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1.
Summary Two pyridine bases were isolated from the marine hoplonemertineAmphiporus angulatus (Fabricius) and identified by mass and PMR-spectroscopy as 2,3-bipyridyl and 3,2; 3,2; 4,3'-tetrapyridyl (Nemertelline). Nemertelline, the first tetrapyridyl natural product to be reported, shows a structural resemblance to the tobacco constituent nicotelline. The crustacean toxicity of 2,3-bipyridyl is very similar to that of nicotine, but its mammalian toxicity is negligible.We thank DoctorsN. Meinkoth andN. Riser for collecting specimens, Dr.F. Kuffner for providing the nicotelline sample, Dr.C. Westerman for recording initial PMR-spectra, and Dr.R. King for furnishing the computer simulation program and recording the high resolution mass spectra, and Mr.J. Babashak for use of the Kontes densitometer. This research was supported by an NIH-GRS grant and by the Veterans Administration (No. MRIS-9416).  相似文献   

2.
Conclusion Geminus account of lunar motion in chapter 18 of hisIntroductio astronomiae is, in our view, an important contribution to Greco-Latin astronomy because, in attempting to reconstruct arithmetically (the parameters of) the Moon's motion in longitude, he undermines the task astronomers had hitherto set for themselves. This undermining of a commonly acknowledged view of the purpose of astronomy is articulated in a whole new set of questions concerning the nature and place of both observation and mathematical reasoning in the science of the heavens. Yet, one must not overlook the fact thatGeminus reconstruction also indicates resources for addressing these questions. Of these resources, the most powerful proved to be the idea that irregular motion could be quantified as a systematic departure from a mean motion, and the idea that observational data could be organized and structured by means of genetic arithmetical reconstructions.But, since we limit our attention to extant treatises and decline to speculate about works or parts of works that have not survived, we must say that it would takePtolemy to discern the new direction for astronomy thatGeminus opened up and to pursue it. In part, this involved straightening out the conflated conception of mean motion in chapter 18 — the qua arithmetic mean daily displacement can only be anapparent lunar motion in longitude and not one the Moonreally makes, but the same need not be true of the qua periodic mean daily displacement — and determining its proper relation to real and apparent planetary motion. Indeed,Ptolemy's genius lay, we think, in seeing that even though, in assimilating Babylonian astronomy, earlier and contemporary Greco-Latin writers betrayed a confused, inconsistent, and unsophisticated grasp of the proper role of arithmetic, geometry, and observation in astronomical argument [seeBowen 1994], the solution lay in a mathematical reconstruction of the observed celestial motions, in which mean motion played an essential role.  相似文献   

3.
A historical sketch is given of Wallis's infinite product for 4/, and of the attempts which have been made, over more than three centuries, to find the method by which Brouncker obtained his equivalent continued fraction. A derivation of Brouncker's formula is given. Early results obtained by Indian mathematicians for the series for /4, later named for Leibniz, are reviewed and extended. A conjecture is made concerning Brouncker's method of obtaining close bounds for .  相似文献   

4.
Zusammenfassung -Pyrrolo-l-alanin, dessen Synthese beschrieben ist, hemmt das Wachstum vonE. coli B auf synthetischen Nährböden. Die Hemmung wird vonl-Phenylalanin undl-Tyrosin vollständig, vonl-Tryptophan teilweise, nicht aber von Histidin aufgehoben. Stämme vonE. coli, die gegen-Pyrrolo-l-alanin bzw.p-Fluorophenyl-dl-alanin resistent sind, zeigen gekreuzte Resistenz.  相似文献   

5.
Zusammenfassung Die Rotationsdispersionskurven einiger optisch aktiver Dekalonderivate sind gemessen worden. Ihre Amplituden (a) und die Amplitudenbeiträge (a) der Substituenten werden im Rahmen der Oktantenregel diskutiert.

Paper V of the series Optical Rotatory Dispersion. For Paper IV seeC. Djerassi andW. Klyne, Proc. Nat. Acad. Sci. Washington, in press (1962).  相似文献   

6.
Résumé L'inoculation intraveineuse d'albumine humaine (HA), provoque chez le cobaye l'apparition d'un anticorps (-1) sensibilisant les cellules mast (CM) homologues. L'inoculation dans le coussinet plantaire (HA et adjuvant de Freund complet) fait apparaître deux anticorps: l'un (-2) sensibilisant les CM hétérologues, l'autre (dans le-1 ainsi que dans le-2) sensibilisant les CM homologues.

We thank Mrs.Nava Raz, Mrs.Tamar Minai and Mr.I. Ofek for technical assistance.  相似文献   

7.
Summary The inhibiting effect of orally administered N-[d-6-methyl-8-isoergolin-I-yl], N, N-diethylurea (VÚFB-6638) on the production of milk was found in rats. The inhibition of lactation was ascertained through the observation of the daily weightgains of the suckled puppies (ED50=0.112 mg/kg/day) and through the observation of the presence of milk in the stomach of these puppies, as seen through their abdomen wall (0.084 mg/kg/day). This inhibition could be abolished with exogenous prolactin, which gives evidence that the drug studied acts via the endocrine system.

Für die technische Assistenz danken wir FrauM. Kommersová und FrauV. Maitová.  相似文献   

8.
Summary The rate of turnover of individual P-compounds, related to the metabolic cycle of some phosphatides, was followedin vivo in the brain of rats a few days old after32P administration. The phosphorylcholine is the precursor of the cytidinediphosphatecholine; this in turn may be the precursor of lecithin. Thel--glyceryl-phosphorylcholine represents the degredation product of lecithin. The specific activity curves of the phosphorylethanolamine and phosphorylse rine are similar to that of the phosphorylcholine; likewise thel--glycerylphos-phorylethanolamine is similar to the activity curve of thel--glycerylphosphorylcholine.  相似文献   

9.
Summary Formulae are fitted to the different sets of values, given by the translators, for the equation of centre for the motion of the moon according to the Romaka Siddhnta, as found in the Pañcasiddhntik of Varha Mihira.  相似文献   

10.
Résumé On décrit une methode pour la synthèse des -brazan et -brazanquinone deKruber.  相似文献   

11.
Summary The contribution of Bayes to statistical inference has been much discussed, whereas his evaluations of the beta probability integral have received little attention, and Price's improvements of these results have never been analysed in detail. It is the purpose of the present paper to redress this state of affairs and to show that the Bayes-Price approximation to the two-sided beta probability integral is considerably better than the normal approximation, which became popular under the influence of Laplace, although it had been stated by Price.The Bayes-Price results are obtained by approximating the skew beta density by a symmetric beta density times a factor tending to unity for n , the two functions having the same maximum and the same points of inflection. Since the symmetric beta density converges to the normal density, all the results of Laplace based on the normal distribution can be obtained as simple limits of the results of Bayes and Price. This fact was not observed either by Laplace or by Todhunter.  相似文献   

12.
Résumé Des épithéliums de muqueuse vésicale de chien, de cobay et de hamster ont été greffés sur des souris préalablement traitées à l'acétate de cortisone. L'induction par ces greffes d'un cartilage et d'un tissu osseux prouve que l'inducteur d'ossification formé et libéré par ces épithéliums manque de spécificité générique. On a montré que le faible pourcentage de l'induction d'ossification est imputable à la faible capacité inductive de cet épithélium et non au manque de sensibilité du tissu conjonctif induit de la souris dans le système allogénique.

We thank MissS. Skaryska, Mrs.E. Ruszkowska and Mr.T. Grabiski for technical assistance and Mr.B. Przybysz for preparing photographs.  相似文献   

13.
Summary The inhibition of RNA synthesis by -amanitin on vitro cultured cells is very slow. The action of various analogues of the toxin was tested and some of them proved more effective. Moreover pretreatment of cell cultures with DEAE-dextran greatly enhanced the effect of -amanitin.Acknowledgments. We thank ProfessorTh. Wieland and Dr.H. Faulstich (Max-Planck-Institut, Heidelberg) for the generous gift of amanitins. This investigation was supported by grant No. 74.00637.65 from C.N.R. (Roma).  相似文献   

14.
Résumé Les membranes plasmatiques des tissus adipeux brun et blanc sont isolées de la fraction microsomale selon une modification de la technique décrite parKamat etWallach 8. Les résultats de l'analyse enzymatique démontrent un degré de purification satisfaisant des membranes plasmatiques et des microsomes.

This work was supported by a grant from the Fonds national suisse de la Recherche scientifique.  相似文献   

15.
Summary Intercisternal injections of-aminobutyric acid,l-asparagin,l-glutamine,l-leucine andl-norleucine exert a strong leukotactic action and in dogs result after a short time in a maximum cell increase of 76,000/3 cells.  相似文献   

16.
Summary With the aid of the differential interference contrast microscope (systemNomarski), the pollen grains ofAlnus rugosa were examined. The characteristic surface structure, the arci and certain structures in the vestibules of the pores are thus very clearly visible. A further use of this microscopic method may be possible for the investigation of pollen grains.  相似文献   

17.
Résumé L'exo--(13) glucanasem isolée duBasidiomycete QM 806 a été utilisée avec succès pour l'analyse des polysaccharides de la paroi cellulaire de la levureSaccharomyces cerevisiae et pour la formation de protoplastes à partir deSaccharomyces cerevisiae etWickerhamia fluorescens.

Acknowledgments. We are indepted to MissE. Sigarlakie and MissE. Wespi for technical assistance during the course of this investigation.  相似文献   

18.
Zusammenfassung Es wird gezeigt, dass die Natriumund Wasserausscheidung hypophysektomierter Ratten durch ein Hypophysenhinterlappenextrakt korrigiert werden kann. Es handelt sich dabei nicht um ADH und das natriuretische Prinzip scheint auch vom Oxytozin verschieden zu sein.

The present results and conclusions were discussed in detail by one of the authors (B. L.) in his Purkynje Lecture on Interaction of hormonal and non-hormonal mechanisms of the body fluids volume regulation at the XIXth Meeting of the Czechoslovak Physiological Society, held in Prague on January 26–28, 1972.

Acknowledgments. We wish to thank Mrs.E. Blaková for her skilled technical assistance.  相似文献   

19.
Zusammenfassung Ein parkinsonähnliches Syndrom von Akinesie, Rigidität und Tremor wurde in Ratten durch Reserpin induziert. Gleichzeitig mit dem Auftreten der Rigidität wurde die spontane Aktivität der einzelnen -Efferenen zum Stillstand gebracht, weil die monosynaptischen Reflexe gesteigert geworden waren. Das reserpininduzierte akinetische Syndrom stellt also eine -Rigidität dar.Die Ähnlichkeit der Wirkung vonl-DOPA auf das reserpininduzierte Syndrom und das Parkinsonsyndrom bei Menschen lässt eine gemeinsame Pathophysiologie vermuten.  相似文献   

20.
Résumé L'acide-amino-butyrique et la-alanine reproduisent l'action du transmetteur inhibiteur du système neuromusculaire de l'écrevisse. Ces deux acids aminés diminuent la contraction musculaire. L'acide-amino-butyrique réduit la différence de potentiel et augmente sa décomposition. L'action de ces acides aminés est bloquée par la picrotoxine comme l'est celle du transmetteur inhibiteur.

The study was supported by Grants B-1089 and B-31 from the National Institute of Neurological Diseases and Blindness, United States Public Health Service. Some of this work was done at the Department of Zoology, Cornell University. We are grateful to Prof.S. C. Wang, Columbia University, for generous assistance.  相似文献   

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