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排序方式: 共有1047条查询结果,搜索用时 46 毫秒
991.
992.
993.
Khairy M. Hassan Ahmed K. El-Shafei Hussein S. El-Kashef Mohamed M. Mashaly 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1982,32(2):416-420
Some new sulpha drugs containing both β-lactam and/or thiazolidinone moieties have been prepared. The biological screening of the prepared compounds has been carried out on some strains of pathogenic bacteria. It is clear that these compounds have a different mechanism of action other than that already known for the sulpha drugs. 相似文献
994.
995.
A detailed study of the optical absorption as a function of temperature and composition for a series of soda-lime-silica glasses
doped with TiO2 oxide is presented. The variations of the optical energy gap with temperature in the range 296 to 483 K are reported. The
UV results are analysed assuming optical absorption by indirect transitions. It was found from these optical absorption data
that the present glass system can be divided into three compositional regions. 相似文献
996.
Mahmoud A. Abbady Hussein S. El-Kahef Mohamed A. Abd-Alla Maymouna M. Kandeel 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1984,34(2):62-72
Cyclonucleophilic addition of N-phthaloylaminoacid chlorides (II on 4-(N-ary-lideneamino)-4′-nitrodiphenyl sulphides (I) in dioxane and triethylamine afforded 4-(4″-aryl-3″-phthalylamino-2″-oxo-azetidin-1″-yl)-4′-nitro-diphenyl sulphides (III). Hydrazinolysis of III yielded 4-(4″-aryl-3″-amino-2″-oxo-azetidin-1″-yl)-4′-nitro-diphenyl sulphide hydrochlorides (IV). Condensation of IV with anisaldehyde using ethanol and piperidine as a basic catalyst gave 4-(4″-aryl-3″-anisylidine amino-2″-oxoazetidin-1″-yl)-4′-nitrodiphenylsulphides (V) in good yields. Interaction of V with chloroacetyl chloride in dioxane and triethylamine produced 4-(4″-aryl-3″-substituted β-lactamyl-2″-oxo-azetidin-1″-yi)-4′-nitrodiphenyl sulphides VI. Oxidation of IV, V and VI using hydrogen peroxide/glacial acetic acid mixtures gave the corresponding sulphones (VII), (VIII) and (IX). Sulphones of the type IX were obtained by unequivocal synthesis through interaction of sulphone-anils VIII with chloroacetyl chloride. The antibacterial activities of some of these compounds were determined. 相似文献
997.
Hussein Ibrahim Malik 《国际钢铁研究》1976,47(7):453-454
Metallographische Untersuchungen zur Ermittlung der Perlitwachstumsgeschwindigkeit in einem Stahl mit 2% Si im Vergleich zu einem unlegierten eutektoidischen Stahl hoher Reinheit. Ermittlung der Ae1-Temperatur und Erörterung der Versuchsergebnisse im Vergleich zu Schrifttumsangaben. 相似文献
998.
High performance liquid chromatographic methods for measuring the concentration of vitamins A and D in fluid milk were validated and used to assess the level of these nutrients in Ontario retail milk samples. Thirteen and fifteen fortified milk samples were tested for vitamins A and D, respectively. Repeatability relative standard deviation values for vitamins A and D in milk were generally less than 10%. Recoveries varied from 87 to 107%. Vitamin D results indicated that only 20% of skim, 40% of 2% fat milk, and 20% of whole milk contained the recommended levels, whereas 46% of skim, and 77% of 2% fat milk had the required levels of vitamin A. The results indicate that vitamin level varies widely in Ontario retail milk. 相似文献
999.
Baoxian Zhang Jun Zheng Hussein T. Mouftah 《International Journal of Communication Systems》2007,20(8):993-1009
Scalability is a great concern in the design of multicast routing protocols for the global Internet. Building shortest path trees (SPT) is currently one of the most widely used approaches to supporting multicast routing because of the simplicity and low per‐destination cost of such trees. However, the construction of an SPT typically involves high protocol overhead, which leads to the scalability problem as the number of concurrent multicast sessions increases. In this paper, we present a destination‐initiated shortest path tree (DSPT) routing protocol. The design objective is to effectively reduce the protocol overhead associated with SPT constructions for providing scalable multicast. To achieve this objective, we introduce destination‐initiated joining operations in constructing SPTs. With DSPT, each router receiving a request to join a specific multicast group makes a local decision on selecting its parent node through which it connects to the existing tree. A source‐rooted SPT is built as a result of such collaborative operations at nodes. DSPT requires only limited routing information at routers. Analytical results demonstrate that DSPT scales well with respect to computation, storage and communication overhead when the number of concurrent multicast requests is large. Simulation experiments are also conducted to verify the correctness of the theoretically deduced analytical results. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
1000.
Reza Katal Sara Pourkarimi Ehsan Bahmani Hamed Aleebrahim Dehkordi Mohhamad Ali Ghayyem Hussein Esfandian 《乙烯基与添加剂工艺杂志》2013,19(2):147-156
The aim of this work was to investigate the sorption characteristics of Fe3O4 coated on polyaniline (Fe3O4/PAn) for the removal of NO3? ions from aqueous solutions. The sorption of NO3? ions by the batch method was carried out. The optimum conditions of sorption were found to be a Fe3O4/PAn dose of 0.4 g in 100 mL of NO3? solution, a contact time of 10 min, pH and temperature 7 and 40°C, respectively. Temperature had a negative effect on the removal efficiency. Three equations, i.e., Morris–Weber, Lagergren, and pseudo‐second‐order, were tested to track the kinetics of the removal process. The Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models were subjected to sorption data in order to estimate sorption capacity, intensity, and energy. The thermodynamic parameters ΔH, ΔS, and ΔG were evaluated. They showed that the adsorption of NO3? onto Fe3O4/PAn was feasible, spontaneous, and exothermic under the studied conditions. It can be concluded that Fe3O4/PAn has potential to remove NO3? ions from aqueous solutions at different concentrations. The system Fe3O4/Pan was successfully tested for a high removal efficiency of NO3? from urban wastewater. J. VINYL ADDIT. TECHNOL., 19:147–156, 2013. © 2013 Society of Plastics Engineers 相似文献