Esta página ha sido traducida por una máquina. Otras páginas pueden seguir apareciendo en inglés.
View in English
Información sobre las publicaciones recientes del JACS, volumen 145, número 31
These videos have been matched automatically. Contact us if they are not relevant.
These videos have been matched automatically. Contact us if they are not relevant.
Estos videos han sido emparejados automáticamente Contact us si no son relevantes
Estos videos han sido emparejados automáticamente Contact us si no son relevantes
Videos de Conceptos Relacionados
79.2K
The energy required to carry out photosynthesis is light— typically electromagnetic radiation from the sun. The range of all possible wavelengths is known as the electromagnetic spectrum.
Photons
A photon is a discrete electromagnetic particle or bundle of energy. Photons are characterized by their frequency, wavelength, and amplitude, similar to the properties of a wave. Waves with higher frequencies transmit more energy and have shorter wavelengths than longer wavelengths that transmit...
192.8K
Overview
All matter is composed of atoms, the smallest individual units of elements. Each atom is made up of three subatomic particles: protons, neutrons, and electrons. Together, these three particles account for the mass and the charge of an atom.
The History of Atomic Theory
The first person to propose that everything on Earth is made up of tiny particles was the Greek philosopher Democritus, around 450 B.C. He used the term atomos, Greek for “indivisible,” from which the...
22.1K
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
Positive Frequency-Dependent Selection
In positive...
99.2K
Overview
Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They reside in locations that are associated with energy levels called shells and are further organized into sub-shells and orbitals within each shell.
Electrons Orbit the Nucleus
Electrons are found in specific locations outside of the nucleus. The shell in which an electron resides indicates the general energy level of the electron: those closer to the...
48.7K
Cancers arise due to mutations in genes involved in the regulation of cell division, which leads to unrestricted cell proliferation. Modern science and medicine have made great strides in the understanding and treatment of cancer, including eradicating cancer in some patients. However, there is still no cure for cancer. This is largely due to the fact that cancer is a large group of many diseases.
Tumors may result in a case where two people have the same mutations in an oncogene or tumor...
21.7K
Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ecological community’s structure. Many factors affect community structure, including abiotic factors (e.g., sunlight and nutrients), disturbances (e.g., fire or flood), species interactions (e.g., predation or competition), and chance events (e.g., foreign species invasion). Certain species—such as keystone species—also play a...