PNAS: Proceedings of the National Academy of Sciences of the United States of America（P-ISSN 0027-8424; E-ISSN 1091-6490）《The Proceedings of the National Academy of Sciences was founded in 1914 and

Historically, Europe stood at the forefront of global mathematical advancement.

Dissertations and theses are a powerful, untapped resource. Often, graduate research remains unpublished in books and journals, leaving these scholarly works and critical insights undiscovered.

ProQuest Ebooks is a new solution that enables libraries to provide uninterrupted access to high-quality, multidisciplinary content at a greater scale.

RSC期刊数据库是RSC（英国皇家化学学会）出版和发行的以化学化工为主，学科覆盖化学化工、环境科学与能源、生命科学、材料科学与工程以及食品工程等20多个学科领域（其中涉及ESI指标22个学科中的10大学科）的专业型数据库。

The Natural Science Citation Index (SCI), is a multi-disciplinary comprehensive database focusing on the field of natural sciences.

Science has been at the center of important scientific discovery since its founding in 1880—with seed money from Thomas Alva Edison.

ScienceDirect is a full-text scientific database launched by Elsevier, offering globally leading full-text literature in science, technology, and medicine.

ScienceDirect, the full-text database platform of Elsevier, the world's leading publishing company, is the world's largest database of full-text electronic resources for science, technology and med

ScienceDirect, the full-text database platform of Elsevier, the world's leading publishing company, is the world's largest database of full-text electronic resources for science, technology and med