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101.
Summary In the subretinal space of albino mice, macrophages appear from the time of eye opening and increase in number for 6 months; thereafter they decline with age. Dark rearing retards the accumulation of these cells, and exposure to constant light results in a rapid increase. Observations suggest that macrophages appear as a response to visual cell decay in albino mice and supplement the phagocytic activity of the pigment epithelium.We thank R.K. Hawkins for efficient management of the animal colony, H.G. Jansen for cooperation in the use of electron microscope and Ms Paula van Alphen for help in preparation of the illustrations. 相似文献
102.
Zusammenfassung Es wird eine Reinigungsmethode beschrieben, die es erlaubt, aus einemB. stearothermophilus Zellaufschluss fünf thermophile Enzyme in reiner Form zu isolieren und weitere zwei Enzyme stark anzureichern. 相似文献
103.
Zusammenfassung Samenleiter und Samenblase vom Meerschweinchen besitzen eine besonders kräftige adrenergische Innervierung, die von Nervenzellen, die in unmittelbarer Nähe der Organe liegen, ausgeht.
This work has been supported by grants from the United States Public Health Service (NB 02854-04) and from Stiftelsen Magnus Bergvalls Minne. 相似文献
This work has been supported by grants from the United States Public Health Service (NB 02854-04) and from Stiftelsen Magnus Bergvalls Minne. 相似文献
104.
Zusammenfassung Die cancerostatischen Viscum-Proteine induzieren im Tierversuch mit geringsten Dosen eine Proliferation des Thymus und verhindern prophylaktisch das Angehen von Tumoren. Höhere Dosen zerstören dagegen den Immunapparat durch Überbeanspruchung und die Tumorhemmung bleibt aus.
We are indebted to the Deutsche Forschungsgemeinschaft for financial support (M. St.) and for granting a Forschungsfreijahr (F. V.). 相似文献
We are indebted to the Deutsche Forschungsgemeinschaft for financial support (M. St.) and for granting a Forschungsfreijahr (F. V.). 相似文献
105.
Ch. H. Stammer 《Cellular and molecular life sciences : CMLS》1964,20(8):417-418
Zusammenfassung Vond-Cycloserin ist die erste Schiffsche Base isoliert und charakterisiert worden. Bei Erhitzen in Äthylalkohol unterbleibt die Umlagerung in einen Cycloserindimerenabkömmling und ergibt Racemisierung. Es wird gefolgert, dass Aldehyde nicht auf das Stickstoffatom des Isoxazolidons reagieren und dass Dimerisation von Cycloserinnicht für die Reaktion mit Aldehyden erforderlich ist.
Cycloserine I. 相似文献
Cycloserine I. 相似文献
106.
Riassunto L'iniezione ad animali normali di ARN estratto dalla milza di animali immunizzati con antigene H diS. typhi, provoca la comparsa, nel siero degli animali riceventi, di anticorpi diretti contro tale antigene. 相似文献
107.
Cassan A Kubas D Beaulieu JP Dominik M Horne K Greenhill J Wambsganss J Menzies J Williams A Jørgensen UG Udalski A Bennett DP Albrow MD Batista V Brillant S Caldwell JA Cole A Coutures Ch Cook KH Dieters S Prester DD Donatowicz J Fouqué P Hill K Kains N Kane S Marquette JB Martin R Pollard KR Sahu KC Vinter C Warren D Watson B Zub M Sumi T Szymański MK Kubiak M Poleski R Soszynski I Ulaczyk K Pietrzyński G Wyrzykowski L 《Nature》2012,481(7380):167-169
Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17-30% (refs 4, 5) of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002-07) that reveals the fraction of bound planets 0.5-10?AU (Sun-Earth distance) from their stars. We find that 17(+6)(-9)% of stars host Jupiter-mass planets (0.3-10?M(J), where M(J) = 318?M(⊕) and M(⊕) is Earth's mass). Cool Neptunes (10-30?M(⊕)) and super-Earths (5-10?M(⊕)) are even more common: their respective abundances per star are 52(+22)(-29)% and 62(+35)(-37)%. We conclude that stars are orbited by planets as a rule, rather than the exception. 相似文献
108.
Late Pleistocene/Holocene wetland events recorded in southeast Tengger Desert lake sediments, NW China 总被引:4,自引:0,他引:4
D.B.Madsen CHENFahu Ch.G.Oviatt ZHUYan P.J.Brantinaham R.GoElston R.L.Bettinger 《科学通报(英文版)》2003,48(14):1423-1429
The area along the eastern and southeastern margins of the Tengger Desert, NW China, which is sensitive to the summer monsoon variations, was selected for studying the environmental conditions surrounding the transition between Paleolithic foragers and Neolithic farmer/pastoral-ists. Short cores were obtained from four lake basins in the southwestern Tengger using a hand-driven piston coringdevice. Proxies from these cores were supplemented by ra-diocarbon ages obtained from lake sediment cores, shoreline features and spring mound deposits. Together these records provide evidence of millennial-scale climate change eventsfrom the Pleistocene-Holocene transition to the present.Lake/wetland events, representing periods of more intensive summer monsoon, occur in the records at-12.7-11.6,-10.1, -9.3, -8.0, -5.4, -1.5, and -0.8 ka BP. They do suggest that century- to miliennial-seale climatic cycles are characteristic of the Holocene in the southeastern Tengger Desert although the chronology must be considered extremely tentative. 相似文献
109.
Summary Modern techniques which trace lineages of individual progenitor cells have provided some clues about the processes that determine cell fate in the brain, and have also given us some information about migratory patterns of clonally related cells. In many parts of the central nervous system, progenitors are multipotent; single clones can contain multiple neuronal types or even mixtures of neurons and glia. In addition, one can observe a wide distribution in clone size, even when marking is done in a narrow time window. This suggests that progenitor cells may be fairly plastic and responsive to environmental signals. In the developing cortex, clonally related cells are initially grouped near each other, as in the retina and tectum. However, the subsequent migration of these cells from the ventricular zone to the cortex along glial fibers is accompanied by a progressive dispersion of clonally related neurons. 相似文献
110.
W. H. Gerwick Ch. Mrozek M. F. Moghaddam S. K. Agarwal 《Cellular and molecular life sciences : CMLS》1989,45(2):115-121
A Caribbean cyanobacterium,Hormothamnion enteromorphoides, was found to produce a complex mixture of ichthyotoxic peptides, perhaps explaining the apparent absence of predation upon these potentially palatable life forms. Bioassay-guided fractionation was used to isolate these toxic and antimicrobial natural products, and a variety of techniques including HR FAB mass spectrometry, 2D-NMR, traditional hydrolysis-amino acid analysis, and several chemical reactions were used to define the basic structural features of the major peptide, hormothamnin A. Hormothamnin A is a cyclic undecapeptide containing six common and five uncommon or new amino acid residues. HPLC analyses indicate that the relative proportions of these peptide natural products remain relatively constant between different collection locations and years, however, they do vary seasonally. Clonal isolates of this cyanobacterium in culture produce the full spectrum of toxic peptides. 相似文献