A case study of forest change in the Swiss lowlands   总被引：2，自引：0，他引：2  

Bürgi  Matthias 《Landscape Ecology》1999,14(6):567-576

This paper presents a regional case study of forest development and the history of forest use and management in the north-eastern lowlands of Switzerland during the 19th and 20th centuries. The analysis draws on historical documents related to forestry to consider the following aspects of forest change: forest types, growing stock, trees species composition and non-timber forest uses. Based on the data presented, three overlapping periods of forest use and management can be discerned. The period of traditional multiple use lasted until the second half of the 19th century. From the mid 19th to the mid 20th century, a period of primacy of timber production occurred. During the 20th century, the period of modern multi-impact management has developed. For these three periods, groups of main actors, their needs and interests, and how they were causing the changes in the aspects under study were defined. This procedure of defining periods and the respective groups of main actors is a critical link between landscape ecology and history, as changes in demands of the society can be directly linked with changes in land-use and land-cover.  相似文献   

Vaccination experiments on pregnant mice with E. coli vaccines prepared from septicaemic and enteropathogenic strains of E. coli     

A Dam 《Acta veterinaria Scandinavica》1973,14(5):691-699

Experiments have been carried out with vaccination of pregnant mice against E. coli, followed by i.p. challenge of the offspring at one week of age.With a septicaemic strain the results were highly significant, and the method is therefore recommendable for testing of vaccines against such strains of E. coli.Results were less clear-cut with enteropathogenic strains of E. coli. However, with mortality rates of 40 to 45 % in baby mice born by non-vaccinated mothers and less than 15 % in baby mice born by vaccinated mothers, the difference in percentage mortality seems sufficient to warrant the use of the method also in the control of vaccines against enteropathogenic E. coli strains.  相似文献   

关于"人居环境"的几点认识   总被引：2，自引：0，他引：2  

王游  吴莹辉 《林业科技情报》2003,35(4):4-4

本文通过"人居环境"应体现现代城市的概念、创造不同形式的完美居住景观、体现人文思想等的论述,阐明了设计者应运用现代城市设计理论与方法进行居住空间设计.  相似文献   

儒家礼教论——论"仁"、"人性"、"文"和"礼"的关系     

张静互 《湖南农业大学学报(自然科学版)》2003,(2)

作为儒家哲学的一个重要范畴,"礼"是先秦儒家教育理论及其实践的核心范畴。儒家的教育理论是完全依靠"礼"如何与其他范畴互相关联而形成发展的。尤其是孔子、孟子和荀子所提出的"仁"、"人性"和"文"等范畴对体现出"礼"的教育内涵是不可缺少的。"仁"只有通过"礼"才能实现自己的价值,"人性"也依靠"礼"的内化过程而能够获得真正的发展。在这一点上,可以说"礼"是文明化了的传统中分化、发展下来的一切标准,"礼教"是以"博文"与"约礼"为主要内容而培养君子的先秦儒家的教育传统。  相似文献   

NDV和IBV感染对肉鸡大肠杆菌病发病的影响     

王晶钰  张万珍  张彦明  郭抗抗 《动物医学进展》2003,24(2):92-93

为了解新城疫弱毒苗和传染性支气管炎弱毒苗接种对肉鸡大肠杆菌病发病的影响。对8日龄肉仔鸡用不同剂量NDVclone-30株或IBV-H120株进行滴鼻及饮水,48h后相同途径接种2株不同“O”血清型的致病性大肠杆菌。结果表明,致病性大肠杆菌单独接种鸡死亡率在20%-25%之间,而NDVclone-30株或IBVH120株与致病性大肠杆菌联合接种鸡死亡率有明显增加达40%-75%。  相似文献   

Risk factors associated with faecal shedding of verocytotoxin-producing Escherichia coli O157 in eight known-infected Danish dairy herds     

Rugbjerg H  Nielsen EM  Andersen JS 《Preventive veterinary medicine》2003,58(3-4):101-113

A risk-factor study was performed in eight dairy herds found to excrete verocytotoxin-producing Escherichia coli (VTEC) O157 in a former prevalence study. Associations between excretion of VTEC O157 and management factors such as housing and feeding were analysed in a generalised linear mixed model. The animals were stratified in three age groups and sampled four times during 1 year. The risk of excreting VTEC O157 was higher among weaned calves than non-weaned calves. Among the calves aged 1–4 months, the risk was reduced if the calf had suckled colostrum from the mother or if the calf had stayed >2 days with the mother after calving. Calves aged 5–24 months that had been moved within the last 2 weeks had a higher risk, but risk was reduced if fed barley silage. Cows fed grain or molasses had a higher risk of excreting VTEC O157.  相似文献   

Efficacy of Sarafloxacin in Broilers after Experimental Infection with Escherichia coli     

Chansiripornchai N  Sasipreeyajan J 《Veterinary research communications》2002,26(4):255-262

Infections of chickens with Escherichia coli serotypeO78 can be treated with the antibiotic sarafloxacin. Three experiments were conducted on the administration of this drug to chickens that had been experimentally infected with E. coli. The birds were monitored for 10 days after infection for their average daily gain (ADG) and feed conversion ratio (FCR), and the post-mortem pathology was assessed. In the first experiment, sarafloxacin (20 mg/L, equivalent to 5 mg/kg live weight per day), given in the drinking water for 3 days after infection, led to a reduction in the mortality from 75% to 27%, but the ADG of the treated birds was still less than that of the uninfected controls. In the second experiment, when the sarafloxacin was administered at the same dose in the water but over only 2 h, there was also a considerable reduction in mortality, and the ADG and the FCR also improved significantly. In the third experiment, the dose dependence of the drug was tested. The birds were given 5 and 10 mg/kg per day sarafloxacin in each group, starting within 2 h after infection. This rapid administration of the drug completely prevented mortality, while the ADG and FCR were similar to those of the uninfected controls.  相似文献   

造血和神经相关标志物在人胎盘的表达     

王跃嗣  孟凡刚  姜昱竹  李建远  范光丽 《畜牧兽医学报》2006,37(4):368-373

为探讨人胎盘组织在造血中的作用以及研究造血和神经标志物在胎盘中的表达和在胚胎发育中的相关性，用免疫组织化学法对人胎盘组织和体外培养的胎盘组织中的贴壁细胞进行染色，观察其造血因子和神经标志物的表达。结果发现人7月龄胎盘组织血管内血细胞表达多种造血细胞因子，如SCF、VEGF、BMP-4和FGF-1和KDR，血管内皮细胞上也有表达；胎盘组织同时表达造血干细胞标记CD34、CD133和神经细胞标记物Nestin和MAP2等。而足月龄胎盘CD34、CD133、KDR和造血相关因子SCF、VEGF、BMP-4、FGF-1等弱表达，不表达Nestin和MAP2。两组胎盘切片都不表达GFAP和MBP。胎盘贴壁细胞（hPDACs）碱性磷酸酶、波形蛋白、CD133、Nestin和MAP2染色呈阳性，CD34、GFAP和MBP阴性表达。人胎盘组织和胎盘贴壁细胞表达多种造血相关因子和神经细胞标志物，提示胎盘具有造血功能，造血形成和神经发生之间可能存在基因表达叠加现象。  相似文献   

人和动物阿米巴原虫病研究进展     

黄道超  杨光友  王强  牛李丽 《动物医学进展》2006,27(5):51-55

阿米巴原虫病主要是由溶组织内阿米巴引起的一种人兽共患寄生虫病。自1875年Feder Losch首次在人体发现该病以来,已有9个不同种属的阿米巴被先后发现,已报道的易感动物达30多种。该类原虫多寄生于人和动物的肠道和肝脏,以滋养体形式侵袭机体,引发阿米巴痢疾或肝脓肿。文章综述了近年来人和动物阿米巴原虫病的病原学、流行病学、发病机理、诊断和防治等方面的研究进展。  相似文献   

大肠埃希菌多重耐药调节子研究进展     

李娟  佟海山  赵泳波  李乾学  邓旭明 《动物医学进展》2006,27(7):42-45

大肠埃希菌多重抗生素耐药主要是由多重耐药调节基因和外输泵共同作用产生的。大肠埃希菌多重耐药调节子是广泛存在于肠杆菌科细菌染色体上的抗生素多重耐药调节中心,是大肠埃希菌耐药的主要组成部分。为解决多重抗生素耐药问题,很多专家和学者对大肠埃希菌多重耐药调节子和外输泵的耐药机制进行了深入的研究,研究开发多重抗生素耐药基因消除剂和外输泵抑制剂,或增加外输泵抑制基因的表达,将成为从根本上解决多重抗生素耐药问题的最好方法。文章对大肠埃希菌AcrAB、AcrAB-Tolc,Mar和膜孔蛋白Ompf、Ompc等多重抗生素耐药调节子的组成、功能及其影响因素进行了综述。  相似文献