Sql group by yesterday's 9am to today's 9pm

50  2016-07-29 04:40:44.000
70  2016-07-29 04:40:33.000
30  2016-07-29 03:50:56.000
15  2016-07-28 00:03:16.000
74  2016-07-28 23:38:18.000
15  2016-07-28 23:30:11.000
7   2016-07-28 23:22:37.000
10  2016-07-28 21:02:19.000

How can i achieve to group yesterday and today?

I must see only one row,

271  2016-07-28

Thanks for any idea.