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171.
AJ Castro-Tirado J Gorosabel N Benitez C Wolf R Fockenbrock E Martinez-Gonzalez H Kristen A Broeils H Pedersen J Greiner E Costa M Feroci L Piro F Frontera L Nicastro E Palazzi C Bartolini A Guarnieri N Masetti A Piccioni M Mignoli M Wold M Lacy K Birkle T Broadhurst al et 《Science (New York, N.Y.)》1998,279(5353):1011-1014
An optical transient within the error box of the gamma ray burst GRB 970508 was imaged 4 hours after the event. It displayed a strong ultraviolet excess, and reached maximum brightness 2 days later. The optical spectra did not show any emission lines, and no variations on time scales of minutes were observed for 1 hour during the decline phase. According to the fireball and afterglow models, the intensity should rise monotonically before the observed optical maximum, but the data indicate that another physical mechanism may be responsible for the constant phase seen during the first hours after the burst. 相似文献
172.
To obviate the destructive interaction of highly reactive metallocene catalysts with classical silica-based supports while retaining the advantage of supported catalysts, a noninteracting polystyrene support was developed. Supported catalysts for the polymerization of alpha-olefins are prepared by treating lightly cross-linked, chloromethylated polystyrene beads consecutively with a secondary amine, an ammonium salt of a weakly coordinating anion, and a neutral dialkylmetallocene. Catalytic sites are distributed homogeneously throughout the support particle, and the polymerization occurs within the bead, in contrast to traditional surface-supported metallocene catalysts. The copolymerization of ethylene and 1-hexene at 40 degreesC affords discrete spherical polyolefin beads with a size (0.3 to 1.4 millimeters) that varies according to the polymerization time. 相似文献
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A 6 year old pluriparous Merino ewe was presented for investigation of a large intra-abdominal mass. Post-mortem examination revealed a 360° clockwise uterine torsion was present with a mummifying fetus. The torsion involved the left ureter resulting in a severe hydroureteronephrosis. Uterine torsion is uncommon in the ewe, occurring in less than 0.1% of pregnancies in one report (Mahmoud et al. Livest Res Rural Dev 2018;30), but cases are likely to be undiagnosed, particularly under the extensive management conditions typical of Australia. The chronicity of the condition in this ewe would support this statement. To the authors' knowledge this is the first reported case of hydroureteronephrosis secondary to uterine torsion in any species. 相似文献
175.
CB O''SULLIVAN AJ DART N MALIKIDES RJ RAWLINSON DR HUTCHINS DR HODGSON 《Australian veterinary journal》1999,77(8):501-503
OBJECTIVE: To evaluate nonsurgical management of type II fractures of the distal phalanx in Standardbred horses. DESIGN: Retrospective study of 48 affected horses. RESULTS: Most fractures occurred on the lateral palmar process of the left forelimb or the medial palmar process of the right forelimb; 81% of horses were considered sound enough to return to training and 63% raced. Of those returning to racing, 41% competed in > 10 races, 37% in 2 to 10 races and 22% in only 1 race. There was no difference in performance before and after fracture. Twenty-four of 25 horses had a bar shoe fitted for > 50% of the treatment phase. Of those horses returning to training without a bar shoe, 89% refractured at the same site. Sixty percent of horses returning to training with a bar shoe raced successfully. The total convalescent time, the time rested in a box and the time spelled in a paddock were similar for horses returning to racing and those that did not. The age of the horse had no effect on the ability to return to racing. CONCLUSION: The prognosis for type II fractures of the distal phalanx is guarded. It is advisable to fit a bar shoe on the horse during convalescence. Horses returning to training and racing with a bar shoe appear less likely to refracture the distal phalanx. Those horses that return to racing can perform at a level similar to that prior to fracture. 相似文献
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Egil AJ Fischer Gert-Jan Boender Gonnie Nodelijk Aline A de Koeijer Herman JW van Roermund 《Veterinary research》2013,44(1):58