Ice Cap of 30 Million Years Ago Detected: The oxygen isotopes of marine sediments are providing strong indirect evidence of an Antarctic ice cap twice as ancient as the present one     

Kerr RA 《Science (New York, N.Y.)》1984,224(4645):141-142

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Quaternary geology: the pleistocene     

Bloom AL 《Science (New York, N.Y.)》1984,225(4659):307-308

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An Encouraging Long-Term Quake "Forecast": The anticipation of the size and location of last April's Morgan Hill earthquake was two-thirds of a prediction; predicting a precise time remains out of reach     

Kerr RA 《Science (New York, N.Y.)》1984,225(4659):300-301

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The deepest hole in the world     

Kerr RA 《Science (New York, N.Y.)》1984,224(4656):1420

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Carbon Dioxide and the Control of Ice Ages: A varying greenhouse effect may provide the leverage needed by Earth's orbital variations to control the 100,000-year ice-age cycle     

Kerr RA 《Science (New York, N.Y.)》1984,223(4640):1053-1054

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Monopoles: magnetic monopoles     

Harvey JA 《Science (New York, N.Y.)》1984,223(4641):1170

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A doctrine in practice: informed consent     

Robertson JA 《Science (New York, N.Y.)》1984,226(4677):960

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Growth Stasis and Limited Shell Calcification in Larvae of Cymatium parthenopeum During Trans-Atlantic Transport     

Pechenik JA  Scheltema RS  Eyster LS 《Science (New York, N.Y.)》1984,224(4653):1097-1099

Larvae of the shallow-water marine gastropod Cymatium parthenopeum show no appreciable shell calcification and no demonstrable growth as they disperse across the Atlantic Ocean. Evidence of what appears to be physiological specialization for prolonged delay of metamorphosis was found in larvae of this prosobranch gastropod.  相似文献   

Antimicrobial substances and chick growth promotion: The growth‐promoting activities of antimicrobial substances,including fifty‐two used either in therapy or as dietary additives     

J. Bunyan  L. Jeffries  Jessica R. Sayers  A. L. Gulliver  K. Coleman 《British poultry science》1977,18(3):283-294

1. Fifty‐five antimicrobial substances were tested for their ability to promote growth when added to the diet of chicks.

2. Both cephalosporins and all the nine penicillins tested were active.

3. Of six aminoglycosides, streptomycin and gentamicin had the greatest activity and neomycin had none.

4. Growth rate was significantly improved by clindamycin, lincomycin, vancomycin, spectinomycin, rifampicin, oxytetracycline, chlortetracycline, erythromycin, tylosin, flavomycin, virginiamycin and zinc bacitracin. Chloramphenicol and nalidixic acid were inactive. Polymixin B, novo‐biocin, cycloserine, phosphonomycin, and sodium fusidate had little activity. Fusidic acid promoted growth at 250 mg/kg diet.

5. Trimethoprim was inactive alone and in combination with sulpha‐diazine. Of seven 5‐nitroimidazoles, only dimetridazole and metronidazole showed slight activity. Of the six 5‐nitrofurans, only nitrovin, the standard reference substance used, promoted growth.

6. Caprylohydroxamic acid, a urease inhibitor, had no beneficial effect on growth rate or on the efficiency of food conversion.

7. The growth‐promoting properties of the various substances could not be related with their known antimicrobial and absorption characteristics in mammals.  相似文献   

Diurnal patterns of feeding and activity in laying hens in relation to dietary restriction and cage shape     

B. O. Hughes  A. J. Black 《British poultry science》1977,18(3):353-360

1. The diurnal feeding pattern and motor activity of medium‐weight hybrid hens housed in groups of four were observed. Cages of two shapes were compared: conventional deep cages (406 × 457 mm) and shallow cages (610 × 305 mm).

2. Birds in conventional deep cages were more active than those in shallow cages in each of four different periods of day. Activity reached a peak between 11.00 and 13.00 h irrespective of cage shape.

3. Mean feeding activity was greater in the shallow (45.6%) than in the conventional deep cages (39.9%).

4. Mean feeding activity was greater in birds fed ad libitum (43.3%) than in those fed on a restricted diet (40.4%).

5. Although restricted birds in shallow cages showed more feeding activity than those in conventional deep cages they consumed less food (56% against 67%) in the 7 h between supply of their daily ration and the onset of the dark period.

6. Feather damage was greater in the conventional deep cages than in the shallow cages.

7. The more efficient utilisation of food by hens in shallow cages is probably due largely to three factors: reduced levels of motor activity and general disturbance, a more leisurely eating pattern and better feather cover.  相似文献