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西域旌节花的雌雄配子体发育及其系统学启示   总被引:1,自引:1,他引:0  
研究西域旌节花(Stachyurus himalaicus Hook.f.et Thoms.ex Benth)雌雄配子体的形成和发育过程,并与“近缘”类群(山茶科,猕猴桃科,山柳科,省沽油科,堇菜科,金缕梅科和Crossomataceae等)的胚胎学特征进行了比较,西域旌节花主要胚胎学特征可概括为:四囊型花药,药壁形成方式为基础型,花药壁由表皮,药室内壁,2-3层中层和绒毡层组成,药室内壁纤维质加厚,腺质绒毡层,小孢子母细胞减数分裂为同时型,小孢子四分体呈四面体形排列,花粉散发时为二细胞,胚珠倒生,双珠被,厚珠心,珠孔由内,外珠被构成,具珠心冠和承珠盘,蓼型胚囊,从目前可资利用的雌雄配子体形成和发育的资料来看,旌节花科与堇菜科最为接近,与金缕梅科的关系值得注意,而与山柳科和猕猴桃科以及山茶科的关系相对疏远,胚胎学证据不支持Nandi等(1998)揭示的旌节花科与Crossosomataceae的姐妹群关系,但他们的分析结果在某种程度上仍然得到了胚胎学证据的支持。  相似文献
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中美中学生物实验教学差异探析   总被引:1,自引:0,他引:1  
生物学实验是生物学教学的重要环节,就中美两国中学生物实验课的课标要求、课时安排、教学内容、教学方式、评价方式等几个方面展开对比,分析其差异,以期取长补短,为国内中学生物实验教学提供参考。  相似文献
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循证医学理念对麻醉科医生的启迪   总被引:1,自引:0,他引:1  
循证医学(EBM)是近年来迅速兴起的一门临床医学,其理论和方法已渗透到医疗决策和临床实践的各个方面.本文分析了麻醉领域运用EBM的必要性,每个麻醉医生必须具备EBM知识.EBM以令人信服的临床证据,带来了麻醉学实践革命性的改变.麻醉医生不仅要有丰富的临床经验和技能,同时要利用最佳的证据来指导麻醉实践,并充分尊重患者的意愿和价值观.  相似文献
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Efforts to bring science into early 19th century breeding practices in Central Europe, organised from Brno, the Hapsburg city in which Mendel would later turn breeding experiments into a body of timeless theory, are here considered as a significant prelude to the great discovery. During those years prior to Mendel’s arrival in Brno, enlightened breeders were seeking ways to regulate the process of heredity, which they viewed as a force to be controlled. Many were specialising in sheep breeding for the benefit of the local wool industry while others were showing an interest in commercial plants, especially fruit trees and vines, and later cereals. Breeders explained their problems in regulating heredity in terms of (1) climatic influences (2) disruption due to crossing (3) sports or saltations. Practical experience led them to the concepts of ‘inheritance capacity’ and the ‘mutual elective affinity’ of parents. The former was seen to differ among individuals and also among traits; the latter was proposed as a means of adding strength to heredity. The breeders came to recognise that traits might be hidden and yet transmitted as a ‘potential’ to future generations. They also grew to understand that heredity would be strengthened when a quality was ‘fixed’ within a lineage by ‘pure blood relations.’ Continued selection of the desired quality might then lead to ‘a higher perfection.’ But the ultimate ‘physiological’ question about breeding, ‘what is inherited and how?,’ found no answer. Major figures in this development included Abbot Napp, the one who asked this question and who was due to receive Mendel into the monastery in 1843, and Professor Diebl whose lectures on agriculture and natural science at the Brno Philosophical Institute Mendel would attend in 1846. Here we analyse their progress in theorizing about breeding up until about 1840. In discussing this development, we refer to certain international contacts, especially with respect to information transfer and scientific education, within the wider context of the late Enlightenment.  相似文献
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为加快我国军队卫生系统的信息化建设,本文阐述了国外以及军内外卫生信息化建设的基本情况,系统分析了我军卫生信息化建设面临的一系列新挑战和问题,并提出了有针对性地应对措施,为全军卫生系统的信息化建设的长远规划打下了坚实的基础。  相似文献
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