Recently, an origin fully-decoupled radio access network (FD-RAN) inspired by neurotransmission has been proposed for B5G/6G mobile communication networks, which achieves the potentials of improving the spectrum efficiency, reducing the energy consumption and meeting personalized user requirement through profound resource cooperation. To explore new radio and networking technologies, in this paper, we propose an elastic and efficient resource allocation for the FD-RAN architecture. First, we assume that the wireless spectrum is integrated for more reasonable allocation and sharing the spectrum dynamically across frequencies, location, users, services and networks. In particular, we propose a user-BS-subchannel matching algorithm to solve the dynamic uplink and downlink spectrum division, BS cooperation and subchannel assignment problems based on the many-to-many matching model. Our algorithm is proved to converge to a stable matching within finite iterations. Then, we propose a power control algorithm for uplink and downlink transmissions to further enhance the system performance based on the successive convex approximation. The obtained power control solution is proved to achieve a Karush-Kuhn-Tucker point. Extensive simulation results demonstrate that the proposed dynamic division of uplink and downlink spectrum, BS cooperation, subchannel assignment and power control can effectively improve the network performance for the FD-RAN architecture.