Топ-100

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Strain (biology)

In biology, a strain is a low-level taxonomic rank below the rank of species. This is seen in microbiology where strains are got from a single cell colony, and are quarantined by being in a Petri dish. Strains are also commonly referred to in vir ...

                                               

Ranoidea (superfamily)

The Ranoidea are a superfamily of frogs in the order Anura. These frogs have a fused pectoral girdle bone in their chests, no ribs, and the males hold on to the female with an axillary grip during mating. The tadpoles have a single spiracle on th ...

                                               

Species

A species is a kind of organism. It is a basic unit of biological classification, and a formal rank in taxonomy. Originally, the word was used informally in a rather vague way, but now there are at least 26 different ways it is used. All animals ...

                                               

Synonym (taxonomy)

Synonyms in taxonomy are similar to normal synonyms, there are two names for the same thing in a scientific classification. For example, the cat has a few scientific names in: Felis silvestris catus, Felis catus, and Felis catus domestica. In bot ...

                                               

Taxon

A taxon is a taxonomic group or taxonomic unit. It is a group of organisms which a taxonomist decides belong together. Taxa can be big or small, a fairly small taxon is the giraffes, a very big one is the beetles. A taxonomist can assign a scient ...

                                               

Type species

The term type species is used in the scientific naming of living things, and is part of a system using a so-called "type". The type system is central to the scientific naming of living things organisms. How exactly it works is different depending ...

                                               

Animal track

An animal track is the imprint left behind in soil, snow, mud, or other ground surfaces that an animal walks across. Animal tracks are used by hunters to track their prey, and by naturalists to identify animals living in an area. Tracks can be fo ...

                                               

Bergmanns rule

Bergmanns rule is an ecogeographic principle. It states that, within a widely distributed group of animals, the larger ones are found in colder environments, and the smaller ones are found in warmer regions. So, for example, with bears the larges ...

                                               

Colony (biology)

A colony in biology refers to a life-style or habit where members of the same species live together. Usually the members of a colony are genetically linked by common heredity. Sometimes, as in bryozoa, they are genetically identical clones, somet ...

                                               

Gastrolith

Gastroliths, or gizzard stones, are small rocks kept by an animal inside its stomach or at an early part of the alimentary canal. The function of these is to mash up the food so digestion takes place faster. Typically, animals which do this do no ...

                                               

Presociality

Presociality is a term which applies to animal behaviour. Presocial animals have close family relationships, more than just sexual interactions with members of the same species. However, they do not form the extreme colonies of eusocial insects, ...

                                               

Segmentation

Segmentation in biology means the division of some animal and plant bodies into a series of repeat sections or parts. It is common in some of the most successful groups of animals, such as arthropods, vertebrates and annelid worms. Segmentation o ...

                                               

Terrestrial locomotion

Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial places. Movement on land makes different problems than that on water, with less friction instead being the effects of gravity. There are three basic forms of moveme ...

                                               

Titration

Titration is a type of quantitative chemical analysis. It is used to work out the unknown concentration of a known substance. It makes the use of two main chemical apparatus namely, pipette and burette. External indicators like phenolphthalein or ...

                                               

Covalent bond

A covalent bond is a chemical bond between two non-metal atoms. An example is water, where hydrogen and oxygen bond together to make. A full outer shell usually has eight electrons, or two in the case of hydrogen or helium. Valence electrons are ...

                                               

Aromatic hydrocarbon

An aromatic hydrocarbon, or arene, is a hydrocarbon ring compound. It has alternating double and single bonds between carbon atoms forming rings. Many of the compounds have a sweet scent, hence the term aromatic. The ring of six carbon atoms in a ...

                                               

Conjugated system

In chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons. Conjugated systems are created by several multiple bonds, each separated by single bonds. In general, conjugated systems may lower the overall energ ...

                                               

Crystal field theory

Crystal Field Theory is a scientific representation of how metals behave when dissolved in water to form a special type of chemical called a complex. This model may be used to predict the colors of certain metal containing chemicals when dissolve ...

                                               

Ionic bond

An ionic bond is the electrostatic forces of attraction between a non-metal and a metal ion in a giant ionic crystal lattice. This occurs when charged atoms attract. This happens after a metal atom loses one or more of its electrons to the non-me ...

                                               

Metallic bond

A metallic bond is the sharing of many detached electrons between many positive ions, where the electrons act as a "glue" giving the substance a definite structure. It is unlike covalent or ionic bonding. Metals have low ionization energy. Theref ...

                                               

Oxidation state

The oxidation state of an element is used to predict what sort of chemical compounds form. For example, if you put hydrogen and oxygen together, they form H 2 O, and not H 3 O because the oxidation number of oxygen is −2, which means that we need ...

                                               

Pi bond

In chemistry, a pi bond is a covalent chemical bonds where the orbital path of one electron crosses with the path of another. The electrons have a lobe shaped figure of eight path. There are two areas of overlap as the paths overlap on both lobes ...

                                               

Chemical compound

A chemical compound is a chemical formed from atoms of different chemical elements. The different atoms are joined by chemical bonds. Each compound has a fixed ratio between the elements. The elements stick together so strongly that the compound ...

                                               

Aldrin

Aldrin is an insecticide, which was used against termites, locusts and the larvae of Click beetles. Most plants and animals convert it to Dieldrin. It is listed in the Stockholm Convention on Persistent Organic Pollutants, its production, use and ...

                                               

Castoreum

Castoreum is the liquid released from the castor sacs of the beaver. It is a yellowish liquid. It is mixed together with the beavers urine. It is used to mark territory. Both male and female beavers have two castor sacs. They have two glands in t ...

                                               

Chloroform

Chloroform is a chemical substance. It is an organic compound. Chloroform is one of the intermediate substances that occur in the production of Polytetrafluoroethylene, better known as Teflon. Chloroform is used as a solvent. In the 19th century, ...

                                               

Chromophore

A chromophore is the part of a molecule responsible for its colour. The colour is caused when a molecule absorbs certain wavelengths of visible light. It transmits or reflects only other wavelengths, which causes the colour we see. In biological ...

                                               

Cyanide

Cyanides are chemicals that contain the cyano-group C≡N. Organic compounds that contain the CN group are called nitriles. In that group a carbon atom has three chemical bonds to a nitrogen atom. The group is present in many substances. Those subs ...

                                               

Ephedrine

Ephedrine has effects on the human body. It can be used as a stimulant or a decongestant. It is also used to treat certain forms of low blood pressure or to help hunger. Ephedrine is like amphetamine and methamphetamine. The herb ma huang 麻黄, E ...

                                               

Epoxy

Epoxy is the end product of epoxy resins. It is also a common name for the epoxide functional group, and a common name for a type of strong adhesive used for sticking things together. Typically, two resins need to be mixed together before use. Ep ...

                                               

Fuel oil

Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue at the oil refinery. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or u ...

                                               

Glue

Glue is a sticky material that can stick two or more things together. Glue can be made from plant or animal parts, or it can be made from oil-based chemicals. The first glues may have been natural liquids that come out of trees when they are cut. ...

                                               

Lead azide

Lead azide, also known as lead azide, is a chemical compound. Its chemical formula is Pb 2. It contains lead and azide ions. It contains lead in its +2 oxidation state. Lead azide is an explosive. Most other azides just burn rapidly. It is used a ...

                                               

Mauveine

In 1856, William Henry Perkin, then 18, was given a challenge by his professor to synthesize quinine. His professor, August Wilhelm von Hofmann, was the first director of the Royal College of Chemistry in London. In one attempt, Perkin oxidized a ...

                                               

Methane hydrate

Methane hydrate, also called methane ice or methane clathrate, consists of methane, which is enclosed in frozen water. The water molecules completely surround the methane. Methane hydrate is a common constituent of the shallow marine geosphere. I ...

                                               

Phosgene

Phosgene is the chemical compound with the formula COCl 2. This gas has no color. The gas was used as a weapon during World War I. It is responsible for most of the deaths related to poison gas during the war. Today, phosgene is used as a tool. I ...

                                               

Salt

In chemistry, a salt is any neutral chemical compound made of cations attached to anions. The main kind of salt is sodium chloride with the chemical formula NaCl. It is formed when hydrochloric acid is added in sodium hydroxide. The reaction is a ...

                                               

Selenium trioxide

Selenium trioxide, also known as selenium oxide and selenic oxide, is a chemical compound. Its chemical formula is SeO 3. It contains selenium in its +6 oxidation state. It also contains oxide ions.

                                               

Strychnine

Strychnine is a poisonous substance which is naturally produced by the plant Strychnos nux-vomica. Together with brucine, another poison, strychnine is found in the leaves and seeds of this plant. They are a rather extreme example of the way some ...

                                               

Hydrogen

Hydrogen is a chemical element. It has the symbol H and atomic number 1. It has a standard atomic weight of 1.008, meaning it is the lightest element in the periodic table. Hydrogen is the most common chemical element in the Universe, making up 7 ...

                                               

Actinium

Actinium is chemical element 89 on the periodic table. Its symbol is Ac. Actiniums mass is 227 g / mol. Actinium is a silver radioactive, solid metal in actinide group. It is so radioactive that it glows in the dark. Even a small amount of actini ...

                                               

Bismuth

Bismuth is a chemical element. It is element 83 on the periodic table and its symbol is Bi. Its atomic mass is 209. It is only slightly radioactive. The radioactivity is minimal so it is typically seen as nonradioactive. Bismuth is only naturally ...

                                               

Bromine

Bromine is a chemical element. Its atomic number is 35, and its atomic weight is 80. It is part of the Group 7 elements on the periodic table. It is diatomic, which means that two atoms are stuck together to make a molecule in any bromine sample.

                                               

Cadmium

Cadmium is a metal. It is element 48 on the periodic table. Its symbol is Cd. Its atomic number is 48 and its atomic mass is 112.4. It is found in Group 12 on the periodic table.

                                               

Caesium

Caesium is the chemical element with the atomic number 55 on the periodic table. Its symbol is Cs. Caesium is an alkali metal. Its melting point is low 28 °C. It is extremely reactive. Because of its high reactivity, it is a dangerous chemical. I ...

                                               

Cerium

Cerium is a chemical element with an atomic number of 58. This means that the nucleus of cerium has 58 protons in it. The atomic mass of cerium is 140.12. The chemical symbol of cerium is Ce and it is a member of the lanthanide group.

                                               

Chlorine

Chlorine is a chemical element. Its atomic number is 17, and its atomic mass is 35.45. It is part of the 7th column on the periodic table of elements.

                                               

Chromium

Chromium is a chemical element. Its symbol on the periodic table is Cr. It always has 24 protons, so its atomic number is 24. Its mass number is about 54. Most of the times it has 28 neutrons, but different isotopes have more or fewer neutrons. A ...

                                               

Cobalt

Cobalt comes in two oxidation states, +2 and +3. Most soluble cobalt compounds are red. They can also be green, blue, brown, and black. CobaltII compounds CobaltII chloride, red solid, most common cobalt compound. CobaltII fluoride, used in denti ...

                                               

Copper

Copper is a chemical element. It is the 29th element in the periodic table. Its mass number is 63.55. It is a transition metal in the middle of the periodic table. The symbol for copper is "Cu", which comes from the Latin word cuprum, which, in t ...

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Pino - logical board game which is based on tactics and strategy. In general this is a remix of chess, checkers and corners. The game develops imagination, concentration, teaches how to solve tasks, plan their own actions and of course to think logically. It does not matter how much pieces you have, the main thing is how they are placement!

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