4 sentences

1. 这个自然保护区是国家级的。

   zhè gè zì​rán bǎo​hù​qū shì guó​jiā​jí de.

   This nature reserve is of a national level.

   Source: Dong Chinese Dictionary

2. 我在国家级的杂志上发表了作品。

   wǒ zài guó​jiā​jí de zá​zhì shàng fā​biǎo le zuò​pǐn.

   I got published in a national magazine.

   Source: OpenSubtitles

3. 天津滨海新区是国家级新区和经济中心。

   Tiān​jīn Bīn​hǎi xīn qū shì guó​jiā​jí xīn qū hé jīng​jì zhōng​xīn.

   Tianjin Binhai New Area is a national-level new area and an economic center.

   Source: Dong Chinese Dictionary

4. 张教授是这项国家级科研项目的主持人。

   Zhāng jiào​shòu shì zhè xiàng guó​jiā​jí kē​yán xiàng​mù de zhǔ​chí​rén.

   Professor Zhang is the principal investigator of this national research project.

   Source: Dong Chinese Dictionary