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  • Articles  (273)
  • Chemistry  (250)
  • Condensed Matter: Electronic Properties, etc.  (23)
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  • Articles  (273)
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  • 1
    Electronic Resource
    Electronic Resource
    Cyanated liquid crystals with trans-stilbene structure: Syntheses and their cyclotrimerizations (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 313-321 
    Details
    ISSN: 0887-624X
    Keywords: liquid crystals ; cyanate ; cyclotrimerization ; liquid crystalline thermoset ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid crystalline aromatic monocyanate (M) and dicyanates (D1 and D2) with trans-stilbene (—Ph—CH=CH—Ph—) structure were synthesized and their cyclotrimerization reactions were studied by differential scanning calorimetry and infrared spectroscopy. Monocyanate M underwent cyclotrimerization to yield a trimerized material with discotic properties. Dicyanate D2 and its cured product failed to exhibit any mesophase. In contrast, polycyclotrimerization of dicyanate D1 obtained a liquid crystalline thermoset with its schlieren texture prolonged over a wide temperature range. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330213
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  • 2
    Electronic Resource
    Electronic Resource
    Cure kinetics of a flexible aromatic dicyanate with schiff base structure (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1585-1592 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polycyclotrimerization of a flexible aromatic dicyanate with a Schiff base structure was studied by means of differential scanning calorimetry (DSC). The study on dynamic DSC evaluated an apparent activation energy (Ea) of 75.8 kJ/mol and autocatalytic first-order kinetics with rate expression Af(α) = 1.96 X 105 (1 + 4.39 α) (1 - α) min-1. The kinetic feature can be explained by a proposed mechanism consisting of hydroxyl-catalyzed and autocatalytic paths. The lower value of Ea compared with other aromatic dicyanates is due to the electron-withdrawing linkage of the inherent imine ( - CH=N) structure. The kinetic feature is affected by the content of the residual impurities (e.g., phenols or absorbed water) in the corresponding sample. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580922
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  • 3
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    Observation of Magnetoelectric Multiferroicity in a Cubic Perovskite System: LaMn_{3} Cr_{4} O_{12} (2015)
    American Physical Society (APS)
    Details
    Publication Date: 2015-08-19
    Description: Author(s): Xiao Wang, Yisheng Chai, Long Zhou, Huibo Cao, Clarina-dela Cruz, Junye Yang, Jianhong Dai, Yunyu Yin, Zhen Yuan, Sijia Zhang, Runze Yu, Masaki Azuma, Yuichi Shimakawa, Huimin Zhang, Shuai Dong, Young Sun, Changqing Jin, and Youwen Long Electric and magnetic polarization are spontaneously produced in an unlikely material—one with a highly symmetric crystal structure. [Phys. Rev. Lett. 115, 087601] Published Tue Aug 18, 2015
    Keywords: Condensed Matter: Electronic Properties, etc.
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society (APS)
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    PAPER CURRENT
  • 4
    Electronic Resource
    Electronic Resource
    Levans. V. Kinetics of the acid hydrolysis of Streptococcus salivarius levan (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2373-2385 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the acid hydrolysis of Streptococcus salivarius levan were studied by examining the weight-average molecular weight. The molecular weights were obtained in a continuous manner from light scattering. Two first order reactions were observed: an initial rapid reaction in competition with a slower reaction.Activation energies, activation entropies, as well as the rate dependence upon substrate and hydrogen ion concentrations were determined. The data seem to indicate that the fast reaction is related to the breaking of branch-point bonds while the slower reaction is related to the breaking of main-chain bonds. Thus, levan hydrolysis seems to be fundamentally different from the completely random degradation of other branched polysaccharides, i.e., dextran, glycogen, and amylopectin.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360141111
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  • 5
    Electronic Resource
    Electronic Resource
    Levans. II. Light-scattering and sedimentation data of Streptococcus salivarius levan in water (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1283-1292 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular weights and radii of gyration of Streptococcus salivarius levan fractions were obtained from light-scattering measurements in water. Sedimentation coefficients and partial specific volumes of the fractions were also obtained. Double logarithmic plots of [η] versus M̄w and S0 versus M̄w yielded slopes having values of 0.17 and 0.62, respectively. The data and various calculated parameters show that levan from Streptococcus salivarius is highly branched and behaves hydrodynamically as a compact particle of spherical symmetry.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140616
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  • 6
    Electronic Resource
    Electronic Resource
    Struktur des Silybins, III. Synthese einer 2,3-unsymmetrisch disubstituierten 2,3-Dihydro-1,4-benzodioxin-6-carbonsäure (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3664-3671 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structure of Silybin, III. Synthesis of a 2,3-Unsymmetrically Disubstituted 2,3-Dihydro-1,4-benzodioxin-6-carboxylic Acidtrans-3-(3,4-Dimethoxyphenyl)-2,3-dihydro-2-(methoxymethyl)-1,4-benzodioxin-6-carboxylic acid (1a) was synthesized by an unambiguous way, and has been proved to be identical with a degradation product previously obtained from dehydrosilybin of natural origin after permethylation and alkali treatment.
    Notes: trans-3-(3,4-Dimethoxyphenyl)-2,3-dihydro-2-(methoxymethyl)-1,4-benzodioxin-6-carbonsäure (1a) wurde auf eindeutigem Wege synthetisiert und erwies sich als identisch mit dem Alkaliabbauprodukt des Dehydrosilybin-pentamethylethers.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771101120
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  • 7
    Electronic Resource
    Electronic Resource
    2,3,6-Unsymmetrisch substituierte 2,3-Dihydro-1,4-benzodioxine: Stellung des Phenylrestes bei der Synthese nach Vorländer (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3867-3873 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensation of 1-Aryl-1,2-dibromopropane with 4-Substituted Catechols: 2-Position of the Phenyl Substituent in the 2,3,6-Unsymmetrically Substituted 2,3-Dihydro-1,4-benzodioxine MoleculeThe reaction of 4-methyl- and 4-formylcatechol with 1-aryl-1,2-dibromopropane leads to 2,3-trans-2,3,6-trisubstituted 2,3-dihydro-1,4-benzodioxine derivatives with the phenyl substituent in position 2 (1b, 2b). The structure of the reaction products is elucidated by comparing the products with those obtained by an unambiguous synthesis.
    Notes: Bei der Umsetzung von 1-substituiertem 3,4-Dihydroxybenzol mit 1-Aryl-1,2-dibrompropan wurden als einzig kristallisierbare Reaktionsprodukte 2,3-trans-2,3,6-trisubstituierte 2,3-Dihydro-1,4-benzodioxin-Derivate mit dem Phenylsubstituenten in 2-Stellung erhalten (1b, 2b). Die Konstitutionsaufklärung der Reaktionsprodukte erfolgte durch Vergleich mit auf eindeutigem Wege erhaltenen Vergleichssubstanzen.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771101217
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and Evaluation of 2-{[(2-Oxo-1H-quinolin-8-yl)oxy]methyl}-Substituted α-Methylidene-γ-butyrolactones (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1161-1168 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: O-Alkylation of 8-hydroxy-1H-quinolin-2-one (1) afforded 8-(2-oxopropoxy)-1H-quinolin-2-one (2) which was immediately cyclized to form the tricyclic 2,3-dihydro-3-hydroxy-3-methyl-5H-pyrido[1,2,3-de][1,4]benzoxazine,-5-one (3). The Reformatsky-type condensation of 3 furnished antiplatelet 8-[(2,3,4,5-tetrahydro-2-methyl-4-methylidene-5-oxofuran-2-yl)melhoxy]-1H-quinolin-2-one (4). Its counterparts 7a-f, Ph-substituted at C(2) of the furan ring, were obtained from 1 via alkylation and the Reformatsky-type condensation. Although compound 4 was less active against platelet aggregation than 7a-f, it was the only compound which exhibited significant inhibitory activity on high-K+ medium, Ca2+-induced vasoconstriction and was more active than most of its Ph-substituted counterparts against norepinephrine-induced vasoconstrictions.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800413
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  • 9
    Electronic Resource
    Electronic Resource
    Syntheses of the First Selenium-Containing Bicyclic β -Lactams as Potent Antimicrobial Agents (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 1037-1045 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of the cis-configurated isodethiaselenapenam 5 (Scheme 1) as well as the isodethiaselenacephems 29 and 31 (Scheme 2) were accomplished, in which the key step involved addition of Se to the corresponding carbanions of 1, 25, and 27 followed by internal alkylation. β-Lactams 29 and 31 were found to possess biological activity against several pathogenic microorganisms in vitro. The electronic activation of the lactam moiety in the isodethiaselenacephem 31 and the corresponding isocephem 33 remarkably enhanced their biological activity. Isodethiaselenacephem 31 was more toxic than isocephem 33 in experimental animals.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770416
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  • 10
    Electronic Resource
    Electronic Resource
    α-Methylidene-γ-butyrolactones: Synthesis and evaluation of quinolin-2(1H)-one derivatives (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1038-1047 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a continuation of our previous studies on the synthesis and antiplatelet activity of quinolin-2(1H)-ones with an α-methylidene-γ-butyrolactone substituted at O(8), the O(6)- and N(1)-substituted isomers were synthesized and evaluated for antiplatelet activity against thrombin (Thr)-, arachidonic acid (AA)-, collagen (Col)-, and platelet-activating-factor (PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from 6-hydroxyquinolin-2(1H)-one via alkylation and Reformatsky-type condensation (Schemes 1 and 2). All of them were found to inhibit the platelet aggregation perfectly which was induced by AA and Col. 6-Substituted isomers 5b-g exhibited very strong inhibitory activities against AA- and PAF- induced aggregation and are approximately ten times more potent than their 8-substituted counterparts. However, the 1-substituted (11a and 11b) and the 1,6-disubstituted (6) counterparts were relatively inactive. Their effects on the Ca2+-dependent vasoconstriction induced by high K+, and the phasic and tonic vasoconstrictions induced by norepinephrine (NE) in rat aorta were also evaluated. Except 5g, all of them were found to have significant inhibitory activity on the NE-induced phasic and tonic vasoconstrictions. Compounds 6 and 11b also exhibited strong inhibitory activity on high-K+ medium, Ca2+-induced vasoconstriction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810517
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