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Among several models, one model has been identified with the statistical criteria r≥0.9, chance>amp;lt;0.02, superimposition match>amp;gt;0.67.


Among the several pharmocophore models, the best model had R2 = 0.69, chance = 0.09, size = 3, match = 0.68.


1) for R isomers with correlation coefficient r =0.9, chance= 0.05 and match= 0.47 has four biophoric sites and three secondary sites while the best model for S isomers (model no.


2) with correlation coefficient r =0.86, chance =0.01 and match = 0.45 has three biophoric sites and two secondary sites.


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 The results presented in this paper may be classified into three categories. First, there is derived the characteristics of gain, bandwidth, and figure of merit of a nondegenerative parametric amplifier of both fundamental and subharmonic pumping; and the comparison between them is carried out in substantial detail. Second, there is devised an analytical method for determining the harmonic contents of the capacitance of a nonlinear semiconductor diode, which is negatively biased and is under the action of... The results presented in this paper may be classified into three categories. First, there is derived the characteristics of gain, bandwidth, and figure of merit of a nondegenerative parametric amplifier of both fundamental and subharmonic pumping; and the comparison between them is carried out in substantial detail. Second, there is devised an analytical method for determining the harmonic contents of the capacitance of a nonlinear semiconductor diode, which is negatively biased and is under the action of a strong high frequency pumping voltage. The magnitudes of bias and pumping voltage are thus found quantitatively. Also, the stability requirements for pumping amplitude and pumping frequency are discussed. Third, the noise figure of a parametric amplifier itself and the effective noise figure of the amplifier loaded with a noisy second stage, which may be a frequency converter, are derived. Factors such as diode loss, match, and the bandwidth ratio of the signal to the idler circuit are all considered in the derivations so as to make the results with greater importance for practical applications. Finally, a numerical example is given to show the utility of the results presented in this paper and to illustrate a possible design procedure of a nondegenerative parametric amplifier.  本文主要结果有三:第一,推导出基波激励和次谐波激励参量放大器的优值、功率增益、和通带等主要特性,并就这些特性对基波激励源的和次谐波激励源的参量放大器进行比较;第二,通过半导体二极管非线性电容的谐波分量的分析,在激励电压、偏压和放大器的特性间得出定量关系,并且对给定放大器特性求出激励源幅度和频率的稳定要求;第三,推导出放大器的有效噪声,并给出最低有效噪声的设计条件。 以上特性的探讨和二极管损耗、信号迴路和镜象迴路通带比、匹配等因子结合在一起进行,使所得结果更具有实际意义。最后举出一数字例子,说明应用本文结果来设计参量放大器的一种可能步骤。  A practical means is presented for the design of a coherent Integrating Filter (GIF) covering the whole doppler frequency range with a single channel, as it is much simpler than the usual way of implementing the coherent integration by a large number of parallel channels each matched at a different doppler frequency, therefore it is easier to implement and superior than the parallel matched filters scheme. The paper has analyzed the principle of operation of the GIF, pointed out that it is equivalent to a set... A practical means is presented for the design of a coherent Integrating Filter (GIF) covering the whole doppler frequency range with a single channel, as it is much simpler than the usual way of implementing the coherent integration by a large number of parallel channels each matched at a different doppler frequency, therefore it is easier to implement and superior than the parallel matched filters scheme. The paper has analyzed the principle of operation of the GIF, pointed out that it is equivalent to a set of high frequency sweeping comb filters but with no sweeping loss. GIF implements the optimum receiver by inclined cutting the Woodward's "uncertainty function" as contrast with the axis parallel cutting implemented by the matched filters.The block diagram of a radar system with GIF is presented in the last section and the choice of some system parameters is explained.  提出一个具有能在未知多卜勒频移情况下不需分路的相参积累器,它比一般分路方案可以简单得多。因此在从噪声中发现微弱信号的角度来看,优于其他曾提出过的任何积累方案。文中分析了这种积累器的作用原理,提出了利用这种积累器组成的积累滤波器如何能对脉冲串高频信号获得最佳信噪比,并用模糊度函数的概念说明了这种积累滤波器的实质,指出它比脉冲串匹配滤波器更优越和具有较大的实现可能性。最后还讨论了利用这种设备进行雷达站设计的要点和某些工作参数的选择与考虑。  ~~  本文介绍了匹配滤波器的概念及利用延时线系统构成匹配滤波器的原理,并说明了利用具有反馈电路的延时线系统实现在雷达接收机检波器以前对雷达回波信号近似匹配滤波器的原理,实现方法,以及与理想匹配滤波器的比较。实现这种系统的雷达在抗人为干扰、抗固定目标干扰、测速、增加作用距离等方面具有独特的优点。   << 更多相关文摘 
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