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Pollen grains are highly variable in size and shape ranging from 5μ to over 200μ in diameter and from circular to tetrahedral or dumbbell shaped.
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花粉粒的壁由两层构成，外壁为孢粉素壁，具有很强的抵抗力，其上有特征性雕纹或孔纹。 |
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Pollen grains are rich in mitochondria, Golgi apparatus, and endoplasmic reticulum.
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花粉粒富含线粒体、高尔基体以及内质网上。 |
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Pollen mother cell (PMC) In angiosperms and gymnosperms, a somatic cell that gives rise to four haploid pollen grains by meiosis.
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花粉母细胞（PMC）：指在被子植物和裸子植物中，能通过减数分裂产生4个单倍体花粉粒的体细胞。 |
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Pollen never deteriorates. It is one of the few naturally secreted su tances that last indefinitely.
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花粉永远不会变质，是自然界中少有的几种可以无限期存在的物质之一。 |
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Pollen never deteriorates. It is one of the few naturally secreted substances that last indefinitely.
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花粉永远不会变质，是自然界中少有的几种可以无限期存在的物质之一。 |
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Pollen sac A chamber in which the pollen is formed in the angiosperms and conifers.
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花粉囊：在被子植物和针叶类中形成花粉的小室。 |
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Pollen that floats is light and water repellent, and may have a coating of oil that alters the surface tension of the water.
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漂浮在水面的花粉非常轻且具有疏水性，其原因可能是花粉表面具有一层油脂使得水的表面张力发生改变。 |
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Pollen tubes are the polarized tip-growing system that delivers the male gametes towards the ovaries, which is very essential for sexual reproduction in higher plants.
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摘要花粉管的极性顶端生长是将雄配子体运输到子房的过程，在高等植物有性生殖过程中起著重要的作用。 |
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Pollination. The researchers looked at the value of crops that are insect-pollinated (not including crops pollinated by domesticated honeybees). Value: $3 billion (euro2.5 billion).
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传授花粉。研究者计算了昆虫授粉作物的价值（还不包括由家养蜜蜂授粉的作物），此项估价为30亿美金。 |
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Polling is the fax mode of operation where the caller requests the remote answering machine to send a fax.
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轮询:传真的一个操作模式，通常是主叫请求远程应答主机发送传真。 |
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Polling-place practices add further hazards of insecurity and potential malfunctions.
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投票所则会进一步增添安全和故障的风险。 |
