Cytogenetical and histological studies in testis of Tayassu tajacu (Cateto), Tayassu pecari (Queixada) and a natural interspecific hybrid

The karyotype, the histological structure of the testis and the synaptonemal complex (SC) of the mammalian species Tayassu tajacu , Tayassu pecari and of an interspecific male hybrid captured in nature were analysed. The specimens of T. tajacu (2n=30) and T. pecari (2n=26) exhibited seminiferous tubules with germ cells in all spermatogenesis stages. In the SC studies both species had a regular structure, easily identified in the autosomes and in the sex chromosomes. The hybrid (2n=28) had seminiferous tubules with almost all germinal cells in the spermatogonium stage and only a few cells in the primary spermatocyte stage. Gross abnormalities in SC were observed. A few lateral elements showed regular or partially regular synapsis, other lateral elements were synapsed as multivalents, and most axial elements remained unsynapsed. The results suggest that the karyotypes of the parental species have sufficient differentiation to avoid chromosome synapsis. Alternatively, the hypothesis of the existence of genetic incompatibilities between the parental species is discussed.     

促进我国汽车检修行业发展的模块化仿真

本文以汽车检修企业为例分析了集中优化的必要性和重要性，利用模糊数学综合评判理论的基本原理和方法，建立优化的数学模型，阐明优化检修企业的具体方法和步骤，并应用有关数据进行分析和验证，说明集中优化汽车检修企业具有广阔的发展前景。     

PRENATAL SONOGRAPHIC DIAGNOSIS OF FETAL DEATH AND HYDRANENCEPHALY IN TWO CHIHUAHUA FETUSES

Hydranencephaly and fetal death was diagnosed in two of three fetuses during the abdominal sonographic examination of a 2.5-year-old, intact female Chihuahua that had clinical signs of dystocia 63 days after mating. A cesarean section was performed and one live normal puppy was present. Two dead puppies, each with a markedly enlarged and fluid filled skull were removed.     

干旱对草坪草的影响

综述了干旱条件下草坪草的生态适应性,细胞膜、细胞壁、叶绿体超微结构的变化,草坪草对干旱胁迫的生理生化反应,以及提高草坪抗旱性的途径。     

论农村产业结构调整与农业产业化

农村产业结构是指一个国家或地区的农村各产业间的关系,各产业内部各部门之间的关系,产业内部的组织关系以及各地农村产业结构之间的关系的总和。合理的农村产业结构能使当地的资源条件被充分地利用,最大限度地提高当地农村经济效益;合理的农村产业结构影响着农业内部各个生产部门和生产项目之间的物质能量相互转化,保持和改善生态平衡,提高农业生产的生态效益;合理的农村产业结构能促进农村各产业之间协调发展,形成良性循环,促进农村经济全面发展。1目前我国农村产业结构中存在的主要问题新中国成立以来,我国农村产业结构经过了多次的调整,…     

大骨鸡MSTN基因的表达检测

以大骨鸡为试材,采用RT-PCR法检测了MSTN基因在大骨鸡不同器官中的表达情况。结果表明,MSTN基因在大骨鸡骨骼肌中表达水平较高,在心肌、肾脏、脑、肠、舌中也有微量表达,但在肺、肝脏中未检测出MSTN mRNA,而且在14日龄时表达水平高于35和56日龄。     

Minimum Error Variance Adaptive Controlling Technique Applied on the Auto Regulation System of the Draw Frames

Firstly, the uncertain factors in drawing process, which cause the changes of the sensor's displacement and the sensor's vibration, are analyzed in terms of mechanics and statistics. Systemic randomictiy and non linearity affect the performance of traditional auto regulation equipment. Using the minimum error variance adaptive controlling technique to solve the uncertainty of controlled system is the ideal method. Secondly, using generalized least square method to achieve the principle and method of the system identifying model is described. Thirdly, the design steps of the minimum error variance adaptive adjustor and the method of the computer simulation are discussed. The result of test running shows that the output of the system follows the input of the system better, the system restrains the random disturbance more efficiently, and the performance of auto regulation is improved apparently.     

由竹书《恒先》看汉晋学术

依据上海博物馆藏战国楚竹书《恒先》篇首强调的“气是自生”的宇宙生成论,对王晓毅先生所整理的战国秦汉宇宙生成论的流变稍作调整。并依照所发现的郑玄注文中与“气是自生”相近的思想,讨论“无中生有”、“有自生”两种宇宙生成论对于魏晋玄学“有无之辨”的影响,分析何晏、王弼、向秀、裴危页、郭象等的有关思想,认为从学理上讲,何晏、裴危页、郭象等虽然使用了佛学词句,但是其思想却可能从中国传统中自己产生。文末还简要分析了张载“太虚即气”的观点与玄学、《恒先》的关系。