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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the reaction of a quasi-aromatic nickel(II) complex, [Ni((PnAO)-6H]0, with formaldehyde (1992)
    s.l. : American Chemical Society
    Inorganic chemistry 31 (1992), S. 2314-2317 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00038a006
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  • 2
    Electronic Resource
    Electronic Resource
    Optically active polyamides consisting of anti head-to-head coumarin dimer and α,ι-alkanediamine. Odd-even discrimination in chiral recognition ability depending on the number of the diamine component and correlation between the ability and crystallizability (1990)
    s.l. : American Chemical Society
    Macromolecules 23 (1990), S. 2830-2836 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00213a002
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of Hydrogen Passivation on Lightly n-Doped GaAs (1993)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 117-118 (Jan. 1993), p. 429-434 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/59/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.117-118.429.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal evolution of TEOS-Al(secBuO)3-etac mullite gels (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 399-402 
    Details
    ISSN: 1573-4846
    Keywords: mullite ; sol-gel process ; crystallization ; sinterability ; chemical modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mullite gels have been prepared using tetraethyl orthosilicate and aluminium tri-sec-butoxide chemically modified by ethylacetoacetate as precursors. The hydrolysis conditions are shown to have a very noticeable influence on the evolution of both phase and microstructure of the resulting xerogels. The optimization of thermal treatment allows well crystallized mullite samples with a density more than 90% of the theoretical value after sintering at 1200°C for 4 hours to be obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486278
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  • 5
    Electronic Resource
    Electronic Resource
    Crosslinked particles of poly[n-(1-phenylethyl)acrylamide]: Preparation and application as chromatographic stationary phases (1994)
    Springer
    Journal of polymer research 1 (1994), S. 115-122 
    Details
    ISSN: 1572-8935
    Keywords: Poly [N-(1-phenylethyl)acrylamide] ; Suspension polymerization ; Crosslinked particles ; Chromatographic stationary phase ; HETP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Crosslinked particles of poly [N-(1-phenylethyl)acrylamidel have been successfully prepared by suspension polymerization of N-(1-phenylethyl) acrylamide and ethylene dimethacrylate in water using poly(vinyl alcohol) as dispersant. The particle morphology is investigated by optical microscope and scanning electron microscope (SEM). The pressure resistance of the crosslinked particles, evaluated after packing as stationary phases of high-performance liquid chromatography (HPLC), increases from 7 to 20 kg/cm2 as the mole percent of ethylene dimethacrylate increases from 10% to 30%. The particles were sieved into four sieve fractions, i.e. 37–63 μm, 63–88 μm, 88–105 μm, and 105–149 μm, and packed into HPLC columns, respectively. The chromatographic performances of these columns have been investigated in HPLC system thoroughly, using benzene as solute and mixtures ofn-hexane and 2-propanol as eluents. The crosslinked particles show potential application as stationary phases for HPLC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378602
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  • 6
    Electronic Resource
    Electronic Resource
    Radical copolymerization behaviors of styrene and coumarin (1994)
    Springer
    Journal of polymer research 1 (1994), S. 295-303 
    Details
    ISSN: 1572-8935
    Keywords: Coumarin ; 7-Acetoxycoumarin ; Radical copolymerization ; Monomer reactivity ratio ; Terminal model ; Penultimate model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The radical copolymerizations of styrene (M1) with coumarin (M2) (and 7-acetoxycoumarin) have been first carried out in benzene (and in DMF) at 60° C using AIBN as initiator. The terminal model monomer reactivity ratios (MRR) were determined by Fineman-Ross method, Kelen-Tudos method and nonlinear method. The respective estimated values are r1 = 43.08, r2 = 0.63; r1 = 39.17, r2 = 0.43; and r1 = 49.94, r2 = 1.04 for styrene-coumarin (S-C) system. For styrene-7-acetoxycoumarin (S-AC) system, the values are r1 = 51.44, r2 = 1.24; r1 = 50.56, r2 = 1.20 and r1 = 56.23, r2 = 1.48, respectively. The penultimate model MRRs are determined by Fenn-Barson method and nonlinear method to be r1= 49.18, r1′ = 2.01, r2 = r2′ = 0.43 and r1 = 51.21, r1′ = 0.86, r2= r2′ =0, respectively, for S-C system; r1 = 64.76, r1′= 3.46, r2 = r2′= 1.20 and r1 = 59.90, r1 = 0.57, r2 = r2′ = 0. respectively, for S-AC system. It is found that coumarin is about 1.2 times more reactive toward styrene-terminated radical than 7-acetoxycoumarin for steric reasons. The penultimate model of Fenn-Barson is fairly adequate in describing the copolymerization mechanism of styrene-coumarin system, while the terminal model is more suitable for styrene-7-acetoxycoumarin system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01374554
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of polyesters containing coumarin dimer components by photopolymerization of 7,7′-coumarinyl polymethylene dicarboxylates (1994)
    Springer
    Journal of polymer research 1 (1994), S. 285-293 
    Details
    ISSN: 1572-8935
    Keywords: 7,7′-Coumarinyl polymethylene dicarboxylate ; Photopolymerization ; Coumarin dimer ; Polyester, Cyclobutane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Eight 7,7′-coumarinyl polymethylene dicarboxylates have been successfully synthesized by solution condensation of 7-hydroxycoumarin (umbelliferone) or 7-hydroxy-4-methylcoumarin (4-methylumbelliferone) with various polymethylene diacid chlorides. Upon benzophenone-sensitized irradiation with 350 nm light, the terminal coumarin chromophores dimerize to form intermolecular cycloadducts or intermolecular polyesters with three kinds of cyclobutanes (syn head-to-head,anti head-to-head,anti head-to-tail), depending on structure of the dicarboxylates and reaction conditions. The structures of the cycloadducts and polyesters have been characterized by1H NMR spectra. When the methylene units exceed seven, intermolecular reaction becomes predominant and result inanti-rich configuration photo-cyclized products with higher viscosity. Lower polar solvents and 4-methyl substitution in coumarin chromophores also promote intermolecular reaction. The highest viscosity (ηred = 0.42 dL/g) is obtained with polyester from 7,7′-(4-methyl coumarinyl) decamethylene decarboxylate. Irradiation of the polyesters with 254 nm light leads to symmetric cleavage of the cyclobutane linkage in the main chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01374553
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of Re-B modification on the strength and toughness of 30CrMn2Si cast steel (1994)
    Springer
    Journal of materials science 29 (1994), S. 1492-1496 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effects of multi-modification on the strength and toughness of 30CrMn2Si cast steel were investigated. The mechanical properties tested include tensile strength; Charpy impact toughness from room temperature to −60 °C; hardness and fracture toughness. Microanalyses were carried out by optical microscopy, transmission electron microscopy, scanning electron microscopy, and X-ray diffraction, and included the microstructure and submicrostructure of martensites, residual austenites, the size and distribution of non-metallic inclusions, and the original austenite grain size. It was concluded that, with the hardness unchanged, the fracture toughness of the modified steel was raised to 95 MPa m1/2, 34% more than that of the un-modified steel, and the impact toughnesses at normal and low temperatures raised to 62 and 61.2 J cm-2, respectively, 67 and 75% more than those of the un-modified steel. Furthermore, the fracture strength and yield strength of the steel were increased by over 200 MPa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368914
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  • 9
    Electronic Resource
    Electronic Resource
    Dissipation of 2,4-D glyphosate and paraquat in river water (1994)
    Springer
    Water, air & soil pollution 72 (1994), S. 1-7 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Dissipation of herbicides in river water was determined by adding different concentrations of 2,4-D, glyphosate and paraquat to samples of river water. A small variation of dissipation of radioactivity for14C-2,4-D in higher and lower concentrations and in different samples of river water was found. But about half the radioactivity disappeared from water samples of original glyphosate concentration at 100 mg L−1 and, in the case of 100 μg L−1, only 11 to 22% remained in the samples of river water after 56 d incubation except the sample from Hsin-Tien River. More than 80% of paraquat remained in water samples. Determination of octanol-water partition coefficient (Kow) showed a large difference in amounts of 2,4-D partitioned in water phase at different pH values, 97.4% at the higher pH of ionic state and 5.2% at the lower pH of molecular state, implying that pH value of water might affect the bioaccumulation process of 2,4-D. The result showed that 95.0% of glyphosate present in water phase in ionic form (higher pH) and 82.3% in molecular form (lower pH), indicating that glyphosate might have no affect on the biomagnification, since most of glyphosate could be excreted with water by organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01257113
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and conformational properties of poly(N4-1-phenylethyl-L-asparagines) (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 1303-1308 
    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: Poly(N4-1-phenylethyl-L-asparagines) (1a, 1b, and 1c) containing DL-, (R)-, and (S)- side group chirality were prepared by aminolysis of poly(β-methyl-L-aspartate) (PMLA) with DL-, (R)- (+)-, and (S)- (-)-1-phenylethylamine, respectively. The PMLA was synthesized by ring-opening polymerization of β-methyl-L-aspartate-N-carboxy anhydride (NCA) using triethylamine as initiator. The conformations of these polypeptides in the film state were investigated by IR and circular dichroic spectra. The PMLA, 1a, and 1b exist mainly in β-sheet conformation, while 1c forms α-helix that is induced by the (S)-chirality of the side groups. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470718
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