Science & Nature
1439 sites
Subcategories:
- Astronomy & Space (396)
- Chemistry (8)
- Earth Sciences (26)
- Biology (79)
- Physics (30)
- Mathematics (59)
- Weather & Climate (104)
- Amateur Radio (682)
- Electronics (47)
https://kb9ocq.tripod.com/CW
A reference page by KB9OCQ dedicated to Morse code (CW) abbreviations and Q-signals used in amateur radio communication. It covers everything from common shorthand like TU and B4 to a full table of Q-codes with their question and statement meanings, making it a handy quick-reference for ham radio operators.
http://elasmo.com/
Elasmo.com is a detailed reference site covering the teeth of both extinct and living elasmobranchs, the group that includes sharks and rays. Fossil enthusiasts and paleontology hobbyists will find specialized information on elasmobranch dental morphology, with a focus on Neogene-era specimens from sites like Lee Creek.
http://setileague.org/
The SETI League is a nonprofit membership organization dedicated to the privatized electromagnetic search for extraterrestrial intelligence, coordinating amateur radio astronomers worldwide in the hunt for signals from other civilizations. The site offers extensive technical resources covering antennas, receivers, and software, alongside publications, press releases, and the popular "Ask Dr. SETI" column.
http://company7.com/
Company Seven is a long-established astro-optics retailer and resource hub based in Laurel, Maryland, serving both amateur and professional astronomers with telescopes, binoculars, rare optical instruments, and expert consultation. Notable for its involvement with NASA missions including the Hubble Space Telescope Repair and the James Webb Space Telescope, this site blends a brick-and-mortar showroom presence with a deep online resource for the astronomy community.
https://tgale.home.xs4all.nl/valves.html
Trevor Gale's comprehensive reference site covers vintage vacuum tubes and valves, offering pinout data, characteristics lists, military-to-commercial conversion tables, repair hints, substitution guides, and circuit diagrams for old receivers and amplifiers. Maintained as a companion to the rec.antiques.radio+phono newsgroup FAQ, it serves as a practical technical resource for both seasoned restorers and newcomers to valve/tube circuitry.
https://mineralienatlas.de/
Mineralienatlas is a comprehensive German-language encyclopedia and community platform covering mineralogy, geology, paleontology, and mining, supported by thousands of members worldwide. Visitors can search minerals by chemical properties, browse fossil and mineral portraits, explore collecting locations, and dive into crystallography and systematic mineralogy.
https://mostlydiyrf.com/
Mostly DIY RF is a specialized resource for amateur radio builders, offering PCB kits and detailed documentation for RF circuits including IF amplifiers, low-pass filters, VFOs, crystal filters, and MMIC amplifiers. The site covers designs by well-known ham radio engineers like Hayward and Kopski, making high-performance transceiver building accessible to hobbyists.
http://ukesca.org/
The UK ESCA Users Group is a professional forum connecting scientists from academia and industry around Electron Spectroscopy for Chemical Analysis and surface science, meeting twice yearly and publishing an online newsletter. The site offers an extensive guide to surface science techniques and acronyms, tutorials, online databases of binding energies and elemental properties, and a global directory of surface science laboratories.
http://aleph0.clarku.edu/~djoyce/java/compass
David E. Joyce of Clark University presents a detailed mathematical exploration of compass-only geometric constructions, proving that a straightedge is unnecessary for any Euclidean construction. The site covers circle inversion, stereographic projection, inversive geometry, and involutory quandles, drawing on the historical work of Mohr and Mascheroni.
https://hc2ae.tripod.com/
HC2AE is a Spanish-language ham radio hub created by an amateur radio operator in Guayaquil, Ecuador, serving as a meeting point for Latin American radioaficionados. The site features a Guayaquil callbook searchable by callsign or name, DX information, contest listings, propagation resources, software links, and a chat and forum for the ham radio community.