极性转换

本文主要论述极性转换的基本概念和它在有机合成中的作用。

In this article , the fundamental concept of umpolung and its role in organic synthesis are briefly discussed .

在有机合成中一些不能用常规反应合成的有机化合物可以通过极性转换的方式来完成。

The organic compounds unable to be synthesized under normal reaction can be fulfilled by means of umpolung .

通过极性转换，可迅速得到基于XOR门的静态逻辑电路的最优结构，达到优化功耗的目的。

Based on polarity conversion , an optimal XOR gate decomposition for static logic circuit is designed in order to minimize the power dissipation .

系统数据传输码为非归零码，所以在传输E1数据前，通过CPLD编程和极性转换电路，实现非归零码和HDB3码之间的转换。

The system data transmission code is NRZ , so in the E1 data transmission , through CPLD programming and polarity circuit to achieve the conversion between the HDB3 code and NRZ .

基带双极性光码分多址（OCDMA）系统，采用码的极性转换思想，实现在考虑信道非理想下的单极性信道中传输双极性码。

The base-band bipolar optical code division multiple access ( OCDMA ) system is introduced , with transform of unipolar-bipolar and bipolar-unipolar , transmission of signal with bipolar codes is realized through unipolar medium .

羰基极性转换中间体&1,3-二噻烷在有机合成中的应用

Application of 1 , 3-dithane , as intermediate compound of reversed polarity of carbonyl , in organic synthesis

极性转换方法是一种重要的有机合成新方法，对极性转换的概念和应用作了论述，并对一些极性转换的新技术作了简。

The concept and some applications about umpolung were expounded , and some new methods about the application of the umpolung were given .

先介绍了羰基化合物（醛、酮）的极性转换的各种方法，然后谈到胺的极性转换方法和最常用的极性转换试剂。

The various methods for the umpolung of carbonyl compounds ( aldehydes and ketones ), secondary amines and the most frequently used umpolung reagents are introduced .

2.magneticfieldn.磁场磁场极性逆转就是磁极转换。

Magnetic field polarity reversals are magnetic poleshifts .

以双Al单层模型讨论了用MOVPE和MBE法在蓝宝石衬底上生长GaN的极性选择的机理，并对AlN在极性转换过程中的作用给出了适当的解释。

The mechanisms for polarity selection of GaN on sapphire substrate both in MOVPE and MBE growth are discussed based on the " two monolayers of Al " model , which also gives a reasonable explanation to the polarity reversion mechanism by AlN .