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排序方式: 共有387条查询结果,搜索用时 9 毫秒
51.
Rosario Benavente Teresa Scrivani Maria L. Cerrada Galina Zamfirova Ernesto Prez Jos M. Perea 《应用聚合物科学杂志》2003,89(13):3666-3671
Vickers microhardness as a function of temperature was determined in a series of norbornene‐ethylene copolymers synthesized with a metallocene catalyst. The norbornene content in the samples ranges from 31 to 62 mol %, and all of them were found to be amorphous. The possibility of studying the glass‐transition temperature by plotting the microhardness‐temperature dependencies is discussed in addition to the limits and the reliability of the suggested method. Moreover, a linear dependency between microhardness at different temperatures and glass‐transition temperature was established. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3666–3671, 2003 相似文献
52.
A. G. Vereshchagin Galina V. Novitskaya 《Journal of the American Oil Chemists' Society》1965,42(11):970-974
The triglyceride composition of linseed oils obtained under different ecological conditions and having different fatty acid
compositions was determined by a combination of several chromatographic techniques. The triglyceride mixture was first separated
in 8 fractions of different polarity by reversed-phase paper chromatography. Each glyceride fraction was then separated in
a partition chromatographic system as the triglyceride coordination complexes with silver ions into individual compounds.
The fatty acid compositions of the original oil, single glyceride fractions, and individual triglycerides were determined
by gas-liquid chromatography. The molar ratio between the two neighboring glyceride fractions was determined by relating the
fatty acid composition of each fraction to the fatty acid composition of their sum. The triglyceride composition of the total
oil was then calculated from these results.
The presence of 18–19 triglycerides was ascertained in the samples studied, and the molar concentration of each glyceride
was estimated. Linseed oil contains only triunsaturated and monosaturated-diunsaturated triglycerides. Within each of these
types the fatty acid distribution is close to random. At the same time, the content of some triglycerides departed regularly
from a random pattern.
A method for calculation of linseed oil triglyceride composition from the fatty acid composition is given.
The same general pattern of glyceride formation in linseed is followed regardless of ecological conditions; therefore, the
qualitative and quantitative triglyceride composition reflects the differences in fatty acid composition of linseed oil. 相似文献
53.
V. A. Sadykov Svetlana N. Pavlova Galina V. Zabolotnaya Raisa I. Maximovskaya Sergei V. Tsybulya Elena B. Burgina Vladimir I. Zaikovskii Galina S. Litvak Marina V. Chaikina Valerii V. Lunin Natalya N. Kuznetsova Rustum Roy Dinesh K. Agrawal 《Materials Research Innovations》1999,2(6):328-337
High-power ball mill activation of the mixture of hydrated zirconium and lanthanum salts (oxonitrates, oxochlorides) with
ammonium phosphate followed by hydrothermal treatment at temperatures not exceeding 200°C and a nearly neutral pH was found
to yield crystalline dispersed phase of a cubic NH4Zr2(PO4)3 type along with admixtures of disordered orthorhombic compounds of a zirconium orthophosphate type. In the same conditions
and at the same Zr/P ratio, hydrothermal treatment of gels obtained by reacting mixed zirconium and lanthanum nitrates solutions
with ammonium phosphates yields no crystalline products, and only treatment in acid media generates a phase of the α-ZrPO4(OH) type coexisting with the NH4Zr2(PO4)3 phase if polyethylene oxide is present. X-ray powder diffraction, transmission electron microscopy, 31MAS-NMR, FTIRS and thermal analysis were applied to elucidate factors affecting crystallization of complex zirconium phosphates
in the hydrothermal conditions. The most essential factor appears to be generation of some nuclei of zirconium phosphates
under high pressures developed in the course of mixed solids mechanical activation. These nuclei are embedded into matrix
of such well-crystallized solid products as ammonium nitrate or chloride. Hence, metastable cubic or orthorhombic structure
of the phases obtained via mechanical activation route can be assigned to the nuclei-matrix orientation relationship. Due
to easily scaled-up synthesis procedure, these results appear to be very promising for manufacturing of dispersed framework
zirconium phosphates as acid catalysts or fast proton conductors.
Received: 18 November 1998 / Reviewed and accepted: 2 December 1998 相似文献
54.
Luybov A. Wasserman Natalia S. Eiges Galina I. Koltysheva Nicolai R. Andreev Vladimir G. Karpov Vladimir P. Yuryev 《Starch - St?rke》2001,53(12):629-634
Starches isolated from wheat (Rapoport's variety) at different stages of maturation and from completely maturated rye (Viatka‐2 variety) were investigated in excess of water and in 0.6 M KCl using high sensitivity differential scanning microcalorimetry (HSDSC). Applying some physico‐chemical approaches, the starch polymorphous structure, the thickness of the crystalline lamellae and the thermodynamic parameters characterizing their surface faces were determined. It has been established that wheat and rye starches belong to the A‐type starches. It is suggested that during biosynthesis of granules the formation of the A‐type structure is accompanied by an accumulation of crystal defects. This process leads to a decrease in the melting temperature of starches. 相似文献
55.
Ayush Mittal Galina Jelkina Albertsson Govind Sharan Gupta Seshadri Seetharaman Sankaran Subramanian 《Metallurgical and Materials Transactions B》2014,45(2):338-344
To understand Cr emissions from slag melts to a vapor phase, an assessment of the stabilities of the chromium oxides at high temperatures has been carried out. The objective of the present study is to present a set of consistent data corresponding to the thermodynamic properties of the oxides of chromium, with special reference to the emission of hexavalent chromium from slags. In the current work, critical analysis of the experimental data available and a third analysis in the case of Cr2O3 have been carried out. Commercial databases, Fact Sage and ThermoCalc along with NIST-JANAF Thermochemical Tables, have been used for the analysis and comparisons of the results that are presented. The significant discrepancies in the available data have been pointed out. The data from NIST-JANAF Thermochemical Tables have been found to provide a set of consistent data for the various chromium oxides. An Ellingham diagram and the equations for the ΔG° (standard Gibbs free energy change) of formation of CrO x have been proposed. The present analysis shows that CrO3(g) is likely to be emitted from slag melts at high oxygen partial pressures. 相似文献
56.
Boris A. Trofimov Marina V. Markova Inna V. Tatarinova Al’bina I. Mikhaleva Lyudmila V. Morozova Ol’ga V. Petrova Lyubov’ N. Sobenina Konstantin B. Petrushenko Tamara I. Vakul'skaya Spartak S. Khutsishvili Galina F. Prozorova 《Synthetic Metals》2010,160(23-24):2573-2580
I2-doped and pyrrole ring-iodinated semi-conducting oligomers of N-vinyl-3-alkyl-2-phenylpyrroles have been synthesized by free-radical polymerization of the above monomers (AIBN, 2–5 wt%, 60–80 °C) and further exposure of the oligomers obtained to I2 vapor. The parent oligomers exhibit paramagnetic and fluorescent properties and stable up to 300–370 °C. 相似文献
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