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The reproductive cycle in Belding ground squirrels was studied in the Sierra Nevada Mountains at two locations, one at 2,100 m elevation, the other at 3,000 m. Adults emerged from hibernation completely prepared physiologically for reproduction. Males tended to emerge slightly ahead of females and yearlings tended to emerge later than adults. Yearling females were fertile but produced smaller litters than adults, 4.48 vs. 6.31. Yearling males were infertile. They exhibited a slight seasonal cycle in testicular growth but did not reach sexual maturity. Testicular growth and spermatogenesis were incipient in many adults and in yearlings prior to hibernation. 相似文献
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Summary Sleep deprivation was associated with decreased stature and it blunted the normal 24-h rhythm in young and in middle-aged men. Loss in stature was regained during the first recovery night of sleep. The 24-h rhythm in height is not an endogenous circadian rhythm but depends upon the periods of recumbency over the sleep/wake cycle.Acknowledgments. The first author was a Medical Research Council scholar; the second was supported by the Scottish Hospital Endowments Research Trust. 相似文献
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R. E. Morton 《Cellular and molecular life sciences : CMLS》1990,46(6):552-560
Summary The hydrophobic lipid components of lipoproteins, cholesteryl ester and triglyceride, are transferred between all lipoproteins by a specific plasma glycoprotein, termed lipid transfer protein (LTP). LTP facilitates lipid transfer by an exchange process in which cholesteryl ester and triglyceride compete for transfer. Thus, LTP promotes remodeling of the lipoprotein structure, and plays an important role in the intravascular metabolism of these particles and in the lipoprotein-dependent pathways of cholesterol clearance from cells. The properties of LTP, its mechanisms of action, its roles in lipoprotein metabolism, and its modes of regulation are reviewed along with recent data that suggest a possible role for this protein in directly modifying cellular lipid composition. 相似文献
46.
Three abundance classes in HeLa cell messenger RNA 总被引:68,自引:0,他引:68
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Early pregnancy factor is immunosuppressive. 总被引:2,自引:0,他引:2
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Summary 3, 16-diacetoxy-5-pregnane-20-one and the analogue pregn-5-ene derivative have been converted into (22R, 25R)-22, 26-imino-5-cholestane-3, 16-diol. The configuration at C-22 and C-25 was determined by transformation into the known (22R, 25R)-5-solanidane-3-one. Application of the Ruschig method led to (25R)-22,26-imino-5-cholest-22(N)-ene-3, 16-diol.
Solanum-Alkaloide. XVI. Mitteilung. — XV. Mitteilung:K. Schreiber undH. Ripperger, Tetrahedron Letters Nr.27, 9 (1960). 相似文献
Solanum-Alkaloide. XVI. Mitteilung. — XV. Mitteilung:K. Schreiber undH. Ripperger, Tetrahedron Letters Nr.27, 9 (1960). 相似文献
50.
Reaction of gold with collagen in vivo 总被引:1,自引:0,他引:1