Not exactly. A DSLR’s focal-plane shutter is still not a true global shutter.

The shutter curtains move across the sensor at a fixed transit time, typically a few milliseconds. For very short exposures, the second curtain follows the first closely, so different parts of the frame are exposed at different times via a moving slit. For longer exposures, the first curtain opens fully, the whole sensor remains uncovered for a while, then the second curtain closes.

In that long-exposure case, all pixels do share a long common exposure interval, so the timing difference across the frame becomes very small relative to the total exposure time. But exposure still starts and ends at slightly different times in different rows/areas because the curtains do not open and close everywhere simultaneously.

So: a long exposure can reduce rolling-shutter-like timing differences enough to be negligible for some uses, but it is not the same as a true global shutter. If your research cannot tolerate any timing skew, you’d need a true global-shutter solution, or in some cases flash can provide near-simultaneous scene illumination.