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  • 1
    ISSN: 1439-6327
    Keywords: Diffusing capacity ; Oxygen intake ; Exercise ; Diffusion pulmonaire ; Consommation d'O2 ; Exercice musculaire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Chez sept sujets sains, la capacité de transfert du CO a été mesurée pendant des exercices musculaires d'intensité croissante répétés à de nombreuses reprises, á l'aide d'une méthode en régime stable, avec analyse directe de Pco dans l'air alvéolaire. Lorsque la dépense énergétique augmente, la capacité de transfert du CO ne cesse de s'accroître, même pour des consommations d'O2 très élevées, atteignant 4 à 5 L/min. Chez chaque individu examiné, la relation entre la consommation d'O2 et la capacité de transfert est variable; chez le groupe de sujets soumis à des mesures répétées, la relation entre ces deux paramètres semble linéaire. L'éventualité d'une perméabilité pulmonaire maximum impliquant une altération humorale lors des exercices musculaires épuisants est discutée.
    Notes: Summary The CO diffusing capacity has been measured by a “steady state” method with direct measurements of PCO in the alveolar air. Seven young males where tested during muscular exercises. The CO diffusing capacity increased without levelling off in relation to the energetic expense even till very high O2 intake, ranging about 4 or 5 l/min. By each subject, the relation between the O2 intake and the diffusing capacity was variable; by the whole group of subjects submitted to many tests, this relation seems to be linear. The possibility of a maximal pulmonary permeability that involves a humoral impairing during exhaustive work is discussed.
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  • 2
    ISSN: 1439-6327
    Keywords: Heart Rate ; Body Temperature ; Exercise ; Fréquence cardiaque ; Température corporelle ; Exercice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'évolution comparée de la fréquence cardiaque et de la tempërature corporelle est mesurée chez 23 sujets effectuant des exercices musculaires d'une durée d' 1/2 H, avec un métabolisme d'environ 1 L O2/min, à température très élevée (ts 46 °C; th 35 °C). La relation qui unit ces deux paramètres est linéaire tout au moins pour la partie moyenne du diagramme. Pour les valeurs plus faibles, en-dessous de 100 pulsations/min, la fréquence cardiaque est influencée de façon variable par la température corporelle. Au-delà de 170 pulsations/min, la fréquence cardiaque, approchant de sa valeur maximum, n'est plus fonction de l'hyperthermie. L'amplitude de la réaction cardiaque présente de grandes variations individuelles. En moyenne, une élévation de température interne de 1 °C entraîne une accélération cardiaque de 32,3 pulsations/min, cependant, les extrêmes s'étendent de 21 à 46 pulsations/min. La linéarité de la relation justifie l'emploi de la fréquence cardiaque comme témoin d'une surcharge thermique pendant le travail musculaire à haute température. Le comportement individuel est un reflet de l'aptittide de chaque sujet à supporter les températures élevées.
    Notes: Summary Heart rate and body temperature were measured in 23 men walking on a treadmill during 1/2 an hour in a very hot environment (ta 46 °C; twb 35 °C), with an energy expenditure of about 11 O2/min. A linear relationship was found between the two parameters, at least for the middle part of the diagram. For lower values, below 100 beats/min, heart rate is influenced in a variable manner by the body temperature. Above 170 beats/min, heart rate approaches its highest value, and is hence no more influenced by hyperthermy. From one subject to another, the extent of cardiac reaction varies considerabily. On the average, when body temperature increases by 1 °C, heart rate increases by 32,3 beats/min, but extreme values are 21 and 46 beats/min. The linearity of the diagram justifies the use of heart rate as a reference of a thermal overloading during muscular exercise in hot environment. The individual comportment truly reflects each subject's capacity in bearing hot climates.
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  • 3
    ISSN: 1439-6327
    Keywords: Muscle Blood Flow ; Exercise ; Xenon 133 ; Débit sanguin musculaire ; Exercice ; Xénon 133
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Eésumé. Une méthode d'étude du débit sanguin musculaire au cours même de l'exercice est décrite. Elle est basée sur la mesure de la disparition d'un traceur radioactif (Xénon 133) injecté au sein du tissu. La vascularisation du quadriceps est étudiée pendant des exercices à plusieurs intensités, sur bicyclette ergométrique. Le débit sanguin musculaire s'accroît proportionnellement à l'intensité de l'exercice. Pour 100 g de muscle, le débit sanguin passe de 13,3 à 39,1 ml/min lorsque la puissance de l'effort fourni est accrue de 50 à 250 watts. La reproductibilité d'une même mesure est satisfaisante: le coefficient de variation de 5 mesures répétées vaut 10 à 17%. Les causes d'erreurs de cette technique sont discutées; ses avantages sont mis en évidence.
    Notes: Summary A method for the measurement of the muscular blood flow during rhythmic exercise is presented. An external counter follows the clearance rate of a radioactif tracer (Xenon 133) injected into the tissu. The circulation in the quadriceps was measured for several workloads on a bicycle ergometer. It was found that the muscular blood flow increased proportionately to the intensity of muscular work. For 100 g of muscle, the blood flow rose from 13.3 to 39.1 ml/min when the workload increased from 50 to 250 watts. The reproductibility for the test was satisfactory; the coefficient of variation for 5 similar measures reached 10 to 17%. The causes of error from such a technique were discussed as well as the advantages.
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  • 4
    ISSN: 1439-6327
    Keywords: Body-Temperature ; Exercise ; Environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les températures rectale et tympanique ont été mesurées chez 12 sujets; elles ont été comparées a la température oesophagienne chez six d'entre eux. La température rectale évolue avec un certain retard vis-á-vis des températures tympanique et oesophagienne dont le comportement est pratiquement identique. La température tympanique, plus aisée à mesurer et n'exigeant pas de cathétérisme paraît le meilleur témoin de l'évolution de la température du noyau central au cours de contraintes thermiques et d'exercises musculaires de courte durée.
    Notes: Summary Measurements of rectal and tympanic temperatures are made on 12 subjects; on 6 of them, these results are also compared to measurements of esophageal temperature. The rectal temperature changes with some delay in relation to tympanic and esophageal temperatures whose evolutions are nearly the same. The tympanic temperature is more easy to test and requires no catheterism. Furthermore, it seems to be the more representative of the central nucleus temperature evolution during hot stress and muscular exercise of short duration.
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  • 5
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Solvolysis Mechanism of cis - and trans-2-Arylcylopentyl p-Toluenesulfonates. The Step: 1-Deuterium Isotope Effects, Basic Salt Effects, and Special Salt EffectWe have studied the first step of the solvolysis of cis and trans-2-arylcyclopentyl p-toluenesulfonates in HCOOH, AcOH, and EtOh. All substrates show a high kinetic 1-deuterium isotope effect (kH/kD(1) 〉1.15). This fact indicates that first step leads to classical intimate ion-pair Which dissociates to a solvet-separated ion-pair, without participation either of solvent, the 2-aryl group, or a H-atom at C(2). The slight influence of added basic ions on reaction rate allows us to exclude any direct solvent attack on the covalent substrate even in the most favorable case, i.e. ethanolysis of 2-(p-nitrophenyl)cylopentyl-p-toluenesulfonates. Furthermore, solvent-separated ion pair formation is indicated by the special salt effect induced by LiClO4.
    Notes: No abstract.
    Additional Material: 1 Ill.
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  • 6
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Di(tert-butyl)- and Diphenyldiazomethane and 1,3-Thiazole-5(4H)-thiones: Isolation and Crystal Structure of the Primary CycloadductReactions of diazo compounds with C=S bonds proceed via the formation of thiocarbonyl ylides, which, under the reaction conditions, undergo either 1,3-dipolar cycloadditions or electrocyclic ring closer to thiiranes (Scheme 1). With the sterically hindered di(tert-butyl)diazomethane (2c), 1,3-thiazole-5(4H)-thiones 1 react to give spirocyclic 2,5-dihydro-1,3,4-thiadiazoles 3 (Scheme 2). These adducts are stable in solution at -20°, and they could be isolated in crystalline form. The structure of 3c was established by X-ray crystallography. In CDCl3 solution at room temperature, a cycloreversion occurs, and the adducts of type 3 are in an equilibrium with 1 and 2c. In contrast, the reaction of 1 with diphenyldiazomethane (2d) gave spirocyclic thiiranes 4 as the only product in high yield (Scheme 3). The crystal structure of 4b was also determined by X-ray analysis. The desulfurization of compounds 4 to 4,5-dihydro-5-(diphenylmethylidene)-1,3-thiazoles 5 was achieved by treating 4 with triphenylphosphine in boiling THF. The crystal structure of 5f is shown.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Phenyldiazomethane with 1,3-Thiazole-5(4H)-thiones: Base-Catalyzed Ring Opening of the Primary AdductReaction of 1,3-thiazole-5(4H)-thiones 1 and phenyldiazomethane (2a) in toluene at room temperature yields the thiiranes trans- and cis-1,4-dithia-6-azaspiro[2.4]hept-5-enes (trans- and cis-4; Scheme 2). With Ph3P in THF at 70°, these thiiranes are transformed stereospecifically into (E)- and (Z)-5-benzylidene-4,5-dihydro-1,3-thiazoles 5, respectively. In the presence of DBU, 1 and 2a react to give 1,3,4-thiadiazole derivatives 6 or 7 via base-catalyzed ring opening of the primary cycloadduct (Scheme 3). In the case of 2-(alkylthio)-substituted 1,3-thiazole-5(4H)-thiones 1c and 1d, this ring opening proceeds by elimination of the corresponding alkylthiolate, yielding isothiocyanate 7. The structures of (Z)-5c and 6b have been established by X-ray crystallography.
    Additional Material: 1 Ill.
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  • 8
    ISSN: 0899-0042
    Keywords: solvent ; basic medium ; competitive solubilities ; optimization ; optical resolution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several preparative resolutions of 5,5-disubstituted hydantoins have been achieved via fractional crystallization of diastereoisomeric salts. The process can be extended by making use of the difference between the variation of solubilities of the hydantoins and their salts with α-methylbenzylamine as a function of the alkalinity of the medium. Optimization for each resolution procedure involves a refinement of the excess amount of base needed. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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