网站简介：italki.com is an online destination for learning foreign languages. italki connects people from around the world in a friendly community to learn from each other. italki helps people meet online to do free language exchanges. italki also helps students connect with teachers for paid online lessons. In addition, italki has many free language learning features, such as questions and answers, group discussions, and multimedia materials for self-study. italki is both a social network and a marketplace. The social network helps bring people together to communicate and learn. The marketplace gives students, teachers, and companies the abililty to transact online.
网站简介：Official web site of the Nobel Foundation. Offers a biography of Alfred Nobel, information about the organization, and details of individuals who have received a Nobel Prize.
网站简介：An online journal publishing peer-reviewed research across all areas of biology and medicine with immediate, barrier-free access for all, plus commentary, reviews, collaboration tools, and database links.
网站简介：Scientific literature digital library and search engine.
网站简介：Offers daily news from several areas of science and technology.
网站简介：Advocates the free distribution of science and medical published articles.
网站简介：An international journal, published weekly, with original, groundbreaking research spanning all of the scientific disciplines.
网站简介：Online graphing calculator. Free to use, supports hundreds of simultaneous equations, and supports interactive exploration via sliders.
网站简介：Promotes research and represents the professional interests of psychologists in the United States. Includes information on publications and conferences, and a find-a-psychologist referral feature.
网站简介：The meaning and history of first names.
网站简介：Provides a complete web based educational environment for K-12 and Higher Education mathematics science, statistics, and business.
网站简介：Customizable source for current news in physics, technology, space, and earth science topics. Includes a weblog.
网站简介：אנציקלופדיה חופשית לשימוש המזמינה את ציבור הגולשים להשתתף בכתיבתה.
网站简介：Provides information on what's new and what's next in the realm of Science, including the Internet, medicine, biotechnology, computers, and space.
网站简介：Information, member directory and many links.
网站简介：Free datasheet archive and search for electronic components and semiconductors.
网站简介：Manufactures analytical instruments plus reagents and consumables, laboratory equipment, software and services for the laboratory.
网站简介：R, also called GNU S, is a strongly functional language and environment to statistically explore data sets, make many graphical displays of data from custom command line, shell has option to save one full environment per working directory. Descriptions, documents, downloads. [Open Source, GPL]
网站简介：Current issues information (Sept. 11, anthrax), reports on 17 key environmental topics from air to water, kids page, laws/regulations and further official agency information. EPA protects human health by safeguarding the natural environment - air, water and land.
网站简介：Glossary of terms. Material ranges from undergraduate to research level.
网站简介：A quarterly journal of international affairs and diplomacy founded by Irving Kristol. Noted for its issue featuring the "End of History" by Francis Fukuyama.
网站简介：Includes data for the latest Census of Population and Housing, the U.S. and World Population clocks.
网站简介：Hindawi is a commercial publisher of peer-reviewed journals. Founded in 1997, Hindawi currently employs more than 300 employees and publishes 200+ open access, peer-reviewed journals. Hindawi is a member of several industry organizations including ALPSP, STM, UUKSG, OASPA, and IDPF. Hindawi was also an early member of CrossRef, the scholarly DOI linking organization. All of Hindawi's content is archived in Portico, which provides permanent archiving for electronic scholarly journals.
网站简介：Principal fact-finding agency for the Federal Government in the broad field of labor economics and statistics. Collects, processes, analyzes, and disseminates essential statistical data to the American public, the U.S. Congress, other Federal agencies, State and local governments, business, and labor.
网站简介：USA. Federal agency, cooperating with industry to develop and apply technologies, measurements, and standards.