频率

The crossover frequency is sweepable from 60Hz to 1KHz providing an ideal frequency split suitable for feeding subs and full range units with discrete bandwidths right out of the box.

交叉频率是sweepable从60赫兹到1kHz时提供一个理想的频率分裂喂养潜艇和右开箱即用离散带宽适合各种单位。

The stretching vibrational frequencies of C-H and N-H bonds of the tetrazole rings are higher than those of substituents'.

环C-H或N-H键伸缩振动频率均较取代基相应的C-H和N-H伸缩振动频率高。

Reactive oxygen species causing DNA oxidative damage comes from two kinds of ways:one is from cellular normal physiological metabolism;the other is from outer environment.Redox-sensitive green fluorescent protein was expressed in Saccharomyces cerevisiae.Recombinant cells were evaluated in monitoring the changes in the redox state of living cells when challenged with toxicologically relevant metal ions NaAsO_2 or Pb(NO_3)_2 by measuring emission intensity at 510 nm with a Hitachi F6500 fluorescence spectrophotometer,roGFP expressed in yeast responded not only to typical membrane-permeant oxidants H_2O_2 and reductants DTT,but also to toxicological metal ion-induced intracellular redox changes in a dose-dependent manner.Moreover,exposure of yeast cells to NaAsO_2 or Pb(NO_3)_2 at concentrations that induced redox changes reported by roGFP caused up to 2～3 fold increases in DNA mutation frequency.This mutagenic effect was largely caused by oxidative stress since blocking the production of hydryl radicals with thiourea significantly reduced the mutation rate as well as delayed the cell death.

本文将对氧化还原状态变化敏感的绿色荧光蛋白roGFP1-R12，在酵母细胞中实现了多拷贝强表达；荧光扫描经强氧化剂H_2O_2和还原剂DTT以及环境中重金属NaAsO_2或Pb(NO_3)_2处理后的酵母细胞悬液，测定510 nm处的荧光发射强度结果显示，表达的绿色荧光蛋白对氧化还原水平敏感，且在510 nm处的荧光强度与一定的重金属浓度呈正相关，即roGFP1-R12在510nm处的荧光发射值随重金属浓度的增高而增强，从而说明重金属对细胞的毒性在一定程度上很可能是通过破坏细胞内的氧化还原平衡发生作用；同时通过该绿色荧光蛋白对胞内氧化还原状态变化的响应情况可以来实时检测环境中的重金属；遗传学的点突变频率及致死率实验数据表明，重金属能导致菌体的点突变频率和致死率升高，且活性氧的清除剂巯基脲能明显降低这种点突变和致死率，说明由重金属引发的这种点突变和致死效应在很大程度上是依赖于重金属对细胞诱导产生的氧化胁迫。

C8051F005 is the control center of the survey meter, the signal is obtained by jaw pressure transformator and current transformator. Direct Digital Frequency Synthetics technology is adopted to automatically adjust the frequency of the actuating signal and avoid the interference of the signal in the ground network.

该检测仪采用C8051F005单片机作为控制处理中心，钳口式电压互感器和电流互感器检测接地电阻信号，运用直接数字频率合成技术自动调整激励信号频率，从而避免地网中干扰信号源的影响。

Based on the characteristic of tristate BBPDs, only adding an AND gate can realize the FD function which has unilateral wide frequency locking range.

利用bang- bang 相位侦测器的三状态特性，只需要加入一个AND闸便可以实现单方向无限频率锁定的频率相位侦测器。

The concentration of NO and NO2 increases with increasing of frequency and increasing of the distance between electrodes. Electrode polarity unconspicuously affects the concentration of NO and NO2. The distance between electrodes considerably affects radio of NO2 /.

结果发现：放电频率、电极间距对NO 和NO2的浓度影响显著， NO 和NO2浓度随放电频率和放电间距的提高而增加，电极极性对NO 和NO2浓度的影响不明显，电极间距对 NO2 /的比值影响明显。

The wavelet time-frequency properties of the uncracked rotor and the cracked rotor were discussed by the continuous wavelet time-frequency analysis algorithm. A new algorithm using the wavelet time-frequency analysis algorithm to detect the crack was proposed. The influence of the sampling frequency on the wavelet time-frequency analysis algorithm was analyzed through the numerical simulation research; the valid sampling frequency was presented.

利用连续小波时频分析方法，讨论了裂纹转子与无裂纹转子的小波时频特性，提出了利用小波时频分析方法识别裂纹的新方法；数值仿真研究了采样频率对小波时频分析方法的准确性和有效性的影响，并给出了建议性的采样频率。

This compensation circuit can make the stability of the LDO linear regulator undependent on the effect of load capacitor's equivalent serial resistance, and it also makes the unit gain frequency bandwidth change slightly when the load is varying, thus greatly improving the performance of transient response, Furthermore, on the basis of dynamic frequency compensation, an overcurrent protection circuit is designed.

文章针对LDO稳定性的问题，提出了一种内部动态频率补偿电路，使LDO线性稳压器的稳定性不受负载电容的等效串联电阻的影响，其单位增益带宽也不随负载电流变化而改变，大大提高了瞬态响应特性；采用Hynix 0.5μm CMOS工艺模型对电路进行仿真；此外，该电路在实现动态频率补偿的基础上又加入了系统的过流保护功能，当负载电流大于限制电流时，LDO不能正常工作；当负载电流小于限制电流时，又自动恢复到正常工作状态。

A new method of optimizing the Underfrequency load shedding has been developed in the paper.

低频减载是电力系统抑制频率下降、维持系统频率稳定的有效方法。

Power system ; Underfrequency load shedding; Load frequency characteristics ; Frequency regulation factor

电力系统；低频减载；负荷频率特性；频率调节系数

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐