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  • Chemistry  (27)
  • Withdrawal  (3)
  • Polysilane  (2)
  • Polysilanes  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Ethynylene-disilanylene copolymers (1991)
    Springer
    Journal of inorganic and organometallic polymers and materials 1 (1991), S. 545-565 
    Details
    ISSN: 1572-8870
    Keywords: Polysilanes ; sigma-pi conjugation ; mesophases ; polymer crystals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Polymers of structure (SiR2SiR2-C ≡ C-SiR2′SiR2′-C ≡ C) n , in which ethynylene units alternate with disilylene units, have been prepared by two routes: (a) condensation of dichlorodisilanes with dilithium derivatives of 1,2-diethynyldisilanes and (b) ring-opening polymerization of strained cyclic disilanylene-acetylnes, (SiR2SiR2C ≡ C)2. The polymers display UV absorption near 240 nm indicative of σ − π conjugation between the Si2 and the C ≡ C moieties. Polymers with R=R′=n-Bu or R=n-Bu, R′=Ph, undergo solid-state transitions to form liquid crystalline mesophases resembling those observed for many poly(silylenes). Single crystals were obtained for the polymer with R=R′=CH3, by precipitation from dilute cyclohexane solution. The solid-state properties and structures of this family of polymers are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683516
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  • 2
    Electronic Resource
    Electronic Resource
    Properties of some polysilane polymers: (n-PrSiMe) n , (i-PrSiMe) n , and (sec-BuSiMe) n (1995)
    Springer
    Journal of inorganic and organometallic polymers and materials 5 (1995), S. 31-42 
    Details
    ISSN: 1572-8870
    Keywords: Polysilane ; nematic mesophase ; liquid crystal ; isotopic phase ; thermochromic transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three polysilane polymers, (n-PrSiMe) n , (i-PrSiMe) n , and (sec-BuSiMe) n , were synthesized and characterized by DSC. UV spectroscopy, wide-angle X-ray diffraction, and optical microscopy, all at variable temperatures. The known thermochromic transition of (n-PrSiMe) n at ∼48 C is associated with a change from an orthorhombic to an isotropic phase. (i-PrSiMe) n was examned as an insoluble and soluble (lowM w) fraction, both existing mainly in an orthohombic lattice at room temperature. (sec-BuSiMe) n has a mesophase structure at 25 C, undergoes a weak endothermic transition to a second (nematic) mesophase near 65 C, and becomes isotropic at ∼160 C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01157521
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of alternating silane copolymers: (Me2Si−R2Si−Me2Si) n (1995)
    Springer
    Journal of inorganic and organometallic polymers and materials 5 (1995), S. 217-236 
    Details
    ISSN: 1572-8870
    Keywords: Polysilane ; NMR ; pyrolysis ; randomization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bimodal molecular weight distributions of alternating copolymers of the type (Me2Si−R2Si−SiMe2) n , where R=hexyl and butyl, were obtained by polymerization of BrSiMe2−R2Si−Me2SiBr, using the Wurtz coupling method. Analysis of the samples by pyrolysis GC MS and solution29Si NMR indicated that some randomization occurred, due to cleavage of the original Si−Si bonds in the monomer. The extent of randomization was significantly greater in the high molecular weight fractions. Based on the nature of the rings from the py MGC/MS traces and the number on nonads found in the29Si spectra, two types of randomization processes have been proposed, involving backbiting followed by (1) ring expulsion or (2) redistribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01057894
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  • 4
    Electronic Resource
    Electronic Resource
    Cigarette withdrawal symptoms in adolescent smokers (1986)
    Springer
    Psychopharmacology 90 (1986), S. 533-536 
    Details
    ISSN: 1432-2072
    Keywords: Cigarette smoking ; Withdrawal ; Adolescents ; Cotinine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract One hundred and sixteen female adolescent smokers were asked about withdrawal symptoms experienced during past attempts to give up smoking for good. Sixty-three percent reported difficulties during abstinence of the kind experienced by adult smokers. Daily smokers were more likely to report withdrawal effects than non-daily smokers (74% versus 47%, P〈0.005). Reported experience of withdrawal symptoms was positively related to self-reports of cigarette consumption and depth of inhalation and nicotine intake as indexed by salivary cotinine concentrations. Reported occurrence of at least one withdrawal effect correlated positively with nicotine intake after controlling for behavioural variables. Our results indicate that teenage smokers are likely to suffer withdrawal symptoms when they try to give up. Behavioural factors and expectations based on observations of adults may have played a part in their experience of withdrawal, but it is also likely that pharmacological factors are implicated even at this early stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174074
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  • 5
    Electronic Resource
    Electronic Resource
    Pre-abstinence smoke intake and smoking motivation as predictors of severity of cigarette withdrawal symptoms (1985)
    Springer
    Psychopharmacology 87 (1985), S. 334-336 
    Details
    ISSN: 1432-2072
    Keywords: Withdrawal ; Cigarette ; Nicotine ; Dependence ; Motivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twenty-nine cigarette smokers completed a smoking motivation questionnaire and had expired-air carbon monoxide (CO) and plasma nicotine concentrations measured prior to abstaining from smoking for 24 h. Before and after the abstinence period, the subjects rated mood and physical symptoms known to be affected by cigarette abstinence (e.g. irritability, restlessness). Scores on the “dependent smoking” subscale of the smoking motivation questionnaire correlated significantly with overall withdrawal severity, craving, and increased irritability. “Indulgent smoking” scores correlated positively with increased hunger. Pre-abstinence plasma nicotine concentration significantly pedicted craving, hunger, restlessness, inability to concentrate and overall withdrawal severity, while expired-air CO predicted craving and restlessness only. Usual daily cigarette consumption did not significantly predict any withdrawal effects. The data indicate that pre-abstinence measures of smoking motivation and smoke intake may provide a guide to withdrawal severity on smoking cessation and that smokers with a high pre-abstinence nicotine intake experience the greatest discomfort.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432717
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of buspirone on cigarette withdrawal symptoms and short-term abstinence rates in a smokers clinic (1991)
    Springer
    Psychopharmacology 104 (1991), S. 91-96 
    Details
    ISSN: 1432-2072
    Keywords: Buspirone ; Smokers ; Withdrawal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper reports on a double blind trial of the effect of buspirone, 15 mg per day, on cigarette withdrawal symptoms and ability of smokers to maintain abstinence during treatment. A total of 61 smokers were randomly assigned to active or placebo conditions. They were maintained on their drug for 2 weeks prior to attempting abstinence and then for a further 4 weeks of abstinence. Subjects attended weekly group sessions of a psychological treatment programme. There was no evidence that the side effects in the active drug group were worse than those in the placebo group. Although there was no significant difference between active and placebo conditions on withdrawal symptoms, smokers in the active drug condition were more than twice as likely to maintain abstinence for the duration of the study than those in the placebo condition (47% versus 16%, chi square = 5.3,P〈0.025). The results provide preliminary evidence for short-term efficacy of buspirone as an aid to smoking cessation at a low dose. They also provide evidence of a dissociation between withdrawal symptoms and successful abstinence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244560
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  • 7
    Electronic Resource
    Electronic Resource
    Synthetic and Structural Studies of 1-Sila-2,5-diaryltetrazenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1579-1583 
    Details
    ISSN: 0009-2940
    Keywords: Silatetrazenes ; Nitrogen-silicon ring systems ; Bissilylamines ; Silicon-29 solid state NMR ; Aryl azides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between aryl azides and lithiated aryl amines leads to tetrazenes 3 and 9 which contain a chain of four nitrogen atoms. Reaction with different halosilanes gives the cyclic silatetrazenes 10, 12, and 15 where substitutents on the silicon vary form alkyl to hydrogen and chlorine atoms. The structures of 10, 12, and 15 in the solid state are reported. Variation of the solvent and the Lewis acidity of the halosilane influence the ratio of silatetrazene to side products, bissilyated amines. These effects are studied for different halosilanes.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301105
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  • 8
    Electronic Resource
    Electronic Resource
    29Si nuclear magnetic resonance of dimethyl and phenylmethyl containing polysilanes (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 701-712 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 29Si-NMR spectra are reported for poly(methylphenylsilylene), 1, poly(1,1,2-trimethyl-2-phenyldisilene) 2, two samples of poly(dimethylsilylene-co-phenylmethylsilylene), 3a and 3b, and poly(phenylmethylsilylene-co-n-hexylmethylsilylene), 4. The spectra of 3a, 3b, and 4 indicate that these polymers contain blocklike regions with considerable segregation of RMeSi and PhMeSi groups. The spectrum of 2 shows no evidence for stereospecific polymerization. The preparation of 2 from 1,1,2-trimethyl-2-phenyldichlorosilane is also described.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260303
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  • 9
    Electronic Resource
    Electronic Resource
    29Si nuclear magnetic resonance of dialkylpolysilanes (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 713-720 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The silicon-29 nuclear magnetic resonance spectra of a number of dialky- and alkylmethylpoly-silanes are reported. Polysilanes composed of asymmetrically substituted silylenes (i.e., alkylmethylsilylenes) exhibited very broad resonance lines attributed to diastereomeric chemical shifts of stereogenic silylenes alpha and beta to the observed nucles Symmetrically substituted polysilanes showed a single narrow peak. The 29Si chemical shifts for these polysilanes decrease with increasing steric bulk of the substituents, varying inversely with the electronic excitation energy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260304
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  • 10
    Electronic Resource
    Electronic Resource
    The wonderful world of organosilicon chemistryAs presented at the Ninth International Symposium on Organosilicon Chemistry, Edinburgh (scotland); July 16-20, 1990. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 2 (1991), S. 335-355 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hc.520020216
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