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排序方式: 共有159条查询结果,搜索用时 187 毫秒
101.
I. V. Bagrov I. M. Belousova S. I. Gorelov M. V. Dobrun V. M. Kiselev I. M. Kislyakov A. V. Kris’ko T. K. Kris’ko 《Optics and Spectroscopy》2017,122(2):163-167
The photosensitizing ability of an agent based on chlorin e6 (Photoditazin), which is used for photodynamic diagnosis and therapy, is compared with that of a new preparation on the basis of coproporphyrin III in the environment of a phosphate buffer and a simulated biological environment (albumin solution). The efficiency of singlet-oxygen production was estimated by EPR spectroscopy and spectroscopy in the UV and visible ranges with the use of “chemical traps” of singlet oxygen. By irradiating drugs with LED emission centered at λmax = 520 nm, we determined the quantum yield of singlet-oxygen production in a buffer solution; the obtained values are 0.60 and 0.37 for chlorine and coproporphyrin, respectively. The steady-state concentration of singlet oxygen upon irradiation of solutions of the studied photosensitizers with concentrations of 12–43 μМ and the density of radiation power within the 6–96 W/cm2 region was found to be in the region of 1010–1011 molecules/cm3. It is shown that the introduction into the solution of egg albumin (0.1%) reduces the sensitizing properties of the two drugs by two to three times, while the efficiencies of the preparations with respect to singlet-oxygen production become almost identical (0.19 and 0.17). 相似文献
102.
Kuldeep Wadhwa Chengxi Yang Kris C. Deming Sanjay R. Chemburkar Rajarathnam E. Reddy 《合成通讯》2013,43(24):4434-4444
Abstract A variety of substituted arylglyoxylic acids (2a?g) were synthesized via oxidation of the corresponding aryl-methylketones (1a–e) using selenium dioxide or Friedel–Crafts acylation of phenol (3) with ethyl chlorooxoacetate and further transformations. It was found that the arylglyoxylic acids (2) undergo facile unimolecular dissociation with loss of carbon monoxide to give the corresponding arylcarboxylic acids (7) under collisionally induced mass spectrometric conditions. 相似文献
103.
Kris Frost Erik Johansson Robert Shanks Susumu Goto Gemma M. Kirwan 《Polymer Testing》2013,32(2):343-352
The combined effect of a plasticiser (glycerol) and a cross-linking agent (borax) on the mechanical properties of commercially extruded thermoplastic hydroxypropylated starch films was examined. The use of Design of Experiment (DOE) was demonstrated and used to predict and optimise formulations for a given set of material properties. As an extension to DOE, Orthogonal 2 Partial Least Squares (O2PLS) provided insight into joint correlations between the machine and transverse direction mechanical properties. Specific information regarding individual measurements or samples was also obtained with this analysis. O2PLS identified unique variables in individual compositions that were potentially incorrect measurements, or processing defects, which in turn can be used to aid quality control or processing optimisation with regards to DOE. Overall, DOE and O2PLS showed that within a starch borax-glycerol blend, borax increased mechanical strength and enhanced creep and recovery, whilst glycerol increased elongation and decreased modulus. There were competing interactions between the two dependent on concentration, and variation between machine and transverse properties was due to the extrusion induced molecular orientation of amylose. The optimum concentrations of borax and glycerol needed to achieve higher elongation, tensile strength, modulus and creep recovery than a control was found to be approximately 0.5% and 10%, respectively. 相似文献
104.
Kris McDonough Ngoc Chau Vy Dipti Sharma 《Journal of Thermal Analysis and Calorimetry》2014,116(3):1515-1520
This study explores the presence of time lag in crystalline to smectic A (K–SmA) phase transition of 4-decyl-4-biphenylcarbonitrile (10CB) liquid crystal. A non-isothermal heating and cooling study were performed for 10CB liquid crystal using calorimetric technique where heating scan was performed from 250 to 350 K, and cooling scan was performed from 350 to 250 K. A clear difference in K–SmA phase transition was observed between heating and cooling scans. An attracting inclination effect in K–SmA transition was observed on cooling which is completely absent on heating. The inclination of the K–SmA transition peak increases and shows an existence of time lag during cooling, whereas other family member shows no effect i.e., 8CB. K–SmA peak shows a lower enthalpy with higher activation when compared with 8CB. The presence of time lag and increase in activation can be explained in terms of the density and nature of the material. 相似文献
105.
Bert De Rybel Dominique Audenaert Grégory Vert Wilfried Rozhon Juliane Mayerhofer Frank Peelman Silvie Coutuer Tinneke Denayer Leentje Jansen Long Nguyen Isabelle Vanhoutte Gerrit T.S. Beemster Kris Vleminckx Claudia Jonak Joanne Chory Dirk Inzé Eugenia Russinova Tom Beeckman 《Chemistry & biology》2009,16(6):594-604
106.
Tünde Alapi Kris Van Craeynest Herman Van Langenhoeve András Dombi 《Reaction Kinetics and Catalysis Letters》2006,87(2):255-262
Summary The effect of H/Cl atomic ratio on the relative contribution of direct photolysis and reactions based on •Cl radical to the
photodecomposition of chlorinated methanes was investigated in their binary mixtures.</o:p> 相似文献
107.
Kris Randell 《Journal of organometallic chemistry》2006,691(16):3411-3415
The attempted synthesis of bis(NHC)palladium complexes via the direct reaction of an imidazolium salt with palladium acetate results in the formation of a mixed NHC/aniline complex. The route by which the aniline is formed has not been completely elucidated, but it does originally derive from an imidazolium salt. 相似文献
108.
Wim Schelles Stefan De Gendt Kris Maes René Van Van Grieken 《Fresenius' Journal of Analytical Chemistry》1996,355(7-8):858-860
A direct current glow discharge mass spectrometer has been used to analyse solid non-conducting samples: glass, polycarbonate, marble, aluminium oxide and Teflon. This is made possible by the use of a so-called secondary cathode. The methodology of this concept is investigated and analytical figures of merit are presented. 相似文献
109.
This article is the first of the two-part discussion of thedevelopment of a new Freshman Business Mathematics (FBM) courseat our college. Part I of the article describes the backgroundand history behind the course, and provides a theoretical frameworkfor the design of the course. This design involves studentsin learning and applying mathematics to real world problemsusing common business tools, in this case spreadsheets. Thisnew course is centered on the concept of building and interpretingmodels of data, but touches on many topics in statistics, pre-calculusand calculus. 相似文献
110.
De Vriendt K Van Driessche G Devreese B Bebrone C Anne C Frère JM Galleni M Van Beeumen J 《Journal of the American Society for Mass Spectrometry》2006,17(2):180-188
Metallo-beta-lactamases are zinc containing enzymes that are able to hydrolyze and inactivate beta-lactam antibiotics. The subclass B2 enzyme CphA of Aeromonas hydrophila is a unique metallo-beta-lactamase because it degrades only carbapenems efficiently and is only active when it has one zinc ion bound. A zinc titration experiment was used to study the zinc affinity of the wild-type and of several mutant CphA enzymes. It shows that a second Zn(2+) is also bound at high ion concentrations. All samples were analyzed using mass spectrometry in combination with an automated nanoESI source. The metal-free enzyme has a bimodal charge distribution indicative of two conformational states. A completely folded enzyme is detected when the apo-enzyme has bound the first zinc. Intensity ratios of the different enzyme forms were used to deduce the zinc affinities. CphA enzymes mutated in metal ligands show decreased zinc affinity compared to wild-type, especially D120 mutants. 相似文献