We investigate the fluorene-vinylene unit dependent photo-physical properties of multi- branched truxene based oligomers （Tr-OFVn, n=1-4） employing steady-state absorption and emission spectroscopy, transient absorp...We investigate the fluorene-vinylene unit dependent photo-physical properties of multi- branched truxene based oligomers （Tr-OFVn, n=1-4） employing steady-state absorption and emission spectroscopy, transient absorption spectroscopy, two-photon fluorescence, and z-scan technique. The results show that the increasing of fluorene-vinylene unit leads to a red-shift in the spectra of absorption and fluorescence, and shortens the excited state lifetime. Meanwhile, two-photon fluorescence efficiency and two-photon absorption cross section of truxene based oligolners gradually enhance in company with the extension of π- conjugated length. In addition, the values of two-photon absorption cross section modeled on the sum-over-state approach agree well with the experimental ones. The results indicate multi-branched truxene based oligomers bearing organic materials for two-photon applications.展开更多
The pattern of change of the microtubule cytoskele-ton of the root-tip cells of rice during mitosis was studied using immunofluorescence technic and confocal laser scanning microscopy. All the major stages of cell div...The pattern of change of the microtubule cytoskele-ton of the root-tip cells of rice during mitosis was studied using immunofluorescence technic and confocal laser scanning microscopy. All the major stages of cell division including preprophase, prophase, metaphase, anaphase and telophase were observed. The most significant finding was that in the preprophase cells microtubules radiating from the nuclear surface to the cortex were frequently seen. During development these microtubules became closely associated with the preprophase band and prophase spindle indicating that the microtubules radiating from the nuclear surface, the preprophase band and the prophase spindle were structurally and functionally closely related to each other. Granule-like anchorage sites for the radiating microtubules at the nuclear surface were often seen and the possibility that these granule-like anchorage sites might represent the microtubule organizing centres was discussed.展开更多
文摘近年来,海上油气化探已在世界范围内展开,各国先后在东西太平洋、墨西哥湾、北大西洋、南波沸特海、澳洲大陆边缘、北令海、北海、地中海、波罗的海、东海及南海等海域开展了油气化探的试验、研究和生产工作。采集的样品包括水样和海底浅表层土样,分析检测的指标主要为烃类气体,此外还有紫外、荧光,δ^(13)C、△C、氦、微生物、汞气、金属及 API
文摘We investigate the fluorene-vinylene unit dependent photo-physical properties of multi- branched truxene based oligomers （Tr-OFVn, n=1-4） employing steady-state absorption and emission spectroscopy, transient absorption spectroscopy, two-photon fluorescence, and z-scan technique. The results show that the increasing of fluorene-vinylene unit leads to a red-shift in the spectra of absorption and fluorescence, and shortens the excited state lifetime. Meanwhile, two-photon fluorescence efficiency and two-photon absorption cross section of truxene based oligolners gradually enhance in company with the extension of π- conjugated length. In addition, the values of two-photon absorption cross section modeled on the sum-over-state approach agree well with the experimental ones. The results indicate multi-branched truxene based oligomers bearing organic materials for two-photon applications.
文摘The pattern of change of the microtubule cytoskele-ton of the root-tip cells of rice during mitosis was studied using immunofluorescence technic and confocal laser scanning microscopy. All the major stages of cell division including preprophase, prophase, metaphase, anaphase and telophase were observed. The most significant finding was that in the preprophase cells microtubules radiating from the nuclear surface to the cortex were frequently seen. During development these microtubules became closely associated with the preprophase band and prophase spindle indicating that the microtubules radiating from the nuclear surface, the preprophase band and the prophase spindle were structurally and functionally closely related to each other. Granule-like anchorage sites for the radiating microtubules at the nuclear surface were often seen and the possibility that these granule-like anchorage sites might represent the microtubule organizing centres was discussed.
