Keeping up     

Vives SP 《Science (New York, N.Y.)》1984,224(4648):446

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Soviet science     

Boas HP 《Science (New York, N.Y.)》1984,224(4648):446

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Kin recognition     

Bateson P 《Science (New York, N.Y.)》1984,224(4648):446

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Atomic physics before 1920: the infancy of atomic physics     

Galison P 《Science (New York, N.Y.)》1984,225(4659):307

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Esoteric Math Has Practical Result: A new method of computer graphics relies on math results that seemed so abstruse that they were never published     

Kolata G 《Science (New York, N.Y.)》1984,225(4661):494-495

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Effect of photoperiod on gonadotrophin concentrations in domestic turkeys     

Patricia M. M. Godden  C. G. Scanes 《British poultry science》1977,18(6):687-694

1. Circulating immunoreactive luteinising hormone (LH) and follicle stimulating hormone (FSH) concentrations have been measured during photoperiodically‐induced changes in the reproductive state of turkeys.

2. In a period of sexual quiescence on short photoperiods (6L : 18D) LH concentrations were higher during the hours of darkness in both sexes.

3. Transfer to long photoperiods (16L : 8D) stimulated a rapid increase in LH and FSH concentrations. This was maintained for between 2 to 3 months when the concentrations of both gonadotrophins decreased as the birds became photorefractory.

4. Return to short photoperiods had no immediate effect on the concentrations of LH and FSH in females. The concentration of LH was increased during the 3rd week of short photoperiods when the hens were moulting.

5. LH concentrations fluctuated during the ovulatory cycle and were highest about 6 h before ovulation.  相似文献   

Hydrolysed feather protein as a source of amino acids for broilers     

R. MaCalpine  C. G. Payne 《British poultry science》1977,18(3):265-273

1. The inclusion of 25 g hydrolysed feather meal (HFM) in each kilogram of diet (floor experiment) and 60 g/kg (cage experiment) did not depress performance.

2. Chemical tests indicated 72.5% of the total lysine in HFM was available.

3. Total lysine concentration of 11.3 g/kg diet maximised performance during the period 0 to 34 d.

4. Reduction in dietary methionine content during the period 0 to 34 d from 4.2 g/kg to 3.2 g/kg did not depress performance on diets containing 60 g HFM/kg.

5. The results indicate that at least 57% by weight of the total sulphur amino acid requirement of broilers can be provided by cystine.  相似文献   

Biochemical,physiological and production indices related to fat metabolism in the laying fowl at various stages of physiological development     

A. R. Neill  K. G. Reichmann  J. K. Connor 《British poultry science》1977,18(3):315-324

1. The significance of fat accumulation during physiological development of layers was studied using White Leghorn x Australorp pullets from 12 weeks of age.

2. Liver fat, carcass fat, liver weight and body weight increased markedly at the onset of sexual maturity.

3. Within the liver, the protein to DNA ratio did not alter significantly during development; glycogen was not consistently depleted by egg production.

4. Liver fat content was significantly correlated with carcass fat, liver weight and DNA concentration, and plasma total lipid and cholesterol, independent of stage of development; with body weight, liver protein, moisture, and protein to DNA ratio, excluding the period prior to commencement of sexual maturation; and with plasma phospholipid during lay.

5. Obesity was a feature of faster growing fowls which matured earlier, consumed more, utilised food less efficiently for egg production and produced fewer saleable eggs.  相似文献   

Nitrate and nitrite: origin in humans     

Witter JP  Gatley SJ  Balish E 《Science (New York, N.Y.)》1979,205(4413):1335-1337

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Vapor phase explosions: elementary detonations?     

Fowles GR 《Science (New York, N.Y.)》1979,204(4389):168-169

Although liquid-vapor explosions are widely observed, there is no established explanation for their initiation and propagation. Thermodynamics admits the possibility that superheated liquids can support detonations analogous to those that occur in chemical explosives. For liquid methane superheated 50 K above its boiling point at 1 atmosphere, the energy of explosion is 2 to 3 percent of that of TNT.  相似文献