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Joseph Samuel Hepburn 《Journal of The Franklin Institute》1915,179(5):581-585
The power to survive prolonged exposure to low temperatures is possessed by various enzymes, including those producing hydrolysis of fats, of carbohydrates, and of proteins, those concerned in biochemical oxidations and reductions, the clotting enzymes and that of alcoholic fermentation. The enzymes retained their catalytic power after exposure, either in situ or in solution in vitro, to temperatures varying from a few degrees above 0° C. to the temperature of liquid air (?180° to ?191° C.). The shortest periods of holding, invariably less that one day and usually less than one hour, were at the temperature of liquid air. The longest period of holding was eighty-nine months at a temperature of ?9.4° to ?12.2° C.The activity of certain of these enzymes, including rennin, zymase, and those hydrolyzing fats, carbohydrates, and proteins, has been studied at low temperatures, varying from that of an ice-box to one of ?9° to ?12° C. While the enzymes produced autolytic digestion or acted on artificial media at these temperatures, the velocity of the reaction was always lessened to a considerable degree. 相似文献
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Interchange - Positive behaviour for learning (PBL) was introduced to the state education sector in Queensland in the early 2000s in an effort to move schools away from use of punitive disciplinary... 相似文献
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Joseph S. Hepburn 《Journal of The Franklin Institute》1917,183(2):244-245
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Joseph S. Hepburn 《Journal of The Franklin Institute》1920,189(5):676-677
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Joseph S. Hepburn 《Journal of The Franklin Institute》1927,203(6):870-871
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Joseph S. Hepburn 《Journal of The Franklin Institute》1934,218(5):643
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This study inquires into the influence of subject communities on the practice of secondary school teachers as they teach a new science and technology course that crosses traditional subject and department boundaries. The study focuses on two teachers from different professional communities—a science teacher and a technology teacher—who were teaching an applied physics course that was piloted in British Columbia. Interview and observational data were collected that illuminate the classroom practices and perspectives of the two teachers. As the teachers taught the course, they both changed their normal teaching practice. Their respective new practices, however, were different in important ways even though they both started with the same course outline, textbooks, and laboratory materials. We interpret these differences in the teachers' practices using sociocultural practice theory and argue that the differences can be understood in terms of the influence of their different professional communities which are shown to provide the backdrops against which the teachers developed their approaches to the course. Recommendations are made that encourage using the subject community as a unit of analysis in educational change studies and using sociocultural practice theory as a theoretical perspective for thinking about educational change and making policy decisions. © 1998 John Wiley & Sons, Inc. J Res Sci Teach, 35: 777–789, 1998. 相似文献