No. Why do you even think it would make sense? It essentially says what pixels to consider when doing a morphological operation. How can you consider the pixel a fractional amount? Like in dilation, you look at some pixels and take the max in a window. Let's say the window is a 3x3 window. You look at all 9 pixels and take the max of the 9 pixels. What would you take for the max if your structuring element was 0.7 in the corners instead of 1? If you just want to multiply your window by the image, then you should be using the conv2() function, not a morphological operation that uses a structuring element.
I'm not even sure why you consider that thresholding.
Perhaps you want fspecial() and/or conv2, or imfilter().