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1.
Our object in this paper is to study the antecedents, contents, implications, and impact of a not well-known or appreciated paper by EHRENFEST in 1911 on the essential nature of the different quantum hypotheses in radiation theory. After a careful analysis of EHRENFESTs notebooks, correspondence, and publications, we conclude that the essential points of EHRENFESTs paper were not perceived to a large extent, and hence that its implications were not considered thoroughly. Specifically, we show that EHRENFEST contributed significantly to the clarifications of the differences between PLANCKs and EINSTEINs respective quantum hypotheses, as well as to those of the concepts discontinuity, quantization, and corpuscularity.  相似文献   

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The paper reports on the molecular analysis of samples of approximately 5,300-year-old grass found at the alpine archaeological site where the so-called Tyrolean Iceman was discovered. The grass comes from a cloak made of long grass blades and/or the stuffing of the snow footwear worn by the Iceman. The results show that while the largest fraction of the DNA extractable from the grass is of foreign origin, a much smaller part belongs to the original genetic material of the grass itself, and can be used as a valuable taxonomic clue to the plant species utilized by neolithic men to manufacture their equipment. On the other hand, the foreign DNA, or at least a portion of it, comes from microorganisms-mainly filamentous fungi and unicellular algae-which seem to have been associated with the grass since the time the grass was harvested.  相似文献   

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Summary One part of the microsomal galactosyl-transferase activity of splenic cells of rats can by solubilized by the action of Triton X-100 and Tween 20. Its purification on a Sephadex G-200 column and by electrophoresis on a polyacrylamide gel leads to a solution of high specific enzymic activity.This work has benefited from the help of the Centre National de la Recherche Scientifique, the Direction des Recherches et Moyens d'Essais, the Institut National de la Santé et de la Recherche Médicale, the Fondation pour la Recherche Médicale Française the Délégation Générale à la Recherche Scientifique et Technique and the Université de Lyon (UER Lyon-Sud et Biologie Humaine).  相似文献   

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Summary During the development of anthers inTulipa cv. Apeldoorn the following chalcones were isolated: 2, 3, 4, 4, 6-pentahydroxychalcone as the main component and 2, 4, 4, 6-tetrahydroxy-3-methoxychalcone as well as 2, 4, 4, 6-tetrahydroxychalcone in a very small amount.

Die Untersuchungen wurden mit Mitteln der Deutschen Forschungsgemeinschaft unterstützt.  相似文献   

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Summary An empirical and mathematical model for self-organization is proposed, based on elemental properties, on unique interaction and on the combination of hierarchical elements. In the model, higher elements are stabilized by the cognitive (strong) interaction of subelements, disregarding intermediate elements. This is called elementary reductionism and is illustrated by the sequence quarks-elementary particles-atoms-molecules-cells-organisms-societies. Optimal dynamic interaction of nonidentical elements is called cognitive stability. This is compared with thermodynamic equilibrium. The principal differences are outlined.  相似文献   

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Summary Kinetics studies of haemolymph -glucosidase inhibition by D. glucose led to general correlations between inhibition and control parameters, all over the honeybee development. Maximum velocities are not affected by the inhibition, while affinity constants are always significantly increased, and Hill coefficients tend to decrease, especially in foraging adults and in prenymphs. In this later case, the n-type effect tends to break the manifestation of the K-type mechanism.  相似文献   

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Summary Photorefractory male yellow-throated sparrows (Gymnorhis xanthocollis) were subjected to six resonance light cycles, consisting of 6 h basic photophase coupled with scotophases of longer durations (in cycles of 12 (6L6D) h, 24 (6L18D) h, 36 (6L30D) h, 48 (6L42D) h, 60 (6L54D) h and 72 (6L66D) h). Termination of photorefractoriness was evident in cycles of 24, 48 and 72 h, but not in 12, 36 and 60 h. The results are consistent with the external-coincidence model (Bünning hypothesis) and suggest that endogenous circadian rhythmicity is involved in the termination of photorefractoriness.To whom reprint requests should be addressed.This investigation was supported by a UGC grant to PDT and BHU to PMT.  相似文献   

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Summary Axillary 5-androst-16-en-3-one (5-androstenone) levels were found to be significantly higher in men than in women but do not vary between left and right axillae, are not related to age, handedness or degree of hirsutism (in women) nor to anosmia to this steroid. In men (but not in women), levels are related linearly to axillary cholesterol concentrations but not to squalene. Olfactory thresholds for 5-androstenone varied widely, the lowest recorded being 0.2 ppb, but there was no difference in thresholds between men and women. Women (70%) found the smell repellant but anosmia did not differ greatly between men and women (9–20%). Anosmia to the smell of 5-androst-16-en-3-ol was most marked in women (90%) rather than in men (45%). Axillary 5-androstenone values were generally consistent with the musky or strong smells of male axillary extracts, compared with the sweet smell of those from female subjects.Supported by the Herbert Dunhill Trust.  相似文献   

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Summary In the host-symbiont-cycle ofEuscelis plebejus and its bacterial symbionts each of both symbionts (a and t) appears in an infection form during the intraovarial transmission (adult female) as well as during the entrance into the mycetocytes (embryo) and in a vegetative form during the remaining time of the cycle.This work was supported in part by a grant from the Deutsche Forschungsgemeinschaft to ProfessorK. Sander, whom I thank for helpful discussions.  相似文献   

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Summary Glutamate decarboxylase (GAD) activities were determined in homogenates of 8 brain regions of mice that had been differentially housed (isolated vs grouped) for 4–9 weeks. GAD activity was lower in whole forebrains and in olfactory bulbs of isolated mice, changes which might be associated with their increased aggressiveness.  相似文献   

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Summary The interaction of a specific ligand at substrate binding site was shown to be responsible for the catalytic efficiency of trypsin. The reasoning of induced fit theory was refined by kinetic analysis of characteristic properties of inverse substrates.This work was supported by grants from the Ministry of Education, Science and Culture, Japan.  相似文献   

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Conclusions The decrease of circulating blood volume, resulting in oligemic hypotension, may evoke in anaesthetized cat the active constrictory coronary vessel responses of 2 types, one occuring immediately after start of the hypotension and the other having a significantly prolonged latency.
, , , , ( 4 ), ( 45 ).
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-Spermophilus brunneus . , 13 18 ,S. brunneus S. townsendii mollis (2n=38) , , ; ;S. brunneus . S. brunneus , Spermophilus.

Supported by National Science Foundation Grants No. GB32114X and No. GB 29131X, and the Sprague Foundation. We thankD. Pozin for technical assistance.  相似文献   

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Summary The addition of some halogenated alkanes (bromotrichloromethane, carbontetrachloride and chloroform) to cultures ofA. parasiticus andA. flavus have shown a high stimulating effect on aflatoxin biosynthesis. When the production of aflatoxin increases during the stimulating effect the peroxidase activity is inhibited.Acknowledgments. Supported by Cassa di Risparmio di Roma, funds from Ministry of Education and Faculty of Science of La Sapienza Rome University.  相似文献   

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Summary ,-unsaturated terpenoid ketones have a root-inducing property on the hypocotyl cuttings ofPhaseoulus aureus. Significantly isopathcoulenone, (I) is distinctly more active in causeing rooting over IAA.Acknowledgment. The work was financially supported by the Punjab State Government, India, under the scheme Chemistry of some natural products and their significance in agriculture. The authors thank Dragoco, Holzminden, Federal Republic of Germany, for supplying the samples of monoterpenes.  相似文献   

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