From the historical, natural and ecological point of view, this article researched the course of evolution of the ecological environment in the middle reaches of Yellow River.

从历史、地理、自然、生态的角度，大跨度、高视野、多方位对黄河中游生态环境演变过程进行了探讨。

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A new method of changing screen is adopted and the point where ship drives into the screen is determined in accordance with the ship's course to make the ship located at the middle of the screen.

针对原系统图形换屏显示时船舶航迹有时位于屏幕一角及航迹偏差带有时宽窄不一致的问题，重新设计了换屏技术及采用了新的偏差带的画法，根据船舶运动计划航线决定船舶进入屏幕的点，保证了船舶位于屏幕中部。

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If safeguarding international security is the chief aim of US President Barack Obama's foreign policy, then at some point he can be expected to change course in the Middle East.

CENTERFORSECURITYPOLICY: Barreling on, regardless