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91.
The paper reports a structural study of some memory and threshold chalcogenides in terms of coordination numberC, defined byC=8−N, and is the average coordination number for covalently bonded materials. The average number of nearest neighbours surrounding
a central atom, obtained for As-Ge-Te (memory) and Se-Ge-Te (threshold) systems have been used to estimate the cohesive energies,
assuming simple additivity of bond energies. The bonding pattern so obtained, explains certain properties of these glasses. 相似文献
92.
Anil B. Goel 《Tetrahedron letters》1984,25(41):4599-4600
A reverse migration of allylic group from palladium to phosphorus and the formation of diaryl(allyl)phosphine in the π -allyl palladium(II) induced cleavage of triarylphosphines has been demonstrated. 相似文献
93.
94.
Summary Di--chlorobis(arylazooximato)dipalladiuni(II) compounds react with PPh3 to give the four-coordinate complexes (5) and (4) in which the azooxime acts as a unidentate and bidentate ligand respectively. Hydrogen bonding in polar solvents such as MeOH or EtOHetc. stabilize (5) whereas, polar solvents such as Me2CO, py and Et2O convert (5) into (4). The equilibrium: (4) + PPh3 (5) exists in PhH solution and equilibrium constants at 30°C have been calculated spectrophotometrically. The variation in equilibrium constants and the stabilities of (5) have been explained on the basis of electron-releasing and electron-withdrawing properties of substituents, R, in the azooxime ligand. 相似文献
95.
Amorphous Fe74Co10B16 (METGLAS 2605CO) has been studied in the temperature range of 77 K – 700 K by Mössbauer spectroscopy. Its crystallization temperature is found to be 665 ± 5 K and Curie temperature is estimated to be 760±10 K. The observed rapid decrease in reduced hyperfine fields can be explained well by Handrich's model for amorphous ferromagnets if one assumes a temperature dependent δ, a measure of fluctuations in the exchange interactions in such solids. 相似文献
96.
Graeme Butt N. Pirzada Ronald D. Topsom William Adcock Anil N. Abeywickrema 《Tetrahedron letters》1982,23(21):2161-2162
The carbon-13 substituent chemical shifts of 4-substituted bicyclo[2.2.2]oct-1-yl cyanides are a linear function of the substituent inductive parameters. 相似文献
97.
98.
Summary Silver can be separated as its Bismuthiol II complex from OsO4
4
2–
, Os4+, Ir4+, Ru3+, Rh3+ with thiosulphate or complexone III as the masking agent at a pH between 5 and 9. Au3+ can be kept in solution only by thiosulphate at a pH 8–9 and cyanide complexes palladium at a PH of about 6. Separation from platinum in presence of a mixture of tartaric acid and complexone III is possible only to a limited extent.Part VI see Z. analyt. Chem. 155, 86 (1957) 相似文献
99.
Das R Kumar SK Kumar A 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,177(2):318-328
Geometric phases have stimulated researchers for its potential applications in many areas of science. One of them is fault-tolerant quantum computation. A preliminary requisite of quantum computation is the implementation of controlled dynamics of qubits. In controlled dynamics, one qubit undergoes coherent evolution and acquires appropriate phase, depending on the state of other qubits. If the evolution is geometric, then the phase acquired depend only on the geometry of the path executed, and is robust against certain types of error. This phenomenon leads to an inherently fault-tolerant quantum computation. Here we suggest a technique of using non-adiabatic geometric phase for quantum computation, using selective excitation. In a two-qubit system, we selectively evolve a suitable subsystem where the control qubit is in state |1, through a closed circuit. By this evolution, the target qubit gains a phase controlled by the state of the control qubit. Using the non-adiabatic geometric phase we demonstrate implementation of Deutsch-Jozsa algorithm and Grover's search algorithm in a two-qubit system. 相似文献
100.
Glycogen phosphorylase (GP(a)) is a specific target for the design of inhibitors and may prevent glycogenolysis under high glucose conditions in type II diabetes. The carboxamides first reported by Hoover D. J. et al. (J. Med. Chem. 1998, 41, 2934-2938) are one of the major classes of GP(a) inhibitors other than glucose derivatives. The recent, X-ray crystallographic analyses (Oikonomakos et al. Biochim. Biophys. Acta 2003, 1647, 325-332) have revealed a distinct mechanism of action for these inhibitors, which bind at a new allosteric site away from the inhibitory and catalytic sites. To elucidate the essential structural and physicochemical requirements responsible for binding to the GP(a) enzyme and to develop predictive models, CoMFA and docking studies have been carried out on a series of indole-2-carboxamide derivates. The CoMFA model developed using pharmacophoric alignments and hydrogen-bonding fields demonstrated high predictive ability against the training (r2 = 0.98, q2 = 0.68) and the test set (r2pred = 0.85). Further the superimposition of PLS coefficient contour maps from CoMFA with the GP(a) active site (PDB: 1lwo) has shown a high level of compatibility. 相似文献