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排序方式: 共有490条查询结果,搜索用时 15 毫秒
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23.
S. Padmaja V. Ramakrishnan J. Rajaram J. C. Kuriacose 《Journal of Chemical Sciences》1988,100(4):297-303
The borate radical is produced by the flash photolysis of an aqueous alkaline solution of NaBO2 and K2S2O8. The absorption spectrum of the transient borate radical shows two maxima. The self decay of this radical is second order.
Rate constants for the reactions of this radical with some organic substrates have been determined. 相似文献
24.
Reaction of β-naphthyl cinnamate with anhydrous aluminum chloride afforded 9-hydroxyphenalenone5 by a Fries rearrangement followed bya dearylative cyclisation. 9-Hydroxy-3-phenyl-2,3-dihydrophenaIen-l-one7 was identified as an intermediate. 相似文献
25.
T. P. Elango V. Ramakrishnan S. Vancheesan J. C. Kuriacose 《Journal of Chemical Sciences》1984,93(1):47-52
Rate constants for the reaction of carbonate radical with aniline and some parasubstituted anilines have been determined by
the flash photolysis technique. Using σ+ para values the rate constants at pH 8.5 correlate very well with the Hammett equation yielding ρ= − 1. The carbonate radical oxidises aniline giving the anilino radical. The products so formed have been identified through
studies under conditions of continuous irradiation. 相似文献
26.
L. Ramakrishnan Prof. Dr. S. Soundararajan 《Monatshefte für Chemie / Chemical Monthly》1977,108(1):225-231
Complexes of 2,6-dimethylpyridine 1-oxide with lanthanide iodides of the formulaeLn(2,6-LTNO)5I3 whereLn=La, Tb and Yb,Ln(2,6-LTNO)4I3 whereLn=Pr and Nd and Er(2,6-LTNO)4.5I3 have been prepared and characterised by chemical analysis, infrared and conductance studies. Infrared and conductance data have been interpreted in terms of dimeric (or polymeric) structures involving bridging amine oxide groups.
Mit 2 Abbildungen 相似文献
Mit 2 Abbildungen 相似文献
27.
Narayani Ramakrishnan Nancy L. Oleinick Marian E. Clay Min-Fen Horng Antonio R. Antunez Helen H. Evans 《Photochemistry and photobiology》1989,50(3):373-378
Two closely related strains of mouse lymphoma L5178Y cells, LY-R and LY-S, have been found to differ in their sensitivity to the cytotoxic effects of photodynamic treatment (PDT) with chloroaluminum phthalocyanine (CAPC) and red light. Strain LY-R is more sensitive to photodynamic cell killing than strain LY-S. Differences in uptake of CAPC could not account for the differences in cytotoxic effects. There was no marked difference between the two strains in the induction of single-strand breaks (which includes frank single-strand breaks and alkali-labile lesions), but substantially more DNA-protein cross-links were formed in strain LY-R by CAPC and light. Repair of single-strand breaks proceeded with similar kinetics in both strains for the first 30 min post-irradiation, suggesting that these lesions are not responsible for the differential sensitivity of the two strains to the lethal effects of photodynamic treatment. Thereafter, alkaline elution revealed the presence of increasing DNA strand breakage in strain LY-R. DNA degradation, as measured by the conversion of prelabeled [14C] DNA to acid-soluble radioactivity, was more rapid and extensive in strain LY-R. 相似文献
28.
Banerjee A Grewer C Ramakrishnan L Jäger J Gameiro A Breitinger HG Gee KR Carpenter BK Hess GP 《The Journal of organic chemistry》2003,68(22):8361-8367
The synthesis and characterization of a new photolabile protecting group (caging group) for carboxylic acids, the 2-(dimethylamino)-5-nitrophenyl (DANP) group, is described. This compound has a major absorption band in the visible wavelength region with a maximum near 400 nm (epsilon400 = 9077 M(-1) cm(-1) at pH 7.4 and 21 degrees C). The caging group is attached through an ester linkage to the carboxyl functionality of beta-alanine, which activates the inhibitory glycine receptor in the mammalian central nervous system. Such caged compounds play an important role in transient kinetic investigations of fast cellular processes. Upon photolysis of DANP-caged beta-alanine, the caging group is released within 5 micros. Quantum yields of 0.03 and 0.002 were obtained in the UV region (308 and 360 nm) and the visible region (450 nm), respectively. Laser-pulse photolysis experiments, using 337 or 360 nm light, were performed with the caged compound equilibrated with HEK 293 cells transiently transfected with cDNA encoding the alpha1 homomeric, wild-type glycine receptor. The experiments demonstrated that neither DANP-caged beta-alanine nor its byproducts inhibit or activate the glycine receptors on the cell surface. Under physiological conditions, the DANP-caged beta-alanine is water-soluble and stable and can be used for transient kinetic measurements. 相似文献
29.
T. P. Elango S. Vancheesan V. Ramakrishnan J. C. Kuriacose 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(1):151-155
Carbonate radical shows moderate reactivity (k2=1.8·106 M–1 s–1) with nickelglycine complex. As an oxidizing free radical, it may attack the ligand to form Ni(II) coordinated glycine radical or oxidize the metal center to form a Ni(III) glycine transient. Continuous -irradiation of the complex-bicarbonate mixture yields glyoxalic acid (G=1.7) as the major product. The reaction involves an attack of the ligand and precludes the oxidation of metal center. 相似文献
30.
Narayani Ramakrishnan Marian E. Clay Liang-YAN Xue Helen H. Evans Antonio Rodriguez-Antunez Nancy L. Oleinick 《Photochemistry and photobiology》1988,48(3):297-303
Abstract— Chloroaluminum phthalocyanine (CAPC) is an efficient photosensitizer for the inactivation of Chinese hamster V79 cells. In order to investigate possible molecular mechanisms in the photo-dynamic action of CAPC and visible light, the induction and repair rate of two classes of DNA lesions have been determined, i.e. DNA single-strand breaks and DNA-protein cross-links. In cells pretreated with 1 μ.M CAPC, a fluence of 12 kJ/m2 of red light (>600 nm) kills approximately 50% of the cells and induces 3 to 3.5 Gy-equivalents of single-strand breaks. The repair of these breaks was slower than the repair of single-strand breaks induced by -irradiation. The photodynamic action of CAPC also induces a large number of DNA-protein cross-links which, in contrast to -radiation-induced DNA-protein cross-links, do not appear to be repaired during 4 h of post-treatment incubation in fresh medium. These studies suggest that DNA may be an important target for the cytotoxicity of CAPC + red light. 相似文献