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  • 1
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Doubly charged ion mass spectra have been obtained for 15 n-alkane hydrocarbons. Spectra were measured using a Nier-Johnson geometry Hitachi RMU-7L mass spectrometer operated at 1.6kV accelerating voltage. Fragment ions, which resulted from C—C bond rupture and extensive H loss, dominated the spectra. Molecular ions have not been observed. The most intense ions in the doubly charged ion mass spectra of n-alkanes were [C2H4]2+, [C3H2]2+, [C4H3]2+, [C5H2]2+, [C6H6]2+, [C6H8]2+, [C7H6]2+, [C7H8]2+, [C8H6]2+ and [C8H8]2+. Appearance energies for forming the prominent doubly charged fragment ions have been measured and range from 27.5 eV to energies greater than 60eV. A geometry optimized SCF approach has been used to compute the energies and structures of prominent ions in the doubly charged mass spectra.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Doubly charged ion mass spectra of 20 aliphatic and 3 aromatic acetylenic compounds have been measured using a double focusing Hitachi RMU-7L mass spectrometer. Spectra were obtained using 100 eV ionizing electron energy and 3.2 kV ion accelerating voltage. In general, the spectra of aliphatic type acetylenic compounds were dominated by fragment ions formed by extensive H loss from doubly charged molecular ions. Intense molecular ions were observed in the doubly charged ion spectra of phenyl-substituted acetylenes. Total product ion intensities for doubly charged ion spectra of acetylenic compounds were found to be smaller, in general, than the total product ion intensity observed in the benzene doubly charged ion mass spectrum. Measured appearance energies of intense product ions ranged from 24 to 47 eV. A geometry optimized quantum mechanical self-consistent field molecular orbital treatment was employed to compute energies and structural parameters of prominent ions in the doubly charged ion mass spectra of acetylenic compounds.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Doubly charged ion mass spectra were obtained for 46 low molecular weight oxygen containing compounds. A double focusing Hitachi RMU-7L mass spectrometer, operated at 3.2 kV accelerating voltage, was used to measure spectra for aliphatic alcohol, ketone, ether, aldehyde, ester and acid molecules, as well as several aromatic oxygen containing compounds. In general, the spectra were dominated by fragment ions which resulted from extensive H loss and C—C bond rupture as well as O elimination from the doubly charged molecular ions. Total product ion intensities from doubly charged ion spectra of aliphatic oxygen containing compounds were approximately 1% of the corresponding total ion intensity in the benzene doubly charged ion spectrum. Appearance energies for forming prominent doubly charged molecular and fragment ions were determined. Measured values ranged from 26 to 45 eV. A geometry optimized quantum mechanical SCF treatment was used to compute the energies, charge densities and structures for several of these oxygen containing doubly charged ions.
    Additional Material: 8 Ill.
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  • 4
    ISSN: 1432-1106
    Keywords: Choline ; Choline-acetyltransferase ; Retrograde transport ; Brainstem ; Forebrain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In an attempt to identify cholinergic neurons of the brain stem which project to the forebrain, retrograde labeling of neurons in the brain stem was examined by autoradiography following injections of 20 μCi [3H]choline into the thalamus, hypothalamus, basal forebrain and frontal cortex. After injections into the thalamus, retrogradely labeled neurons were evident within the lateral caudal mesencephalic and dorsolateral oral pontine tegmentum (particularly in the laterodorsal and pedunculopontine tegmental nuclei) and in smaller number within the latero-medial caudal pontine (Reticularis pontis caudalis, Rpc) and medullary (Reticularis gigantocellularis, Rgc) reticular formation. Following [3H]choline injections into the lateral hypothalamus and into the basal forebrain, retrogradely labeled neurons were localized in the dorsolateral caudal midbrain and oral pontine tegmentum and in smaller number in the medial medullary reticular formation (Rgc), as well as in the midbrain, pontine and medullary raphe nuclei. After injections into the anterior medial frontal cortex, a small number of retrogradely labeled cells were found in the brain stem within the laterodorsal tegmental nucleus and the dorsal raphe nucleus. In a parallel immunohistochemical study, choline acetyltransferase (ChAT)-positive neurons were found to be located in most of the regions of the reticular formation where cells were retrogradely labeled from the forebrain following [3H]choline injections. These results suggest that multiple cholinergic neurons within the lateral caudal midbrain and dorsolateral oral pontine tegmentum and a few within the caudal pontine and medullary reticular formation project to the thalamus, hypothalamus and basal forebrain and that a limited number of pontine cholinergic neurons project to the frontal cortex.
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  • 5
    ISSN: 1432-2072
    Keywords: Single-spatial alternation ; Dog ; Relative potency ; Methylphenidate ; Cocaine ; d-Amphetamine ; Phenmetrazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Dogs were trained to pedal press for drinking water in a noncued, single-spatial alternation task. After the dogs were exhibiting stable performance at or above predetermined criteria levels, they were given three doses of four different drugs (methylphenidate, 0.2, 0.4, and 0.8 mg/kg; d-amphetamine, 0.15, 0.3, and 0.6 mg/kg; cocaine, 0.5, 1, and 2 mg/kg; and phenmetrazine, 0.6, 1.2, and 2.4 mg/kg). In general, all four drugs produced similar changes in performance. The number of correct responses was an especially sensitive indicator of drug effects. All four drugs also produced significant increases in both the average response latency and total session duration, but there were few significant changes in either the total number of responses or number of intertrial interval responses. Relative to d-amphetamine, the potencies of cocaine and phenmetrazine, but not methylphenidate, were generally higher for the measures of single-spatial alternation than for self-administration.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 30 (1973), S. 1-12 
    ISSN: 1432-2072
    Keywords: Relapse ; Morphine ; Dog ; Self-Administration ; Drug Dependence ; Amphetamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intravenous self-administration of morphine by dogs was studied before and during dependence on morphine, and after 1 to 6 months of enforced abstinence. In comparison to pedal response rates during a saline control period, 18 of 22 dogs studied showed decreased rates of responding for morphine during the initial 3-week exposure. Following subsequent passive establishment of dependence in 7 dogs, they self-administered morphine and maintained dependence. Following enforced abstinence for periods of 1 to 6 months the 7 dogs relapsed to self-administration of morphine when it was again made available. In contrast, additional dogs offered food or amphetamine reinforcements showed marked increases in pedal responding for these reinforcements within a few days after initial exposure. The results indicate that in post-dependent dogs that had maintained their dependence on morphine by self-administration, effects other than those experienced during the initial exposure to morphine are responsible for relapse.
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  • 7
    ISSN: 1432-2072
    Keywords: Methadone maintenance ; Morphine ; Self-administration ; Drug-seeking behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of methadone and morphine maintenance on morphine self-administration were studied in the dog. Methadone was given passively for 2 weeks by continuous i.v. infusion. The amount of methadone administered daily was the same in mg/kg as the mean daily mg/kg of morphine the dogs had self-administered during the premaintenance control week. Morphine self-administration was markedly reduced initially but returned to normal levels within 2 weeks of methadone administration. Following the methadone maintenance period, morphine self-administration was increased over the premaintenance period for 2 weeks. A result similar to that with methadone was obtained in a second experiment when morphine was used as the maintenance drug in an amount that was three times the amount the dogs had been self-administering during the premaintenance control week.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 74 (1981), S. 204-207 
    ISSN: 1432-2072
    Keywords: Response-contingent ; Morphine ; Self-administration ; Dog ; Addiction ; Behavior ; Reinforcement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Each of five dogs that had been trained to chronically self-administer IV morphine was tested with changes in the morphine dose from the baseline dose (1 mg/kg/infusion) to 0.125, 0.5, or 2 mg/kg/infusion, and with passive administration of the usual daily morphine intake while either continuing the morphine self-administration at the baseline dose or changing the self-administered solution to saline. Each treatment lasted 5 weeks. Results indicated that there is a significant negative regression of response on dose, and chronic self-administration of morphine is not entirely accounted for by a need to avoid abstinence or to obtain a direct drug effect. A third element, which may be an acquired need to obtain a response-contingent drug effect, is necessary to account for the chronic self-administration of morphine by the dog.
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  • 9
    ISSN: 1432-2072
    Keywords: State Dependent Learning ; Dissociation ; Morphine ; Pentobarbital
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were trained in state dependent discrimination to escape shock in a T-maze by turning one way under a drug and the other way under saline without aid of exteroceptive cues. In experiment 1, 9.0 nig/kg of morphine, 20 mg/kg of pentobarbital and 0.3 cc of saline were used with a balanced order of training which employed 18 training days under one condition followed by 18 days in the other condition; twelve test days were then given in which conditions were alternated daily. Pentobarbital produced strong state dependent behavior but morphine did not. Experiment 2 used 4.5, 9.0, 18.0, and 36.0 mg/kg of morphine and 0.3 cc of saline with the same procedures as for the first study. Orderly state dependent learning was not found. In experiment 3, the dose levels and procedures were the same as for the second study except that training under the two conditions was carried out concurrently, i.e. morphine and saline trials were given alternately in balanced order. Highly significant dose-related state dependent behavior occurred in both the training and test periods. The results were discussed in relation to state dependent learning, dissociation and opiate addiction.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 41 (1975), S. 7-10 
    ISSN: 1432-2072
    Keywords: Drug-Seeking Behavior ; Methadone Maintenance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Six subjects were given the opportunity to work for saline placebo and hydromorphone (4 mg i.v.) several times weekly before and during a period of maintenance on methadone (100 mg p.o. daily). Measures of pupillary change and reports of “liking” in response to hydromorphone dropped to saline control levels when the daily dose of methadone was approximately 60 mg. Half of the subjects continued to work intermittently for hydromorphone for four weeks while they were receiving 100 mg of methadone daily. These data support the assumption that methadone maintenance reduces the reinforcement value of other opiates and behaviors associated with obtaining them.
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