越桔对长白山区酸性土壤的适应性

在长白山区３种类型的酸性土壤上栽培越桔，研究结果表明，｀北空＇、｀美登＇、｀斯卫克＇在暗棕色森林土上生长结果较好，树体营养关系合理；在草甸沼泽土上３个种生长结果均较差，｀北空＇在水湿地潜育土上生长旺盛，但产量低，综合分析认为，矮丛越桔类型品种对我国长白山区酸性土壤条件的适应性较强，半高丛越桔则适应性差，针对长白山不同类型的土壤，以美登最为适宜暗棕色森林土栽培，斯卫克次之；水湿地潜育土可栽培美登品种     

摆动平底从动件盘形凸轮廓解析设计的应用

本文根据具体机器动作协调性要求及其具体空间几何条件,采用了摆动从动件盘形凸轮机构。其摆杆推程在O°～52°及52°～62°范围内分别采用了等加速——等速合理拼接运动规律。回程在62°～153°范围内采用了正弦加速度运动规律。用极坐标矢量分析法建立方程、微分,通过电脑程序计算,设计制造出凸轮轮廓,用于禾苗移植机的擒纵机构处,完全符合生产要求,获得了理想的效果。     

不同氮源对红檬实生苗菌根依赖性的影响

将红檬实生苗培养于改良无土基质中，接种泡囊－丛枝菌根Ｇｌｏｍｕｓｃｉｔｒｏｃｏｌｕｍ，以不接种菌根为对照，并分别施用含氮量相等的３种氮肥，即硝酸按（ＮＯ３－Ｎ）、尿素（ＮＨ２－Ｎ）和硫酸铵（ＮＨ４－Ｎ）。接种菌根１６周后，施不同氮肥的红檬实生苗均有效地感染了菌根，并促进了植株的生长。试验证明，红实生苗施硝态氮（ＮＯ３－Ｎ）使植株的菌根依赖性有明显提高。     

Studies on efficacy and stability of a vaccine bait containing ERA strain of rabies virus propagated in a BHK-21 cell line.

In a dose response study in foxes, the median protective dose of ERA BHK21 vaccine in a blister pack bait was 10(6.0) tissue culture infective doses (TCID)/mL, while artificially aged baits with titers of 10(6.3) TCID/mL induced seroconversion in 78% of foxes. There was no significant difference in the development of antibodies in foxes receiving 1, 2 or 3 mL volumes of vaccine in the bait. When baits were exposed to the elements and fed to foxes over a 21 day period, 85% of the animals seroconverted. Age, sex and the way in which the vaccine container was contacted did not appear to be factors in the responses of these animals. Juvenile foxes, approximately six months of age, were marked more readily with the tetracycline bait marker than older animals. Approximately 25% of foxes did not appear to respond well to vaccination and the titer of the vaccine was a critical factor in producing seroconversion in these animals.     

Inheritance of myotonic discharges in American quarter horses and the relationship to hyperkalemic periodic paralysis.

Electromyography (EMG) was used to detect myotonic discharges in Quarter Horse breeding stock and to follow the results of mating horses with hyperkalemic periodic paralysis (HPP). The studies were performed on two brood mare farms. A total of six breeding stock showed myotonic discharges and 15 were nonmyotonic. Myotonic discharges were seen in five of six horses belonging to the blood line previously implicated as being predisposed to HPP. Two of these horses had shown clinical signs of HPP. Only one of 15 breeding horses unrelated to the HPP predisposed blood line showed myotonic discharges. When both parents were non-myotonic on EMG than the F1 generation (n = 6) were also nonmyotonic. When a stallion with HPP and myotonic discharges was mated to eight nonmyotonic mares over a six year period half the animals of the F1 generation (n = 25) showed myotonic discharges. When both parents showed myotonic discharges four F1 offspring were myotonic and two were nonmyotonic on EMG testing. There was no evidence of sex linkage. The results are consistent with an autosomal dominant mode of inheritance. Hyperkalemic periodic paralysis and myotonic discharges on EMG may be different manifestations of the same underlying defect.     

Studies on mutlispecific resistance of gastrointestinal nematodes to benzimidazoles on dairy-goat farms

Multispecific resistance to benzimidazoles was studied in three selected farms. These farms had bred dairy goats for more than 15 years. The helminths were introduced with the goats at the establishment of the farms which afterwards remained isolated. Nematode resistance could then be related to their own management practices. Faecal egg count tests and egg hatch assays were performed to assess intensity of resistance. The generic (infective larvae in faecal cultures) and specific richness (adult worms) were assessed. The resistant species were Trichostrongylus colubriformis, Teladorsagia circumcincta, Haemonchus contortus and Oesophagostomum venulosum. Faecal egg count reduction tests and egg-hatch assays did not match exactly. Faecal larval counts after treatments gave a distorted picture of multispecific resistance: Haemonchus and Oesophagostomum were very largely over represented. The number of species found in the three farms was relatively low compared with other reports in goat farms of the area. This reduction of diversity might also be due in part to characteristics of breeding management and history (use of permanent pasture and introduction of goats at the establishment of farm).     

黄土丘陵区不同恢复阶段狼牙刺种群动态研究

以荒草坡为对照,对黄土丘陵区封禁8 a、20 a和30 a的狼牙刺群落的狼牙刺种群结构进行了研究,分析了种群的年龄结构、垂直结构、生命表,存活曲线规律.结果表明:不同恢复阶段的狼牙刺种群个体平均基径、高度差异明显:30 a的垂直高度＞20 a垂直高度＞8 a垂直高度＞荒草坡,说明不同恢复阶段狼牙刺种群年龄结构均属于进展型.随着狼牙刺恢复,种群稳定性增加.狼牙刺种群适应力、繁殖力强,是严酷条件下植被恢复的优良树种,应该充分利用其优良特性,抑制不利的环境因素,以封禁和生态修复为主,迅速恢复严酷生境条件下的植被.