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生长激素梯度促成植物顶-基轴的形成
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作者 杨志军 《科学》 2004年第1期64-64,共1页
关键词 生长激素梯度 植物 基轴 形成 发育 PIN7蛋白 合子分裂
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Stage-specific appearance of cytoplasmic microtubules around the surviving nuclei during the third prezygotic division of Paramecium
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作者 Yiwen WANG Jinqiang YUAN +1 位作者 Xin GAO Xianyu YANG 《Zoological Research》 CAS CSCD 北大核心 2012年第6期I0036-I0041,共6页
There are six micronuclear divisions during conjugation of Paramecium caudatum: three prezygotic and three postzygotic divisions. Four haploid nuclei are formed during the first two meiotic prezygotic divisions. Usua... There are six micronuclear divisions during conjugation of Paramecium caudatum: three prezygotic and three postzygotic divisions. Four haploid nuclei are formed during the first two meiotic prezygotic divisions. Usually only one meiotic product is located in the paroral cone (PC) region at the completion of meiosis, which survives and divides mitotically to complete the third prezygotic division to yield a stationary and a migratory pronucleus. The remaining three located outside of the PC degenerate. The migratory pronuclei are then exchanged between two conjugants and fuse with the stationary pronuclei to form synkarya, which undergo three successive divisions (postzygotic divisions). However, little is known about the surviving mechanism of the PC nuclei. In the current study, stage-specific appearance of cytoplasmic microtubules (cMTs) was indicated during the third prezygotic division by immunofluorescence labeling with anti-alpha tubulin antibodies surrounding the surviving nuclei, including the PC nuclei and the two types of prospective pronuclei. This suggested that cMTs were involved in the formation of a physical barrier, whose function may relate to sequestering and protecting the surviving nuclei from the major cytoplasm, where degeneration of extra-meiotic products occurs, another important nuclear event during the third prezygotic division. 展开更多
关键词 PARAMECIUM CONJUGATION MEIOSIS Paroral cone region Cytoplasmic microtubules
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Splitting and Restoration of Kondo Peak in a Deformed Molecule Quantum Dot Coupled to Ferromagnetic Electrodes
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作者 王瑞强 蒋开明 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第2期370-376,共7页
We adopt the nonequilibrium Green's function method to theoretically study the Kondo effect in a deformed molecule, which is treated as an electron-phonon interaction (EPI) system. The self-energy for phonon part i... We adopt the nonequilibrium Green's function method to theoretically study the Kondo effect in a deformed molecule, which is treated as an electron-phonon interaction (EPI) system. The self-energy for phonon part is calculated in the standard many-body diagrammatic expansion up to the second order in EPI strength. We find that the multiple phonon-assisted Kondo satellites arise besides the usual Kondo resonance. In the antiparallel magnetic configuration the splitting of main Kondo peak and phonon-assisted satellites only happen for asymmetrical dot-lead couplings, but it is free from the symmetry for the parallel magnetic configuration. The EPI strength and vibrational frequency can enhance the spin splitting of both main Kondo and satellites. It is shown that the suppressed zero-bias Kondo resonance can be restored by applying an external magnetic field, whose magnitude is dependent on the phononic effect remarkably. Although the asymmetry in tunnel coupling has no contribution to the restoration of spin splitting of Kondo peak, it can shrink the external field needed to switch tunneling magnetoresistance ratio between large negative dip and large positive peak. 展开更多
关键词 Kondo splitting molecular electronics magnetoresistance effect electron-phonon interaction
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A New Determination of the Lambda-Nucleon Coupling Constants in Relativistic Mean Field Theory
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作者 王小素 桑红毅 +1 位作者 王家慧 吕洪风 《Communications in Theoretical Physics》 SCIE CAS CSCD 2013年第10期479-484,共6页
A new determination of the Lambda-nucleon coupling constants in relativistic mean field theory is presented by optimizing both hyperon binding energy and spin-orbit splitting, ttypernuclear single particle spectra wit... A new determination of the Lambda-nucleon coupling constants in relativistic mean field theory is presented by optimizing both hyperon binding energy and spin-orbit splitting, ttypernuclear single particle spectra with the new coupling constants suggest the good agreement between the calculation and available data. The spin-orbit splitting of hyperon in medium mass hypernuclei is systematically larger than that in light- or heavy-mass hypernuclei. The sensitivity of the Lambda spin-orbit splitting to the omega-Lambda-Laznbda tensor coupling term is also explored. 展开更多
关键词 effective Lambda-nucleon interaction relativistic mean field theory single particle spectra
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