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221.
Ali A. Moshfegh Rashid Badri Massoud Hojjatie Mehrangiz Kaviani Basirat Naderi Aboul H. Nazmi Merrikh Ramezanian Bizhan Roozpeikar Gholam H. Haakimelahi 《Helvetica chimica acta》1982,65(4):1221-1228
The synthesis of the title compounds is described. Some of the compounds prepared exhibited antimicrobial activity in vitro. Structure-activity relationship is briefly discussed. 相似文献
222.
An earlier procedure based on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol is adapted for use with a Technicon AutoAnalyzer; 60 samples per hour can be analyzed. The range is 0.2–3 g of uranium per litre of extract. The method is readily modified for the determination of uranium (?200 μg l-1) in ground waters. 相似文献
223.
Amanlou M Asmardi G Andalibi PC Javadi N Khodadady F Omarny ZB 《Journal of chromatography. A》2005,1088(1-2):136-139
An isocratic, reversed-phase liquid chromatographic method was developed for determination of tropicamide using atropine as an internal standard in a pharmaceutical dosage form. Tropicamide and atropine sulfate were separated using a microBondapak ODS (C18) column by isocratic elution of mobile phase with flow rate of 2.0 ml/min. The mobile phase composition was methanol-50 mM phosphate buffer (pH 4; 30:70, v/v). The eluate was monitored at 257 nm with detector range setting fixed at 0.01 AUFS. Under these conditions, the retention times were 4.81 min for atropine and 11.89 min for tropicamide. The standard calibration curve was linear over a sample concentration range from 2 to 300 microg/ml, with limit of detection of 0.15 microg/ml. The assay linearity was good (typically r2 = 0.9992) and the standard curves were linear in the detection range. The precision of the method (expressed by relative standard deviation) and the accuracy (mean error in percent) were <5% for both intra- and inter-day assays. Recovery at 80-120% of labeled claim ranged from 98.4 to 100.7% for tropicamide. The proposed method was satisfactorily applied to the determination of tropicamide in pharmaceutical preparation and stability indicating studies. 相似文献
224.
Lincomycin analogues. I. Chain-extensions of [1,2:3,4]-di-O-isopropylidene-α-D -galacto-hexodialdo-1,5-pyranose The title aldehydosugar 1 treated with Wittig reagents led in good to excellent yields to the unsaturated sugar derivatives 3–7 and 10–15, 8 having been prepared by condensation of 1 with malonic acid. The configuration (Z or E) of each compound obtained has been established by 1H-NMR. These chain-extensions constitute the first synthetic step towards the preparation of lincomycin analogues. 相似文献
225.
The complex trans-[Co(dmen)2Cl2]Cl (dmen=N,N-dimethylethylenediamine) has been prepared and characterized by elemental analysis, u.v.-vis. and i.r. spectra. The kinetics of the primary aquation of trans-[Co(dmen)2Cl2] in H2O, H2O–MeOH and H2O–i-PrOH have been examined over a wide range of solvent compositions and temperatures (40–55°C). Plots of rate constants (log k) versus the reciprocal of the dielectric constant of the medium (Ds–1) and Grunwald–Winstein values of the solvent (Y) were found to be non-linear. The variation of enthalpies (H) and entropies (S) of activation with solvent composition has been determined. Plots of H or S versus the mole fraction of each solvent exhibit extrema at x2=ca. 0.16 and 0.27 for MeOH and at x2=ca. 0.03 and 0.14 for i-PrOH. Furthermore, the cycle relating the free energy of activation in H2O to that in H2O–co-solvent shows that the stabilizing influence of the changes in the solvent structure is greater on the emergent five-coordinate cation in the transition state than that on the complex ion in the initial state, with the difference becoming greater as the mole fraction of the co-solvent increases. 相似文献
226.
227.
It is shown that if satisfies , where σk(A) denotes the sum of all kth order subpermanent of A, then Per[λJn+(1?λ)A] is strictly decreasing in the interval 0<λ<1. 相似文献
228.
Single-walled carbon nanotube (SWCNT) bundles have the potential to provide an attractive solution for the resistivity and electromigration problems faced by traditional copper interconnects. This paper discusses the modeling of nanotube bundle resistance for on-chip interconnect applications. Based on recent experimental results, the authors model the impact of nanotube diameter on contact and ohmic resistance, which has been largely ignored in previous bundle models. The results indicate that neglecting the diameter-dependent nature of ohmic and contact resistances can produce significant errors. Using the resistance model, it is shown that SWCNT bundles can provide up to one order of magnitude reduction in resistance when compared with traditional copper interconnects depending on bundle geometry and individual nanotube diameter. Furthermore, for local interconnect applications, an optimum nanotube diameter exists to minimize the resistance of the carbon nanotube bundle. 相似文献
229.
Mostafa El Massoud 《Journal of Mathematical Analysis and Applications》2005,302(2):269-281
As many equations in fluid mechanics, the thermocline equations, in standard notation, are composed of quasi-linear, first-order partial differential equations. The aim of this paper is to establish an existence, uniqueness result for the solution of such a problem. 相似文献
230.