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971.
Syntheis of tetramethoxybiphenyl 21 was accomplished from 4-phenylcylohexane-1,3-dione 13 by aromatization to biphenyl 19 and reductive removal of the phenolic OH group as phenyltetrazolyl ether. Tertramethoxybiphenyls 34 and 40 were obtained from 4-phenylcyclohexenone 26 via ester 27 . The tetramethoxybiphenyls 21, 34 , and 40 , and analogs 28, 29 , and 31 were evaluated for antitubulin activity and as antimitotic agents with L1210 murine leukemia cells. Compounds 31 and 34 had significant effects on the in-vitro polymerization of tubulin. Compound 31 was the most cytotoxic of the six new biphenyls studied (IC50 for cell growth, 0.6M ) and caused the accumulation of cells in metaphase arrest. 相似文献
972.
The synthesis of 1,2,3,4-tetrahydroazepine[3,2,1-kl]phenothiazin-4-one was accomplished by cyclization of phenothiazine-10-butanoic acid using phosphorus pentoxide and absolute ethanol. The title compound represents the first reported example of the azepino[3,2,1-kl]phenothiazine ring system. A vastly improved malonic ester-type synthesis of the precursor acid has also been developed. 相似文献
973.
F. Hermes E.W. Jasper H.E. Kurz T. Mayer-kuckuk P.F.A. Goudsmit H. Arnold 《Nuclear Physics A》1974,228(1):175-179
Excitation functions for the reactions and were measured at bombarding energies up to 75 MeV. The data are compared to the results of an equilibrium statistical model calculation including angular momentum conservation and γ-ray competition. Satisfactory agreement was found except for the high energy tails. 相似文献
974.
Joseph Kiss Klaus Peter Berg Adolf Dirscherl Willi E. Oberhnsli Wolf Arnold 《Helvetica chimica acta》1980,63(6):1728-1739
Synthesis and Properties of 6-Deoxy-6-halogeno-Derivatives of L -Ascorbic Acid 6-Deoxy-6-chloro-, -6-bromo-, -6-iodo- and -6-fluoro derivatives of L -ascorbic acid have been synthesized and characterized. The physiological properties of the chloro derivative have been investigated. It shows a high antiscurvy activity. The chloro- and bromo-derivatives have been reduced to the corresponding deoxy compound, which is an interesting chiral intermediate for the preparation of rare ω-deoxy sugars. 相似文献
975.
J.O. Arnold S.R. Langhoff 《Journal of Quantitative Spectroscopy & Radiative Transfer》1978,19(5):461-466
Self-consistent-field plus configuration-interaction calculations have been performed on the a3Πu and d3Πg states of C2. Good agreement is obtained between the theoretical potential energy curves and these obtained by a Klein-Dunham analysis of measured molecular constants. The sum of the squares of the theoretical transition moments Σ|Re|2 between these states at 2.44 bohr is 4.12, a.u. which is in good agreement with the range of values of 3.3–3.6 a.u. obtained from shock tube measurements. The computed variation of the Σ|Re|2 with internuclear distance is in remarkably good agreement with the relative measurements by Danylewych and Nicholls. 相似文献
976.
977.
978.
Abstract –An acoustic method is outlined to detect triplet states formed by radical pair recombination in photosyn-thetic reaction centers. It is based on magnetic field effect on the probability of triplet state formation by recombination. Using a periodically modulated magnetic field in the presence of constant exciting light, a periodic modulation of the triplet state concentration is set in the sample, which is detected through the corresponding modulated heat emission, transduced to acoustic vibration of the gas phase around the sample. This effect is similar to the photoacoustic effect, except that here the light is not modulated. The feasibility of detecting such an effect was proven experimentally, by obtaining a signal from quinone-depleted reaction centers of Rhodobacter sphaeroides. The signal had twice the frequency of the magnetic field modulation; it was proportional to the light intensity and significantly stronger at the lower temperatures (in the investigated range 113–278 K). No signal was obtained from quinone-containing reaction centers, which do not produce triplets. A theoretical outline of the effect and the experimental set-up are described. The "magnitude of the effect was calibrated against ordinary photoacoustic measurements, allowing numerical evaluation of certain parameters of the triplet state ( e.g. triplet energy or yield) with the aid of auxiliary information from the literature. 相似文献
979.
980.
Gerhard Schütte Peter Möller J. Rayford Nix Arnold J. Sierk 《Zeitschrift für Physik A Hadrons and Nuclei》1980,297(4):289-294
We calculate the non-adiabatic excitations of pair states in a BCS formalism for a fissioning236U nucleus. The single-particle spectrum is calculated for a folded-Yukawa potential along a deformation path that is determined classically for one-body dissipation. The resulting microscopic energy dissipation is compared to that due to one- and two-body dissipation. 相似文献