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1.
Summary A yellow flavonoid pigment, which occurs as a companion of the lignan glycosides inPodophyllum peltatum L. andP. emodi Wall. has been identified as astragalin (=kaempferol-3-glucoside).

18. Mitt. über mitoschemmende Naturstoffe. 17. Mitt.:E. Schreier, Helv. chim. Acta47, 1529 (1964).  相似文献   

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3.
This paper charts P.A.M. Dirac's development of his theory of the electron, and its radical picture of empty space as an almost-full plenum. Dirac's Quantum Electrodynamics famously accomplished more than the unification of special relativity and quantum mechanics. It also accounted for the ‘duplexity phenomena’ of spectral line splitting that we now attribute to electron spin. But the extra mathematical terms that allowed for spin were not alone, and this paper charts Dirac's struggle to ignore or account for them as a sea of strange, negative-energy, particles with positive ‘holes’. This work was not done in solitude, but rather in exchanges with Dirac's correspondence network. This social context for Dirac’s work contests his image as a lone genius, and documents a community wrestling with the ontological consequences of their work. Unification, consistency, causality, and community are common factors in explanations in the history of physics. This paper argues on the basis of materials in Dirac's archive that --- in addition --- mathematical beauty was an epistemological factor in the development of the electron and hole theory. In fact, if we believe that Dirac's beautiful mathematics captures something of the world, then there is both an epistemology and an ontology of mathematical beauty.  相似文献   

4.
3 experimentally distinct transverse relaxation components of the water in frog sciatic nerve are obtained by Carr-Purcell-Meiboom-Gill technique. The relative weights of these components: approximately 29%; approximately 50%; approximately 21% fit well with water compartments in this tissue as revealed by previous methods.  相似文献   

5.
14C-Indomethacin (ID) was applied to the skin of guinea-pigs as an ointment. After several applications, the concentration of ID in the skin and muscle under the applied site reached a constant level. The concentration of ID in the muscle as well as the skin may be enough to exert an anti-inflammatory effect.  相似文献   

6.
Summary Antidesmanol (1), a new pentacyclic triterpenoid, has been isolated along with n-tritriacontane, friedelin, canophyllal and canophyllol from the aerial parts ofAntidesma menasu. Based on chemical and spectroscopic evidence, its structure has been established as 3-keto-16-hydroxyfriedelane. n-Tritriacontane and friedelin have shown antiinflammatory and diuretic activities respectively in experimental animals.CDRI Communication No. 2536.  相似文献   

7.
L Weber  W Schmahl 《Experientia》1979,35(12):1656-1657
X-irradiation of pregnant NMRI-mice on gestational days 11-13 with 3 x 10.5 Gy increased postnatal mortality of the female offspring only. Weights, protein content and acetylcholinesterase, as well as Na,K-ATPase activities in the brains of all treated offspring, were changed. There were, however, no differences between females and males with respect to these parameters.  相似文献   

8.
In this paper we compare the out of sample forecasts from four alternative interest rate models based on expanding information sets. The random walk model is the most restrictive. The univariate time series model allows for a richer dynamic pattern and more conditioning information on own rates. The multivariate time series model permits a flexible dynamic pattern with own- and cross-series information. Finally, the forecasts from the MPS econometric model depend on the full model structure and information set. In theory, more information is preferred to less. In practice, complicated misspecified models can perform much worse than simple (also probably misspecified) models. For forecasts evaluated over the volatile 1970s the multivariate time series model forecasts are considerably better than those from simpler models which use less conditioning information, as well as forecasts from the MPS model which uses substantially more conditioning information but also imposes ‘structural’ economic restrictions.  相似文献   

9.
Summary We have shown the recently proposed method for prediction of carcinogenicity by average quasi-valence number to be neither a good predictor of carcinogenicity, nor of non-carcinogenicity.Grants to Edward J. Klekowski Jr from the U.S. National Science Foundation and from the office of Water Resources Research, U.S. Department of the Interior under the Water Resources Research Act of 1964, as amended, supported this research.  相似文献   

10.
Summary In the centre of the septum between phialide and mutula of certain imperfect penicillia a plug was observed as electron dense mechanism. This observation is rather similar to that ofMoore in the case of 2 Ascomycetes. The author believes these plugs are nuclei migrating through septa. This is because they are not enclosed by the endoplasmatic reticula.  相似文献   

11.
H Nikaido  J Reid 《Experientia》1990,46(2):174-180
The prokaryotic pore-forming proteins are synthesized in the cytoplasm, and are assembled in their functional form in the outer membrane. They begin to traverse the cytoplasmic membrane via the SecY/SecA export pathway, which is shared also by periplasmic proteins. The sorting signals that direct these proteins to the outer membrane could be present in the three-dimensional conformations of the proteins, but some results suggest that they may be present in short, contiguous sequences. Outer membrane proteins share a rather hydrophilic amino acid composition, and appear to be rich in beta-sheets (with the exception of lipoproteins). This observation as well as the demonstration of periplasmic export intermediates favor the secretion pathway through the periplasm, as opposed to export through fusion sites between the inner and the outer membrane, but such intermediates have not yet been observed with the wild type proteins under physiological conditions.  相似文献   

12.
Summary The activity of glutathione peroxidase decreases and that of catalase does not change during erythrocyte aging, as judged from a comparison of bovine red cell fractions separated by density.We are indebted to Prof. W. Leyko for many stimulating discussions.  相似文献   

13.
Making use of a source previously unknown to historians, this article sheds new light on the British expedition to the Sandwich Islands to observe the 1874 transit of Venus. This source, a series of caricature drawings that follow the expedition from departure to return, gives insight into expeditionary culture and the experience of a previously unremarked member of this astronomical expedition, Evelyn J.W. Noble, a career officer of the Royal Marine Artillery. It also reveals overlapping military, scientific and masculine identities, developed in dialogue with, and often deliberately subverting, more public accounts. The article explores this unique source as a product of naval, imperial and expeditionary cultures; as a contribution to the wide textual and visual culture that surrounded the transit expeditions; and as a series of drawings that united the expedition members through the use of humour and irony, by differentiating the group from others they encountered, and by reflecting or rejecting ideas about the nature of scientific work and personae. The artist represented himself not as a serving officer but as part of a (mostly) united group, dedicated to but humorously self-deprecating about their contribution to the scientific effort.  相似文献   

14.
Taken together with my previous articles [77], [80] devoted to the history of finite random sums and to Laplace's theory of errors, this paper sheds sufficient light on the whole work of Laplace in probability. Laplace's theory of probability is subdivided into theory of probability proper, limit theorems and mathematical statistics (not yet distinguished as a separate entity). I maintain that in its very design Laplace's theory of probability is a discipline pertaining to natural science rather than to mathematics. I maintain also the idea that the so-called Laplacian determinism was no hindrance to applications of his theory of probability to natural science and that one of his utterances in this connection could have well been made by Maxwell's contemporaries.Two possible reasons why the theory of probability stagnated after Laplace's work are singled out: the absence of new fields of application and, also, the insufficient level of mathematical abstraction used by Laplace. For all his achievements, I reach the general conclusion that he did not originate the theory of probability as it is now known. Dedicated to the memory of my Father, Boris A. Sheynin (1898–1975), the first generation of the Russian revolution Cette inégalité [Lunaire] quoique indiquée par les observations, était négligée par le plus grand nombre des astronomes, parce qu'elle ne paraissait pas résulter de la théorie de la pesanteur universelle. Mais, ayant soumis son existence au Calcul des Probabilités, elle me parut indiqués avec une probabilité si forte, que je crus devoir en rechercher la cause.(P. S. Laplace (Théor. anal. prob., p. 361))  相似文献   

15.
Phenylethanolamine, p-octopamine and m-octopamine contents were determined in the hypothalamus and the brain stem of spontaneously hypertensive Rats (S.H.R. Kyto) and the corresponding controls (Wistar Kyoto). In three-week-old Rats, phenylethanolamine and p-octopamine are found to be present in S.H.R. hypothalamus and brain stem at concentrations twice as high as compared to Wistar Kyoto Rats. The amount of m-octopamine is 5-fold higher in the brain stem of S.H.R. Rats as compared to Wistar Kyoto Rats.  相似文献   

16.
An enzyme, galactosyltransferase, able to catalyze the formation of galactose polymers was detected in cell-free extracts of a wild type strain of Neurospora crassa. Enzyme activity was found in both the supernatant and the particle fractions after centrifugation at 100,000 X g. The enzyme assayed in the 100,000 X g supernatant showed a 4fold difference in specific activity as compared to that found in the particle fraction.  相似文献   

17.
J P Rosenbusch 《Experientia》1990,46(2):167-173
Porin is a channel-forming, voltage-dependent protein of E. coli outer membranes. It exhibits relatively unspecific molecular sieve properties (exclusion size 600 Da). The trimer (110 kDa) consists of three identical polypeptides. Its secondary structure is mostly beta-structure, part of which can be visualized by electron microscopy to form a single beta-pleated sheet near the protein-lipid interface of the trimer. This folding pattern is significantly different from those of the reaction centers and of bacteriorhodopsin. Moreover, it contains many polar and ionizable side chains. It is argued that local as well as global electroneutrality, and complete saturation of the entire hydrogen bonding potential not only allow the protein to reside in the hydrophobic membrane core, but also confer upon it its unusual stability.  相似文献   

18.
Injection of a subconvulsive dose of strychnine (which blocked the inhibitory synapses) increases respiratory muscle activity evoked by stimulation of a sciatic nerve as well as by inhalation of hypercapnic gas mixture. Thus the inhibitory synapses prevent an excessive hyperventilation.  相似文献   

19.
A O Prakash 《Experientia》1979,35(8):1122-1123
Ethanolic extracts (50%), as well the benzene extracts, of H. rosa-sinensis Linn. have reduced significantly the glycogen contents in the uterus of adult rat. Both the extracts exhibit a clear-cut dose-response relation. The inhibition in glycogen contents increases as the dose is increased. Of the 2, benzene extract seems to be more potent. The results are due to antiestrogenic nature of the extracts.  相似文献   

20.
Rats with streptozotocin-induced diabetes mellitus showed a 3.4-4.5 times increased angiogenic response following mast-cell activation in situ as compared with age-matched normal controls. The test tissue used was the mesenteric window, which we have previously exploited as a quantitative angiogenesis assay. In the present study two independent techniques for quantifying the angiogenic response showed essentially the same result. The finding of a pathologically increased angiogenic reaction in the diabetic animals is noteworthy since some of the most harmful complications of diabetes in man relate to proliferative vascular lesions.  相似文献   

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