摘要:

The systems of gossypol-metal cation in acetonitrile have been studied by UV-visible absorption spectroscopy. The formation of 1:1 complexes between gossypol and Be+2, Cu+2, Dy+3, and Zn+2has been proved and their formation constants, K, have been determined to be of an order of 104M.

ISSN:0038-7010    

DOI:10.1080/00387019108021760

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An interface system between planar gel electrophoresis and mass spectrometry is described that includes a means of rapid electrophoretic gel disruption, concentration of extracted sample in a pre-column, and transfer of the sample molecules to the continuous flow FAB source of a mass spectrometer. Spatial resolution achieved on the surface of the gel is on the order of 2 mm diameter for a spot, and 4 mm2for a band. Sensitivities to 50 picomoles have been demonstrated for the analysis of small peptides with continuous-flow fast atom bombardment mass spectrometry.

ISSN:0038-7010    

DOI:10.1080/00387019108021761

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A study of the influence of thickness and wave-length on the ultraviolet scattering of polyethylene films is reported in this paper. The scatter of samples was measured by considering the difference between absorbances values obtained with the sample placed in two positions at different distance from the detector in a UV/Vis Spectrophotometer.

ISSN:0038-7010    

DOI:10.1080/00387019108021762

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Lead lanthanum Zirconate Titanate (PLZT 7/65/35) powders were prepared by a sol-gel process, using lead acetate, lanthanum acetate, zirconium n-propoxide and titanium n-propoxide as precursors along with 2-methoxyethanol as the solvent. Nitric acid was used to catalyze the sol-gel reaction. FTIR spectroscopy characterized the starting precursors, monitored the sol to gel transformations involving solutions with different molar ratios of water to alkoxide precursors, and tracked the crystallization behavior of the gels upon heat treatment. Raman spectroscopy was employed at room temperature to follow vibrational spectral changes for the samples that were cooled after various stages of heat treatment and crystallization of the gels. The resulting spectral changes were analyzed in terms of the structural changes that occurred during the sol-gel process.

ISSN:0038-7010    

DOI:10.1080/00387019108021763

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The mutual orientation of pigments in living organisms, for example the antenna pigments in photosynthetizing Organisms, have strong influence on molecular processes such as excitation energy transfer which are closely related to physiological function of photosynthetizing apparatus of plants, algae and bacteria [l].

ISSN:0038-7010    

DOI:10.1080/00387019108021764

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

1H and13C NMR chemical shift assignments were obtained for the local anesthetics etidocaine (1) and etidocaine hydrochloride (2) in CDCl3solution, as well as for2in D2O solution. The COSY experiment was employed for proton-proton correlation, while onebond and long-range 2D heteronuclear techniques allowed the assignments of all13C chemical shifts in each molecule. Etidocaine has a chiral carbon; etidocaine hydrochloride has, in addition to the natural chiral center, an acid-induced chirality at the protonated amine nitrogen, resulting in solvent-dependent diastereomers. Ten of the fourteen magnetically nonequivalent13C nuclei of2exhibit doubled13C resonance peaks (50.3 MHz, 20°C, CDCl3solution) due to the presence of the two diastereomers.

ISSN:0038-7010    

DOI:10.1080/00387019108021765

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The molecular structure of septuplinolide fromCalea septuplinervawas determined by single crystal X-ray diffraction analysis. This requires revision of stereochemistry at C4 from 4β-OH to 4α-OH in the septuplinolide molecule. Also, high-field1H and13C NMR spectral assignments of the lactone are given.

ISSN:0038-7010    

DOI:10.1080/00387019108021766

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The temperature and concentration dependence of1H NMR chemical shifts of pentafluoroaniline and aniline in acetone (Ac), dimethylsulphoxide (DMSO) and hexamethylphosphortriamide (HMPA) indicate that the effect of hydrogen bond formation, δ = δobs- δA' is similar for both anilines. The analysis of1H NMR spectra showed, that proton exchange of t-butyl alcohol (tBA) and 2,6-di-t-butylphenol (DTBPh) with pentafluoroaniline is slower than that with aniline.

ISSN:0038-7010    

DOI:10.1080/00387019108021767

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The 200 MHz1H NMR Spectra of methsuximide, 1,3-dimethy1-3-ogebt1-2,5-otrrikudubeduibem1, havebeen studied in CDC13 solution with the chiral reagent, tris[3-(heptafluoropropy1-hydroxymethylene)-d-camphorato] europium (III),2, Eu(HFC)3. Substantial lanthanide-induced shifts are seen. In addition, significant enantiomeric shift differences are observed for several of the nuclei of1. With a2:1molar ratio near 1.0, the CCH3 and NCH3 signals show nearly baseline resolution between the peaks from each enantiomer, providing excellent potential for direct determinations of enantiomeric excess of samples of1. As little as 2% of a minor enatiomer should be readily detectable.

ISSN:0038-7010    

DOI:10.1080/00387019108021768

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The electronic absorption spectra of crystals of the title componds were recorded and the experimental results were explained quantitatively with the ligand field theory and the radial wave function of bound Cu(II) cation. With these spactra, the range of magnetic interactions between two Cu(II) ions of the title compounds are discussed.

ISSN:0038-7010    

DOI:10.1080/00387019108021769

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor