Jiefang Ribao is included in WiseSearch (https://wisesearch6.wisers.net/) from Wisers in Hong Kong starting from the issues August 2000 onwards. Many libraries subscribe to this database.
You can also try the 全国报刊索引 (https://www.cnbksy.com). They have indexed 解放日报(上海) 1955-2019 (but I am not sure how complete the index is). You can order individual articles for scanning. Some libraries offer to cover this for their readers.
Chinese Studies Librarian
East Asian Library