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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Kerr RA 《Science (New York, N.Y.)》1983,219(4589):1205-1206
992.
Shurcliff WA 《Science (New York, N.Y.)》1983,221(4613):808-810
993.
994.
995.
Gingerich PD 《Science (New York, N.Y.)》1983,222(4620):159-161
Rates of morphological evolution documented in laboratory selection experiments, historical colonization events, and the fossil record are inversely related to the interval of time over which they are measured. This inverse relationship is an artifact of comparing a narrow range of morphological variation over a wide range of time intervals, and it is also a product of time averaging. Rates measured over different intervals of time must be scaled against interval length before they can be compared. 相似文献
996.
997.
998.
Intensive microearthquake swarms with the appearance of volcanic tremor have been observed in the southwest part of Long Valley caldera, southeastern California. This activity, possibly associated with magma injection, began 6 weeks after several strong (magnitude 6+) earthquakes in an area south of the caldera and has continued sporadically to the present time. The earthquake sequence and magmatic activity are part of a broad increase in tectonic activity in a 15,000-square-kilometer region surrounding the "White Mountains seismic gap," an area with high potential for the next major earthquake in the western Great Basin. 相似文献
999.
Keane DP Horney FD Ogilvie TH 《The Canadian veterinary journal. La revue veterinaire canadienne》1983,24(2):57-59
A four day old Holstein calf was presented with a history of recurrent free gas bloat. An exploratory laparotomy was performed and no abnormalities were discovered in the gastrointestinal tract. An esophagotracheal fistula was suspected and confirmed by endoscopy. Surgical correction was performed by ligating the tubular connection between the trachea and esophagus and suturing closed the defects in these structures. 相似文献
1000.
Barber SM McLaughlin BG Fretz PB 《The Canadian veterinary journal. La revue veterinaire canadienne》1983,24(2):46-49
A one month old Quarterhorse colt was presented after a week history of bilateral nasal discharge and respiratory difficulty. The cervical esophagus was greatly dilated, tortuous and filled with diluted milk. A nasogastric tube could not be passed beyond the base of the heart. An aspiration pneumonia was found at postmortem examination and the esophageal segment from the pharynx to the base of the heart was dilated, thin-walled, had degenerative muscular changes, and a reduction in size and number of ganglion cells of the myenteric plexus. Muscular hypertrophy of the terminal esophagus had reduced its lumen size. Some similarities and disparities of this condition to achalasia of man and megaesophagus of dogs are discussed. 相似文献