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D. N. Wheatley 《Cellular and molecular life sciences : CMLS》1982,38(7):818-820
Summary Incorporation of amino acids into mammalian cell protein shows immediate linear kinetics when measured at intervals as small as 5 sec. Free amino acids equilibrate instantaneously across the cell membrane, acting as the precursor supply. Glycine, which does not initially show linear kinetics, may have a significant endogenous precursor supply, but this is not the acid-soluble pool.Acknowledgments. I thank the University of Aberdeen Medical Faculty Endowment Fund for support, and Mrs J. Robertson for technical assistance. 相似文献
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P-fluorophenylalanine and 'division-related proteins' 总被引:1,自引:0,他引:1
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Résumé L'arrêt de la métaphase se produit dans les cellules de HeLa S-3 au contact d'un milieu de tonicité accrue (>165 mM). L'accumulation optimale intervient à 277 mM lorsque du NaCl a été utilisé pour augmenter l'influence du milieu. Les effets de l'usage d'autres sels et d'autres types de cellules sont décrits. La dilution du milieu à 165 mM donne lieu à un arrêt synchrone du processus de la mitose dans les cellules et assure la conservation d'un bon synchronisme au cours de la division cellulaire suivante. 相似文献
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Ionic liquids and eutectic mixtures as solvent and template in synthesis of zeolite analogues 总被引:3,自引:0,他引:3
The challenges associated with synthesizing porous materials mean that new classes of zeolites (zeotypes)-such as aluminosilicate zeolites and zeolite analogues-together with new methods of preparing known zeotypes, continue to be of great importance. Normally these materials are prepared hydrothermally with water as the solvent in a sealed autoclave under autogenous pressure. The reaction mixture usually includes an organic template or 'structure-directing agent' that guides the synthesis pathway towards particular structures. Here we report the preparation of aluminophosphate zeolite analogues by using ionic liquids and eutectic mixtures. An imidazolium-based ionic liquid acts as both solvent and template, leading to four zeotype frameworks under different experimental conditions. The structural characteristics of the materials can be traced back to the solvent chemistry used. Because of the vanishingly low vapour pressure of ionic liquids, synthesis takes place at ambient pressure, eliminating safety concerns associated with high hydrothermal pressures. The ionic liquid can also be recycled for further use. A choline chloride/urea eutectic mixture is also used in the preparation of a new zeotype framework. 相似文献
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CONSTANS mediates between the circadian clock and the control of flowering in Arabidopsis 总被引:58,自引:0,他引:58
Flowering is often triggered by exposing plants to appropriate day lengths. This response requires an endogenous timer called the circadian clock to measure the duration of the day or night. This timer also controls daily rhythms in gene expression and behavioural patterns such as leaf movements. Several Arabidopsis mutations affect both circadian processes and flowering time; but how the effect of these mutations on the circadian clock is related to their influence on flowering remains unknown. Here we show that expression of CONSTANS (CO), a gene that accelerates flowering in response to long days, is modulated by the circadian clock and day length. Expression of a CO target gene, called FLOWERING LOCUS T (FT), is restricted to a similar time of day as expression of CO. Three mutations that affect circadian rhythms and flowering time alter CO and FT expression in ways that are consistent with their effects on flowering. In addition, the late flowering phenotype of such mutants is corrected by overexpressing CO. Thus, CO acts between the circadian clock and the control of flowering, suggesting mechanisms by which day length regulates flowering time. 相似文献
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Madhusudhan N Harrington J Stevenson KB Nymeyer S Campo CJ Wheatley PJ Deming D Blecic J Hardy RA Lust NB Anderson DR Collier-Cameron A Britt CB Bowman WC Hebb L Hellier C Maxted PF Pollacco D West RG 《Nature》2011,469(7328):64-67
The carbon-to-oxygen ratio (C/O) in a planet provides critical information about its primordial origins and subsequent evolution. A primordial C/O greater than 0.8 causes a carbide-dominated interior, as opposed to the silicate-dominated composition found on Earth; the atmosphere can also differ from those in the Solar System. The solar C/O is 0.54 (ref. 3). Here we report an analysis of dayside multi-wavelength photometry of the transiting hot-Jupiter WASP-12b (ref. 6) that reveals C/O?≥?1 in its atmosphere. The atmosphere is abundant in CO. It is depleted in water vapour and enhanced in methane, each by more than two orders of magnitude compared to a solar-abundance chemical-equilibrium model at the expected temperatures. We also find that the extremely irradiated atmosphere (T?>?2,500?K) of WASP-12b lacks a prominent thermal inversion (or stratosphere) and has very efficient day-night energy circulation. The absence of a strong thermal inversion is in stark contrast to theoretical predictions for the most highly irradiated hot-Jupiter atmospheres. 相似文献
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