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When crushed, the leek,Allium porrum emits propyl propanethiosulfinate. The unstable thiosulfinate decomposes during GC analysis in numerous compounds, except on very short columns. The propyl propanethiosulfmate is the most attractive substance for the leek moth,Acrolepiopsis assectella. This thiosulfinate is not active onPlutella xylostella orPlodia interpunctella and seems to be repulsive onEphestia kuehniella. 相似文献
995.
Skin optics 总被引:6,自引:0,他引:6
Van Gemert M.J.C. Jacques S.L. Sterenborg H.J.C.M. Star W.M. 《IEEE transactions on bio-medical engineering》1989,36(12):1146-1154
Quantitative dosimetry in the treatment of skin disorders with (laser) light requires information on propagation of light in the skin related to the optical properties of the individual skin layers. This involves the solution of the integro-differential equation of radiative transfer in a model representing skin geometry, as well as experimental methods to determine the optical properties of each skin layer. These activities are unified under the name skin optics. This paper first reviews the current status of tissue optics, distinguishing between the cases of: dominant absorption, dominant scattering, and scattering about equal to absorption. Then, previously published data as well as some current unpublished data on (human) stratum corneum, epidermis and dermis, have been collected and/or (re)analyzed in terms of absorption coefficient, scattering coefficient, and anisotropy factor of scattering. The results are that the individual skin layers show strongly forward scattering (anisotropy factors between 0.7 and 0.9). The absorption and scattering data show that for all wavelengths considered scattering is much more important than absorption. Under such circumstances, solutions to the transport equation for a multilayer skin model and finite beam laser irradiation are currently not yet available. Hence, any quantitative dosimetry for skin treated with (laser) light is currently lacking. 相似文献
996.
The best compromise between coupling efficiency, accuracy of positioning and reproducibility has been obtained for a high index hemispherical lens melted on the tip of an intermediate fibre between the GaAlAs laser and the transmission fibre. The letter describes the lens fabrication technique and gives various experimental results of coupling efficiencies and mechanical tolerances. 相似文献
997.
Reviews the book, The Visual World of the Child by Elaine Vurpillot (1972). By reading this work in which Vurpillot approaches, by the genetic method, the problem of the perceptive conduits of identification and differentiation, it is difficult to envision a confrontation between this new approach and that of Eleanor Gibson (1969). It is done from a point of view of comparison which the work of Vurpillot will be analyzed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Jean-François Brice René Gérardin Abdallah El Maslout Michel Zanne Alain Courtois Jacques Aubry 《Materials Research Bulletin》1975,10(11):1243-1248
The phosphidation of beryllium in the presence of traces of hydrogen leads to non stoichiometric ternary phases BeP2?xHy. The stoichiometric diphosphide BeP2 cannot be obtained. The hydrogenated phases are black and non hygroscopic. The structural study with X rays diffraction, neutrons diffraction, electronic microdiffraction, as well as the crystallographic data from single crystal, provide evidence for a quadratic cell with & . The stacking is diamond type when considering all the atoms : Be, P and H. 相似文献
1000.
Jrme Alric Ghislain David Bernard Boutevin Alain Rousseau Jean‐Jacques Robin 《Polymer International》2002,51(2):140-149
The mode of termination of 2,2,2‐trifluoroethyl α‐fluoroacrylate (FATRIFE) in radical polymerization was studied, and only termination by recombination occurred, which led to telechelic macromolecular structures. The radical polymerization in acetonitrile was carried out to synthesize oligomers with a low number average degree of polymerization ( )cum (about 20), using tert‐butylcyclohexyl peroxydicarbonate (TBCPC) as initiator at 75 °C. The initial [TBCPC]0/[FATRIFE]0 molar ratio was monitored to evaluate its influence on the ( )cum of α‐fluoroacrylic oligomers. The 1H NMR analysis of the polymers showed that the ( )cum values obtained were higher than 40, in spite of a high C0 value. To explain these results, the mode of termination was evaluated using the following kinetic law: . The development of kinetic relationships allowed us to calculate the ratio kprt/ki·kp as about 17–30 mol s l?1, and to confirm that primary radical termination (PRT) was in competition with bimolecular macromolecular termination (BMT). © 2002 Society of Chemical Industry 相似文献