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1.
2.
Synthesis, absolute configuration, and analysis of malathion, malaoxon, and isomalathion enantiomers
Syntheses of the enantiomers of malathion, malaoxon, and isomalathion are reported herein. Malathion enantiomers were prepared from (R)- or (S)-malic acid in three steps. Enantiomers of malathion were converted to the corresponding enantiomers of malaoxon in 52% yield by oxidation with monoperoxyphthalic acid, magnesium salt. The four isomalathion stereoisomers were prepared via two independent pathways using strychnine to resolve the asymmetric phosphorus moiety. The absolute configurations of the four stereoisomers of isomalathion were determined by X-ray crystallographic analysis of an alkaloid salt precursor. A high-performance liquid chromatography technique was developed to resolve the four stereoisomers of isomalathion, and to determine their stereoisomeric ratios. 相似文献
3.
Véronique Baroghel-Bouny Patrick Belin Matthias Maultzsch Dominique Henry 《Materials and Structures》2007,40(8):759-781
Within the framework of the evaluation and the prediction of chloride-induced corrosion risks, simple and rapid AgNO3 spray tests can be proposed for various issues. This paper forms the first part of a series. In this first part, the Maultzsch
procedure (spraying of 0.1-N AgNO3 solution + K2CrO4) as well as the procedure based on the use of a sole AgNO3 solution have been investigated on a broad range of concretes. These procedures have also been compared to the Collepardi
procedure (spraying of 0.1-N AgNO3 + fluoresceine). The feasibility of these colorimetric techniques on saturated specimens cast in laboratory, after non-steady-state
diffusion tests carried out in various conditions, is discussed. In addition, the results obtained from applying such spray
tests in field conditions on cores drilled out from various RC test specimens exposed to a marine environment (tidal zone)
and to a road and cold environment (freezing-thawing cycles and spraying of deicing salts) are presented. Colorimetric methods
have in particular been applied here to the assessment of the average chloride penetration depth and of its evolution versus
time (kinetics). Moreover, the detection threshold of these techniques has been investigated in various environments. The
possible sources of discrepancy on the results have been analysed. 相似文献
4.
In order to know the limit of validity of the concept of hydrical diffusivity, DW, we tried to validate the Boltzmann's method used to identify it. We show that for a medium strictly satisfying the equation of diffusion, the method gives quite good results with nevertheless some inaccuracies for the extreme values of water contents. For the real studied material, a backed clay, its identification becomes more difficult because of the dispersion of the wetting phenomenon observed for different specimens of the same material. We are showing that the mean behaviour of one sample is near to be the same as the more probable behaviour of all the samples. Otherwise the values of DW determined for a wetting cannot be used to describe a drying process. It practical interest is then considerably reduced. In order to test the influence of the gas phase pressure effects on the behaviour of the material, we have determined all the parameters necessary to describe, numerically, wetting and drying processes without to resort to DW. We noticed an overpressure of the gas phase inside the material due to drying. If the gas pressure effects are, numerically, switched off, we cannot notice any influence on water content profiles for this type of material. 相似文献
5.
Giuseppe G. G. Manzardo Sandra Kürsteiner-Laube und Daniel Perrin 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1996,203(6):501-506
In diethyl ether extracts from celeriac (Apium graveolens L. var.rapaceum) all four stereoisomers of (3a–7a)-cis-3-butylhexahydrophthalide were found to be present. The analyses were carried out by means of GC, enantioselective GC and GC-MS. The assignment of the relative configuration of the diastereomers3 and4 was accomplished by NOE difference spectroscopy. 相似文献
6.
7.
The authors present the design and the development of integrated microwave filters using suspended substrate microstrip, a technology that provides many advantages. Through quasi-static approximation the propagation structure has been treated using integral equations solved with the method of moments. Thanks to this tool of analysis and to an accurate synthesis method, a series of bandpass filters have been designed and manufactured. The results presented validate the accuracy of our design method. 相似文献
8.
André Girard Pierre Dominique Lansard Bernard Liau Anne Marie Mongeon Jean Luc Thibault 《电信纪事》1991,46(5-6):335-350
Classical hierarchical routing in telephone networks is extended to a wider class called out-of-chain routing in such a way that some useful properties of hierarchical routing are retained. This new routing pattern offers more potential paths than the fixed hierarchical one and can be introduced as a dynamic routing where the fixed alternate sequences change at some predetermined instants during the day. The effect of this new routing pattern on the network performances is examined. The main topic of this paper is to present heuristic methods used to optimise such routings in large networks. We show on artificial networks that the throughput of a given network can be significantly improved by suitable routing choices. We demonstrate that the integration of routing changes within a multihour dimensioning process is possible but the lack of realistic data does not permit at this time to quantify the value of routing optimization on real networks. 相似文献
9.
A new theory of similarity, rooted in the detection and recognition literatures, is developed. The general recognition theory assumes that the perceptual effect of a stimulus is random but that on any single trial it can be represented as a point in a multidimensional space. Similarity is a function of the overlap of perceptual distributions. It is shown that the general recognition theory contains Euclidean distance models of similarity as a special case but that unlike them, it is not constrained by any distance axioms. Three experiments are reported that test the empirical validity of the theory. In these experiments the general recognition theory accounts for similarity data as well as the currently popular similarity theories do, and it accounts for identification data as well as the longstanding "champion" identification model does. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
M. Le Pallec C. Kazmierski E. Vergnol S. Perrin J.G. Provost P. Doussiere G. Glastre D. Carpentier S. Fabre 《Photonics Technology Letters, IEEE》2003,15(3):362-364
Integrated laser modulators are attractive devices for wavelength-division-multiplexing optical systems due to their compactness, high output power, and low cost. Their fabrication simplicity is a way to decrease further the transmitter cost and address new opening markets of short range and metropolitan networks. We report a new integration scheme electroabsorption-modulator distributed feedback (DFB) laser based on well-established industrial solutions for discrete buried ridge (BRS) DFB lasers and discrete shallow ridge modulators. Processing simplification with an identical active layer has been possible due to a good behavior of strongly positively detuned BRS lasers. The integrated devices demonstrated 30-dB extinction ratio with 10-GHz bandwidth and P/sub out/=10 dBm for emission in 1.55-/spl mu/m range. 相似文献