Title: वैकल्पिक

Text: The full journal is available online, through the main journal website, only to subscribers, AAAS members, and for delivery to IP addresses at institutions that subscribe; students, K-12 teachers, and some others can subscribe at a reduced fee. However, research articles published after 1997 are available free (with online registration) one year after they are published. प्रत्येक पराग्राफले परीक्षण हुनेछ।

Save test: यदि तपाईं यो टाइपिङ परीक्षणलाई साझा गर्न चाहानुहुन्छ भने यो प्रयोग गर्नुहोस् (केवल प्रमाणीकृत प्रयोगकर्ताहरूको लागि)।