Scientific and technological literature refers to all kinds of literature materials that record and disseminate scientific and technological information and research results in the fields of science, technology and engineering. According to the nature of content, scientific and technological literature can be divided into the following levels.

1. Basic research literature: Basic research literature refers to the research results of exploring natural phenomena and laws in the scientific field. This kind of literature usually contains profound theoretical analysis and experimental research, which plays an important role in promoting the development of science.

2. Applied research literature: Applied research literature refers to the research results of applying basic research results to actual production and engineering in the technical field. This kind of literature usually contains more specific experimental data and application cases, which plays an important role in promoting the development of technical field.

3. Review literature: Review literature is a comprehensive summary of the research progress, present situation and future development trend in a certain field. This kind of literature usually contains a review and summary of previous research results, which has important reference value for researchers in this field.

4. Experimental reports and technical documents: Experimental reports and technical documents refer to documents that record and summarize the experimental process and technical details in laboratories and engineering projects. This kind of literature usually contains a lot of experimental data and technical details, which has important reference value for researchers in laboratories and engineering projects.

5. Dissertations and patent documents: Dissertations and patent documents refer to documents that summarize and summarize the research results in a certain field in the field of science and technology. This kind of literature usually has high academic value and practical value, and has important reference value for researchers and practitioners in this field.

To sum up, the level of scientific and technological documents can be divided into basic research documents, applied research documents, review documents, experimental reports and technical documents, dissertations and patent documents according to the nature of content. Each type of literature has its unique characteristics and value, and plays an important role in scientific research and technological development.