新型电控液驱车辆燃油经济性计算与分析

利用系统辨识的原理建立发动机数学模型,建立了电控液驱车辆不同行驶状态下的燃油经济性计算模型。采用基于MATLAB/Simulink语言编写计算程序进行仿真分析,通过实例计算得出了电控液驱车辆不同行驶工况下的燃油消耗指标,与传统车辆进行比较,电控液驱车辆具有明显的节能效果。     

临床上宠物犬难产病例的调查研究

调查了临床上母犬难产的原因，并分析了40例病历，结果表明：发生难产的犬品种以北京犬和博美犬多见，年龄以1-2岁多发，营养过剩、运动少的犬易发生难产，难产原因以胎儿过大为主。     

农村体育和谐发展模式及其运行机制研究

从系统论角度,运用逻辑推理、因果分析等方法对农村体育和谐发展的基本内涵、影响因子及其运行机制进行了深层次阐述,认为农村体育和谐发展系统总体运行效果,是农村体育和谐发展系统各影响因子相互协调程度,以及该系统的发展潜力和人为调控和谐发展的能力的综合体现。     

农业类专业校内经营性实训基地运作机制的思考与实践

经营性校内实训基地是一种更能体现陶行知“教学做合一”教育思想的产学结合模式.本文阐述了校内经营性实训基地的内涵,分析了目前农业类专业校内经营性实训基地运作中的诸多矛盾,从运作机制构建角度的提出了五条措施,在此基础上开展了的实证研究.     

Vertebral Fractures in Newborn Calves

A prospective study on vertebral fractures in newborn calves is described. Vertebral fractures were found in 7.0% of necropsied calves of the Danish Holstein-Friesian (SDM) and Red Danish Dairy (RDM) breeds. Cases were not found in submitted calves of the Jersey breed or beef breeds. At least in beef breeds this was probably due to the low number necropsied. The rate of vertebral fractures in SDM and RDM breeds and between males and females were similar. Most cases occurred in calves born by heifers, and manual traction force had been applied in all cases. All fractures which in most cases consisted of a simple epiphysiolysis were located at the thoraco-lumbar area, and especially the posterior epiphysis of T13 was afflicted.     

Risk factors for dystocia in farmed red deer (Cervus elaphus).

OBJECTIVE: To analyse data from a study of deer herd health and productivity to identify potential risk factors for the occurrence of dystocia. DESIGN: A 2-year longitudinal observational study of 14 red deer farms was carried out in New Zealand. About 2700 hinds were monitored each year for individual characteristics including body condition score (BCS), and reproductive performance. Grazing and calving management practices were recorded. During calving, farmers recorded calving difficulties (dystocia) that needed human assistance or caused the death of the hind. Risk factors potentially affecting the occurrence of dystocia were identified and analysed by multivariable statistical techniques. RESULTS: The percentage of hinds with dystocia was 0.52% (95% CI 0.32 to 0.78). Hinds with a post-winter BCS over 3.5 were 2.7 times as likely to experience dystocia as hinds scoring 3.5 or less. Given the same BCS class, bodyweight gain in late pregnancy was associated with an increased risk of dystocia. Grazing steep paddocks in the last trimester of pregnancy decreased the risk of dystocia in hinds with a BCS over 3.5. CONCLUSIONS: The risk of dystocia on red deer farms may be reduced if key individual animal, management and environmental factors are optimal.     

振动式蓝莓采摘机槽型凸轮传动装置的设计与分析

为研制振动式蓝莓采摘原理样机,对蓝莓采摘机的凸轮传动装置进行设计与分析,选择凸轮结构类型及轮廓曲线种类,建立凸轮曲线方程。在MATLAB环境下,依据槽型凸轮设计参数对其进行运动学、动力学仿真分析,以此为基础研制蓝莓采摘原理样机。并对槽型凸轮传动装置运行卡点问题进行研究,提出解决方法:将凸轮滚子双边倒角,并使其能够绕轴转动。经测试,修整后的采摘装置运行平稳,满足振动式蓝莓采摘机设计要求。     

重庆市城乡居民收入差距的调节对策——基于农村公共产品供给的视角

定量分析了重庆市在经济快速发展的同时,城乡居民收入呈扩大趋势的现状,提出增加农村公共产品有效供给可以促进农民增收,缩小城乡居民收入差距。针对当前重庆市农村公共产品供给中存在的问题,提出了多种解决机制。     

The effect of twinning on milk yield,dystocia, calf birth weight and open days in Holstein dairy cows of Iran

Calving records of Iranian Holsteins from April 1998 to September 2006 comprising 16 herds with 104 572 calving events representing 4045 twin births were used to evaluate reported open days, calving difficulties and calf birth weight in single‐ and twin‐births and the relationship exists between twinning and milk production. A logistic regression model was constructed to analyse dystocia for single‐ and twin‐births. In addition, statistical analyses of 305‐day milk yield, open days and calf birth weight were performed using the general linear models procedure. The odds of dystocia was greater after twin births [p < 0.0001; odds ratio (OR) = 2.32]. The odds of dystocia decreased from parity 1 to parity 2 and beyond (p < 0.0001; OR = 0.44). Open days were significantly different between single (129.28 days) and twin (144.88 days) births (p < 0.05). Calf birth weights were significantly greater for singletons than twins (43.33 kg vs. 34.36 kg; p < 0.05). In addition, twin‐calved cows had greater 305‐day milk production than single‐calved cows (p < 0.05). In general, development of practical management strategies to cope with the negative effects associated with twinning on dairies is critical, especially if the trend towards increased twinning in the dairy cattle population continues.