scientificamerican.com 的前十大競爭對手

livescience.com

The first vagina-on-a-chip replicates the cellular environment of the vagina.

science.org

science/aaas peer-reviewed journals deliver impactful research, daily news, expert commentary, and career resources.

nature.com

Nature is the foremost international weekly scientific journal in the world and is the flagship journal for Nature Portfolio. It publishes the finest ...

newscientist.com

Unlock the following benefits with a subscription

phys.org

Daily science news on research developments, technological breakthroughs and the latest scientific innovations

space.com

The latest aurora forecast for tonight help you make sure you're in the right place at the right time to see the northern lights.

science.nasa.gov

F.10 Payloads and Research Investigations on the Surface of the Moon (PRISM) solicits development and flight of a science-driven suite of instruments and

sciencedaily.com

Parallel evolution is the independent evolution of similar traits, starting from a similar ancestral condition. Frequently this is the situation in more closely related lineages, where several species respond to similar challenges in a similar way. One of the most spectacular examples of parallel evolution is provided by the two main branches of the mammals, the placentals and marsupials, which have followed independent evolutionary pathways following the break-up of land-masses such as Gondwanaland roughly 100 million years ago. In South America, marsupials and placentals shared the ecosystem (prior to the Great American Interchange); in Australia, marsupials prevailed; and in the Old World the placentals won out. However, in all these localities mammals were small and filled only limited places in the ecosystem until the mass extinction of dinosaurs forty million years later. At this time, mammals on all three landmasses began to take on a much wider variety of forms and roles. While some forms were unique to each environment, surprisingly similar animals have often emerged in two or three of the separated continents. Examples of these include the litopterns and horses, whose legs are difficult to distinguish; the European sabre-tooth tiger (Smilodon) and the South American marsupial sabre-tooth (Thylacosmilus); the Tasmanian wolf and the European wolf; likewise marsupial and placental moles, flying squirrels, and (arguably) mice.

sciencealert.com

A cross between a domestic pig and wild boar was bred in Canada decades ago.