Ramifications of work experience: work and personality     

Campbell RT 《Science (New York, N.Y.)》1984,224(4649):594-595

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Solution of a protein crystal structure with a model obtained from NMR interproton distance restraints     

Brünger AT  Campbell RL  Clore GM  Gronenborn AM  Karplus M  Petsko GA  Teeter MM 《Science (New York, N.Y.)》1987,235(4792):1049-1053

Model calculations were performed to test the possibility of solving crystal structures of proteins by Patterson search techniques with three-dimensional structures obtained from nuclear magnetic resonance (NMR) interproton distance restraints. Structures for crambin obtained from simulated NMR data were used as the test system; the root-mean-square deviations of the NMR structures from the x-ray structure were 1.5 to 2.2 A for backbone atoms and 2.0 to 2.8 A for side-chain atoms. Patterson searches were made to determine the orientation and position of the NMR structures in the unit cell. The correct solution was obtained by comparing the rotation function results of several of the NMR structures and the average structure derived from them. Conventional refinement techniques reduced the R factor from 0.43 at 4 A resolution to 0.27 at 2 A resolution without inclusion of water molecules. The partially refined structure has root-mean-square backbone and side-chain atom deviations from the x-ray structure of 0.5 and 1.3 A, respectively.  相似文献   

Galilean satellites of jupiter: 12.6-centimeter radar observations     

Campbell DB  Chandler JF  Pettengill GH  Shapiro II 《Science (New York, N.Y.)》1977,196(4290):650-653

Observations of the Galilean satellites with the radar system at the Arecibo Observatory, Puerto Rico, show that their surfaces are highly diffuse scatterers of radio waves of length 12.6 centimeters; spectra of the radar echoes are asymmetric and broad. The geometric radar albedos for the outer three satellites-0.42 +/- 0.10, 0.20 +/- 0.05, and 0.09 +/- 0.02 for Europa, Ganymede, and Callisto, respectively-show about the same relative decreases as do the optical albedos, although the latter presumably bear only on material much nearer the surface. Radii of 1420 +/- 30, 2640 +/- 80, and 2360 +/- 70 kilometers for Europa, Ganymede, and Callisto were determined from the radar data and are in good agreement with the corresponding optically derived values. Io, observed successfully only once, appears to have an albedo comparable to Ganymede's, but no radius was estimated for it.  相似文献   

Genetic engineering of livestock   总被引：20，自引：0，他引：20  

V G Pursel  C A Pinkert  K F Miller  D J Bolt  R G Campbell  R D Palmiter  R L Brinster  R E Hammer 《Science (New York, N.Y.)》1989,244(4910):1281-1288

Genetic engineering of livestock is expected to have a major effect on the agricultural industry. However, accurate assessment of the consequences of transgene expression is impossible without multigenerational studies. A systematic study of the beneficial and adverse consequences of long-term elevations in the plasma levels of bovine growth hormone (bGH) was conducted on two lines of transgenic pigs. Two successive generations of pigs expressing the bGH gene showed significant improvements in both daily weight gain and feed efficiency and exhibited changes in carcass composition that included a marked reduction in subcutaneous fat. However, long-term elevation of bGH was generally detrimental to health: the pigs had a high incidence of gastric ulcers, arthritis, cardiomegaly, dermatitis, and renal disease. The ability to produce pigs exhibiting only the beneficial, growth-promoting effects of growth hormone by a transgenic approach may require better control of transgene expression, a different genetic background, or a modified husbandry regimen.  相似文献   

Venus volcanism: initial analysis from magellan data     

Head JW  Campbell DB  Elachi C  Guest JE  McKenzie DP  Saunders RS  Schaber GG  Schubert G 《Science (New York, N.Y.)》1991,252(5003):276-288

Magellan images confirm that volcanism is widespread and has been fimdamentally important in the formation and evolution of the crust of Venus. High-resolution imaging data reveal evidence for intrusion (dike formation and cryptodomes) and extrusion (a wide range of lava flows). Also observed are thousands of small shield volcanoes, larger edifices up to several hundred kilometers in diameter, massive outpourings of lavas, and local pyroclastic deposits. Although most features are consistent with basaltic compositions, a number of large pancake-like domes are morphologically similar to rhyolite-dacite domes on Earth. Flows and sinuous channels with lengths of many hundreds of kilometers suggest that extremely high effusion rates or very fluid magmas (perhaps komatiites) may be present. Volcanism is evident in various tectonic settings (coronae, linear extensional and compressional zones, mountain belts, upland rises, highland plateaus, and tesserae). Volcanic resurfacing rates appear to be low (less than 2 Km(3)/yr) but the significance of dike formation and intrusions, and the mode of crustal formation and loss remain to be established.  相似文献   

THE ORIGIN OF LAND PLANTS     

Campbell DH 《Science (New York, N.Y.)》1930,72(1860):177-187

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HUMAN NATURE AS A REPEATING FACTOR: THAT THRICE TOLD TALE     

Campbell WW 《Science (New York, N.Y.)》1921,53(1366):211-212

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Avian and Mammalian mitochondrial ammonia-detoxifying systems in tortoise liver     

Campbell JW  Smith DD  Vorhaben JE 《Science (New York, N.Y.)》1985,228(4697):352-351

Liver mitochondria from the desert tortoise Gopherus agassizii and the Texas tortoise G. berlandieri contain glutamine synthetase, the enzyme used by birds and higher reptiles to detoxify ammonia generated intramitochondrially during amino acid catabolism. Tortoise mitochondria also contain carbamyl phosphate synthetase-I and ornithine transcarbamylase, the enzymes used by mammals for this purpose. Since chelonid reptiles have changed little since their divergence from the stem reptiles, this finding suggests that both systems were present in the latter before the emergence of the ruling reptile, avian, and mammalian lines of descent.  相似文献   

OBSERVATIONS ON THE SOLAR ECLIPSE MADE BY THE CROCKER EXPEDITIONOF THE LICK OBSERVATORY     

Campbell WW 《Science (New York, N.Y.)》1918,48(1228):34-35

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Auroral Display     

Campbell JT 《Science (New York, N.Y.)》1892,20(495):65-66

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