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111.
112.
113.
2-Amino-and 2-hydrazino-5-(3 or 4-pyridyl)-1, 3, 4-oxadiazoles [IIi-k] have been prepared by racting 2-chloro derivatives with the corresponding amines or hydrazines, the 2-hydrazino (IIi-k) compounds that obtained were heated with carbon disulphide and alcoholic potassium hydroxide where 5-(3 or 4-pyridyl)-1,3,4-oxadiazolo (2,3-C)-1,2,4-triazole 5-thione (IIIa-c) were obtained, the given structures were biologically screened. 相似文献
114.
《Electroanalysis》2004,16(5):410-414
Mercury electrodes modified with supercoiled (sc) DNA have been used as highly sensitive tools for the detection of DNA strand breaks or as sensors for DNA cleaving substances. In this paper we show that silver solid amalgam electrode (AgSAE), in connection with alternating current voltammetry, provides similar information about DNA damage as the hanging mercury drop electrode. The AgSAE can be used for the detection of enzymatic or chemical DNA cleavage in solution or at the electrode surface. AgSAE modified with scDNA can be utilized as a sensor for DNA nicking substances. 相似文献
115.
116.
Information content of data and variables and types of weighting in least-squares regression methods
Algorithms are given for evaluating the relative amount of useful information related to a particular parameter which is carried by individual data points and intervals of the variables. The algorithms provide an efficient means of using the information contained in a set of data. Applications to the optimization of weighting in regression methods are described. Several informational and combined informational-statistical types of weighting are studied as a means of improving the accuracy and precision of the parameters obtained by non-linear regression. 相似文献
117.
E. L. Anderson M. M. Thomason H. T. Mayfield W. Bertsch 《Journal of separation science》1979,2(6):335-342
A versatile two-dimensional gas chromatograph is described, consisting of 2 separate ovens, one intermediate trap, an auxiliary inlet, and the necessary hardware to effect off-line switching according to the principle of Deans. The unit has been designed for use with high resolution glass capillary columns. The performance of individual instrumental components was critically evaluated. Results showed that low dead volume glass to metal connections were required in the manifold and detector lines to minimize extra-column effects. The mass of the intermediate trap must be low to allow rapid heating. Operational parameters are discussed and examples of some applications are shown. 相似文献
118.
治理塑料废弃物新技术途径探讨--专论可降解塑料的研究开发 总被引:24,自引:0,他引:24
综述了可降解塑料的研究开发现状及其进展。可降解塑料的降解时控性研究,合成,加工工艺改进以及降低成本的研究,可控光-生物降解的合成降解性研究和一次性使用塑料实用性研究,仍是今后需要深入探讨的重要研究课题。 相似文献
119.
J. Ståhlberg 《Chromatographia》1987,24(1):820-826
Summary A quantitative model for ion pair chromatography based on the electrostatic theory is described. The model is based on the
solution of the linearised Poisson-Boltzmann equation in a cylinder. The obtained equations are compared with experimental
data from a number of different systems. The agreement between theory and experiments is satisfactorily. Systematic deviations
due to the use of the linearised equation and ion correlation effects are discussed. 相似文献
120.
A new series of photoactivated DNA oxidizing agents in which an acridine moiety is covalently linked to viologen by an alkylidene spacer was synthesized, and their photophysical properties and interactions with DNA, including DNA cleaving properties, were investigated. The fluorescence quantum yields of the viologen-linked acridines were found to be lower than that of the model compound 9-methylacridine (MA). The changes in free energy for the electron transfer reactions were found to be favorable, and the fluorescence quenching observed in these systems is explained by an electron transfer mechanism. Intramolecular electron transfer rate constants were calculated from the observed fluorescence quantum yields and singlet lifetime of MA and are in the range from 1.06x10(10) s(-1) for 1 a (n=1) to 6x10(8) s(-1) for 1 c (n=11), that is, the rate decreases with increasing spacer length. Nanosecond laser flash photolysis of these systems in aqueous solutions showed no transient absorption, but in the presence of guanosine or calf thymus DNA, transient absorption due to the reduced viologen radical cation was observed. Studies on DNA binding demonstrated that the viologen-linked acridines bind effectively to DNA in both intercalative and electrostatic modes. Results of PM2 DNA cleavage studies indicate that, on photoexcitation, these molecules induce DNA damage that is sensitive to formamidopyrimidine DNA glycosylase. These viologen-linked acridines are quite stable in aqueous solutions and oxidize DNA efficiently and hence can be useful as photoactivated DNA-cleaving agents which function purely by the co-sensitization mechanism. 相似文献