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  • Polymer and Materials Science  (212)
  • Life and Medical Sciences  (79)
  • General Chemistry  (59)
  • Inorganic Chemistry  (38)
  • 1985-1989  (284)
  • 1970-1974  (104)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    The effect of temperature on nucleotide pool formation in Tetrahymena pyriformis (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 81 (1973), S. 149-151 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Warming of exponentially growing T. pyriformis to 34°C results in severe inhibition of nucleotide pool formation. The utilization of the pool for stable RNA synthesis is poorly affected at the high temperature. It thus appears that the synthesis and processing of ribosomal RNA precursors are not primarily impaired at 34°C.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040810203
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  • 2
    Electronic Resource
    Electronic Resource
    The radical initiation of vinyl polymerization by α.α.α′.α′-Tetrasubstituted dibenzyls (1972)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 157 (1972), S. 279-298 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Im Temperaturbereich von 60 bis 100°C wird die radikalische Polymerisation von Styrol, Methylmethacrylat und Acrylnitril von α.α′-Dicyanodibenzylen ausgelöst, die in α-und α′-Stellung mit Ester-, Nitril-, Amid- oder Phenylgruppen disubstituiert sind. Bei 100 bis 110°C ist auch das α.α.α′.α′-Tetracarboxymethyldibenzyl aktiv. Vinylacetat und Vinylchlorid werden durch diese Initiatoren kaum polymerisiert.Fur die Polymerisation des Styrols wurden die Bruttogeschwindigkeitskonstanten Kp, für viele Dibenzyle und fur Peroxide vergleichbarer Aktivitat dilatornetrisch bestirnrnt. Norrnalerweise sind die Zeit-Urnsatz-Kurven rnit den Dibenzylen und den Peroxiden vergleichbar; das Tetracyanodibenzyl allerdings bewirkt nur eine unvollstandige Polymerisation.Der große Einfiuß von Substituenten in α-Stellung oder in den Phenylringen der Dibenzyle auf die Polymerisation des Styrols wird diskutiert. Dabei ist auch die Stereochernie wichtig. Die meso-Form des Dinitrildiesters ergibt eine 2.5- bis 3.5 ma1 schnellere Polyrnerisation als das dl-Isornere.Die Dissoziationsgeschwindigkeitskonstanten kd der Initiatoren wurden NMR-spektroskopisch aus der Linienbreite bestirnmt. Die Dinitrildiester sind gute Initiatoren, wahrend die α.α′-Dicyanodibenzyle rnit weiteren Nitril- oder Phenylgruppen in α- und α′-Stellung wenig geeignet sind. SchlieBlich wurde die 1.2-Addition einiger der Dibenzyle an Styrol im Ternperaturbereich von 120 bis 150°C rnit der Methode der chernisch induzierten KernPolarisation (CIDNP) untersucht.
    Notes: The radical polymerization of styrene, methyl methacrylate and acrylonitrile is initiated by α.α′-dicyanodibenzyls α.α′-disubstituted with ester, nitrile, amide or phenyl groups in the temperature range 60 to 100°C and by α.α.α′.α′-tetracarboxymethyldibenzyl at 100 to 110°C. Vinylacetate and vinylchloride show a low reactivity.The overall polymerization rate constants Kp have been determined dilatometrically for styrene initiated by a large number of dibenzyls and comparable peroxides. The styrene polymerization curves are generally comparable with those of peroxides. A notable exception is tetracyanodibenzyl.The strong influence of α- and ring-substituents in the dibenzyls on the styrene polymerization rate is discussed. The stereochemistry is also important : the meso α.α′-dicyanodibenzyls α.α′-disubstituted with ester groups give a 2.5 to 3.5 fold faster polymerization than their dl isomers.The initiator efficiency is related to the kd values, determined from NMR line width measurements. The α.α′- dicyanodibenzyls α.α′-disubstituted with ester groups are good initiators, while those with phenyl groups and nitrile groups are inefficient.Relevant to initiation and termination, the 1.2-addition of some of the dimers to styrene at 120 to 150°C has been studied with chemically induced dynamic nuclear polarization (CIDNP).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1972.021570128
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  • 3
    Electronic Resource
    Electronic Resource
    Iminophosphorane-mediated synthesis of mesoionic 1,3,4-Oxadiazolo-[3,2-a]pyridinylium-2-aminides (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1495-1500 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Iminophosphoran-vermittelte Syntheses von mesoionischen 1,3,4- Oxadiazolo[3,2a]pyridinylium-2-aminidenDas Iminophosphoran 2 reagiert mit Methylisocyanat zu dem mesoionischen 1,3,4-Oxadiazolo[3,2-a]pyridinylium-2-methylaminid 3, das durch CF3SO3CH3 zum 1,3,4-Oxadiazolo[3,2-a]-pyridinium-Kation 4 methyliert wird. Struktur 4 wurde durch Röntgenstrukturanalyse gesichert. Durch Einwirkung von Base lagert das mesoionische Aminid 3 zum isomeren mesoionischen 1,3,4-Triazolo[3,2-a]pyridinylium-2-olat 11 um. Verbindung 3 wird durch (Arylimino)triphenylphosphorane in die entsprechenden 1,3,4-Oxadiazolo[3,2-a]pyridinium-2-arylaminide 12 umgewandelt, die auch aus Iminophosphoran 2 und Hydroximoylchloriden zugänglich sind.
    Notes: Reaction of iminophosphorane 2 with methyl isocyanate yields the mesoionic 1,3,4-oxadiazolo[3,2-a]pyridinylium-2-methylamindie 3, which undergoes N-methylation with CF3SO3CH3 to give the 1,3,4-oxadiazolo[3,2-a]pyridinium cation 4. The structure of compound 4 has been established by means of X-ray crystallography. Mesoionic aminide 3 undergoes rearrangement by the action of base to give the isomeric mesoionic compound 1,3,4-triazolo[3,2-a]pyridinylium-2-olate 11. Compound 3 by the action of (arylimino)triphenylphosphoranes is converted into the corresponding 1,3,4-oxadiazolo[3,2-a]pyridinylium-2-arylaminides 12, which can be also prepared from iminophosphorane 2 and hydroximoyl chlorides.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210825
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of chemical structure on glass transition temperatures of poly(propylene terephthalate) and poly(propylene isophthalate) (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 691-699 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(propylene terephthalate)Systematic IUPAC name: poly(oxypropyleneoxyterephthaloyl). (PPTP) and poly(propylene isophthalate)Systematic IUPAC name: poly(oxypropyleneoxyisophthaloyl). (PPIP) were prepared by melt polycondensation. Different fractions with number-average molar masses in the range 5 000 - 20 000 g·mol-1 were obtained and their respective glass transition temperatures (Tg) determined by calorimetry. The solubility parameters of the polymers were obtained by viscosity measurements in different solvents and were found to be 9,4 and 9,5 cal1/2·cm-3/2 (19,2·103 and 19,4·103 J1/2·m-3/2) for PPIP and PPTP, respectively. The glass transition temperatures were compared with those reported for analogous polyesters and it was shown that intramolecular interactions highly influence the Tg of these polyesters, whereas the effect of intermolecular interactions seems to be less important.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890321
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and viscosity behavior of poly(γ-p-biphenylmethyl-L-glutamate) in benzene/dichloroacetic acid mixtures, a comparison with poly(γ-benzyl-L-glutamate) (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 3193-3206 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Darstellung von Poly(γ-p-biphenylmethyl-L-Glutamat), PBPLG, (Poly{L-imino-1-[2-(4-biphenylmethoxycarbonyl)äthyl]-2-oxoäthylen}), (1d) wird beschrieben. Das Viskositätsverhalten dieses Polymers in Mischungen aus Benzol und Dichloressigsäure (c=0,2.10 - 3 - 1,4.10 - 3g/cm3) bei 25°CC wird untersucht. Die Ergebnisse werden verglichen mit Messungen unter den gleichen Bedingungen an Poly(γ-benzyl-L-Glutamat),PBLG, (Poly[ L-imino-l-(2-benzyloxycarbonylathyl)-2-oxoathylen]), (lc). In beiden Fallenfindet ein zweistufiger Ubergang von einer starren, von Wasserstoffbrucken stabilisiertenHelix in ein statistisches, solvatisiertes Knduel statt : PBPLG (erste Stufe CrSSX,, zweite Stufe 55-100%, Dichloressigsaure und PBLG (erste Stufe 0-70%, zweite Stufe 70-100%,Dichloressigsaure)).Die Einfiihrung eines p-Phenylsubstituenten in PBLG fuhrt deshalb in Mischungen aus Benzol- und Dichloressigsaure zu einer weniger stabilisierten Helix.Die Stabilitat und das Viskositatsverhalten von PBLG in Mischungen aus Benzol und Dichloressigsaure (c=0,2.10-3 -14.10-3g/cm3) sind denjenigen von PBLG in Mi-schungen aus m-Kresol und Dichloressigslure ( c = 1,0.10-3-4,0. 10-3g/cm3) ähnlich.
    Notes: The synthesis of poly(γ-p-biphenylmethyl-L-glutamate), PBPLG, (poly{L-imino-1-[2-(4-biphenylylmethoxycarbonyl)ethyl]-2-oxoethylene}), (1d) is described. The viscosity behavior of this polymer in benzene/dichloroacetic acid mixtures (c=0,2.10 - 3 - 1,4.10 - 3 g/cm3) at 25°CC is investigated. The results are compared with measurements on poly(γ-benzyl-L-glutamate), PBLG, (poly[L-imino-1-(2-benzyloxycarbonylethyl)-2-oxoethylene]), (1c) under the same conditions. A transition from a rigid hydrogen bonded helix to a random solvated coil occurs in two stages for both: PBPLG (first stage 0 - 55%, second stage 55 - 100% dichloroacetic acid) and PBLG (first stage 0 - 70%, second stage 70 - 100% dichloroacetic acid).Therefore, the introduction of a p-phenyl substituent in PBLG leads to a less stable helix in benzene/dichloroacetic acid mixtures.The stability and viscosity behavior of PBLG in benzene/dichloroacetic acid mixtures (c=0,2.10 - 3 - 1,4.10 - 3g/cm3) is quite similar to the behavior of PBLG in m-cresol/dichloroacetic acid mixtures (c=1,0.10 - 3 - 4,0.10 - 3 g/cm3).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021751113
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  • 6
    Electronic Resource
    Electronic Resource
    Quantitative electromyography of the masticatory muscles of Pteropus giganteus (Megachiroptera) (1988)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 196 (1988), S. 73-106 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mastication has been studied by cinematography and quantitative electromyography while flying foxes, Pteropus giganteus, were freely feeding on standardized pieces of apple, soaked raisin, and banana.The primarily orthal mandibular movements are caused by mainly bilaterally symmetrical firing of all the masticatory muscles. Asymmetric activity in the superficial and deep masseter and medial pterygoid causes slight protrusion early in opening. Slight lateral deviations at the end of opening and at the start of closing are caused by asymmetric and asynchronous activity in the pterygoids and digastrics, and by asynchronous firing of the deep temporalis and zygomaticomandibularis. Food consistency affects movement characteristics as well as characteristics of muscular activity.In this study electromyograms were digitized and the number of spikes and mean amplitude per interval (set by the filming rate) recorded. Although a significant correlation exists between these descriptors, the product thereof appears to be the best predictor of certain kinematic variables (cycle length and maximum excursion of the mandible). On the other hand, the changes in magnitude of muscular activity as a function of the position of a cycle in the reduction sequence and as a function of food consistency are more translated in a variation of the mean amplitude than in a variation of the number of spikes per interval. Observed variation differs among muscles studied. It is most apparent in the superficial and deep masseter and least in the temporalis and zygomaticomandibularis.Late cycles of apple and raisin mastication are long and exhibit large gapes but almost no anterior movement. The adductor activity frequently shows a synchronized, pulsatile pattern leading to an unfused tetanus.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051960107
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  • 7
    Electronic Resource
    Electronic Resource
    Short fiber-reinforced thermoplastic elastomers from blends of natural rubber and polyethylene (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 5123-5146 
    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: Thermoplastic elastomer blends of natural rubber (NR) with high density polyethylene (HDPE) and with low density polyethylene (LDPE) were reinforced with short silk fiber. Processing characteristics such as torque and temperature developed during mixing and the effect of processing parameters such as nip gap and number of passes in the mill necessary to secure maximum orientation of the fibers in the blends were studied. A small nip gap and a single pass in the mill were found to give best results. Of the different mixing sequences studied, the sequence where short fibers followed by rubber were added to the molten thermoplastic was found to give a uniform dispersion of fibers. Fiber breakage and the change in aspect ratio of the fibers after mixing were also examined. It was observed that, as a direct consequence of the mixing sequence, each fiber was coated with a layer of thermoplastic. Although the properties improved on the addition of the dry bonding system of silica-resorcinol-hexamethylenetetramine, the comparatively long curing time required for full development of adhesion between the fibers and the matrix proved to be a major disadvantage associated with the incorporation of the bonding system. The tensile and tear properties were substantially enhanced, but the ultimate elongation decreased sharply with increasing loading of short fibers in the blends. The effect of fiber orientation and the development of anisotropy in the properties was also noted. Scanning electron microscopy (SEM) studies of the benzene-extracted surfaces of the NR/HDPE (high density polyethylene) blends substantiated the theory of fibers behaving like “mechanical anchors” between the rubber and thermoplastic phase. The effect of fiber loading on the tear and tensile properties of the blends of NR/LDPE with varying blend ratios was studied. Most pronounced improvement in the properties on the addition of short fibers was observed in the high rubber blends. As the plastic content in the blends increased, the short fibers were found to have a lesser influence on the properties. SEM photomicrographs of the tensile and tear fracture surfaces indicated the fiber orientations and the effect of orientation, fiber loading, and blend ratios on the nature of fracture.
    Additional Material: 31 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320530
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  • 8
    Electronic Resource
    Electronic Resource
    Aromatic polyisophthalamides with oxybenzoyl pendent groups (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 483-493 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of polyisophthalamides containing pendent oxybenzoyl groups were prepared from 5-oxybenzoyl-isophthaloyl chloride and aromatic diamines. The analogous unsubstituted polyisophthalamides were also prepared in order to compare the two series and to determine the effect of oxybenzoyl pendent groups on the properties of aromatic polyamides. The modified polymers exhibited better solubility than, and approximately the same glass transition temperatures (in the range 260-290°C) as, the parent unsubstituted polymers. The mechanical strength of polymer films was affected only to a small extent by the presence of side groups, but the thermal resistance was negatively affected, with the result that polyisophthalamides with oxybenzoyl pendent groups began to decompose at about 360°C (TGA), 60-100°C lower than the unsubstituted polyisophthalamides. By means of an appropriate thermal treatment, crosslinking of the modified polymers was achieved and their thermal resistance significantly enhanced.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240307
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  • 9
    Electronic Resource
    Electronic Resource
    Fully aromatic poly(ether-esters) (1988)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 26 (1988), S. 313-317 
    Details
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1988.140260707
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  • 10
    Electronic Resource
    Electronic Resource
    The use of submicroscopic gold particles combined with video contrast enhancement as a simple molecular probe for the living cell (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 105-113 
    Details
    ISSN: 0886-1544
    Keywords: video-microscopy ; colloidal gold ; immunocytochemistry ; microtubules ; receptors ; saltatory motion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe a new approach to probe the molecular biology of the living cell that uses small colloidal gold particles coupled to specific ligands. They are visualized in cells by bright-field, video enhanced contrast microscopy. We describe the basic aspects of the technique and provide examples of applications to intracellular motility, cell membrane dynamics, receptor translocation, internalization, and intracellular routing. We also provide examples of the use of this approach in immunospecific labelling of cells and tissue sections.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060207
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