排序方式: 共有42条查询结果,搜索用时 15 毫秒
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The use of hafnium-tungsten chronometry to date the Moon is hampered by cosmogenic tungsten-182 production mainly by neutron capture of tantalum-181 at the lunar surface. We report tungsten isotope data for lunar metals, which contain no 181Ta-derived cosmogenic 182W. The data reveal differences in indigenous 182W/184W of lunar mantle reservoirs, indicating crystallization of the lunar magma ocean 4.527 +/- 0.010 billion years ago. This age is consistent with the giant impact hypothesis and defines the completion of the major stage of Earth's accretion. 相似文献
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Lawrence J. Kleine DVM MS Christopher R. Lamb MA ETMB MRCVS 《Veterinary radiology & ultrasound》1989,30(3):133-141
Diagnostic radiology of the esophagus, stomach, small and large intestine, mesentery, and pancreas is reviewed. Survey and contrast radiography remain the principal imaging methods used to evaluate gastrointestinal diseases in animals. Of the other imaging techniques, scintigraphy has potential in assessment of esophageal and gastric motility disorders, and detection of intestinal hemorrhage. Ultrasonography is useful for imaging the pancreas and gastrointestinal mass lesions. 相似文献
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Christopher R. Lamb MA VetMB Lawrence J. Kleine DVM MS Majorie C. McMillan DVM 《Veterinary radiology & ultrasound》1991,32(5):211-220
A wide variety of normal and pathologic factors may induce intraabdominal calcification. In general, the most reliable indication of the cause of a calcification is its location; therefore, if the affected organ can be identified the radiographic diagnosis is often straightforward or, at least, limited to relatively few possibilities. With this principle in mind, a series of patients with abdominal calcification are described for the purpose of illustrating the appearance of calcification of various abdominal organs. In addition, etiology for the calcification in each patient is discussed. Certain extraabdominal calcifications which may be seen on abdominal radiographs are also mentioned. 相似文献
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Mhairi A. Sutherland Keith Erlandson Joe F. Connor Janeen L. Salak-Johnson Paul Matzat Jerry F. Smith John J. McGlone 《Livestock Science》2008,116(1-3):237-245
Loss of pigs during or after transport is a welfare concern, but also an economic concern for producers. Transport losses include animals that are dead on arrival (DOA) at the plant, pigs that are injured, and pigs which are not obviously injured but unwilling or unable to walk (non-ambulatory, non-injured or NANI). The objective of this research was to assess the health of non-ambulatory, non-injured (NANI) pigs relative to control pigs at the processing plant by looking at a range of measures, including complete blood chemistry, anatomy, and pathology to determine potential factors associated with pigs going down. Data were collected from NANI and control pigs at five plants in the midwest USA. Feet and legs and internal organs were inspected and the severity of the pathology scored. Alveolar macrophages were collected and counted. Blood was collected for analysis of hematology, blood chemistry and cortisol concentrations. Titers to common porcine respiratory viruses were measured in pigs from one plant. Hoof and pad problems did not differ overall between control and NANI pigs, however the percentage of severe foot problems was greater (P < 0.05) in NANI compared with control pigs at plants A and E. The percentage of total ulcers, rhinitis, and empty stomachs differed (P < 0.05) between control and NANI pigs at individual plants, but not overall. Blood hematology and chemistry differed (P < 0.05) between NANI and control pigs. Cortisol concentrations did not differ between NANI and control pigs. Titers to swine influenza virus (SIV) H1N1 and H3N2 and porcine circovirus (PCV) were lower (P < 0.01) among NANI compared with control pigs. However, more (P < 0.01) NANI pigs were positive for SIV H1N1 and H3N2 compared with control pigs. Blood hematology, chemistry, and pathology indicate a large difference between NANI and controls pigs. No single health problem was higher among NANI pigs compared to plant-matched control pigs. Rather, several problems appear to contribute to pigs becoming NANI which may differ from one plant too another. 相似文献