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排序方式: 共有159条查询结果,搜索用时 15 毫秒
91.
猪舍内气流变化的模拟研究 总被引:6,自引:0,他引:6
圈养动物舍内的气流变化对于室内的污染物扩散起到非常关键的作用,采用基于有限容积方法的计算流体动力学(CFD)软件对建于奥胡斯大学农业工程研究所空气物理实验室中的1:12.5猪舍模型内的气流进行了稳态和三维模拟。将模拟的气流速度与室内一个参考点的实际测试速度进行了对比,同时分析了气流入口不同紊流动能及扩散率取值对室内测试参考点气流速度模拟值的影响。结果表明,模拟值与测试值的相对误差在0.4%~11.4%之间。 相似文献
92.
He L Lu XY Jolly AF Eldridge AG Watson SJ Jackson PK Barsh GS Gunn TM 《Science (New York, N.Y.)》2003,299(5607):710-712
mahoganoid is a mouse coat-color mutation whose pigmentary phenotype and genetic interactions resemble those of Attractin (Atrn). Atrn mutations also cause spongiform neurodegeneration. Here, we show that a null mutation for mahoganoid causes a similar age-dependent neuropathology that includes many features of prion diseases but without accumulation of protease-resistant prion protein. The gene mutated in mahoganoid encodes a RING-containing protein with E3 ubiquitin ligase activity in vitro. Similarities in phenotype, expression, and genetic interactions suggest that mahoganoid and Atrn genes are part of a conserved pathway for regulated protein turnover whose function is essential for neuronal viability. 相似文献
93.
One hundred veterinarians and 100 breeders of traditionally docked dogs from Queensland were surveyed by telephone to determine their attitudes towards tail docking. Eighty-four percent of the breeders surveyed were in favour of docking, whereas 83% of veterinarians were opposed to the practice. Most pups were docked between 1 and 3 days of age. All veterinarians surgically amputated the tail, whereas 16% of breeders applied rubber bands to the tail. Seventy-six percent of the veterinarians, but only 18% of the breeders believed that docking caused significant to severe pain. No veterinarians, but 25% of the dog breeders believed that docking was painless. Although recent changes to the Queensland Canine Control Council's rulings allow dogs with intact tails to be shown in traditionally docked classes, the requirement of breed standard was cited as the major reason for tail docking by both breeders and veterinarians. 相似文献
94.
Introduction of Pinus radiata for afforestation: a review with reference to Aba, China 总被引:3,自引:0,他引:3
BIHui-quan JackSimpson LIRong-wei YANHong WUZong-xing CAIShi-min RobertEldridge 《林业研究》2003,14(4):311-322
Pinus radiata D. Don, native to a Californian coastal environment, has been introduced to many parts of the world as an exotic species for afforestation. It is now a major plantation species in the Southern Hemisphere. In 1990, it was introduced to the heavily degraded, dry Min river valley area in Aba prefecture of Sichuan Province, P. R. China. Survival and growth of young trees planted at several sites appear to be reasonable. This review is to serve as an introduction to the large body of literature on P.radiata for forest scientists in China. It covers the following aspects: P. radiata in its native environment and in ex situ plantations,provenance and genetic variations, environmental limitations and climate niche, diseases and pests, lessons from unsuccessful introductions, and the use of P. radiata for ecological restoration. The early growth of P. radiata planted in the dry river valley area is briefly described. Potential problems associated with the introduction of P. radiata in Aba and future research needs are also identified. 相似文献
95.
Fifteen controlled field trials were conducted to evaluate the efficacy against gastrointestinal nematodes and safety of ivermectin when applied topically to cattle in Australia. Three hundred and fifty-one cattle received ivermectin, and 88 were untreated controls. The trials were conducted in 3 States and included a variety of cattle breeds and environmental conditions. Faecal samples were collected before treatment and 11 to 14 days after treatment for nematode egg counts. Data from these trials show that under Australian conditions, ivermectin applied along the mid line of the back from the withers to the sacral region at a dose rate of 500 mcg/kg body weight, effectively controlled gastrointestinal nematode infections, and did not produce unacceptable adverse reactions in the animals. 相似文献
96.
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98.
Ages of prehistoric earthquakes revealed by cosmogenic chlorine-36 in a bedrock fault scarp at hebgen lake 总被引:3,自引:0,他引:3
Cosmogenic chlorine-36 reveals dates of the multiple prehistoric earthquakes that have produced a scarp on the Hebgen Lake fault. Apparent chlorine-36 ages are stratigraphically correct, follow a predicted theoretical pattern, and produce geologically reasonable model ages of 24, 20, 7.0, 2.6, 1.7, and 0.4 thousand years ago. This result demonstrates the feasibility of using cosmogenic chlorine-36 to extract paleoearthquake records from bedrock fault scarps. 相似文献
99.
Abstract CASE HISTORY: In 2008, six lambs within a flock of Dorpercross sheep were born with musculoskeletal and neurological disease. Clinical signs included hindlimb weakness, and urinary incontinence. CLINICAL FINDINGS: All lambs had focal, inverted areas of alopecic skin over the caudal sacrum, and short, often kinked tails. Four affected lambs were subject to euthanasia, and necropsied. On gross examination, the arches of sacral vertebrae were absent, and spinal nerves and meninges were adherent to the overlying subcutis. Other gross lesions included narrow, elongated skulls, herniation of the occipital lobes into the caudal fossas, hydrocephalus, and syringomyelia. One lamb had coning of the cerebellar vermis, but cerebellar herniation through the foramen magnum was not identified. DIAGNOSIS: Spina bifida, with associated malformations of the central nervous system. CLINICAL RELEVANCE: Examination of breeding records suggested either an autosomal recessive or partially penetrant autosomal dominant pattern of inheritance. Because of the associated tail lesions it is proposed that the pathogenesis of this syndrome involves a defect in development of the tail bud (secondary neurulation), that tethering of the spinal cord resulted in the clinical signs, and abnormal pressure of the cerebral spinal fluid resulted in the defects in the skull and brain. 相似文献
100.
In 2009–2010, an unusual lymphoproliferative disease was identified in multiple siblings from successive litters of Manx cats, suggesting a genetic predisposition to development of this disease. Presentation of disease in the cats had multiple similarities with the human disease ALPS, a rare inherited disorder that causes persistent lymphoproliferation, together with variable manifestations of autoimmunity and increased susceptibility to neoplasia. The majority of human ALPS patients have inherited Fas gene mutations, causing defective apoptosis of lymphocytes, although for a proportion of ALPS patients the underlying genetic mutations remain unknown. In order to identify the likely mode of inheritance of the disease, further matings of potential carrier cats are in progress. Studies to investigate the potential role of abnormalities in the Fas gene in the development of the disease in cats are also proposed. Identifying and further characterising the nature and mechanism of the disease in cats may allow better understanding of the development, progression, and treatment of ALPS in humans. 相似文献