共查询到19条相似文献，搜索用时 44 毫秒
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对西康蔷薇进行了植物生境调查,通过根系的生物量、长度、土壤有机质含量和水稳性指数的测定,并采用石蜡制片法对其根茎结构进行观察。研究表明,各级别根系长度顺序依次是：二级〉三级〉四级〉一级;生物量分布是一级〉二级〉三级〉四级,其中二级根系伸展能力最强;生物量随着土层深度依次减少;根系对土壤抗蚀性能的水稳系数小于草玉梅和川西千里光而大于荒坡地;它根茎的表皮细胞较小、排列紧密、细胞壁较厚、气孔较密的特点;机械组织发达、髓部能储存大量营养物质。具有耐干旱、耐瘠薄、根系分蘖能力强的特性;有较好的绿化观赏、涵养水源、保持水土等作用,成为治沙造林的优良树种,能为林芝植被建设提供优良的造林树种。 相似文献
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语文综合性学习是由学生自行设计和组织的语文活动,特别注意探索和研究过程,在学习活动中注重对母语听、说、读、写能力培养的活动课。这种活动课给学生提供了充分展示自我的广阔舞台。它的设置,对语文学科教学来说是一项重大改革,也是一道亮丽的风景。 相似文献
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李非多 《大科技．科学之谜》2014,(1)
正财富与长生在大多数的人眼里,西方的炼金术和东方的炼丹术分别是东西方神秘文化的代表,其主要区别在于,前者追求的是"点石成金",而后者追求的则是"长生不老"。其实这样的理解不免有些望文生义了,事实上,炼金术和炼丹术所追 相似文献
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通过刺激——反映（S-R）联结,每个人在学习历程中建立起一系列习得性的对自身行之有效的学习策略和学习习惯。作为教师,针对学生不同学习类型的认识,可以更好的引导学生,帮助他们认识自己,发掘自身潜质,形成自己独创性的良好学习习惯,从而极大的发挥其主观能动性。 相似文献
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向秋云 《中国科学院研究生院学报》1987,25(2):125-131
Cornus L. s. 1. is a large polytypic genus. The classificantion of which has been
so different that some authors recognize several separate genera, while others treat them as ei-
ther subgenera or sections. New evidence from many disciplines such as palynology, cyto-
logy, wood anatomy and embryology supports the view that the genus should remain in the
broad sense. I basically agree with the treatment by Ferguson (1966b) before my finishing
a comprehensive study on Cornus L. s. 1. except for supporting the separation of subgenus
Afrocrania as an independent genus. A new subgenus Sinocornus Q. Y. Xiang, containing
one species, C. chinensis Wangerin, is established here on account of its inflorescence axillary
and different from the other members of the genus which all have terminal inflorescences only.
The inflorescence developed from a terminal bud implicates the sympodial nature of axis of
stem and the one from an axillary bud the monopodial one. It is reasonable to regard the
character as of subgeneric value. Also a new combination, Cornus subgen. Syncarpea (Na-
kai) Q. Y. Xiang, is proposed here as a substitute for Cornus subgen. Benthamia (C. B. Clar-
ke) Schneider used for a long time. Because the valid publication of the former name subgen.
Syncarpea Nakai is earlier than the latter one. The types of inflorescences of 8 subgenera re-
presented by type or selected species are illustrated. 相似文献
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