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121.
Photonic Network Communications - In recent years, owing to the consistent increase in volume and heterogeneity of the traffic, telecommunication networks have undergone significant innovations.... 相似文献
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A new and efficient synthesis of a variety of highly embellished bicyclooctenones having an endo-vinyl moiety and their sigmatropic shifts in ground and excited states leading to a stereoselective route to substituted cis-decalins and diquinane frameworks have been described. Functionalized bicyclo[2.2.2]octenones having an endo-vinyl group and a beta,gamma-enone chromophore were prepared by in situ generation of 6-chloromethyl-6-hydroxycyclohexadienones and cycloaddition with butadiene (also generated in situ) followed by manipulation of the adducts. The presence of contiguous carbonyl, hydroxyl, and chloromethyl groups in adducts led to the introduction of various alkyl groups alpha to the ketone in a stereoselective fashion. The 3,3-sigmatropic shift in the bridged bicyclic compounds gave the corresponding cis-decalins, whereas the triplet sensitized irradiation led to the formation of diquinanes as a result of a 1,2-acyl shift. 相似文献
124.
Lata Mathew Talasila Prasada Rao Chonatumatom S. P. Iyer Alathur D. Damodaran 《Mikrochimica acta》1995,118(3-4):249-256
A first-order derivative spectrophotometric method has been developed for the simultaneous determination of copper, mercury and lead at g/L levels using dithizone as reagent. The procedure involves the simultaneous extraction of these elements by dithizone in chloroform from weakly alkaline solutions. Linear calibration curves were obtained in the ranges 0.5–10 (Cu), 1–10 (Hg) and 1–10 (Pb) g present in 40 ml of aqueous phase with detection limits of 5 g/L (Cu) and 20 g/L (Hg and Pb). The R.S.D.s for 100 g/L of copper, mercury and lead were 2.5, 2.6 and 3.1% respectively, for 5 determinations. The method is applicable for the determination of copper and lead in marine sediment samples with good precision and accuracy. 相似文献
125.
Savithri R. Iyer David R. Tueting Neil E. Schore 《Journal of organometallic chemistry》1987,320(3):339-348
The synthesis of the potential bridging ligand (C6H5)2PCH2CH2Si(CH3)2C5H4 (3) is described. The ferrocene (6 derived from 3 has been found to form macrocyclic complexes with metal fragments NiCl2, NiBr2, and Co2(CO)6. Although monomeric, bimetallic products might have been expected based upon the reduced steric demands of ligand 3 relative to an analogous ligand, (C6H5)2PCH2Si(CH)3)2C5H4 (1), it appears that the increased flexibility in 3 is the overriding factor leading to a preference for inter- rather than intramolecular coordination of the second phosphine function in 6. 相似文献
126.
Srinivas N. Iyer 《The Journal of the Operational Research Society》1989,40(10):889-894
Consider a k-out-of-n system where the lifetimes of the components are independent and identically distributed exponential (λ) random variables. Each component has its own repair facility, the repair times being independent and identically distributed exponential (μ) random variables, independent of the failure times. The mean operating time and mean repair time during the cycle between two successive breakdowns are found using renewal theory and the expression for the system availability. Using these, the mean first-passage times from any of the operating states of the system to the down state, and the mean first-passage times from any of the down states to the operating state are found recursively. 相似文献
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129.
Pan D Iyer M Liu J Li Y Hopfinger AJ 《Journal of chemical information and computer sciences》2004,44(6):2083-2098
A new method, using a combination of 4D-molecular similarity measures and cluster analysis to construct optimum QSAR models, is applied to a data set of 150 chemically diverse compounds to build optimum blood-brain barrier (BBB) penetration models. The complete data set is divided into subsets based on 4D-molecular similarity measures using cluster analysis. The compounds in each cluster subset are further divided into a training set and a test set. Predictive QASAR models are constructed for each cluster subset using the corresponding training sets. These QSAR models best predict test set compounds which are assigned to the same cluster subset, based on the 4D-molecular similarity measures, from which the models are derived. The results suggest that the specific properties governing blood-brain barrier permeability may vary across chemically diverse compounds. Partitioning compounds into chemically similar classes is essential to constructing predictive blood-brain barrier penetration models embedding the corresponding key physiochemical properties of a given chemical class. 相似文献
130.
A. N. Iyer R. Jammy U. Balachandran M. Suenaga P. Haldar 《Journal of Electronic Materials》1995,24(12):1873-1876
Long lengths of mono-and multifilament Ag-clad BSCCO superconductors were fabricated by the powder-in-tube technique. Critical
current density (Jc) up to 12,000 A/cm2 has been achieved in an 850 m long multicore conductor. Long length conductors were formed into pancake-shaped coils by the
wind-and-react approach. Test magnets were then fabricated by stacking the pancake coils and connecting them in series. The
magnets were characterized as a function of applied magnetic field at various temperatures. A test magnet, fabricated with
≈770 m of BSCCO tape, generated fields of ≈1 T at 4.2K and ≈ 0.6 T at 27K, both in an applied background field of 20 T. Additionally,
the strain tolerance of both mono-and multifilament conductors at 77K in 0.5 T applied field has been studied. We observed
that multifilament conductors have better strain tolerance than monofilament tapes, retaining more than 90% of the initial
critical current (at 0.5 T) with strain ≥1%. 相似文献