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991.
V. S. Urusov 《Journal of Structural Chemistry》1994,35(1):101-114
Development of the orbital electronegativity concept since, 1934 is considered. It is shown that the concept is well substantiated
from the quantum chemical viewpoint and is used in such fields of chemistry and crystal chemistry as the Lewis acid-base theory,
the reactivity theory, etc. Its application is based on the electronegativity balance principle, which includes not only intraatomic
effects but also different interatomic interaction contributions. The concept became a natural tool in modern methods for
predicting and modeling the structure and properties of molecules and crystals.
M. V. Lomonosov Moscow State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 1, pp. 111–127, January–February, 1994.
Translated by L. Smolina 相似文献
992.
993.
C. Oproiu S. Marghitu S. Jipa I. Mihalcea 《Journal of Radioanalytical and Nuclear Chemistry》1994,181(1):109-116
This paper presents the results of an experimental study undertaken on the irradiation process of polyethylene tubing in an electron beam. Isodoses of distribution through material thickness in case of irradiation in one or two irradiation directions have been analyzed. 相似文献
994.
Patrick Mather Nino Grizzuti Glenn Heffner Mathias Ricker Willie E. Rochefort Markus Seitz Hans-Werner Schmidt Dale S. Pearson 《Liquid crystals》1994,17(6):811-826
In this paper, we report on the synthesis and detailed characterization of a new semiflexible nematic liquid crystalline polyester which could serve as a 'model' polyester for a variety of physical and physico-chemical investigations. The polymer is a nematic liquid over a wide temperature range-from the glass transition temperature at ∼95°C to the isotropic transition at ∼240°C. We expect this polyester to be particularly useful for studying the effect of flow on the orientation of liquid crystalline polymers, as well as the production and removal of disclinations. 相似文献
995.
In this paper we show that the director profile of a low pre-tilt surface stabilized ferroelectric liquid crystal passes through quasi-static stressed states during domain switching under direct drive conditions. Using polarized stroboscopic microscopy, we have observed two quasi-static transmission levels during a domain switching transition from dark to light. This is a result of the directors reorienting into stressed profiles both before and after the chevron interface has switched. By modelling the interaction between the elastic forces and the torque from the applied field, we have determined these voltage dependent director profiles and, by calculating their corresponding transmissivities, have shown very good agreement with the experimentally observed values. 相似文献
996.
D.G. Seapy S.S.H. Al-Mahmoodi N.M.M. Al-Belushi F.A.M. Al-Mjeni 《Journal of photochemistry and photobiology. A, Chemistry》1994,80(1-3):241-249
The relatives photoreactives of bridged-ring systems 1, 3, 5-X and 6-X (X ≡ Cl or Br) have been studied at 254 nm in acetic acid. The formation of photosolvolysis product was rationalized in terms of photoinduced intramolecular electron transfer (ET) processes. The relative ease of ET in these donor—bridge—acceptor model system was analyzed in terms of known ET variables including free-energy changes, orientation effects and ridigity effects. The observed relative photoreactivities agreed better with the calculated free-energy changes when relative rigidities of the electron acceptor termini were evaluated. In general, the more rigid system were more photoreactive. 相似文献
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