restricted diffusion

The oil vapor contamination in the old vacuum furnace was inherited from its oil diffusion pump, and the inaccuracy temperature control of the furnace chamber was resulted from the manual temperature adjust-ment. These problems have severely restricted the development of vacuum technology in our laboratories.

老式真空炉由于采用了油扩散泵和手动控温方式，存在真空系统被油污染和控温精度差的问题，严重影响了真空工艺质量。

Background: Magnetic resonance diffusion-weighted imaging ( DWI) has been used in many diseases of central nervous system, but were restricted in the use of abdominal imaging, because of the movement of breathing exercise and other factors affecting the imaging quality.

研究背景磁共振弥散加权成像已成功应用于中枢神经系统病变的临床诊断和相关病变的基础研究；而对于腹部成像，由于呼吸运动等因素对图像质量的影响，其应用一直受到限制。