sistema de información científica redalyc. red de revistas científicas. acceso abierto sin fines de lucro propiedad de la academia. modelo de acceso abierto diamante.

access 160+ million publications and connect with 25+ million researchers. join for free and gain visibility by uploading your research.

sci-hub website. get free access to academic journals. download research papers for free from sciencedirect, ieee, wiley, springer, nature and others

the world’s largest collection of open access research papers

mdpi is a publisher of peer-reviewed, open access journals since its establishment in 1996.

semantic scholar uses groundbreaking ai and engineering to understand the semantics of scientific literature to help scholars discover relevant research.

the research, society and development journal (whose abbreviated title is res., soc. dev.) is a multidisciplinary scientific publication focused on promoting the social, scientific and technological development through the publication of the findings that have occurred in different areas. this is a monthly journal, which publishes various types of manuscript, such as scientific articles, reviews and case teaching in diversified areas of knowledge. the journal receives many contributions from researchers in the area of teaching, which allows to evaluate and publish also educational objects.

library genesis is a scientific community targeting collection of books on natural science disciplines and engineering.

internet archive is a non-profit digital library offering free universal access to books, movies & music, as well as 624 billion archived web pages.

Centro Nacional de Metrología, patrones de medición, hora oficial de México