i got a cake recipe in which it is written that the temp  is 350 degree for 35 min.i followed the same,but the middle portion of the cake didn't cook well.so i wait till 45 min,result was the same. i am using a microwave convention oven.can anybody please help me to solve my problem,thanx...

At some point, you just have to bake until it's done. 

Then, you can go through your checklists:  check the oven temp with a thermometer, it sounds like it is a small oven - they are prone to wide temperature swings,  did you adjust down for convection?, how big is the cake?, did it need a baking nail or heating core?.

The list goes on, but that is a place to start.
 

i hear some people have troubles baking in convection ovens, maybe try baking on the regular setting! i know i do :)