importing XML schema

Can I import XML schema into my XSD file as given below?

<xs:import namespace="http://www.w3.org/2001/XMLSchema"/>
<xs:complexType name="MyType">
	<xs:sequence>
		<xs:element ref="xs:restriction" minOccurs="1" />
	</xs:sequence>
</xs:complexType>

Regars,
GSK