1. A method for time-resolved phase-contrast magnetic resonance (MR) imaging with speed encoding, comprising: operating an MR data acquisition unit comprising a plurality of radio-frequency (RF) receivers to acquire MR signals originating from stationary nuclear spins and non-stationary nuclear spins in an examination subject situated in the MR data acquisition unit, using multiple RF receivers among said plurality of RF receivers, in each of a plurality of time segments, with different speed encodings; for each of said time segments, entering raw data, corresponding to the MR signals detected in the respective time segment, into an electronic memory as raw data points; in a processor having access to said electronic memory, reconstructing intermediate images from said raw data, and automatically identifying in said intermediate images, stationary image points originating from said stationary nuclear spins and non-stationary image points originating from said non-stationary nuclear spins; in said processor, defining a mask comprised of mask values that differ within said mask dependent on said stationary image points and said non-stationary image points; and in said processor, reconstructing a plurality of final MR images respectively from the MR signals acquired in the respective segments by executing an iterative reconstruction algorithm with a temporal regularization that is dependent on said mask.