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In Descartes, the concept of a ‘universal science’ differs from that of a ‘mathesis universalis’, in that the latter is simply a general theory of quantities and proportions. Mathesis universalis is closely linked with mathematical analysis; the theorem to be proved is taken as given, and the analyst seeks to discover that from which the theorem follows. Though the analytic method is followed in the Meditations, Descartes is not concerned with a mathematisation of method; mathematics merely provides him with examples. Leibniz, on the other hand, stressed the importance of a calculus as a way of representing and adding to what is known, and tried to construct a ‘universal calculus’ as part of his proposed universal symbolism, his ‘characteristica universalis’. The characteristica universalis was never completed—it proved impossible, for example, to list its basic terms, the ‘alphabet of human thoughts’—but parts of it did come to fruition, in the shape of Leibniz's infinitesimal calculus and his various logical calculi. By his construction of these calculi, Leibniz proved that it is possible to operate with concepts in a purely formal way.  相似文献   

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Galileo and Descartes were on the front lines of the defense of Copernicanism against theological objections that took on special importance during the seventeenth century. Galileo attempted to overcome opposition to Copernicanism within the Catholic Church by offering a demonstration of this theory that appeals to the fact that the double motion of the earth is necessary as a cause of the tides. It turns out, however, that the details of Galileo's tidal theory compromise his demonstration. Far from attempting to provide a demonstration of the earth's motion, Descartes ultimately argued that his system is compatible with the determination of the Church that the earth is at rest. Nonetheless, Descartes's account of the cause of the tides creates difficulty for this argument.  相似文献   

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LmrP from Lactococcus lactis is a 45-kDa membrane protein that confers resistance to a wide variety of lipophilic compounds by acting as a proton motive force-driven efflux pump. This study shows that both the proton motive force and ligand interaction alter the accessibility of cytosolic tryptophan residues to a hydrophilic quencher. The proton motive force mediates an increase of LmrP accessibility toward the external medium and results in higher drug binding. Residues Asp128 and Asp68, from cytosolic loops, are involved in the proton motive force-mediated accessibility change. Ligand binding does not modify the protein accessibility, but the proton motive force-mediated restructuring is prerequisite for a subsequent accessibility change mediated by ligand binding. Asp142 cooperates with other membrane-embedded carboxylic residues to promote a conformational change that increases LmrP accessibility toward the hydrophilic quencher. This drug binding-mediated reorganization may be related to the transition between the high- and low-affinity drug-binding sites and is crucial for drug release in the extracellular medium.  相似文献   

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Zusammenfassung Je nach dem Alter wirken Pharmaka sehr verschieden. Hexobarbital ist bei alten Tieren stärker narkotisch; Amphetamin und Ritalin weniger erregend; Amphetamin und Preludin wirken stärker appetithemmend und nach Novokain ist die Hemmung der Wärmeregulation stärker bei alten Tieren. Peripher angreifende Pharmaka zeigen keine Unterschiede.  相似文献   

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Summary Cardiac output distribution in the rat was found to be affected by age. Cardiac index and blood flow to the liver, kidneys, skin and skeletal muscle were lower in 11–12 month compared to 3–4 month old rats.Acknowledgments. This work was supported by grants from I.C.I. Pharmaceuticals and Mersey Regional Health Authority (Research Scheme No.338). We wish to thank Mr P.J. Roberts for invaluable technical assistance.  相似文献   

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通过回顾控制科学的发展历程,总结其成功经验,阐述了控制科学的定位以及当前控制科学面临的新局面,并结合信息时代控制科学的新特点提出了促进我国该学科发展的一些建议.  相似文献   

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Cardiac output distribution in the rat was found to be affected by age. Cardiac index and blood flow to the liver, kidneys, skin and skeletal muscle were lower in 11-12 month compared to 3-4 month old rats.  相似文献   

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Résumé A partir d'un stock de souris albinos non inbred, deux lignées ont été formées, l'une par reproduction á l'âge de deux á trois mois, l'autre par reproduction á plus d'un an. Les individus de 3e génération de cette seconde Iignée se montrent, á l'âge d'un an, supérieurs aux individus de même âge des générations 12 á 14 de la premiére lignée pour ce qui concerne l'apprentissage du parcours dans un labyrinthe en double-T. A 2 et á 5 mois des différences de mêmes sens ont été trouvées entre les deux lignées, mais ces différences ne sont pas significatives.  相似文献   

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This essay examines the curious relationship between Charles Darwin and the palaeontologist William Boyd Dawkins (1837–1929). Dawkins was a beneficiary of Darwin's patronage and styled himself as a Darwinian to Darwin and the public, yet viciously attacked Darwin and his theory in anonymous reviews. This has confused historians who have misunderstood the exact nature of Dawkins's attitude towards evolution and his relationship to Darwin. The present study explains both the reasons for Dawkins's contradictory statements and his relationship with Darwin. I introduce Batesian mimicry as a conceptual framework to make sense of Dawkins's actions, suggesting that Dawkins mimicked a Darwinian persona in order to secure advancement in the world of Victorian science. Dawkins's pro-Darwinian stance, therefore, was a façade, an act of mimicry. I argue that Dawkins exploited Darwin for his patronage – which took the form of advice, support from Darwin's well-placed friends, and monetary assistance – while safely expressing his dissent from Darwinian orthodoxy in the form of anonymous reviews. This is, therefore, a case study in how scientific authority and power could be gained and maintained in Victorian science by professing allegiance to Darwin and Darwinism.  相似文献   

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I examine two challenges that collaborative research raises for science. First, collaborative research threatens the motivation of scientists. As a result, I argue, collaborative research may have adverse effects on what sorts of things scientists can effectively investigate. Second, collaborative research makes it more difficult to hold scientists accountable. I argue that the authors of multi-authored articles are aptly described as plural subjects, corporate bodies that are more than the sum of the individuals involved. Though journal editors do not currently conceive of the authors of multi-authored articles this way, this conception provides us with the conceptual resources to make sense of how collaborating scientists behave.  相似文献   

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Zusammenfassung Nach Pinealektomie unterbleibt eine Hypertonie (Skelton), falls einseitige Nephrektomie und Adrenektomie mit Enukleation der übrigen Nebenniere bei jungen Ratten durchgeführt wurde. Wird die experimentelle, Hypertonie verursachende Operation bei adulten Tieren praktiziert, so bleibt Pinealektomie ohne jeden Effekt.  相似文献   

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Résumé L'acide cannabidiolique pouvant être considérée comme la substance initiale dans la conversion graduelle des composants de la résine du chanvre (Cannabis sativa), le taux de la fraction acide peut servir d'indication sur l'avance du processus de «mûrissement» de la résine. La teneur en acide a été trouvé la moins élevée dans la résine du chanvre provenant de régions tropicales, ce qui s'explique par la conversion plus avancée dans des variétés dévelopées sous un climat favorable et chaud. D'après les résultats obtenus, cette conversion semble continuer pendant la conservation de la drogue.  相似文献   

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