Abstract: The invention relates to a device for carrying out of chemical or biological reactions with a reaction vessel receiving element for receiving a microtiter plate with several reaction vessels, wherein the reaction vessel receiving element has several recesses arranged in a regular pattern to receive the respective reaction vessels, a heating device for heating the reaction vessel receiving element, and a cooling device for cooling the reaction vessel. The invention is characterized by the fact that the reaction vessel receiving element is divided into several segments. The individual segments are thermally decoupled from one another, and each segment is assigned a heating device which may be actuated independently of the others. By means of the segmentation of the reaction vessel receiving element, it is possible for zones to be set and held at different temperatures.