实现父子进程的同步，当父进程试图从一空管道中读取数据时，便进入等待状态，直到子进程将数据写入管道返回后，才将其唤醒。
Son process to achieve the synchronization, when the parent tried to read an empty pipe, they enter the wait state until the child process to write data pipeline to return only after its wake.
在进入脱机状态之前需要进行同步吗？
结论：进入气功状态后，脑运动功能皮质低频活动的同步性会明显增强。
Conclusion: Under the state of qigong, the synchrony of the brain motor cortex was enhanced obviously.
结论：进入气功状态后，脑运动功能皮质低频活动的同步性会明显增强。
Conclusion: Under the state of qigong, the synchrony of the brain motor cortex was enhanced obviously.
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