熔喷过程湍流模型中的气流场数值模拟     

李建国  特铮 《沈阳农业大学学报》2007,38(4):631-633

以熔喷过程中的气流场为核心,建立熔喷过程的数学物理模型,采用数值模拟的方法进行研究。以Navier-Stocks方程为基础,应用基于同位网格的SIMPLER算法并行化计算气流场的速度分布,将试验测试值与数值模拟进行比较,结果表明:采用的数值模拟方法是有效的,完全可以用于模拟双槽钝头型模具的熔喷过程。  相似文献   

Ulcerative mycosis: a serious menhaden disease of the southeastern coastal fisheries of the United States   总被引：1，自引：0，他引：1  

M. J. DYKSTRA  J. F. LEVINE  E. J. NOGA  J. H. HAWKINS  P. GERDES  W. J. HARGIS JR  H. J. GRIER  D. TE STRAKE 《Journal of fish diseases》1989,12(2):175-178

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玉米大斑病菌对广州地区甜玉米的致病性观测   总被引：2，自引：1，他引：2       下载免费PDF全文

周伯扬; 谢伟烈  谢壮锋; 特拉康 《玉米科学》2004,12(1):090-092

通过对桂甜和华珍两个甜玉米品种的玉米大斑病病斑扩展速率及病情指数的研究结果表明,不同品种对玉米大斑病菌的抗性存在明显的差异;病斑的产孢特性显示,病斑首次产孢量显著高于再次产孢量。通过比较不同温度下的菌丝生长量,分析出广州地区玉米大斑病菌的主要构成属于高温型。  相似文献   

Determination of the median toxic dose of type C botulinum toxin in lactating dairy cows.     

Robert B Moeller  Birgit Puschner  Richard L Walker  Tonie Rocke  Frank D Galey  James S Cullor  Alex A Ardans 《Journal of veterinary diagnostic investigation》2003,15(6):523-526

Because of the difficulty in identifying botulinum toxin in cattle, it is hypothesized that cattle are sensitive to levels of toxin below the detection limits of current diagnostic techniques (the mouse protection bioassay and the immunostick enzyme-linked immunosorbent assay [ELISA] for type C botulinum toxin). Using an up-down method for toxicologic testing, the median toxic dose (MTD50) for cattle was determined. Four lactating Holstein cows were dosed at 0.125 or 0.25 ng/kg with Clostridium botulinum type C toxin and failed to develop clinical signs of botulism during the 7-day observation period. Three cows given 0.50 ng/kg of toxin developed clinical signs of botulism. From these results, the MTD50 was calculated at 0.388 ng/kg (3.88 mouse lethal doses/kg) using the trim-logit method. These results suggest that cattle are 12.88 times more sensitive to type C botulinum toxin than a mouse on a per kilogram weight basis. The mouse protection bioassay and the immunostick ELISA for type C botulinum toxin failed to identify the presence of the toxin in the serum, blood, and milk samples taken from all 7 animals.  相似文献   

虫生真菌在准格尔旗沙棘木蠹蛾上的流行   总被引：1，自引：0，他引：1  

彭凡  黄勃  周根土  特木钦  王瑛凯  李增智 《经济林研究》2007,25(4):38-40,49

为了了解沙棘木蠹蛾Holcocerus hippophaecolus幼虫的虫生真菌的物种多样性和流行情况,对内蒙古准格尔旗某沙棘林中的虫生真菌进行了调查,采集到11个虫生真菌标本。经实验室显微观察鉴定,其中1个为雷州被毛孢Hirsutella leizhouensis侵染,1个为一种被毛孢Hirsutella sp.侵染,9个为球孢白僵菌Beauveria bassiana侵染;分离纯化得到7株球孢白僵菌菌株。  相似文献   

浅析伊图里河林业局森林资源消长趋势     

特木 《内蒙古林业调查设计》2007,30(2):17-18,74

文章通过对伊图里河林业局1994年、2005年两次二类调查数据的分析,详细阐述了森林资源消长变化总趋势,在此基础上对伊图里河林业局森林资源现状及其特点进行了分析,提出了对森林资源管理利用的建议。  相似文献   

Improving the Well-being of Animals in the Research Environment     

TE Jones 《Australian veterinary journal》1996,74(2):139-139

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Spatial analysis of seroconversion of sentinel cattle to bluetongue viruses in Queensland     

MP WARD  TE CARPENTER  SJ JOHNSON 《Australian veterinary journal》1996,74(2):128-131

Objective To assess quantitatively the spatial distribution of seroconversion of Queensland cattle to bluetongue viruses.
Design A sentinel herd study. Sample population Sixty-nine sentinel herds at 30 locations.
Procedure Spatial clustering of seroconversion to blue-tongue viruses was investigated during the period from 1990 to 1994.
Results Seroconversion to only two bluetongue virus serotypes, 1 and 21, was observed. The 14 herds, in which seroconversion to bluetongue virus serotype 1 was detected, were located only along the eastern coastal and subcoastal region of Queensland, and were significantly (P < 0.05) clustered. Locations at which seroconversion to serotype 21 was detected, were not significantly clustered. The results generally agree with field observations, except for the failure to detect seroconversion to bluetongue viruses in north-western Queensland.
Conclusion Bluetongue infection of cattle in north-western Queensland may be temporally sporadic. The dominance of serotype 1 in the Queensland cattle population may be the result of differential transmission by potential vector species. Long-term surveillance programs are important for defining disease status of animal populations.  相似文献   

A cross-sectional study to show Eperythrozoon ovis infection is prevalent in Western Australian sheep farms   总被引：4，自引：0，他引：4  

MJ KABAY  RB RICHARDS  TE ELLIS 《Australian veterinary journal》1991,68(5):170-173

A serological survey and risk factor study was conducted to estimate the prevalence of Eperythrozoon ovis infection in Western Australian weaner sheep, the prevalence of farms with infected sheep, and to identify factors affecting initiation and maintenance of infection on the farm. The study was conducted on 91 farms, purposively chosen from 41 randomly selected regional shires stratified by sheep number and rainfall zones. Twenty sheep were selected systematically from a mixed-sex flock on each farm and tested for serum antibody to E ovis using an enzyme-linked immunosorbent assay. Information on putative risk factors was collected using an interview questionnaire. Antibody to E ovis was detected in 4.5% of sheep on 47% of the farms sampled. The prevalence of E ovis infection in sheep was estimated at the 95% confidence level to be between 3.6 and 5.5%, and the prevalence of farms with infected sheep was estimated to be between 37.5 and 56.5%. Most farms with serological evidence of infection occurred in the Great Southern agricultural region (79.5%), south-east of Perth through to Albany (latitude 32 to 34 degrees S, longitude 116 to 120 degrees E), and in the Northern region (12.8%) surrounding Geraldton (latitude 29 degrees S, longitude 114 degrees E). There were significantly more farms (P less than 0.05) with evidence of infection in the Great Southern region compared to the Central region between Geraldton and Perth, and on farms in the region south compared to north of latitude 32 degrees S. None of the putative risk factors examined in the questionnaire were associated with serological evidence of infection on the farm.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Food insecurity, weight control practices and body mass index in adolescents     

Gulliford MC  Nunes C  Rocke B 《Public health nutrition》2006,9(5):570-574

OBJECTIVE: We investigated whether experienced food insecurity was associated with weight control behaviour of adolescents. DESIGN: A national survey of 16-year-old students with the six-item food security scale, questions concerning intentions of trying to change weight, physical activity patterns, and measurement of height and weight. SETTING: Representative sample of 29 schools in Trinidad, West Indies. SUBJECTS: Data analysed for 1903 subjects including 1484 who were food-secure and 419 who were food-insecure. RESULTS: In the whole sample, food security status did not vary by body mass index (BMI) category. 'Trying to gain weight' and 'spending most free time in activities involving little physical effort' were each associated with lower BMI. 'Trying to gain weight' was more frequent in food-insecure subjects (135, 32%) than in food-secure subjects (369, 25%, P = 0.012). After adjustment for BMI, age, sex, ethnicity and socio-economic variables, the adjusted odds ratio (OR) of 'trying to gain weight' for food-insecure subjects was 1.39 (95% confidence interval (CI) 1.07-1.82, P = 0.014). Food-insecure subjects (197, 47%) were more likely than food-secure subjects (575, 39%) to report that most of their free time was spent doing things that involved little physical effort (P = 0.003). This association was not explained by adjustment for BMI, age, sex and ethnicity (OR = 1.41, 95% CI 1.13-1.76, P = 0.002) or additional socio-economic variables (OR = 1.27, 95% CI 1.02-1.57, P = 0.033). CONCLUSIONS: Adolescents who experience food insecurity are more likely to intend to gain weight but engage in less physical activity than food-secure subjects with the same BMI.  相似文献