摘要:

The structure of 5-Bromo-4, 6-dimethoxy-4-(trichloromethyl)hexahydro 2-pyrimidinone (3), synthesized from the reaction of 4-methoxy-4-(trichloromethyl)tetrahydro-2-pyrimidinone (2) with bromo and methanol, was determined by nmr spectroscopy, X-ray diffraction, and semiempirical MO calculations.

ISSN:0038-7010    

DOI:10.1080/00387019808003290

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The SERS spectra of copper (II) complex ofmeso-tetris (4-N-cyano methyl pyridyl) porphyrin (Cu11NACN) and the complexes with the calf thymus double-stranded and denatured DNA on silver sols obtained by reducing AgNO3with citrate and the effect of pH and the concentration of Cu11NACN have been investigated. It was pointed out that, pH=5∼6, the concentration of Cu11NACN ca 1 × 10−5mol/L are better for SERS. Cu11NACN acts on Ag sols through the pyridyl N and the porphyrin core together, and is absorbed on Ag sols in the slope-on form which is not influenced by adding the double stranded and the denatured DNA. In the system of Ag sols, Cu11NACN acts on the double stranded DNA at phosphate by electrostatic force, but maybe part-intercalates the single stranded of the denatured DNA accompanied with the electrostatic force similar to the double stranded DNA.

ISSN:0038-7010    

DOI:10.1080/00387019808003291

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The excitation temperatures of sputtered gadolinium and uranium atoms in an argon hollow cathode discharge have been determined by diode laser-excited optogalvanic spectroscopy. These results have been compared to those determined by conventional emission spectroscopy. It was found that the temperatures derived from each method do not differ very much, but the optogalvanic method revealed a better standard deviation uncertainty due to the good signal-to-background ratios and excellent spectral resolutions. Temperature variations with discharge currents ranging from 15 to 50 mA have been examined.

ISSN:0038-7010    

DOI:10.1080/00387019808003292

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The fluorescent and photochemical properties of Eu (III) with copolymers of acrylic acid and butyl methacrylate were investigated. It was found that photochemical behavior of Eu3+complexes with copolymers is essentially different from those of Eu3with polyacrylic acid - in the former Eu3luminescence intensity during photolysis noticeably enhances rather than reduces. It has been found that the presence of steric hindrances and coordinatively unsaturated structures in the initial complexes with copolymer and peculiarities of the photodecomposition of macromolecular ligand favors the enhancement of the luminescence during the photolysis

ISSN:0038-7010    

DOI:10.1080/00387019808003293

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Mass spectra of a series of substituted salicylaldehyde and 2-hydroxy-naphthaldehyde Schiff bases were used to investigate enol-keto tautoraeric equilibrium. Two model compounds, namely, salicylidinaniline and naphthylidinequinolineamine Schiff bases were used to represent the enol and keto forms, respectively. Mass spectral measurements reveal the fragmentation pattern in all compounds studied. Only naphthylidinequinoline amine Schiff base show a different fragmentation pattern compared to the other Schiff bases in the series which give an evidence for its suggested keto structure.

ISSN:0038-7010    

DOI:10.1080/00387019808003294

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The Fourier transform (FT) infrared and Raman spectra of newberyite, MgHPH4- 3H2O are studied in the region where the stretching vibrations of the water molecules (protiated and deuterated) and the O-H/O-D stretches of the hydrogenphosphate anions are expected to appear. The O-H stretching vibrations give rise to a complex feature known as theA,B,Ctrio. Since neither of the maxima found below 3000 cm−1represents a true band arising from a given fundamental, it is pointless to correlate their frequencies with the observed O…O distances. In the water stretching region, the two bands with highest frequencies undoubtedly correspond to the anti symmetric and symmetric stretch of one type of the water molecules. The stretching vibrations of one of the remaining two types of H2O molecules are clearly uncoupled and the O-H oscillator involved in the weaker hydrogen bond is responsible for a band at 3376 cm−1whereas the rest of the water stretchings are apparently overlapped yielding the complex band below 3320 cm−1. Thus the situation is again complicated and the correlations between the frequencies and the Ow…O distances are inappropriate. The two bands at highest frequencies (3522 and 3483 cm−1at RT) exhibit a positive temperature coefficient.

ISSN:0038-7010    

DOI:10.1080/00387019808003295

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A radioisotope excited X-ray fluorescence Emission - Transmission (E -T) technique was applied for the determination of inorganic contents of some diuretic pharmaceutical herbs growing in Turkey. Folia Betulae, Stylus Maydis, Flores Verbasci, Equisetum Arvense and Flos Helichrysi herbs which are widely used by public at the cure of kidney diseases were investigated. The study was based on advantages of the XRF E-T method by means of the neglectable enhancement effect and analysis without reference material. An annular source of Cd-109 (3.7 MBq) was employed for excitation of characteristic K X-rays of the elements in the herbs. Herb samples were prepared in dry and wet forms for the method. The leaching ratios of the elements in these herbs in the period of steeping were calculated. Toxic elements in the considerable amount were not found. It was observed that the other element contents in the dry and wet forms are different.

ISSN:0038-7010    

DOI:10.1080/00387019808003296

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

d-cycloserine (CS) is transformed intocis-3, 6-bis(aminooxymethyl)-2, 5-piperazinedione (CS-dimer) in the solid state under a humid atmosphere. This dimerization process was followed by measuring the IR bands characteristic of CS and CS-dimer. The reaction was accelerated by the presence of increased water vapor. The X-ray analysis of CS monohydrate (CS · H2O) revealed that the CS molecules exist as a zwitter ion where the α-amino N atom is protonated and the amide N atom is deprotonated in the crystal. Participation of water molecules was suggested in the dimerization of CS.

ISSN:0038-7010    

DOI:10.1080/00387019808003297

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Intensities and decay rates of delayed luminescence (DL) initiated by a pulse ofN2laser were employed to probe collisional relaxation of complex molecules (benzophenone, acetophenone) diluted with bath gasesAr, Kr, Xe, C2H4, SF6, C5H12.It was shown that vibrational relaxation can be interpreted in terms of two consecutive processes: vibration-vibration (V-V) and vibration-translation (V-T).The results clearly demonstrated that fast component ofDLcan be used to studyV-Venergy transfer. It was found that at relatively small internal energy the collisional efficiences ofV-Vprocess had the values typical for molecular processes in which supercollisions contribute. The average energies transferred per collision, (ΔE), well correlated with predictions of the simple ergodic collision theory of intermolecular energy transfer.

ISSN:0038-7010    

DOI:10.1080/00387019808003298

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A microwave-assisted digestion procedure has been developed for the treatment of silicone oil samples. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentration level of 40 trace element impurities, like Li, Na, Mg, Al, P, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Rb, Zr, Nb, Mo, Ag, Cd, Sn, Sb, Ba, La, Ce, Nd, Hf, W, Au, Pb, Hg, Th, Bi and U in these samples, having obtained average relative standard deviation values of 9.6%. The methodology developed has been tested by recovery studies on different natural samples spiked with known amounts of Mg, Cr, Mn, Fe, Zn and Pb at concentration levels of 10, 0.5, 5, 5, 10 and 1 μgg−1and recovery percentage values varies from 97 to 105 %.

ISSN:0038-7010    

DOI:10.1080/00387019808003299

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor