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921.
Synthesis and Antimycobacterial Evaluation on Arylsulfonyl and Arylcarbonyl Derivatives of Ofloxacin
Yeh‐Long Chen Yu‐Wen Chen We‐Fen Lo Chai‐Lin Kao Yu‐Shuan Liu Chen‐Wen Yao Chemg‐Chyi Tzeng 《中国化学会会志》2009,56(2):374-380
Four ofloxacin derivatives 3, 5, 6 , and 11 were found to exhibit > 90% inhibition on the growth of M. tuberculosis at a concentration of 6.25 μg/mL. Compounds 3, 5 and 11 have also exhibited a broad spectrum of antibacterial activities while 8‐fluoro‐3‐methyl‐9‐[4‐(4‐nitrophenylsulfonyl)piperazin‐1‐yl)‐6‐oxo‐2,3‐dihydro‐6H‐1‐oxo‐3a‐azaphenalene‐5‐carboxylic acid ( 6 ), which exhibited potent activity against the growth of TB with the MIC of 2.23 μg/mL and a selectivity index (SI) of > 14.80, was inactive against the growth of G(+)‐ and G(‐)‐bacteria. Selective anti‐TB activity was achieved by the introduction of an arylsulfonyl group at C‐7 piperazin‐4‐yl of N‐demethyl ofloxacin. Compound 6 is species‐specific, exhibiting no significant activity against the growth of bacterial species other than M. tuberculosis, which implied the possibility of developing new specific anti‐TB drug candidates without inducing cross resistance with other currently used antibacterial drugs. Structural optimization of 6 is on‐going. 相似文献
922.
Small-angle x-ray scattering study of the formation and growth of δ' in binary Al-7.87at% Li alloy
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The formation and growth of δ' particles in an alloy of Al-7.87at% Li have been investigated using the small angle x-ray scattering technique. It has been shown that a transition zone, which exists between the δ' phase and the matrix after ageing for 16 h, disappears after ageing for 32 h. The existence of a transition zone indicates that the δ' phase is precipitated in the process of spinodal decomposition. This result also indicates that the growth of δ' particles should be divided into two stages. During the first stage, the δ' phase increases eating up the transition zone before ageing for 32 h, and in the second stage it grows by swallowing up each other after ageing for 32 h. In the latter stage, the larger and smaller δ' particles can coexist in the alloy. 相似文献
923.
Higher-order squeezing of quantum electromagnetic fields and higher-order uncertainty relations in two-mode squeezed states
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It is found that the two-mode output quantum electromagnetic field in two-mode squeezed states exhibits higherorder squeezing to all even orders, and the degree of higher-order squeezing is greater than that of the second-order.The higher-order squeezed parameter and squeezed limit due to the modulation frequency are investigated. The smaller the modulation frequency is, the stronger the degree of higher-order squeezing becomes. Furthermore, the higher-order uncertainty relations in two-mode squeezed states are presented for the first time. The product of higher-order noise moments is related to even order number N and the squeeze factor r. 相似文献
924.
B. Ben-Nissan D.D. Green G.S.K. Kannangara C.S. Chai A. Milev 《Journal of Sol-Gel Science and Technology》2001,21(1-2):27-37
31P nuclear magnetic resonance (NMR) spectroscopy was used to determine the structure of the intermediate species of sol derived from triethyl phosphite, calcium diethoxide and acetic acid. NMR spectral data revealed that the reaction proceeds via a dialkyl phosphite intermediate. The use of a dialkyl phosphite precursor (diethyl phosphite) with calcium diethoxide eliminated the aging time required in triethylphosphite method and offered an effective sol-gel procedure for monophasic hydroxyapatite. 相似文献
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927.
Ching-yue Wang Yong Wang Lu Chai Weili Zhang Qirong Xing Zhigang Zhang 《Optics & Laser Technology》2001,33(2):81
Dynamic process of self-started self-mode-locked Ti : sapphire laser with a semiconductor saturable absorber mirror (SESAM) was investigated and two mode-locking starting processes were found in which one is fast and the other is slow. In the fast starting process, a mode-locking build-up time of about 400 μs was needed during which pure passive mode-locking process was caused by the SESAM and Kerr-lens mode-locking process arose from the nonlinearity of the Ti : sapphire gain medium. In the slow starting process, a build-up time of about several minutes was found in which temperature effect of the SESAM dominates the dynamic process. 相似文献
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930.
The effect of the diminution of the sensitizing intensity from initially high value on two-center recording is experimentally and theoretically investigated. A linear diminution of the sensitizing intensity is designed,and three different diminution rates are employed for the experimental investigation. The results show that the dynamic range can be improved by reducing the diminution rate of the sensitizing intensity. Compared with that of traditional two-center recording, the recording sensitivity obtained in the experiment is more improved when the maximum dynamic range is achieved. The effect of the diminution of the sensitizing intensity on grating uniformity and the effect of the initial sensitizing intensity on the recording sensitivity are theoretically investigated. 相似文献