Genetically haploid spermatids are phenotypically diploid

Because chromosomal homologues segregate from one another during meiosis, spermatids are genetically different. Post-meiotic gene expression could lead to gametic differences, some of which might lead to preferential transmission of certain alleles over others. In both insects and mammals, however, all the cells derived from a single spermatogonial cell develop within a common syncytium formed as a result of incomplete cytokinesis at each of the mitotic and meiotic cell divisions. It has been proposed that the intercellular bridges connecting the cells, which are about 1 micron in diameter, permit the sharing of cytoplasmic constituents, thus ensuring the synchronous development of a clone of cells and gametic equivalence between haploid spermatids. By analysing the product of a transgene which is expressed exclusively in post-meiotic germ cells in hemizygous transgenic mice, we have shown that genetically distinct spermatids share the product of the transgene and hence can be phenotypically equivalent.     

"人文奥运"与"绿色奥运"

“人奥运”和“绿色奥运”北京奥运会的重要理念，“人奥运”是以人为本、追求与人类优秀化精神相结合的奥运，“绿色奥运”以可持续发展理念为指导的、旨在创造良好生态环境的奥运。“人奥运”是北京奥运会的灵魂。是“绿色奥运”的思想基础；“绿色奥运”是“人奥运”的体现，二结合的意义在于人类应在健康洁净的环境中实现身心的和谐发展。     

基因工程抗体

目的 :了解新一代抗体的研究状况。方法 :通过计算机数据库检索相关文献 ,作出综合评述。结果 :利用基因工程技术制备的抗体为新一代的抗体 ,包括人源化的鼠源性抗体、重组抗体片段、转基因动物抗体、植物抗体和噬菌体抗体。结论 :基因工程抗体在疾病的诊断和预防 ,特别是治疗方面有广阔的应用前景。     

世纪之交的物理学

本认为,１８世纪至２０世纪物理学作为主导科学,为推动人类的进步和其它科学的发展作出了巨大的贡献,２０世纪末,由于物理学的发展相对于低潮时期,以及与物理学相关的边缘科学及其科学的蓬勃发展,人们忽视了主导科学－－物理学的重要性,从而在社会上引起了一此不良的后果。本以崇尚科学的精神,重申主导科学－－物理学的重要性,并推测了物理学发展的美好前景。     

未来的汽车动力一燃料电池

介绍了氢燃料电池在汽车上的应用,对燃料电池车的优点、目前存在的技术难题以及发展形势进行了综述.     

人文奥运的理念及实现北京2008年人文奥运的对策研究

在阐述人文奥运的理念和论证东西方文化的相互交融是实现北京2008年人文奥运的理论基础后，对实现北京人文奥运提出4条对策；加强奥林匹克教育；注重弘扬奥林匹克文化；体现以人为本，加强城市文明建设；努力提高运动技术水平。