is it Possible (partial class) concept for controller in angularjs?

You could try to sort the code into logical chunks. after that you could merge logical chunks into objects.

//Do NOT do this!
$scope.firstName = firstname;
$scope.middleName = middleName;
$scope.lastName = lastName;

//instead do this
var person = {
    firstname: "name",
    middleName: "mName",
    lastName: "Lname"
}

//then in your view access them like this
{ { person.firstname } }

Also you could move some code into services or factories. then use those methods inside of you controller.

//take things out of your controller and put then in a service or factory.
app.service('notePad', function () {
    return {

        Read: function (newState) {
            return state += state;
        },

        Write: function (state) {
            return state += state;
        },
        Update: function (state) {
            state = state;
        },
        Delete: function () {
            state = null;
        }

    };
});

//then in your controller access them like this
app.controller('MainController', function ($scope, router, notePad) {
    $scope.Read = notePad.Read();
    $scope.Write = notePad.Write();
    $scope.Update = notePad.Update();
    $scope.Delete = notePad.Delete();
});

If you need the functionality of a controller inside of a service you can still access scope and other controller properties like this.

//pass your scope to your service
app.controller('MainController', function ($scope, router, notePad) {
    notePad.changeView($scope);
});

//munipulate your scope just like you would in a controller
app.service('notePad', function () {
    function changeView(scope) {
        scope.write = 'example';
    }
});

//the result of the scope change in the service will show up in the view
{ { write } } == 'example'