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The meta photocycloaddition of para-fluorotoluene to cyclopentene yields 1-methyl-10-fluoro-endo- and -exo- tetracyclo[6.3.0.02,11.03,7]undec-9-ene as major photoproducts, while the intramolecular photoaddition of 5-(para-fluorophenyl)pent-1-ene gives exclusively 7-fluorotetracyclo[3.2.1.02,8.34,8]undec-6-ene. A reaction pathway via zwitterionic intermediates is proposed. 相似文献
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Noncollinear difference frequency mixing of dye laser and Nd:YAG second harmonic (fundamental) radiation from a commercial
laser system is employed for the generation of 2.7–5.3 μm (1.6–1.7 μm) radiations in a flux-grown KTiOAsO1 crystal. The generated radiation is used to scan the methane absorption in the fundamental (v
3) and its first overtone (2v
3) band at pressure 90 torr in a laboratory made single pass gas cell of length 33 cm. 相似文献
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Fedoryak OD Sul JY Haydon PG Ellis-Davies GC 《Chemical communications (Cambridge, England)》2005,(29):3664-3666
We have synthesized a biologically inert, photosensitive derivative of the major excitatory amino acid, L-glutamate (which we call MDNI-glu) that makes more efficient use of incident light than all other caged glutamates. Laser flash photolysis of MDNI-glu in acutely isolated hippocampal brain slices evoked a rapid increase in intracellular Ca2+ concentration in astrocytes. 相似文献
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Munshi G Mustafa Sudhir Raniwala T Awes B Rai RS Bhalerao JG Contreras RV Gavai SK Ghosh P Jaikumar GC Mishra AP Mishra H Mishra B Mohanty J Nayak J-Y Ollitrault SC Phatak L Ramello R Ray PK Sahu AM Srivastava DK Srivastava VK Tiwari 《Pramana》2006,67(5):961-981
This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and
work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported. 相似文献
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A mathematical model is proposed for the process of vacuum superplasticforming. The model exploits the fact that in most industrialapplications the sheet aspect ratio (thickness/sheet width)is small. After an initial consideration of some of the moregeneral properties and the literature of superplastic materials,the elastic/plastic deformation of an internally-inflated thin-walledcylinder is examined. Plates of arbitrary geometry are thenconsidered. A quasisteady model in which the sheet moves througha sequence of steady states is developed. Some simplified closed-formsolutions are examined, but for general cases a system of nonlinearpartial differential equations must be solved numerically. Anefficient and accurate semi-explicit numerical scheme is proposedand a simplified stability analysis is presented; the methodis then used to compute properties of superplastic vacuum mouldedsheets in a number of practically motivated cases. 相似文献
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2-(1-naphthyl)ethyl vinyl ether undergoes intramolecular 1,2- photocycloaddition whereas the 2-naphthyl isomer yields a product reflecting dimerisation and loss of the elements of acetylene: consistent with such diverse photochemistry, the addition of 2,3-dihydropyran to naphthalene produces only the 1,2-, 1′,2′regioisomer. 相似文献
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We propose to engineer the atomic band structure in optical lattices in order to design a Fabry-Perot interferometer with large mode spacing and strong nonlinear coupling to be employed in atom optics. The use of an optical lattice allows for a significant reduction of the atomic effective mass, while the slow modulation of its parameters spatially confines the matter waves on a length scale of a few dozen optical wavelengths. As a consequence, the mode spacing in such a cavity would be as high as one-tenth of the recoil energy, allowing for a very efficient filter action, while the nonlinear coupling due to interatomic interactions could lead to bistability and limiting effects in the transmission of the atomic beam. 相似文献