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利用扫描电镜对国产凤尾蕨科( Pteridaceae ) 2 属30 种4 变种植物孢子进行了观察。其中凤尾蕨属( Pteris) 29 种4 变种, 孢子三裂缝, 辐射对称; 极面观为钝三角形, 赤道面观为半圆形或超半圆形; 孢子极轴长26~54μm, 赤道轴长34~97μm; 外壁厚, 形成孢子表面纹饰的轮廓; 周壁薄, 紧贴于外壁上; 多数种类孢子外壁具沿赤道加厚的赤道环, 孢子表面呈瘤块状、疣块状, 或隆起的脊连成网状或拟网状等纹饰, 有的种类具近极脊和远极脊。凤尾蕨属植物孢子的形态稳定, 种间差异明显, 但孢子形态特征与孢子体的形态特征是不相关的。栗蕨属( Histiopteris) 植物孢子为单裂缝, 两侧对称, 极面观椭圆形, 赤道面观豆形; 孢子极轴长22~23μm, 赤道轴长29~36μm; 周壁很薄, 由外壁形成孢子纹饰的轮廓; 表面呈粗的块状纹饰。从孢子形态上看, 栗蕨属与凤尾蕨属有很大差异, 将其放在一个科中不合适。 相似文献
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利用扫描电镜对中国产岩蕨科(Woodsiaceae)3属18种植物孢子进行了观察。结果表明,孢子单裂缝,两侧对称,极面观为椭圆形或宽椭圆形,赤道面观为半圆形或超半圆形;极轴长32~50μm,赤道轴长43~61μm;外壁表面光滑,由周壁形成孢子表面纹饰的轮廓,根据表面纹饰,孢子可分为5种类型:(1)片状纹饰:周壁表面形成疏密不一的片状褶皱,并连成网状;(2)脊状纹饰:周壁表面形成脊状褶皱,并连成网状;(3)翅脊状纹饰:周壁表面具脊状褶皱,并连成网状,脊的顶端具流苏状不明显的低翅;(4)翅状纹饰:周壁外层形成翅状纹饰,翅的边缘较薄;(5)丝毛状纹饰:周壁结构疏松,由细丝交织成立体网状。上述孢粉学特征表明,岩蕨科是一个自然的类群,其3属的亲缘关系较近,都是岩蕨科的合理成员。 相似文献
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利用扫描电镜对国产阴地蕨科(Botrychiaceae)3属12种植物孢子进行了观察.结果表明: 孢子具三裂缝;极面观为钝三角形或近圆形;赤道面观为半圆形或超半圆形.极轴长20~34 μm,赤道轴长31~40 μm.由外壁形成孢子表面纹饰的轮廓;周壁薄,疏松地覆盖在外壁表面.孢子表面纹饰可分为以下3种类型:①疣块状纹饰(verrucate-rugulate):孢子远极面形成顶端扁平而大的疣块状纹饰,再由疣块连接成短的条状或拟网状;②疣状纹饰(verrucate):孢子表面具大小不等的疣状纹饰,相邻的疣愈合成短条状或不愈合;③脊状纹饰(lophate):孢子表面具脊状褶皱,并连接成网状.从孢子形态、纹饰类型和孢壁结构看3属属内差异明显,属间差异不明显,研究结果支持阴地蕨科具1属--阴地蕨属,其下可分3个组. 相似文献
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利用扫描电镜对中国产卷柏科25种植物孢子形态进行了观察。结果显示:(1)卷柏科植物大孢子为球状四面体,辐射对称;具三裂缝,裂缝为孢子半径的1/2~3/4;极面观一般为三角圆形或近圆形,赤道面观为近圆形、近扇形或近椭圆形;极轴长为158~548μm,赤道轴长为196~675μm。(2)小孢子为球状四面体,辐射对称;具三裂缝,裂缝为孢子半径的1/2~3/4或几达赤道线;极面观一般为近圆形或三角圆形,赤道面观为近圆形或近扇形;极轴长为10~40μm,赤道轴长为17~63μm。(3)孢子表面具颗粒状、瘤状、疣状、刺状、棒状、网状、片状、疣块状和脑状纹饰。研究认为,孢子形态特征可以作为该科亚属及种的分类学依据。 相似文献
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利用扫描电镜对中国产石松科6属9种1变型植物孢子形态进行了观察.结果表明:石松科植物孢子为四面体形,辐射对称;具三裂缝,裂缝为孢子半径的1/2~3/4或几达赤道线,有些种裂缝具唇状边缘;极面观一般为圆角三角形或近圆形,赤道面观为扇形或近椭圆形;极轴长为23~50 μm,赤道轴长为24~54 μm;由外壁形成孢子表面网状、棒状、脊状、拟网状、瘤状和颗粒状纹饰的轮廓;周壁薄,通常只有1层.从孢粉学特征看,石松属和扁枝石松属孢子形态有交叉,属间特征不明显;而小石松属、卡罗利拟小石松属、垂穗石松属和藤石松属的属间孢子形态特征明显. 相似文献
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利用扫描电镜对中国产叉蕨科7属34种植物孢子的形态进行了观察。叉蕨科植物孢子为左右对称,极面观为椭圆形,赤道面观为半圆形、超半圆形或豆形;极轴长为18~38μm,赤道轴长为23~57μm;单裂缝,裂缝长度为孢子全长的1/2~2/3;孢子具脊状、翅状、刺状和耳状4种纹饰,孢子表面有时具细刺、颗粒或孔。通过孢粉学分析,叉蕨科依据孢子形态特征和依据孢子体形态特征的分类结果并不一致,孢粉纹饰类型呈现一定程度的属间交叉;支持将叉蕨科和鳞毛蕨科进行重新划分的MAARTEN J.M的新分类系统。 相似文献
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Profiles of SARS-CoV-2 RNA and Antibodies in Inpatients with COVID-19 not Related with Clinical Manifestation: A Single Centre Study 下载免费PDF全文
Zhao Li Gao Ruqin Lu Roujian Wang Huijuan Deng Yao Niu Peihua Jiang Fachun Huang Baoying Liang Jiwei Jia Jing Zhang Feng Wang Wenling Wu Guizhen Tan Wenjie 《中国病毒学》2021,36(5):1088-1092
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RICHARD E. NORRIS 《Botanical journal of the Linnean Society. Linnean Society of London》1991,106(1):1-40
Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera. 相似文献
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JOAN VALUÈS MONTSERRAT TORRELL NÚRIA GARCIA JACAS 《Botanical journal of the Linnean Society. Linnean Society of London》2001,137(4):399-407
Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted. 相似文献
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Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme
responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare
the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show
that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by
distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of
demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least
one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of
the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable
potent antiproliferative synthetic drugs. 相似文献
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正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases 相似文献