排序方式: 共有19条查询结果,搜索用时 343 毫秒
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鹅掌楸属植物花粉萌发前后壁的超微结构 总被引:1,自引:0,他引:1
观察描述了在电镜下中国鹅掌楸(Liriodendronchinense)和北美鹅掌楸(L.tulipifera)2种植物花粉壁的超微结构及其水合后的变化。(1)成熟花粉壁由6层组成,即外壁3层──外层,中层1和中层2,内壁3层──内壁1,内壁2和内壁3。(2)花粉水合时,在内壁3与质膜之间由P一粒子(多糖-粒子)和被膜小泡参与形成新层。(3)花粉萌发时,由内壁3的一部分和新层突出萌发孔共同形成花粉管壁。(4)新层于花粉管形成早期分成2层──外染色深的果胶层和内电子透明的胼胝质层。 相似文献
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竹子节部“韧皮部结”的发育与超微结构 总被引:1,自引:0,他引:1
The development, cytological characters and ultrastructure of phloem ganglion in the nodal region of Phyllostachys edulis (Carr.) H. de Lehaie, a most economically important bamboo, were investigated and the possible physiological function of this special structure was proposed. The phloem ganglion derived directly from procambium is situated at the sites where the vascular bundle forks and is present in pairs. The phloem ganglion is spindle-like in appearance and usually consists of 4 to 6 layers. Two kinds of cells in the ganglion could be distinguished. In the middle, there are two layers of filiform cells with pointed ends so that there are no normal sieve plates. Nevertheless, there are many pits on the lateral wall of the filiform cells. The other type of cells located at both ends of the spindle which possess an intermediate form between the filiform cell and the normal sieve tube. The walls of these cells towards the filiform cells are strongly convex forming a special sieve plate. Ultrastructure study showed that cells in the ganglion are connected by enriched plasmodesma. During early differentiation, the paramural body and the ingrowth of cell wall could be observed. It indicates that the cells of phloem ganglion have the character of transfer cells. The organelles in the mature cells are mainly plastids with abundant accumulation of proteins of crystalline structure. The above-mentioned results suggest that the physiological function of the phloem ganglion is closely related with substance transport. 相似文献
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不同施氮量对桑园红壤耕层酶活性的影响 总被引:5,自引:0,他引:5
在广西红壤典型气候区研究施用氮肥对桑园土壤过氧化氢酶、脲酶、酸性磷酸酶和转化酶酶活性的影响,为广西红壤区桑园合理施氮和耕地保育提供科学依据。试验设置3个施氮量水平(N1:120.75 kg N/hm2,N2:172.5 kg N/hm2,N3:207 kg N/hm2),在冬季测定不同氮肥处理下耕层土壤酶活性,并与桑叶产量进行相关分析。结果表明,土壤脲酶和转化酶活性均随着施氮量的增加而增加,过氧化氢酶和酸性磷酸酶活性在中等施氮量(N2处理)下较大。土壤转化酶和脲酶活性呈显著的正相关关系、转化酶和磷酸酶活性呈显著的正相关关系,土壤脲酶、磷酸酶、转化酶活性与桑叶产量呈极显著相关。合理施用氮肥能提高桑园土壤转化酶、磷酸酶、脲酶活性,土壤脲酶和蔗糖酶活性可作为评价桑园土壤肥力质量的指标之一。 相似文献
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应用透射电子显微镜观察了杉木花粉母细胞减数分裂前期的联会复合体。发现杉木花粉母细胞减数分裂的联会复合体中央结构是由两条暗带及一条明带组成,而不是一般描述的一条暗带。 相似文献
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1971年,Mizuhira和Futaesaku在研究电镜放射自显影时,发现鞣酸对微管的亚单位结构有良好的固定作用。此后,一些作者在进行生物超微结构的电镜研究时,都曾使用鞣酸处理样品,并对其作用机制进行了探讨。作者们认为鞣酸具有固定、正染、负染和媒染的作用。目前在透射电镜术中制备动物样品时,鞣酸已得到相当广泛的使用,但关于处理植物样品的研究报道极少。植物样品的制备一般比动物样品困难,其细微结构不易 相似文献