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61.
Horseradish, Armoracia rusticana , is propagated vegetatively through root cuttings. It is described as a male-sterile plant as it does not form seeds or only develops them in small quantities. This study discusses the anatomical structure of anthers and the events throughout meiosis up to the formation of a male gametophyte. Microscopic observations have shown that the anatomical structure of the anther wall of A. rusticana is typical of the whole family of Brassicaceae , and all its layers are properly developed and fully functional. Meiosis in the sporogenous tissue proceeds correctly and leads to the formation of microspores. Also the configurations of the cytoplasmic skeleton are typical of plants with simultaneous cytokinesis. Further development, however, exhibits many abnormalities. A majority of the cells formed in the sample studied were dysfunctional uninucleate microspores with apparent symptoms of degeneration of the cytoplasm and organelles. Binucleate pollen grains, in which mitosis did occur, constituted only 10% of the cells analysed. Anatomical and cytological observations of male sterility in A. rusticana indicated inhibition of development at the microspore, stage which was manifested by cytoplasm degeneration with a low number of membranes and a scarce amount of starch in proplastids. Usually, in the prolonged microspore stage and in the young pollen no mitosis occurs at the time of anthesis. Cytological disorders may, to a great extent, limit the number of functional bicellular male gametophytes. Both in microspores and in pollen grains, there is exceptionally little starch in plastids. 相似文献
62.
甘蔗茎尖细胞有丝分裂过程中微管骨架的变化 总被引:1,自引:0,他引:1
[目的]研究单子叶植物茎尖有丝分裂细胞的微管动态变化情况。[方法]采用冰冻切片法结合间接免疫荧光技术及DAPI染色,利用荧光显微镜观察甘蔗茎尖细胞有丝分裂时微管列阵的排列、转换及与染色体运动的关系。[结果]当周质微管形成时,细胞核保持完整;有丝分裂前期,周质微管转变为早前期微管带;当纺锤体微管形成时,细胞核膜破裂,染色体排列在细胞板位置;之后纺锤体微管向成膜体微管转换,纺锤体微管逐渐缩短而细胞板两侧微管逐渐增加,在这个过程中姊妹染色体被微管从细胞板处分离并牵引至两极,从而形成成膜体微管;之后两个子细胞的细胞核形成,并最终分裂,细胞数量增加。[结论]从细胞微管各时期的排列就可以判断出细胞分裂方向,了解其生长情况,为甘蔗增粗机理的研究提供例证。 相似文献
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Mlody Dutot Elodie Olivier Sophie Fouyet Romain Magny Karim Hammad Emmanuel Roulland Patrice Rat Roxane Fagon 《Marine drugs》2021,19(1)
Phlorotannins are polyphenols occurring exclusively in some species of brown algae, known for numerous biological activities, e.g., antioxidant, antiproliferative, antidiabetic, and antiallergic properties. Their effects on the response of human lung cells to benzo[a]pyrene (B[a]P) has not been characterized. Our objective was to in vitro evaluate the effects of a phlorotannin-rich extract obtained from the brown algae Ascophyllum nodosum and Fucus vesiculosus on B[a]P cytotoxic effects. The A549 cell line was incubated with B[a]P for 48 and 72 h in the presence or absence of the brown algae extract. Cytochrome P450 activity, activation of P2X7 receptor, F-actin disorganization, and loss of E-cadherin expression were assessed using microplate cytometry and fluorescence microscopy. Relative to control, incubation with the brown algae extract was associated with lower B[a]P-induced CYP1 activity, lower P2X7 receptor activation, and lower reactive oxygen species production. The brown algae extract inhibited the alterations of F-actin arrangement and the downregulation of E-cadherin expression. We identified a phlorotannins-rich extract that could be deeper investigated as a cancer chemopreventive agent to block B[a]P-mediated carcinogenesis. 相似文献
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Cytotoxic Effects of Tropodithietic Acid on Mammalian Clonal Cell Lines of Neuronal and Glial Origin
Heidi Wichmann Farina Vocke Thorsten Brinkhoff Meinhard Simon Christiane Richter-Landsberg 《Marine drugs》2015,13(12):7113-7123
The marine metabolite tropodithietic acid (TDA), produced by several Roseobacter clade bacteria, is known for its broad antimicrobial activity. TDA is of interest not only as a probiotic in aquaculture, but also because it might be of use as an antibacterial agent in non-marine or non-aquatic environments, and thus the potentially cytotoxic influences on eukaryotic cells need to be evaluated. The present study was undertaken to investigate its effects on cells of the mammalian nervous system, i.e., neuronal N2a cells and OLN-93 cells as model systems for nerve cells and glia. The data show that in both cell lines TDA exerted morphological changes and cytotoxic effects at a concentration of 0.3–0.5 µg/mL (1.4–2.4 µM). Furthermore, TDA caused a breakdown of the mitochondrial membrane potential, the activation of extracellular signal-regulated kinases ERK1/2, and the induction of the small heat shock protein HSP32/HO-1, which is considered as a sensor of oxidative stress. The cytotoxic effects were accompanied by an increase in intracellular Ca2+-levels, the disturbance of the microtubule network, and the reorganization of the microfilament system. Hence, mammalian cells are a sensitive target for the action of TDA and react by the activation of a stress response resulting in cell death. 相似文献
68.
【目的】比较中国仓鼠卵巢(CHO)细胞和人胚肾T(HEK293T)细胞的迁移能力,筛选适用于细胞骨架形态和外源基因对细胞迁移影响研究的细胞系。【方法】通过免疫荧光组织化学比较CHO和HEK293T细胞骨架的形态差异,通过延时成像和划痕试验比较细胞迁移能力,通过免疫印迹比较2株细胞系细胞骨架基因的相对表达,并从细胞骨架差异和结构基因的选择性表达方面解释细胞迁移能力的差异。【结果】CHO和HEK293T细胞系的细胞骨架在形态上存在较大差异,HEK293T细胞系的核质比是CHO细胞的2.25倍;CHO细胞比HEK293T细胞的迁移能力强,是HEK293T细胞的2.9倍;2种细胞内α-Tubulin/β-Actin的比率存在较大差异,CHO是HEK293T的1.2倍。【结论】细胞中微管微丝的差异性分布及结构基因Tubulin和Actin的选择性表达是细胞迁移特性不同的关键因素。CHO细胞适用于涉及细胞骨架形态和外源基因对细胞迁移影响的研究,HEK293T细胞不适用于此类研究。 相似文献