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排序方式: 共有134条查询结果,搜索用时 15 毫秒
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E. M. Essassi J. P. Lavergne Ph. Viallefont J. Daunis 《Journal of heterocyclic chemistry》1975,12(4):661-663
The condensation of 3,4-diamino 1,2,4-triazole with ethyl aceloacelate gave 6-methyl-8,9-dihydro(7H)-s-triazolo[4,3-b]-1,2,4-triazepin-8-one ( 2 ); 2 has been caracterized by nmr spectroscopy and by comparison with its methylated derivative prepared in an unambigous manner. 相似文献
4.
J. Lavergne 《Photochemistry and photobiology》1986,43(3):311-317
Abstract— The UV absorbance change associated with the oxygen-evolution cycle is investigated as to its correlation with the successive redox (S-) states of the system. This change is probably due to a manganese oxidation within a multinuclear Mn-cluster. The stoichiometry of its formation and destruction during the S-cycle has been a matter of controversy: (0,1,0,-1) according to velthuys, B. R. (1981) in Photosynthesis II , (Edited by G. Akoyunoglou), pp. 75–85. Balaban International Science Services, Philadelphia, or (1, 1, 1, -3) according to Dekker, J. P., Van Gorkom, H. J., Wensink, J. and Ouwehand, L. (1984) Biochim. Biophys. Acta 767, 1–9. We show that the data obtained in flash-series experiments on dark-adapted material may be fitted as satisfactorily by both models. More discriminating tests were devised, varying parameters such as the double-hits probability or the initial distribution of the S-states. These experiments clearly indicate that no (or little) absorbance change occurs both upon S0 →S1 and S2 →S3 transitions. This suggests that the correct stoichiometry is (0,l,0,-1). The possibility of a non-integer stoichiometry may also be considered. 相似文献
5.
The mass spectra of eleven 1,2,4-triazepines with oxo, thioxo, methoxy and methylmercapto groups in the 3 and 5 positions are reported and analysed. Each of the five structures of the triazepine ring present is characterized by a particular group of fragmentations. 相似文献
6.
We report here a one-step synthesis of the 4,5,6,7-tetrahydro-1H- 1,2,4,-triazolo[4,3-d][1,4]diazepine, 4-6, and 1,2,4-oxadiazolo[4,5-d][1,4]-diazepine, 7-10, by 1,3-dipolar cycloaddition of nitrile imines and nitrile oxides with 2,3-dihydro-H-1,4-diazepine, 1. In all cases these cycloaddition are peri- and regioselectives (the C ? N bond is sole affected) and occures with high yields. Structure and conformations of cycloadducts have been assigned by means of nmr analysis 相似文献
7.
Zhaoliang Cao Quanquan Mu Guillaume Dovillaire Thomas Grandin Emeric Lavergne Lifa Hu 《Liquid crystals》2013,40(10):1227-1232
The effect of twisted alignment on the phase modulation of a liquid crystal wave‐front corrector was investigated. First, the effect of twisted alignment is discussed in terms of the modulation principle of the liquid crystal molecule. Only partial incident light can be modulated because of the effect of the twisted alignment. Other unmodulated light will affect the correction accuracy and the resolution of the image. The blazed grating method is proposed to solve this problem. Adaptive correction was performed without the blazed grating method and the correction results are poor. A similar adaptive correction experiment was performed with the blazed grating method and a better correction result is obtained. The residual averaged wave‐front errors are PV = 0.101λ and RMS = 0.015λ and a resolvable image is obtained. 相似文献
8.
F. Jaeger has shown that up to a ± sign the evaluation at (j, j
2) of the Tutte polynomial of a ternary matroid can be expressed in terms of the dimension of the bicycle space of a representation over GF(3). We give a short algebraic proof of this result, which moreover yields the exact value of ±, a problem left open in Jaeger's paper. It follows that the computation of t(j, j
2) is of polynomial complexity for a ternary matroid.E. Gioan: C.N.R.S., MontpellierM. Las Vergnas: C.N.R.S., Paris 相似文献
9.
Sawitree Saengkaew Tawatchai Charinpanitkul Hathaichanok Vanisri Wiwut Tanthapanichakoon Yves Biscos Nicolas Garcia Gérard Lavergne Loïc Mees Gérard Gouesbet Gérard Grehan 《Experiments in fluids》2007,43(4):595-601
The rainbow refractrometry, under its different configurations (classical and global), is an attractive technique to extract
information from droplets in evaporation such as diameter and temperature. Recently a new processing strategy has been developed
which increases dramatically the size and refractive index measurements accuracy for homogeneous droplets. Nevertheless, for
mono component as well as for multicomponent droplets, the presence of temperature and/or of concentration gradients induce
the presence of a gradient of refractive index which affects the interpretation of the recorded signals. In this publication,
the effect of radial gradient on rainbow measurements with a high accuracy never reached previously is quantified. 相似文献
10.
Lavergne A Zhu Y Pizzino A Molinier V Aubry JM 《Journal of colloid and interface science》2011,360(2):645-653
Two agro-based anionic surfactants containing an isosorbide moiety have been synthesized and their amphiphilic properties evaluated. Since isosorbide is now considered as an important platform chemical of the starch industry, these compounds could represent bio-sourced alternatives to the alkyl ether sulfates (notably lauryl ether sulfate, LES) that are based on petroleum-derived ethylene oxides. As isosorbide is an asymmetric diol, two isomers can be prepared (2-O-dodecyl isosorbide sulfate and 5-O-dodecyl isosorbide sulfate) that show significantly different aqueous properties as regards to their Krafft temperatures and critical micellar concentrations. 5-O-dodecyl isosorbide sulfate is the most soluble and the most efficient surfactant. It possesses a much lower critical micelle concentration (cmc) than sodium dodecyl sulfate, SDS, leading to comparable foaming properties with a three times lower concentration. Its behavior compares well with the one of pure diethoxylated dodecyl sulfate that has also been prepared and evaluated in this work. 相似文献