Verify your Object Cycles Setting, Cycles Ray Visibility: Camera checkbox is [enabled] for the missing particles.




Verify that all materials are created for the render engine.  Cycles Render is compatible with Cycles materials.  Blender Render is compatible with Blender Materials.

Verify that the Render visibility is on for the missing materials.  The camera icon in the outliner panel.

[![enter image description here][1]][1]

Verify that you have no  transparency


  [1]: https://i.sstatic.net/yjIZm.png