阻抗

Triple integral expression of the radiation impedance of square piston is deduced and the numerical results of the radiation impedance are calculated with the method of Gaussian numerical integral.

利用高斯数值积分方法，推导了方形活塞辐射阻抗的三重积分表达式，计算了方形活塞声源的辐射阻抗。

Compared to traditional method,this approach replaced tuning capac-itor with PIN diodes,made use of its characteristics of variable impedance to adjust the impedance through the bias voltage to achieve the autotuning of directivity.

与传统方法相比，该方法采用PIN型二极管代替调节电容，利用其阻抗可变特性，通过偏置电压来调节匹配阻抗，最终实现定向耦合器的自动方向性调节。

Aim: To determine whether activation of κ-opioid receptor with U50,4 88 H, a selective κ-opioid receptor agonist, produces any changes in electrical u ncoupling during prolonged ischemia and whether these changes in electrical unco upling is associated with the cardioprotection induced by κ-opioid receptor ac tivation, and to explore the possible mechanism.

测量指标：以分光光度计在490nm波长下测定氯化三苯基四氯唑与活细胞反应的产物formazan含量的方法测定心肌细胞活性、测定冠脉流出液中乳酸脱氢酶的含量以及心室内压；②全心停灌70min，应用四电极法观察不同浓度U50，488H、nor-BNI和5-HD对缺血期间心肌整体阻抗和电脱耦联参数(电脱耦联时间、平台时间、电脱耦联最大速率和阻抗倍数)的影响。

When two elastic components are connected at one point, it is sufficient to know the undamped impedence data of two connected components at the junction point ( determined by measurement or calculation).

在两个弹性部件呈点交联的情况，只要求两个部件在交联点的无阻尼阻抗数据(可由阻抗测试或计算确定)。

The temptation in many approaches to helping is to ignore resistance and find another, easier route toward client verbalization.

许多心理治疗学派的心理咨询师或治疗师不注意阻抗，在发现求助者有阻抗的时候，他们往往寻找求助者什么都可以讲的捷径。

Starting with the traits of zero order impedance and the relationship between zero order current and zero order impedance,analyzes the main differences of electric traits of power cable s and aerial lines and the disadvantages of applying power cable s into the traditional grounded protection.

从正、负、零序阻抗特性以及零序阻抗与零序电流的关系入手，分析了架空线路与电力电缆电气特性的主要区别及传统接地保护应用于电力电缆线路所带来的弊端。

Starting with the traits of zero order impedance and the relationship between zero order current and zero order impedance,analyzes the main differences of electric traits of power cables and aerial lines and the disadvantages of applying power cables into the traditional grounded protection.

从正、负、零序阻抗特性以及零序阻抗与零序电流的关系入手，分析了架空线路与电力电缆电气特性的主要区别及传统接地保护应用于电力电缆线路所带来的弊端。

These antennas can cover GSM900/DCS/PCS/UMTS operation. In the chapter 2, the antenna is designed based on the concept of monopole antenna. Furthermore, the antenna structure have two radiant paths and coupled each other at tail end to do impedance matching. In addition, to raise distance between radiation plane and ground will avoid capacitative effect effectually. In the chapter 3, the antenna is designed based on the concept of planar inverted-F antenna. Furthermore, that the antenna structure have two radiant paths and coupled each other at tail end to do impedance matching is similar to chapter 2. But there is a difference in them. We can choose the short position to change input impedance at this structure. In the chapter 4, the antenna is designed based on the concept of planar inverted-F antenna which takes coupled-fed. It will produce the first mode and high-order mode near the frequency, 900MHz. The feature of this type is to reduce the volume effectually. This antenna can not only cover GSM900/DCS/PCS/UMTS operation but maintain good radiation efficiency. Finally, we will compare three antennas, and develop procedure with industrial view, and propose the prospect of the GSM/GPRS antenna in PND, as a conclusion.

在第二章中，我们使用单极天线设计概念，使用双路径架构并於末端耦合来对天线阻抗做匹配，产生涵盖GSM900/DCS/PCS/UMTS四频操作频带，并提高与接地面的辐射高度，以避免电容效应，使天线具有良好的辐射特性；在第三章中，使用倒F形天线设计概念，使用双路径架构於末端耦合，并於辐射臂上采取适当接地点电感效应作输入阻抗匹配，达成涵盖GSM900/DCS/PCS/UMTS系统的四个操作频带；在第四章中，采用倒F形架构并使用耦合馈入方式，使得长辐射金属臂在低频900 MHz附近产生共振，产生低频基频模态及高阶模态，以达成宽频及频宽涵盖GSM900/DCS/PCS/UMTS频带操作，并有效缩减使用体积；最后，分别比较此三种架构的优缺点，再加以业界角度来思考，研发产品天线的流程及思考方向，以及天线应用於可携式导航装置中未来的展望作为本论文的总结。

LEIS results showed that the surface localized electrochemical impedance in the initial stage increased with time, but distributed dispersively.

局部电化学交流阻抗的测试结果表明，试样表面的局部电化学阻抗随盐雾时间的延长而有所增加，但分布较为分散。

Electrodes of concentric type placed anterior and posterior were proved to be more effective for epigastric impedance measurement.

人体实验表明，胃部体表阻抗的测量能够表征胃的蠕动和排空。另外，前后设置的同心圆电极对胃阻抗的测量更为有效

Cynanchum Lingtai apricot production in the average weight 65 grams, the brightly-colored fruit, juicy rich, sweet-sour taste, sweet from the nucleolus, when the late Qing Dynasty famous Shaanxi, Gansu provinces, the Qing imperial court Tongzhi tribute for years.

灵台生产的牛心杏平均单果重65克，果实色泽鲜艳，汁多味浓，甜酸适口，离核仁甜，清末时就驰名陕、甘两省，清同治年间曾为朝廷贡品。

Chenopodium album,Solanum nigrum, and Amaranthus retroflexus were very susceptible to the herbicides. Polygonum persicaria and Abutilon theophrasti were relatively less susceptible to the herbicides, and Lycopersicon esculentum was not susceptible to it. The relationship between reduction rates of weed biomass and PPM values of weed leaves 2,4, and 6 days after treatment was established.

供试的6种杂草对该混剂的敏感性存在显著差异：红心藜Chenopodium album、龙葵Solanum nigrum和反枝苋Amaranthus retroflexus对该混剂最敏感，ED90值分别为47.65、71.67和29.17g/hm2；春蓼Polygonum persicaria和苘麻Abutilon theophrasti敏感，ED90值分别为96.91、114.20g/hm2；而番茄不敏感。