THE EMERGENCE OF THE BIOLOGY OF FOREST AND RANGE

Whereas, in most lines of agriculture over-production is so outstanding a phenomenon that curtailment is widely recommended by economists, precisely the opposite is the case in silviculture and forage production. America's wild crop of timber and of feed for livestock falls far short of the demand. Careful attention must be given to all the conditions surrounding the growth of these crops. Among the factors of major importance are the native animals of forest and range lands. Some are pests; others are beneficial. Most play mixed r?les. Efficient production of trees and forage necessitates thorough-going study of the life histories and ecology of all the predominants, both plants and animals. Many animals, especially fishes, birds and mammals, are themselves of extraordinary value for recreation, study, and as a source of income. In some instances the value of the animals on a given area may exceed that of forage or trees. The production of wild life should be more than an incident or by-product of forest and range management. The objective should be maximum continuing values from each area. Attainment of this objective necessitates additional information and increasingly enlightened administration. Research is the foundation of our present prosperity. It must be the corner-stone of future advance. "The application of traditional methods will no longer suffice." Biology must participate fully in the solution of the many problems involved.     

哈尔滨西郊赤狐巢穴特征的主成分分析

应用主成分分析和聚类分析方法,在哈尔滨西郊对赤狐巢穴的特征进行了初步分析。结果表明,巢穴结构大小、筑穴地点的拟似小气候条件,以及巢穴周围隐蔽条件是形成该地区赤狐巢穴特征的主要因子。45个赤狐巢穴可基本分成三个类型,即:农田型、堤坝型和草甸型。     

初生仔猪小肠的位置排列及测量

本实验采用民猪和哈白猪的初生仔猪(生后5天以内)各15头,观察总结了小肠位置和排列的各种不同类型,井对两品种小肠各段的长度和周长进行测量比较,为初生仔猪解剖学积累资料。     

狐阴道加德纳氏菌的分离鉴定

本研究对山东省日照地区送检的病死狐样品进行了细菌的分离,根据分离菌株的形态特征、培养特性、生化试验和PCR鉴定,确定为狐阴道加德纳氏菌.对鉴定出的狐阴道加德纳氏菌进行药敏试验,结果表明该分离菌对万古霉素、复合磺胺敏感,而对卡那霉素、氨苄青霉素、头孢他啶等药物有耐药性.该研究为狐阴道加德纳氏菌病的预防、控制和临床治疗提供了重要的参考依据.     

供水泵变频调速范围的确定

本文从影响水泵调速范围的三个因素入手阐述了采用变频调速的供水泵其调速范围的确定方法,并推导了不同抽水装置、不同选泵参数和不同水泵性能时的调速范围参考值.一般情况下损失扬程占总扬程比重较大的泵站可以有较大的调速范围,另外选用高比转速的供水泵、选泵参数靠近水泵高效区右端点在同等条件下都可以获得较大的调速区间,但最大调速范围不宜超过额定转速的40～50%.