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随着有线电视的迅速发展,有线电视网络在不断扩大,有线电视用户也在不断增加,为了保证有线电视系统的安全运行,必须采取许多技术措施来保证,其中良好的接地尤为重要。特别是有线电视机房和干线设备,它是有线电视传输的核心,更应该保持良好的接地,这样既可以有效的减少外界对信号的影响,而且可以有效的保护设备在雷雨季节免受或减少雷击的损坏。下面就介绍一下有线电视的接地技术。 相似文献
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介绍了电信企业渠道的特点以及渠道经营的实质,分析了电信企业客户生命周期的阶段划分和不同阶段的特征,详细阐述了客户生命周期不同阶段所应采取的具体渠道策略。 相似文献
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Shape resonances of electron-molecule system formed in the low-energy electron attachment to four low-lying conformers of serine (serine 1, serine 2, serine 3, and serine 4) in gas phase are investigated using the quantum scattering method with the non-empirical model potentials in single-center expansion. In the attachment energy range of 0-10 eV, three shape resonances for serine 1, serine 2, and serine 4 and four shape resonances for serine 3 are predicted. The one-dimensional potential energy curves of the temporary negative ions of electron-serine are calculated to explore the correlations between the shape resonance and the bond cleavage. The bond-cleavage selectivity of the different resonant states for a certain conformer is demonstrated, and the recent experimental results about the dissociative electron attachment to serine are interpreted on the basis of present calculations. 相似文献
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