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991.
  相似文献   
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Podney W  Sager R 《Science (New York, N.Y.)》1979,205(4413):1381-1382
Fluctuating magnetic gradients over oceans come from electric currents flowing in seawater arising from its motions across the earth's magnetic field. Gradients of 0.3 to 0.6 picoteslas per meter for each meter of internal wave displacement have been measured at frequencies of 2 to 5 millihertz with a superconductive magnetic gradiometer supported 7 meters above the surface of water 18 meters deep about 1.5 kilometers offshore from San Diego, California.  相似文献   
994.
High electric fields have been used to extract organic cations from solutions of small organic molecules in polyphosphoric acid. The cations have been analyzed by mass spectrometry. Production of ions by this method is shown to be related to ease of protonation by acid rather than to ionization potential.  相似文献   
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Nuclear physics     
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999.
1. Agonistic interactions were observed over a 24‐week period in Rhode Island Red and in Nigerian local fowl aged 32 weeks or 12 weeks at the start of the experiments.

2. Agonistic interactions were both more numerous and more severe (fights and peck avoidances) in groups of the local breed than in those of Rhode Island Reds.

3. The outcome of severe interactions favoured local males and Rhode Island females in the first experiment and Rhode Island males in the second.

4. Small body and comb size might account for the relatively high number of agonistic interactions and the submissiveness of local females and young males while physical strength or some other breed characteristic might account for the high number of agonistic interactions of local males as well as their dominance in breed encounters.  相似文献   

1000.
1. The effect of restricted feeding on performance and carcass characteristics of broilers was determined in three experiments.

2. In the first experiment, removal of food for 8 h/d from 42 to 56 d of age significantly improved food conversion efficiency of broilers on deep litter. Removal of food for 16 h/d or on alternate days tended to cause slower growth and also improved conversion efficiency.

3. In the second experiment, denial of food for 8 h/d did not significantly affect either growth rate or conversion efficiency of caged broilers. Denial of food on alternate days, from 28 d of age, depressed food intake and growth rate. Food restriction decreased dressing percentage regardless of the age of introduction. With 32, 40 or 48 h food denial each 72 h there was a large depression in growth rate and dressing percentage. Carcass dry matter was also less, indicating less carcass fat, when food was denied for 48 h each 72 h.

4. In the third experiment, growth rate of broilers on deep litter was significantly improved by denying food for 8 h/d from 28 d of age, and was significantly depressed by food denial on alternate days. This depression was significantly more severe if restriction started at 28 d rather than at 42 d of age. Conversion efficiency was not significantly improved by denial for 8 h/d.

5. In the last two experiments conversion efficiency was much worse in severe restriction.  相似文献   

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