A searchable data bank of NMR spectra is developed. The database includes approximately 64 000 ¹H NMR spectra and 42 000 ¹³C NMR spectra, along with chemical structures and molecular formula of the relevant compounds. The database can be searched by the serial number and molecular formula of the chemicals. The system program is written in Visual Basic language, and runs under Microsoft Windows system. The spectra database and spectral information are administrated by Microsoft Access. The database enables rapid generation of relevant NMR spectra by inputting spectral information and NMR spectra that are unavailable from commercial sources.

¹H and ¹³C NMR spectroscopy was used to study the structure and configuration of 3, 5-dimethyladamantanamine hydrochloride salt. Complete NMR assignments were made using DEPT, ¹H-¹H COSY, HSQC and HMBC techniques. The NMR data indicated that the compound has a rigid structure and is comprised of two diastereomeric forms. There are ten peaks in the ¹³C NMR spectrum of the compound within the region δ C 29~54 ppm. Because the compound has two different molecular configurations, there exist three peaks of quaternary carbons in the ¹³C NMR spectrum and two peaks of methyl groups in the ¹H NMR spectrum. The two plane angles between the tertiary proton H-5 and three adjacent CH₂ are near 60°, resulting in very small coupling constants among these protons. Consequently, the resonance of these protons can not be resolved and presents as a singlet in the ¹H spectrum.

Two polysubstituted biphenyl compounds were synthesized from ellagic acid. Using NMR techniques including HMQC, HMBC and 1D NOE techniques, the ¹³C and ¹H NMR chemical shifts of the two product compounds were assigned.

A sesquiterpene lactone was isolated from Nouelia insignis Franch, and its structure was elucidated (compound 1)by 2D NMR to be 8β, 9-dihydro-onoseriolide. Complete assignment of the ¹H and ¹³C chemical shifts for the compound was obtained. The assignments of H-1 and H-2 of the compound previously reported were found incorrect, and the correct assignments were given. The results of this study may have some practical significance for the structural elucidation of onoseriolide sesquiterpene lactones.

Bimolecular L-valine hydridophosphorane was synthesized by the reaction between L-valine and phosphorus trichloride in tetrahydrofuran (THF). Complete assignment of the ¹³C NMR chemical shifts of the compound was obtained by 2D NMR techniques, including ¹H-¹H COSY, DEPT and HSQC. Based on the results of NMR characterization, the structure of L-valine hydridophosphorane was elucidated. The ³¹P NMR spectrum of the compound showed two separated peaks at δ -64.66 and δ -67.81, suggesting that it is comprised of a pair of diastereomers. The configuration of one of the diastereomers was determined by NOESY, and further confirmed by X-ray crystallography.

1, 1-Dibenzoyl-2-methoxycarbonyl-3-aryl substituted cyclopropane was synthesized under proper reaction conditions. The products were analyzed by ¹H NMR, ¹³C NMR, infrared spectrometry and mass spectrometry. The possible reaction pathways were discussed.

¹H NMR spectra of Scutellaria baicalensis extracts were obtained by PFT-NMR and compared with those of the flavonoids found in the extract including baicalein, oroxylin A, wogonin and baicalin. ¹H NMR chemical shifts were assigned. The spectra of different Scutellaria baicalensis extract samples showed good reproducibility, and all contained the spectral fingerprint of flavonoids. It appears feasible to use the ¹H NMR fingerprints of Scutellaria baicalensis extract as a criterion to check the authenticity of Scutellaria baicalensis and Scutellaria baicalensis products.

The ring current model is often used to interpret the chemical shifts of alkene containing proton and carbon nuclei. However, theoretical interpretation using these models leads to notable inconsistencies with the experimental data. In this paper, the pitfalls of using the p-electron circulation model are discussed. It is also shown that the model of deformation and variation of density of electron clouds around nuclei is a better model for interpreting the chemical shifts of alkene.

The configurations of the title compounds were optimized at the B3LYP/6-31G level. The results show that there is no imaginary frequency in the vibrational analysis. The ¹³C NMR spectra of the compounds were studied at the same level by the GIAO method. The calculated results show that there exist intramolecular hydrogen bonds in the three flavonol derivatives, and the bond lengths are estimated to be about 0.17~0.18 nm. The effects of hydroxyl substituents on the chemical shifts of the adjacent carbons are also discussed. It appears that the more donated electrons from the substituent groups to benzene, the larger the chemical shifts of the adjacent carbons will change.

The present magnetic resonance electrical impedance tomography (MREIT) method can only be used in MRI systems in which the main magnetic fields are parallel to the horizontal plane. In this paper, a new MREIT method with currents injected from an oblique plane is proposed. It can be used on MRI scanners with either permanent magnet or superconductive magnet. Using computers to control the MRI system and the electrical impedance tomography (EIT) equipment, we showed that it is possible to (1) measure the magnetic flux density B(x, y, z) generated by the currents injected; (2) inject currents to the imaging object; (3) match perfectly the MRI and EIT sequences in time; (4) measure the magnitudes of surface voltages. Some experimental results were presented.

A method for measuring the pseudo temperature coefficient (PTC) of rubidium atomic frequency standards was described. The method is highly sensitive, convenient and fast. Based on analyses of physical mechanisms underlying PTC, a method to reduce PTC was proposed. Experimental results showed that the PTC of the rubidium atomic frequency standards can be reduced by one to two orders of magnitude through proper design of the heater used in the physical package.

In previous studies we have developed a nuclear quadrupole resonance (NQR) for detection of explosives. However, the tailing effects of the transmitting pulse in these systems represent a serious technical problem, making the detection of NQR signals difficult. In this paper, an electronic circuit was designed to remove the tails of transmitting pulses. The effectiveness of the circuit was verified by both circuit analysis and experiments.

In this work, EPR spectra and optical absorption spectra of VO²⁺ in KZnClSO₄·3H₂O(PZCST): VO²⁺ single crystal were calculated theoretically based on the two-spin-orbit-coupling parameter model and the corresponding formulae of energy levels for the tetragonal symmetry of 3d¹ cluster. The calculated results were found in good agreement with experimental data. It was deduced from the results that the local symmetry structure along the C₄ axis is compressed tetragonal distortion with a size of 0.47 nm. The large value of κ indicates a large contribution from spin-polarize of unpaired electron to the hyperfine constant.

Atomic electronegativity interaction vector (AEIV) and atomic hybridation state index (AHSI) were employed for quantitative structure spectroscopy relationship modeling of ¹³C NMR chemical shifts of the carbon atoms in protoberberine alkaloids. The five-parameter model yielded r, q, RMSEE and RMSCV of 0.982 9, 0.982 1, 7.732 9 and 7.884 3, respectively. Leave-one-molecule-out (LMO) method and cross test (CT) were combined to test the reliability of this model, and the results appeared satisfactory. Predicted chemical shifts of the samples were in good linear relationship with the experimental data, with r_predof 0.982 9, 0.986 5 and 0.982 1 respectively. The model was also used to predict unknown ¹³C NMR chemical shifts of 58 carbon atoms in four protoberberine compounds, and the results obtained were in agreement with calculated results using the gNMR software.

Dibenzoacridine derivatives can be used as coating materials for microsensor. They have also been widely used as improved receptors in coordination and superamolecule chemistry. In this study, NMR techniques, including ¹H NMR, ¹³C NMR, DEPT, HSQC, HMBC, and mass spectrometry (MS) were used in combination to elucidate the structure of a dibenzoacridine derivative 7-(4-methoxy-phenyl)-5,6,8,9-tetrahydro-dibenzo [c, h]acridine. The ¹H and ¹³C chemical shifts of the compound were assigned.

Four new tetraacetyl galactosylguanidines were synthesized and characterized by NMR spectroscopy. The ¹H and ¹³C NMR chemical shifts of these compounds were assigned using both 1D and 2D techniques, including ¹H NMR, ¹³C NMR, ¹H-¹H COSY, gHMQC, gHMBC and NOESY. The NMR data showed that all galactosyl had the same configuration of β-anomer. The spectral characteristics of the compounds were analyzed and compared.

A new compound ethyl 4-[(E)-2-(3, 4-dimethoxyphenyl)vinyl]phenoxyacetate was synthesized from 3, 4-dimethoxybenzaldehyde and p-nitrotoluene via five steps, including condensation, catalytic reduction, diazotization, hydrolyzation and nucleophilic substitution. The structure of the compound was determined by 1D (¹H and ¹³C NMR) and 2D NMR techniques including ¹H-¹H COSY, HMQC and HMBC. All ¹H and ¹³C NMR chemical shifts of the compound were assigned.