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一类非线性系统的稳定性 总被引:3,自引:0,他引:3
研究了一类非线性系统的输入输出稳定性问题,这类系统的特点是其模型为系统输出的线性拟函数。对非线性稳定性系统,利用稳定性的线性等价原理,提出了这一类非线性系统的稳定性判据;对非线性随机系统,给出了m阶均值意义下的稳定性定义,提出了一种二阶均值下的输入输出稳定性条件,给出了几个示例说明。 相似文献
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Ultraviolet light damages DNA by catalysing covalent bond formation between adjacent pyrimidines, generating cis-syn cyclobutane pyrimidine dimers (CPDs) as the most common lesion. CPDs block DNA replication by high-fidelity DNA polymerases, but they can be efficiently bypassed by the Y-family DNA polymerase pol eta. Mutations in POLH encoding pol eta are implicated in nearly 20% of xeroderma pigmentosum, a human disease characterized by extreme sensitivity to sunlight and predisposition to skin cancer. Here we have determined two crystal structures of Dpo4, an archaeal pol eta homologue, complexed with CPD-containing DNA, where the 3' and 5' thymine of the CPD separately serves as a templating base. The 3' thymine of the CPD forms a Watson-Crick base pair with the incoming dideoxyATP, but the 5' thymine forms a Hoogsteen base pair with the dideoxyATP in syn conformation. Dpo4 retains a similar tertiary structure, but each unusual DNA structure is individually fitted into the active site for catalysis. A model of the pol eta-CPD complex built from the crystal structures of Saccharomyces cerevisiae apo-pol eta and the Dpo4-CPD complex suggests unique features that allow pol eta to efficiently bypass CPDs. 相似文献
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