Whats wrong with this?

create procedure dbo.[schema_update]

@dbname varchar(50)

as

begin

select * from [@dbname].INFORMATION_SCHEMA.COLUMNS 

end

go

now i am executing the sp as 

execute [dbo].[schema_update] 'abcd'

i am getting the following error

invalid object name @dbname..INFORMATION_SCHEMA.COLUMNS 

i am trying to pass database name as parameter