The primary challenge in text-video retrieval lies in achieving cross-modal semantic alignment, particularly the discrepancy between the conciseness of textual descriptions, which often fail to fully encapsulate the breadth of video content, and the redundancy in video data, which introduces noise and masks important semantic features. Current methods align text and video by mapping them into a shared feature space. Despite notable advancements, the inherent differences in modality-specific representations create a bottleneck for fixed-point embedding techniques, making models highly sensitive to dataset distribution and hindering their generalization ability. In this paper, we present DomainDiff, a framework that enhances the embedding space through a two-stage process. In the first stage, stochastic domain modeling, we semantically expand text embeddings to explore potential regions aligned with video content. Simultaneously, we filter video segments to reduce redundancy and highlight key frames. In the second stage, the dynamic agent attention diffusion network, we leverage the generative properties of diffusion models to optimize the embedding space by viewing it from a joint probability distribution perspective. An agent attention mechanism dynamically integrates text and video features, ensuring accurate cross-modal alignment. Experimental results demonstrate that DomainDiff significantly improves retrieval performance across five benchmark datasets, with R@1 improvements ranging from 3% to 7.4%. Moreover, DomainDiff outperforms existing methods in handling long videos and complex textual descriptions, showcasing superior semantic robustness and generalization across varying distributions.

Molecular retrieval is critical in drug discovery and molecular design. Traditional discriminative methods often model the conditional probability distribution of retrieving candidates, treating the query text as a deterministic input. However, these approaches have notable limitations: (1) They often overlook the statistical properties of the original data distributions of queries and candidates, preventing the recognition of out-of-distribution data. (2) They struggle to balance retrieval accuracy and diversity when processing open-ended semantic queries. To address these challenges, we introduce DiffTMR, a novel framework that reformulates text-molecule retrieval as a reverse denoising process, progressively generating the joint distribution of candidates and queries from noises. DiffTMR uniquely integrates hierarchical diffusion alignment with dynamic perturbation embedding mechanisms. By employing text-anchored perturbations, it enhances the diversity of molecular representations, and through global-local progressive denoising, it achieves cross-modal hierarchical alignment. This leads to significant improvements in retrieval accuracy and out-of-domain generalization. Evaluations on benchmark datasets ChEBI-20 and PCdes demonstrate that DiffTMR surpasses current leading baselines by 4.2%-5.4% in Hits@1 metrics and exhibits superior performance in out-of-domain retrieval tasks.