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51.
Summary The feasibility of using columns prepared by mixing together ion exchange and reversed-phase packing materials, for the simultaneous separation of ionised and unionised molecules, has been examined using a range of test solutes. Columns prepared in this way showed chromatographic properties which were intermediate between those of the individual phases. The dual nature of the retention mechanism allowed the retention of ionisable molecules to be adjusted using pH whilst that of uncharged compounds was unaffected. The simultaneous chromatography of model compounds and their glucuronide, sulphate and glycine conjugates, under a variety of conditions, was demonstrated. 相似文献
52.
Stephen T. Ross Robert G. Franz James W. Wilson Richard A. Hahn Henry M. Sarau 《Journal of heterocyclic chemistry》1986,23(6):1805-1814
The three possible mono-O-methyl derivatives of 6-chloro-2,3,4,5-tetrahydro-1-(4-hydroxyphenyl)-1H-3-benzazepin-7,8-diol (SK&F 82526) ( 1 ) have been synthesized to facilitate the isolation and characterization of metabolites of this compound and for biological testing. The syntheses generally involved preparation of appropriately substituted benzaldehydes, conversion of these to phenylacetic acids and use of these to N-acylate arylethanolamines. The phenylacetamides thus formed were reduced to amines and these were deprotected and cyclized to the desired final products. In one case deprotection followed cyclization. These compounds were tested as activators of dopamine-sensitive adenylate cyclase (a measure of DA-1 agonist activity) and as renal vasodilators. All three O-methyl derivatives were much less potent than 1 in cyclase activation and as renal vasodilators. Weak inhibition of adenyl cyclase was also observed for all three compounds and one showed weak renal vasoconstrictor activity. Preliminary investigation of the metabolism of 1 disclosed that two of the three monomethoxy compounds were formed in trace amounts in the rat and the dog. In a related investigation, the trimethoxy derivative of 1 was subjected to acid-catalyzed hydrolysis conditions. The relative ease of cleavage of methoxy groups was 7 > > 4′ > 8. 相似文献
53.
T H Huisman F Kutlar A Kutlar J B Wilson H F Harris 《Journal of chromatography. A》1987,388(2):429-439
High-performance liquid chromatographic procedures have been used in the detection and identification of a new gamma chain of human fetal hemoglobin (Hb). This M gamma chain is characterized by a Leu----Met replacement at position gamma 141; no other structural variations have been observed. The M gamma chain has been detected in red cell lysates of subjects with a heterozygosity for one of many types of so-called hereditary persistence of fetal hemoglobin conditions, which are characterized by an increased level of Hb F in adult life, in sickle cell anemia, and in a few cord blood samples. At present it is not possible to definitely identify the genetic cause of this newly discovered heterogeneity; an infidelity in translation or the existence of an unrecognized gamma globin gene should be considered. 相似文献
54.
A concise synthesis of the complete tricyclic dibenzofuran-1,4-dione aromatic core of popolohuanone E has been demonstrated by mild base treatment of a biquinone intermediate, thus establishing a biomimetic route to this family of heterocyclic ring systems and the total synthesis of popolohuanone E. 相似文献
55.
Extraction and subsequent recovery, in four separate fractions, of naphthenic acids, alkylphenols, pyrrollic compounds and nitrogen bases can be made from petroleum products using macroporous ion-exchange resins. Distinctive features of the technique are the use of dissolved gases in polar solvents as eluants and the application of the carbonate form of anion-exchange resins. The transition metal form of a macroreticular cation exchanger is shown to extract ligands from non-aqueous systems and a specific application to petroleum analysis is given. 相似文献
56.
57.
Cappa CD Smith JD Wilson KR Messer BM Gilles MK Cohen RC Saykally RJ 《The journal of physical chemistry. B》2005,109(15):7046-7052
Measurements of the oxygen K-edge X-ray absorption spectrum (XAS) of aqueous sodium halide solutions demonstrate that ions significantly perturb the electronic structure of adjacent water molecules. The addition of halide salts to water engenders an increase in the preedge intensity and a decrease in the postedge intensity of the XAS, analogous to those observed when increasing the temperature of pure water. The main-edge feature exhibits unique behavior and becomes more intense when salt is added. Density functional theory calculations of the XAS indicate that the observed red shift of the water transitions as a function of salt concentration arises from a strong, direct perturbation of the unoccupied molecular orbitals on water by anions, and does not require significant distortion of the hydrogen bond network beyond the first solvation shell. This contrasts the temperature-dependent spectral variations, which result primarily from intensity changes of specific transitions due to geometric rearrangement of the hydrogen bond network. 相似文献
58.
In the process of bulk photopolymerization of styrene initiated by AIBN decomposition polyvinyl benzophenone (PVB) can supply an effective cage for triplet-triplet energy transfer between PVB macromolecules and small molecules of AIBN to influence the molecular weight of polystyrene in weak magnetic field (less than 0.035T), that was different from the case of polyvinyl naphthalene (PVN) which supplied cages for this system only in the stronger magnetic field (more than 0.2 T) studies. It was found that in the same conditions, PVN could exert more tremendous influences on the bulk photopolymerizatiou system of styrene than PVB because in the stronger magnetic field the triplet PVN had much longer life time than PVB. 相似文献
59.
Light Dosimetry for Intraperitoneal Photodynamic Therapy in a Murine Xenograft Model of Human Epithelial Ovarian Carcinoma 总被引:1,自引:0,他引:1
Lothar Lilge Kelly Molpus Tayyaba Hasan Brian C. Wilson 《Photochemistry and photobiology》1998,68(3):281-288
Few studies have been published to date measuring spatially resolved fluence rates in complex tissue geometries. Here the light distributions of three different intraperitoneal light delivery geometries in a murine ovarian cancer model were investigated to assess their influence on the tumorcidal efficacy of photodynamic therapy (PDT). In vivo fluence rate measurements in the peritoneal cavities of mice, with the light intensity being mapped in three transverse planes, were performed using fiber-optic detectors. Three different source fiber designs and placements were tested for their ability to provide uniform irradiation of the peritoneal cavity. The biological response to a PDT protocol comprising three separate treatments administered at 72 h intervals, each consisting of a 0.25 mg kg intraperitoneal injection of benzopor-phyrin derivative-mono acid ring A followed 90 min later by delivery of 15 J of 690 nm light, was measured. The tissue response was evaluated by measuring the number of remaining visible lesions and the total residual tumor mass. Fluence rate measurements showed large variations in the fluence rate distribution for similar intended treatments. The most uniform and reproducible illumination was achieved using two 18 mm long cylindrical emitting optical fibers. The biological response was comparable to that produced when a flat-cleaved end optical fiber is used to illuminate the four quadrants of the abdomen sequentially. While a good reproducibility in tumor induction in this animal model exists, no correlation was found between the fluence rate distribution measured in one group of animals and the biological response in a separate group of similarly treated animals. Due to the large intra-animal variability in fluence rate distribution, representative fluence rate mapping in complex tissue geometries is of limited value when applied to an individual PDT treatment. Thus, surveillance of the fluence rate during individual treatments will be required for acceptable PDT dosimetry. To improve the versatility of this particular animal model for PDT research, a large number of extended sources are required to increase uniformity of the illumination in order to reduce unwanted cytotoxic side effects resulting from foci of high fluence rates. In this way, subsequent increase of the total energy delivered to the tumor may be possible. 相似文献
60.
LI Chun-Bao Chen Yi LI Song-Lin ZHANG Wen-Qin CUI Yi JI Xiu-Jie ZHENG Peng-Wu 《结构化学》2002,21(5):470-472
1 INTRODUCTION (9S,13R,14S)-7,8-Didehydro-3,7-dimethoxy-4-hydroxy-17-methylmorphinan-6-one I is an impor- tant natural product that was used to ease pain, decrease blood pressure and diminish inflammation. In order to study the stereochemistry of the reduction of I with potassium boronhydride, the crystal structure of the title compound II was determined by X-ray diffraction method. 2 EXPERIMENTAL 2. 1 Instrument The melting point was measured on a Yanagimoto MP-500 apparatus… 相似文献