[Purpose/Significance] The paper aims to reveal richer social relationships beyond formal collaboration networks from the acknowledgment text of the doctoral dissertation, deepen our perception of academic social networks, and provide new evidence for understanding academic social capital and the cultivation of young researchers. [Method/Process] This paper had used the LAC model to extract and identify the people being acknowledged and their social relationships mentioned in the acknowledgment sentences of the acknowledgment text of doctoral dissertations, and had then analyzed the correlation between the social relations between the persons acknowledged and the authors of doctoral dissertations (hereinafter referred to as "dissertation authors") and their cooperation relations in academic publications. [Result/Conclusion] Most of the social relationships mentioned in the acknowledgments did not translate into formal research collaborations. This indicates that acknowledgments can effectively capture implicit social relationships that are often overlooked in traditional collaboration datasets, such as mentorship, peer review, peer networks, academic friendships, and family support. The study shows that nearly half of research collaborations can be traced back to the doctoral stage, demonstrating that social relationships highlighted in acknowledgments have a substantial impact on research output and publication. Among these, mentorship and peer relationships represent the closest types of collaboration, indirectly revealing the patterns of research collaboration among early-career researchers. Moreover, a significant correlation was observed between the order of mention in acknowledgments, the type of relationship, and the intensity of research collaboration, indicating that social networks play a critical and tangible role in the academic growth of early-career researchers.