腐蚀管道剩余寿命的性能衰减模型研究   总被引：4，自引：0，他引：4  

姜如桦  张鹏  陈莉琼  侯向秦 《油气储运》2001,20(11):13-16

管道在长期的运行过程中，由于介质和土壤的腐蚀性，管材的微塑性变形、结构转变和渗氢等。不仅会使管道出现各种腐蚀损伤，而且还存在着老化效应和氢化作用，导致管材的脆变并改变材料的塑性，使机械性质参数发生衰退，从管材性能衰减和腐蚀损伤角度研究了管道的剩余寿命，提出了根据结构承载能力的极限值确定塑性变形时工作寿命的方法，为了确定剩余使用寿命，对剪切损伤率和屈服性能比等概念进行定义，在掌握管材金属剪切损害率和屈服性能比的时间特性基础上，建立了剩余寿命计算模型。并给出了算例。  相似文献   

Hyperadrenocorticism associated with excessive sex hormone production by an adrenocortical tumor in two dogs.     

H M Syme  J C Scott-Moncrieff  N G Treadwell  M F Thompson  P W Snyder  M R White  J W Oliver 《Journal of the American Veterinary Medical Association》2001,219(12):1725-8, 1707-8

An 11-year-old spayed female Labrador Retriever and a 9-year-old castrated male miniature Poodle were evaluated because of clinical signs of hyperadrenocorticism. Cortisol testing did not support a diagnosis of hypercortisolemia in either dog; however, imaging studies revealed unilateral adrenal tumors in both dogs. Serum concentrations of 17-hydroxyprogesterone, progesterone, and estradiol were high in both dogs, and androstenedione concentrations were also high in 1 dog. It is suspected that sex hormone secretion by the adrenal tumors in these dogs resulted in clinical signs of hyperadrenocorticism. Clinical signs and hormonal abnormalities resolved in the male dog after surgical resection of the tumor. There was no improvement in clinical signs after treatment with mitotane in the female dog, which died 2 months after diagnosis. Histologic evaluation confirmed the presence of adrenocortical carcinoma in both dogs.  相似文献   

Milking the golden cow--her comfort.     

S L Berry 《Journal of the American Veterinary Medical Association》2001,219(10):1382-1387

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No effect of turkey herpesvirus infections on the outcome of avian pneumovirus infections in turkeys.     

S Van de Zande  H Nauwynck  M Pensaert 《Avian diseases》2001,45(2):517-521

To determine whether turkey herpesvirus (HVT) impairs the aspecific and specific defense against an avian pneumovirus (APV) infection, specific-pathogen-free turkeys were inoculated at 7 days of age with HVT and 1, 5, or 7 wk later with APV. Clinical signs, APV replication, and development of antibodies against APV were evaluated. No differences were found between the birds that received both HVT and APV and those that received only APV.  相似文献   

Quality Assurance Handbook for Veterinary Laboratories          下载免费PDF全文

John H. Lumsden 《The Canadian veterinary journal. La revue veterinaire canadienne》2001,42(7):567

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Stickstoffdetoxifikation bei künstlich ernährten Zn-Mangelratten     

Von H.-P. Roth 《Journal of animal physiology and animal nutrition》2001,85(5-6):158-163

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Effects of Benzyl Adenine and Abscisic Acid on Grain Yield and Yield Components in Triticale and Wheat     

T. Sivakumar  Virendranath  & G. C. Srivastava 《Journal of Agronomy and Crop Science》2001,186(1):43-46

Grain yield and yield components (grains per ear, grain weight, 1000-grain weight, ear weight, ear seed ratio and dry matter partitioning between ear and seed) were examined in a wheat genotype (PBW-343) with well-filled grains and a Triticale genotype (DT-46) with poorly filled grains (showing grain shrivelling) grown in pots. Six days after anthesis (DAA), benzyladenine (BA) @2 µg ear⁻¹ and abscisic acid (ABA) @4 µg ear⁻¹ were injected at the base of the mother shoot ear in both species. It was observed that, in both wheat and Triticale , BA increased the grain weight, grain number and partitioning of dry matter between ear and seed, whereas ABA decreased the grain weight, grain number and dry matter partitioning between ear and seed. However, these decreases were slower in Triticale than in wheat. BA treatment increased the grain dry matter accumulation, which in turn resulted in better filling of grains and increased the grain weight in both wheat and Triticale . The average grain weight of Triticale was lower than that of wheat. Thus, it appears that variation in grain weight between wheat and Triticale might be due to different availabilities of growth-promoting phytohormones such as cytokinins and assimilates.  相似文献   

Squamous cell carcinoma of the oral, pharyngeal and nasal mucosa in the horse     

J C Schuh 《Veterinary pathology》1986,23(2):205-207

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A primer of conversion genetics     

R.H. Marrs 《Biological conservation》2005,125(1):139

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Trends in mortality ratios among cattle in US feedlots.     

G H Loneragan  D A Dargatz  P S Morley  M A Smith 《Journal of the American Veterinary Medical Association》2001,219(8):1122-1127

OBJECTIVE: To evaluate trends in feedlot cattle mortality ratios over time, by primary body system affected, and by type of animal. DESIGN: Retrospective cohort study. ANIMALS: Approximately 21.8 million cattle entering 121 feedlots in the United States during 1994 through 1999. PROCEDURES: Yearly and monthly mortality ratios were calculated. Numbers of deaths were modeled by use of Poisson regression methods for repeated measures. Relative risks of death over time and by animal type were estimated. RESULTS: Averaged over time, the mortality ratio was 12.6 deaths/1,000 cattle entering the feedlots. The mortality ratio increased from 10.3 deaths/1,000 cattle in 1994 to 14.2 deaths/1,000 cattle in 1999, but this difference was not statistically significant (P = 0.09). Cattle entering the feedlots during 1999 had a significantly increased risk (relative risk, 1.46) of dying of respiratory tract disorders, compared with cattle that entered during 1994, and respiratory tract disorders accounted for 57.1% of all deaths. Dairy cattle had a significantly increased risk of death of any cause, compared with beef steers. Beef heifers had a significantly increased risk of dying of respiratory tract disorders, compared with beef steers. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that although overall yearly mortality ratio did not significantly increase during the study, the risk of death attributable to respiratory tract disorders was increased during most years, compared with risk of death during 1994. The increased rates of fatal respiratory tract disorders may also reflect increased rates of non-fatal respiratory tract disorders, which would be expected to have adverse production effects in surviving animals.  相似文献