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4种一品红亚属植物种皮微形态特征比较研究 被引量:2
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作者 徐瑛 刘丽 +1 位作者 张建成 张慧丽 《西北植物学报》 CAS CSCD 北大核心 2010年第8期1602-1605,共4页
利用光学显微镜(LM)和扫描电镜(SEM)对大戟属一品红亚属(Subgen.Poinsettia)的4种草本植物种子进行了比较观察.结果显示:(1)在光学显微镜下,4种植物种子外形较为一致,为倒卵形至宽倒卵形,表面具瘤突.(2)SEM观察发现,4种植物... 利用光学显微镜(LM)和扫描电镜(SEM)对大戟属一品红亚属(Subgen.Poinsettia)的4种草本植物种子进行了比较观察.结果显示:(1)在光学显微镜下,4种植物种子外形较为一致,为倒卵形至宽倒卵形,表面具瘤突.(2)SEM观察发现,4种植物的种子外种皮表面纹饰等方面存在明显差别,其中猩猩草种子表面纹饰为鳞片状,齿裂大戟为棒状、刺状,E.davidii为横棒状、疣状,而白苞猩猩草种子表面是由分泌层形成的疣状突起或假孔穴组成.研究表明,4种一品红亚属植物种子微形态特征在种的水平上具有一定的分类学意义,并可作为检疫鉴定的参考依据. 展开更多
关键词 一品红亚属 种子外形 表面纹饰 检疫 鉴定
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The Exolife: Gas Dust Streams and Seeds
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作者 Oleg B. Khavroshkin Vladislav V. Tsyplakov 《Journal of Earth Science and Engineering》 2015年第3期203-214,共12页
The hypothesis that bacteria and protozoa microorganisms are able to travel from one planet to another and become of exolife was not taken seriously by the scientific community for a long time. However at the end of t... The hypothesis that bacteria and protozoa microorganisms are able to travel from one planet to another and become of exolife was not taken seriously by the scientific community for a long time. However at the end of the 20th century the situation changed dramatically. Firstly, in 1990, meteorites consisting of Martian rocks were found. Secondly, it became clear that many microorganisms especially bacteria spores have an uncanny ability to endure the rugged environment of the outer space for a long time and then re-activate in a more favorable environment. If we compare these findings, the idea of interplanetary transmigration of the simplest forms of life on meteoroids ceases to look so illusory. The final dot in this issue was made by the works of academician Rozanov, and later Hoover (Professor Richard B. Hoover) through the discovery of fossilized microbes inside of a meteorite massif, that is to say, seeds of life. However, to tie only the simplest forms of life to meteorites or comets is to introduce strong constraints on the likelihood of delivery of seeds (spores of life) to Earth for many obvious reasons. Besides, exobiology does not negate the problem of origin of life, and transfers it into the era of the young universe. Therefore, it is necessary to consider in detail the essence of seeds of life or cosmic particles of dust and gas-dust streams as their carriers, their penetration path to Earth and forms of their existence. 展开更多
关键词 Gas-dust streams spores of life and space viruses comets and meteoroids biological hazards.
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神奇的天下第一树——银杏
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作者 陈育军 《知识就是力量》 1999年第2期25-25,共1页
银杏是裸子植物,没有果实只有裸露的种子(白果),种子外形像杏,故名“银杏”,俗称白果树。 据研究,银杏在距今2亿年前就有了,远在1.4亿年前的时候几乎遍布全球,第四纪冰川时期几乎全部毁灭,留下了无数化石。
关键词 银杏种子 裸子植物 银杏树 第四纪冰川 种子外形 全部毁灭 银杏叶 心血管疾病 广岛原子弹爆炸 中国园林文化
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