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1.
A practical access to alkyl- and aryl-substituted (E)-2-(azidomethyl)alkenoates and related azido compounds from the corresponding allylic bromides in aqueous acetone is described. An alternative method to obtain the starting bromides based on heterogeneous catalysis under mild conditions was also investigated. 相似文献
2.
A free-piston driver that employs entropy-raising shock processes with diaphragm rupture has been constructed, which promises
significant theoretical advantages over isentropic compression. Results from a range of conditions with helium and argon driver
gases are reported. Significant performance gains were achieved in some test cases. Heat losses are shown to have a strong
effect on driver processes. Measurements compare well with predictions from a quasi-one-dimensional numerical code.
Received 7 September 1996 / Accepted 5 October 1996 相似文献
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E. Possenriede P. Jacobs H. Kröse O. F. Schirmer 《Applied Physics A: Materials Science & Processing》1992,55(1):73-81
On the basis of a previous identification of paramagnetic defects in nominally undoped as grown BaTiO3 single crystals, we have investigated the changes of the concentrations of these centers and their optical absorptions under illumination with light of varying wavelengths. The most pronounced charge transfers occur by hole ionization of Fe4+ and — to a lesser extent — of Cr5+ and Cr4+. At low temperatures the created holes are trapped in the form of O–-ions next to Al3+ or unknown acceptor defects. Corresponding Fe4+ and O– absorptions have been identified. 相似文献
6.
We present a new mathematical programming formulation for the Steiner minimal tree problem. We relax the integrality constraints on this formulation and transform the resulting problem (which is convex, but not everywhere differentiable) into a standard convex programming problem in conic form. We consider an efficient computation of an ε-optimal solution for this latter problem using an interior-point algorithm. 相似文献
7.
The 351 nm laser-damage thresholds (at 0.7 nm pulse length) of monomeric liquid crystals are reported and results from aromatic-core samples are compared with those from fully saturated systems. The role of π-electron conjugation is examined and identified as the key cause for laser damage. For UV laser compatibility of devices, the damage behaviour of an alignment-layer polymer (nylon 6/6) was also investigated. 相似文献
8.
To investigate the influence of the anisotropic part of the potential, exact quantum mechanical calculations have been performed of the differential co 相似文献
9.
The rotational distribution of OH(X
2,v=0) radicals was investigated by resonant laser-induced fluorescence (LIF) after photolysis of H2O2 at 193 nm. A microcomputer equipped LIF arrangement allowed special shot-by-shot normalization of the fluorescence signal for noise reduction. Using a least-squares procedure we were able to account for all measured line intensities including overlapping lines (blends) and obtain a complete rotational state distribution of the OH(X
2,v=0) state. The rotational excitation shows a Gaussian-like distribution with a maximum atK=12 and with 16% of the total available energy (17,400 cm–1) appearing in rotation. Only 1% of the available energy is converted into vibration, leaving over 83% for translational excitation. The measured rotational distribution appears to fit a semiclassical theory. 相似文献
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