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101.
Pineal gland: influence on gonads of male rats treated with androgen 3 days after birth 总被引:1,自引:0,他引:1
Either blinding or the injection of 1 milligram of testosterone propionate into male Sprague-Dawley rats, 3 days old, results in testes and accessory organs (seminal vesicles and coagulating glands) that are smaller than normal when the rats are 72 days old. The response to blinding is prevented by removal of the pineal gland, whereas the response to treatment with testosterone is unaffected by pinealectomy. Combination of the two treatments in 3-day- old rats causes testes to be less than one-third their normal size at 72 days of age; pinealectomy in these rats permits the reproductive organs to grow to the same size as those in the androgen-treated animals. 相似文献
102.
Hoffman M 《Science (New York, N.Y.)》1991,252(5009):1070
103.
104.
Comment on "Retrieval practice produces more learning than elaborative studying with concept mapping" 总被引:1,自引:0,他引:1
Mintzes JJ Canas A Coffey J Gorman J Gurley L Hoffman R McGuire SY Miller N Moon B Trifone J Wandersee JH 《Science (New York, N.Y.)》2011,334(6055):453; author reply 453
Karpicke and Blunt (Reports, 11 February 2011, p. 772) reported that retrieval practice produces greater gains in learning than elaborative studying with concept mapping and concluded that this strategy is a powerful way to promote meaningful learning of complex concepts commonly found in science education. We question their findings on methodological and epistemological grounds. 相似文献
105.
The study of magnetic phase transitions in insulating molecular solids provides new insights into mechanisms of magnetic coupling in the solid state and into critical phenomena associated with these transitions. Only a few such materials are known to display cooperative magnetic properties. The use of high-spin molecular components would enhance intermolecular spin-spin interactions and thus a series of chargetransfer (CT) salts have been synthesized that utilize the spin S = 1 molecular cation, [Mn(C(5)(CH(3))(5))(2)](+) (decamethylmanganocenium). The structure and cooperative magnetic behavior of [Mn(C(5)(CH(3))(5))(2)](+)[TCNQ(-) (decamethylmanganocenium 7,7,8,8-tetracyano-p-quinodimethanide) are reported. This salt is a bulk molecular ferromagnet with the highest critical (Curie) temperature (T(c) = 6.2 K) and coercive field (3.6 x 10(3) gauss), yet reported for such a material. 相似文献
106.
107.
Levan AJ Tanvir NR Cenko SB Perley DA Wiersema K Bloom JS Fruchter AS Postigo Ade U O'Brien PT Butler N van der Horst AJ Leloudas G Morgan AN Misra K Bower GC Farihi J Tunnicliffe RL Modjaz M Silverman JM Hjorth J Thöne C Cucchiara A Cerón JM Castro-Tirado AJ Arnold JA Bremer M Brodie JP Carroll T Cooper MC Curran PA Cutri RM Ehle J Forbes D Fynbo J Gorosabel J Graham J Hoffman DI Guziy S Jakobsson P Kamble A Kerr T Kasliwal MM Kouveliotou C Kocevski D Law NM Nugent PE Ofek EO Poznanski D 《Science (New York, N.Y.)》2011,333(6039):199-202
Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray-selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any γ-ray burst, whereas its peak luminosity was ~100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a rare mechanism involving the massive black hole in the nucleus of that galaxy. 相似文献
108.
Identification by ENDOR of Trp191 as the free-radical site in cytochrome c peroxidase compound ES 总被引:8,自引:0,他引:8
The chemical identity of the amino acid free-radical site that represents one of the two oxidizing equivalents stored in the H2O2-oxidized intermediate (compound ES) of the mitochondrial heme enzyme, cytochrome c peroxidase (CcP) has been sought for almost a quarter of a century. Site-directed mutagenesis alone cannot yield this answer. Low-temperature 35-gigahertz (Q-band) electron nuclear double resonance (ENDOR) spectroscopy was used to examine compound ES prepared from proteins containing specifically deuterated methionine or tryptophan, as well as the amino acid replacement Trp51----Phe. The results definitely identify the site of the radical in compound ES as tryptophan, most likely Trp191. 相似文献
109.
"Superantigens" may shed light on immune puzzle 总被引:2,自引:0,他引:2
M Hoffman 《Science (New York, N.Y.)》1990,248(4956):685-686
110.
How parents make their mark on genes 总被引:1,自引:0,他引:1
M Hoffman 《Science (New York, N.Y.)》1991,252(5010):1250-1251