萝卜叶片衰老过程中光合性能变化研究     

王玲平毛伟海  胡天华包崇来 戴丹丽 《华北农学报》2007,22(B10):36-39

研究了萝卜品种CR0502和CR0509叶片生长衰老过程中光合性能的变化。结果表明，萝卜叶片展开至衰老过程中，除气孔限制值（Is）随叶片展开时间的延长而缓慢降低外，叶绿素含量、净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和叶绿素荧光参数（Fv／Fin、ψPSⅡ）的变化趋势一致，呈抛物形，在25d时达到峰值，此后逐渐下降。不同品种间存在明显差异，品种CR0502在叶片衰老期的下降速率明显高于品种CR0509。叶片初展时，气孔和非气孔因素同时影响叶片的Pr，而叶片衰老时，非气孔因素占主要因素。  相似文献   

ORCHITIS IN TWO DOGS WITH ROCKY MOUNTAIN SPOTTED FEVER     

Christopher P. Ober  DVM    Kathy Spaulding  DVM    Edward B. Breitschwerdt  DVM    David E. Malarkey  DVM  PhD    Barbara C. Hegarty  BA 《Veterinary radiology & ultrasound》2004,45(5):458-465

Two dogs with testicular swelling were sonographically diagnosed with orchitis and were subsequently diagnosed with Rocky Mountain spotted fever (RMSF). Use of both gray scale and color Doppler sonography allowed for differentiation of orchitis from neoplasia and torsion. While only experimentally induced RMSF is reported to cause orchitis in dogs, it should be considered in any dog with vascular insult to the testes, especially when other signs of systemic illness are involved.  相似文献   

犬MC4R基因单核苷酸多态性及其与体重的关系     

张轶博巴彩凤  苏玉虹朱宝芹白富春  陈清华谢建中 《黑龙江畜牧兽医》2005,(7):12-13

人和几种动物的遗传学研究显示，MC4R基因在体重和能量平衡调控中具有重要作用，但未见有关犬的MC4R基因多态性、MC4R基因与性状关系的研究报道。以123只成年Beagle犬为试验材料提取血液DNA，利用软件设计PCR引物，经PCR扩增、克隆和测序后，发现了一个新的MC4R基因单核苷酸多态性(single nucleotide polymorphism，SNP)。该多态性恰好产生了限制性内切酶EcoO109Ⅰ的位点多态性。利用PCR-RFLP方法，分析了Beagle犬家系的MC4R基因，并利用SPSS软件分析该多态性与犬体重的关系。结果分析显示：MC4R该多态位点对犬的体重影响不显著。尚需进一步分析MC4R基因的其他片段。  相似文献   

Progressive tetraparesis and laryngeal paralysis in a young Rottweiler with neuronal vacuolation and axonal degeneration: an Australian case     

CE EGER  CRR HUXTABLE  ZC CHESTER  BA SUMMERS 《Australian veterinary journal》1998,76(11):733-737

A 5-month-old female Rottweiler dog was diagnosed to have a neurodegenerative disease that has been recently report ed in Rottweilers from North America and Europe. The dog was presented with progressive signs of ataxia, tetraparesis and inspiratory stridor. The clinical investigation included analysis of CSF, radiography, myelography and electrophysiolog-ical testing. No evidence of vertebral malformation or inflammatory CNS disease was identified. Bilateral laryngeal paraly sis was identified in the lightly anaesthetised dog. Electromyography showed abnormal spontaneous activity from the intrin sic musculature of the larynx. At necropsy there were no gross abnormalities of the nervous system but there was atrophy of the dorsal cricoarytenoid muscles of the larynx. There were widespread histological abnormalities throughout the ner vous system including neuronal vacuolation, spongiform changes in the neuropil and axonal degeneration which was most prominent in the spinal cord. These clinical and pathological findings are consistent with the diagnosis of a new neurode-generative disease reported from North America and Europe. This diagnosis is of particular significance in Australia where transmissible spongiform encephalopathies have not been identified.  相似文献   

AORTO-CARDIAC FISTULAS IN SEVEN HORSES   总被引：1，自引：0，他引：1  

Celia M.  Marr  BVMS  MVM  PhD  MRCVS  Virginia B.  Reef  DVM  T.J. Brazil  BVSc  Cert. EM  MRCVS  W.P. Thomas  DVM  D.C. Knottenbelt  BVM&S  DVM&S  MRCVS  D.F. Kelly  BVSc  MA  FRCPath  MRCVS  J.R. BAKER  BVSc  Ph  D  MRCVS  Johanna M.  Reimer  VMD  Abby D.  Maxson  VMD  J.S. Crowhurst  BA  B Vet Med  MRCVS 《Veterinary radiology & ultrasound》1998,39(1):22-31

This report describes the history, clinical, electrocardiographic and echocardiographic findings, treatment, outcome, and post-mortem findings in seven horses with aorto-cardiac fistula. Affected horses included 5 stallions, one gelding and one mare; 2 each of the Thoroughbred, Arabian and Standardbred breeds and one Thoroughbred-cross with a mean ± s.d. age of 12 ± 4 years, range 6–18 years. The presenting sings were acute distress (four horses), exercise intolerance (two horses) and the lesion was detected during a routine examination in one horse. Five horses had monomorphic ventricular tachycardia on admission and one other had a history of this arrhythmia. Five horses had a characteristic continuous murmur loudes in the right fourth intercostal space. Echocardiography (six horuses) and/or post-mortem examination (four horses) revealed the horses had aorto-cardiac fistulas arising from the right aortic sinus in all five horses in which the site was recorded. Two horses had ruptured aneurysmall dilatations of the aortic wall at this site. Fistulas extended into the right ventricle in four horses; the right atrium in two horses, the left ventricle in one horse, and five horses had dissecting tracts in the septal myocardium. Horses survived for periods ranging from 24th to 4 years. Aorto-cardiac fistula should be considered in the differential diagnosis for horses presenting with acute distress, bounding arterial pulse, a right-sided continuous murmur and/or monomorphic ventricular tachycardia, particularly in middle-aged or older stallions. Echocardiography is the technique of choice for confirming the diagnosis and demonstrating accompanying cardiac changes.  相似文献   

猪新基因CFL2真核表达载体的构建及在C2C12细胞中的瞬时表达     

赵微  苏玉虹  巴彩凤  苏荣健  宋慧娟 《畜牧与兽医》2008,40(12)

从猪的股二头肌中提取总RNA,利用RT-PCR技术从猪骨骼肌中获得CFL2基因的编码区序列,T-A克隆至PMD-18T载体,经HindⅢ和XhoⅠ酶切后定向克隆至真核表达载体pCDNA3.1(+)中。获得的重组质粒pCDNA3.1(+)/CFL2用限制性内切酶酶切分析和DNA测序分析鉴定,并经脂质体瞬时转染C2C12细胞,最后利用PCR检测转基因细胞中CFL2基因的存在及其表达情况。结果显示:猪CFL2基因已克隆到真核表达载体pCDNA3.1(+)中,转染的C2C12细胞中检测到细胞内较高量CFL2的表达。pCDNA3.1(+)/CFL2真核表达载体的成功构建,为深入研究CFL2基因在猪肌肉细胞中的功能奠定基础,为猪肉质品质的改良提供了新的思路。  相似文献   

Factors associated with low vitamin D status of Australian alpacas     

GJ Judson  BA McGregor  DL Partington 《Australian veterinary journal》2008,86(12):486-490

Objective To investigate factors associated with low vitamin D status of alpacas at pasture in southern Australia. Design A 2‐year survey of alpacas from two farms in South Australia and three in Victoria. Blood samples were collected from 20 to 30 alpacas on each farm on five occasions each year. Breed, gender, age and fleece colour of animals were recorded. Method Blood samples were assayed for plasma 2.5‐hydroxycholecalciferol (25‐OH D₃) and plasma inorganic phosphorus (Pi). Data sets from 802 animal samples were analysed by multiple regression to determine variables associated with low vitamin D status of alpacas. The relationship between plasma 25‐OH D₃ and plasma Pi was also investigated. Results Vitamin D status was significantly affected by month of sampling, with low values in late winter and high values in summer. Plasma vitamin D concentrations increased with age, were higher in alpacas with light fleeces than in those with dark fleeces and were also higher in the Suri than in the Huacaya breed. Plasma Pi concentrations were generally lower in alpacas with plasma 25‐OH D₃ values < 25 nmol/L. Conclusions Young alpacas with dark fleeces are most at risk from vitamin D insufficiency in late winter in southern Australia. The present study indicates that plasma Pi values are not a reliable indicator of vitamin D status of alpacas as assessed by plasma 25‐OH D₃ concentrations.  相似文献   

基于StyleGAN2-ADA和改进YOLO v7的葡萄叶片早期病害检测方法     

张林鍹  巴音塔娜  曾庆松 《农业机械学报》2024,55(1):241-252

为实现葡萄早期病害的快速准确识别,针对葡萄病害的相似表型症状识别率低及小病斑检测困难的问题,以葡萄黑腐病和黑麻疹病为研究对象,提出了一种基于自适应鉴别器增强的样式生成对抗网络与改进的YOLO v7相结合的葡萄黑腐病和黑麻疹病的病斑检测方法。通过自适应鉴别器增强的样式生成对抗网络和拉普拉斯滤波器的方差扩充葡萄病害数据。采用MSRCP算法进行图像增强,改善光照环境凸显病斑特征。以YOLO v7网络框架为基础,将BiFormer注意力机制嵌入特征提取网络,强化目标区域的关键特征;采用BiFPN代替PA-FPN,更好地实现低层细节特征与高层语义信息融合,以同时降低计算复杂度;在YOLO v7的检测头部分嵌入SPD模块,以提高模型对低分辨率图像的检测性能;并采用CIoU与NWD损失函数组合对损失函数重新定义,实现对小目标快速、准确识别。实验结果表明,该方法病斑检测精确率达到94.1%,相比原始算法提升5.7个百分点,与Faster R-CNN、YOLO v3-SPP和YOLO v5x等模型相比分别提高3.3、3.8、4.4个百分点,能够实现葡萄早期病害快速准确识别,对于保障葡萄产业发展具有重要意义。  相似文献   

改善管理方法控制猪的传染性疾病     

AndrewJTaylor  BAVetMBMRCVS  张勤 《猪业科学》2006,23(4):64-65

20世纪90年代在英国出现新的猪病如PMWS／PDNS,迫使人们开始重新评估现有的生产系统,疫苗已经不能解决所有问题,养猪场必须采用改进管理方法来控制疾病。如PRRS,离开了综合饲养管理,疫苗仍然不起作用。本文涵盖各种控制疾病的基本饲养管理方法,每个场则须针对各自情况采用合适的方法。  相似文献   

梯形明渠临界水深直接计算公式研究     

徐海嵩  把多铎  张国辉 《西北农林科技大学学报(自然科学版)》2014,42(9):206-210,218

【目的】寻求梯形明渠临界水深的直接计算公式。【方法】针对梯形明渠临界水深传统计算方法计算过程复杂、误差大、适用范围小的缺点,以迭代法为基础,引入无量纲参数单位水面宽度,利用数值计算方法对梯形明渠临界水深的基本计算公式进行恒等变形,得到快速收敛的迭代公式,并对合适的迭代初值进行选取。【结果】提出了新的梯形明渠临界水深的直接计算公式,对其进行的误差分析结果表明,该公式计算临界水深的最大相对误差仅为0.010%。【结论】与现有公式相比,新建立的梯形明渠临界水深直接计算公式计算精度高、适用范围广,可供工程实际参考应用。  相似文献