag-TiO₂ containing 10% Ag is greater than that of the Ag-TiO₂ containing 1% Ag.

A Rapidly-frozen technique and ESR method were used to directly measure free radicals generation in rabbit brain tissues due to venous fat-embolism.It had been found that ESR signal intensities of free radicals for the experimental fat-embolism group are 2-3 times higher than those for norinal contrast groups.The appearance of the lipid peroxyl radicals and the carbon-centered alkyl radicals provides an evidence that the fat-embolism pathologenesis may involve an active-oxygen radical action.In this paper the advantage of the rapidly-frozen method and its feasibility are elucidated.

Complete ¹H and ¹³C NMR resonance assignments were carried out for two compounds:ent-kauran-16β,17-diol(I) and paraquilgin(II).In addition to conventional 1D NMR methods,2D shift correlated,NMR techniques(¹H-¹H COSY,¹H-¹³C COSY.and ¹H-¹H NOESY) ere used for the signal assignment.

Chemical shifts of carbonyl groups in aldehydes,ketones,carbonyl chlorides,carboxylic acids and their esters were calculated with the equation established by our new model.The structural effects of ¹³C NMR were studied,and some abnonnal conditions of carbonyl groups in aldehydes and carboxylic acids were also discussed.

NMR lines of fluids on the rock core surface are found.Analysis indicated that they originate from the diffcrence in susceptibilities between rock matrix and free fluid.When some of the fluids leaked out from the rock pores,the fluids exit in two states,i.e.inside the rock and outside the rock,their susceptibilities are different,The intensity of the new resonance lines increases with time and tends to a constant value,this procedure is rclated to the permeability of the sampie.So it is possible to develop a method to deteimine rock pemeability from the surface fluid lines.

A series of fractions of Fu-shun shale oil were separated through decompressed distillation and silica gel chromatography subsequcntiy.These constituents were studied by ¹H,¹³C high resolution NMR and DEPT and 2D C-H correlation spectroscopies.some infomation of molecular structure was obtained.

The data fit theory of relaxation time measurement is intriduced in this paper.The formulas of error estimates and statistical measure of goodness-of-fit are given.On the basis of these,a program SIMFIT is written in NDP-FORTRAN 386 language.Different fitting methods and fitting functions can be used in this program.The fit curve and fit error can be displayed on the screen.

All new UNITY systems are equipped with computer-controlled 63 dB attenuators on the observe and decouple channels,as well as with linear amplifiers and T-R switch preamplifiers.
The combination of these elements means that the capability for performing shaped pulse experiments is inherent in all UNITY system.
There does exist a routine in/unmr/psg named shape-pulse.c,which generates Gaussian,half-Gaussian,and hermit pulses for attenuators,and this routine is documented in the source code of the routine.