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  • Dioscorea bulbifera (plant and vegetable)

    Dioscoreaceae: batatas); air potato (D. bulbifera); and yampee, or cush-cush (D. trifida).

  • Dioscorea cayenensis (plant)

    yam: rotundata) and yellow Guinea yam (D. cayenensis) are the main yam species grown in West Africa. Lesser yam (D. esculenta), grown on the subcontinent of India, in southern Vietnam, and on South Pacific islands, is one of the tastiest yams. Chinese yam (D. polystachya), also known as…

  • Dioscorea elephantipes (plant)

    Elephant’s-foot, (Dioscorea elephantipes), an odd-looking twining plant of the yam family (Dioscoreaceae), characterized by a large, woody, and partially exposed tuber. It is native to semiarid areas in southern Africa. The tubercle-covered tuber, resembling an elephant’s foot or a tortoise shell,

  • Dioscorea esculenta (plant)

    yam: Lesser yam (D. esculenta), grown on the subcontinent of India, in southern Vietnam, and on South Pacific islands, is one of the tastiest yams. Chinese yam (D. polystachya), also known as cinnamon vine, is widely cultivated in East Asia.

  • Dioscorea polystachya (plant)

    yam: Chinese yam (D. polystachya), also known as cinnamon vine, is widely cultivated in East Asia.

  • Dioscorea rotundata (plant)

    yam: Guinea yam (D. rotundata) and yellow Guinea yam (D. cayenensis) are the main yam species grown in West Africa. Lesser yam (D. esculenta), grown on the subcontinent of India, in southern Vietnam, and on South Pacific islands, is one of the tastiest yams. Chinese yam…

  • Dioscorea trifida (plant)

    Dioscoreaceae: bulbifera); and yampee, or cush-cush (D. trifida).

  • Dioscoreaceae (plant family)

    Dioscoreaceae, the yam family of the flowering plant order Dioscoreales, consisting of 4 genera and 870 species of herbaceous or woody vines and shrubs, distributed throughout tropical and warm temperate regions. Members of the family have thick, sometimes woody roots or tuber-like underground

  • Dioscoreales (plant order)

    Dioscoreales, the yam order of flowering plants, belonging to the monocotyledons (characterized by a single seed leaf) and containing three families, about 22 genera, and more than 1,000 species. Under the Angiosperm Phylogeny Group (APG) botanical classification system, the order contained five

  • Dioscorides, Pedanius (Greek physician)

    Pedanius Dioscorides, Greek physician and pharmacologist whose work De materia medica was the foremost classical source of modern botanical terminology and the leading pharmacological text for 16 centuries. Dioscorides’ travels as a surgeon with the armies of the Roman emperor Nero provided him an

  • Dioscorides, Redacius (Greek physician)

    herbal: … of the Greek physician Pedacius Dioscorides. A Byzantine version of his famous herbal is the Constantinopolitan, or Viennese, Codex (c. ad 512). Some of its illustrations are probably derived from Crateuas, together with plant names, such as Anemone and Anagallis, which are still in use. Many manuscript herbals, drawing largely…

  • Dioscorus (pope)

    Dioscorus, pope, or antipope, for 23 days in 530. A deacon in the Alexandrian Church, he clashed with the Miaphysites (Christians teaching that Christ has one nature, rather than two—i.e., human and divine) and went to Rome. Under Pope Symmachus he was papal legate at Ravenna to the Ostrogothic

  • Dioscorus (patriarch of Alexandria)

    Dioscorus, Christian patriarch of Alexandria and eastern prelate who was deposed and excommunicated by the Council of Chalcedon in 451. Dioscorus was archdeacon at Alexandria when he succeeded St. Cyril as patriarch in 444. He upheld his predecessor’s miaphysitism, or the Christological perspective

  • Dioscorus of Aphrodito (Greek poet)

    calligraphy: Byzantine period: …in an acrostic poem by Dioscorus of Aphrodito; it bears a clear relationship to the Menander Dyskolos hand, which was probably written in the later 3rd century ce. Similar pairs could be found to illustrate the continuity in transformation of the biblical uncial and Coptic styles. The latest Greek papyrus…

  • Dioscuri (Greco-Roman deities)

    Dioscuri, (Dioscuri from Greek Dioskouroi, “Sons of Zeus”), in Greek and Roman mythology, twin deities who succoured shipwrecked sailors and received sacrifices for favourable winds. They were the children of Leda and either Zeus, the king of the gods, or Tyndareus, Leda’s mortal husband and the

  • Diosdado, Ana (Spanish playwright)

    Spanish literature: Theatre: …decades of the 20th century, Ana Diosdado, gained national recognition with Olvida los tambores (1970; “Forget the Drums”). Other woman dramatists are Paloma Pedrero, Pilar Enciso, Lidia Falcón, Maribel Lázaro, Carmen Resino, and María Manuela Reina.

  • diosgenin (chemical compound)

    sapogenin: …of converting the steroid sapogenin diosgenin into progesterone have been developed. An abundant source of diosgenin is a Mexican yam called cabeza de negro, and progesterone made from it is used in producing steroid hormones.

  • Diósgy?r (Hungary)

    Miskolc: …small iron field and with Diósgy?r, farther up the Szinva River valley, which in the 14th and 15th centuries was a regular retreat for royalty; its splendid castle is now largely in ruins. The long-established wealth and importance of Miskolc are apparent in some fine old buildings, including St. Stephen’s,…

  • Diospolis (Israel)

    Lod, city, central Israel, on the Plain of Sharon southeast of Tel Aviv–Yafo. Of ancient origin, it is mentioned several times in the Bible: in a New Testament account (Acts 9:32), the apostle Peter healed the paralytic at Lod. The city was a well-known centre of Jewish scholars and merchants from

  • Diospyros (plant genus)

    Diospyros, genus of some 500 species of trees and shrubs of the family Ebenaceae, most of which are native to the tropics. Some members of the genus are valuable for their timber, particularly several species of ebony. Others are cultivated for their handsome foliage or edible fruit. Members of the

  • Diospyros blancoi (plant)

    Diospyros: Major species: nigra), and the mabolo (D. blancoi), the last being cultivated for its tasty fruit, which is dark red to purple.

  • Diospyros dendo (plant)

    ebony: Native to Angola, D. dendo is a valuable timber tree with very black and hard heartwood known as black ebony, as billetwood, or as Gabon, Lagos, Calabar, or Niger ebony.

  • Diospyros ebenum (plant)

    ebony: …Ceylon ebony is produced by Diospyros ebenum, which grows in abundance throughout the flat country west of Trincomalee in Sri Lanka. The tree is distinguished by the width of its trunk and its jet-black charred-looking bark, beneath which the wood is pure white until the heart is reached. The heartwood…

  • Diospyros kaki (plant)

    persimmon: The Japanese persimmon (Diospyros kaki), an important and extensively grown fruit in China and Japan, where it is known as kaki, was introduced into France and other Mediterranean countries in the 19th century and grown to a limited extent there. Introduced into the United States a…

  • Diospyros melanoxylon (plant)

    ebony: …ebony is yielded by the Coromandel ebony (D. melanoxylon), a large tree attaining a height of 18–24 metres (59–79 feet) and a circumference of 2.4–3 metres (about 8–10 feet) and having irregular branches and oblong leaves.

  • Diospyros montana (plant)

    ebony: Bombay ebony (D. montana) yields a yellowish gray, soft, but durable wood. It is native to India.

  • Diospyros nigra (plant)

    sapote: Black sapote (Diospyros nigra), also known as chocolate pudding fruit, is a member of the family Ebenaceae and is found throughout the Caribbean and Central America. White sapote, or casimiroa (Casimiroa edulis), ranges from Mexico to Costa Rica and is in the Rutaceae family.

  • Diospyros quaesita (plant)

    ebony: The calamander tree (D. quaesita) produces an ebony wood known in Sri Lanka as calamander. Its closeness of grain, great hardness, and fine hazel-brown colour, mottled and striped with black, render it valuable for veneering and furniture making.

  • Diospyros virginiana (plant and fruit)

    Diospyros: Major species: …species are the common, or American, persimmon (Diospyros virginiana), native to North America, and the Japanese, or kaki, persimmon (D. kaki), native to China but widely cultivated in other temperate regions. The globular orange fruit of the common persimmon is about 4 cm (1.5 inches) in diameter. The tree grows…

  • Diószegi Vilmos (Hungarian folklorist, linguist, and ethnographer)

    Vilmos Diószegi, Hungarian folklorist, linguist, ethnographer, Orientalist, and editor of the first Manchu-Tungus dictionary. His research focused on the religious beliefs of the Siberian peoples and of the ancient Hungarians (Magyars) before they migrated to the middle basin of the Danube River.

  • Diószegi, Vilmos (Hungarian folklorist, linguist, and ethnographer)

    Vilmos Diószegi, Hungarian folklorist, linguist, ethnographer, Orientalist, and editor of the first Manchu-Tungus dictionary. His research focused on the religious beliefs of the Siberian peoples and of the ancient Hungarians (Magyars) before they migrated to the middle basin of the Danube River.

  • Diotocardia (gastropod order)

    mollusk: Annotated classification: …at visceral loop; orders include Archaeogastropoda (long cerebropleural connectives) and Apogastropoda (bifurcate tentacle nerves, 2 pedal commissures); at least 20,000 species. Subclass Opisthobranchia (Euthyneura) (bubble shells, sea hares, nudibranchs, and snails) Marine, limnic, or terrestrial snails and slugs without operculum; visceral loop with

  • Diouf, Abdou (president of Senegal)

    Abdou Diouf, politician who was president of Senegal from 1981 to 2000. Diouf, the son of a postman, was a member of the Serer people and a devout Muslim. He attended the well-known Lycée Faidherbe in Saint-Louis, then capital of Senegal, and the University of Dakar. In 1958 he went to Paris and

  • Diouf, El Hadji (Senegalese athlete)

    El Hadji Diouf, Senegalese football (soccer) player who was named African Football Confederation (Confédération Africaine de Football; CAF) Player of the Year for 2001 and 2002. He was a fiery, controversial figure off the field and established himself as either an out-and-out striker or a

  • Diouf, El Hadji Ousseynou (Senegalese athlete)

    El Hadji Diouf, Senegalese football (soccer) player who was named African Football Confederation (Confédération Africaine de Football; CAF) Player of the Year for 2001 and 2002. He was a fiery, controversial figure off the field and established himself as either an out-and-out striker or a

  • Diougou River (river, Africa)

    Cavalla River, river in western Africa, rising north of the Nimba Range in Guinea and flowing south to form more than half of the Liberia–C?te d’Ivoire border. It enters the Gulf of Guinea 13 miles (21 km) east of Harper, Liberia, after a course of 320 miles (515 km). With its major tributaries

  • Dioula (people)

    Dyula, people of western Africa who speak a Mande language of the Niger-Congo language family. Most are Muslims, and they have long been noted as commercial traders. The Dyula were active gold traders as long ago as the time of the ancient African kingdom of Ghana. They flourished under the empire

  • Diourbel (Senegal)

    Diourbel, town, western Senegal, about 90 miles (145 km) east of Dakar. As a market for a peanut- (groundnut-) growing area, Diourbel produces peanut oil as well as beverages and perfume. The town is the site of a beautiful mosque and is a popular stop for Mourides (Murīdiyyah) Muslims making a

  • dioxin (chemical compound)

    Dioxin, any of a group of aromatic hydrocarbon compounds known to be environmental pollutants that are generated as undesirable by-products in the manufacture of herbicides, disinfectants, and other agents. In popular terminology, dioxin has become a synonym for one specific dioxin,

  • dip (geophysics)

    geomagnetic field: Representation of the field: The dip angle, I (for inclination), is the angle that the total field vector makes with respect to the horizontal plane and is positive for vectors below the plane. It is the complement of the usual polar angle of spherical coordinates. (Geographic and magnetic north coincide…

  • dip (geology)

    mining: Underground mining: The orientation, specifically the dip, of the ore body is particularly important in method selection. If the dip is greater than about 50°, then systems using gravity to move the ore can be considered. If the dip is less than about 25°, then systems using rubber-tired equipment for ore…

  • dip angle (geophysics)

    geomagnetic field: Representation of the field: The dip angle, I (for inclination), is the angle that the total field vector makes with respect to the horizontal plane and is positive for vectors below the plane. It is the complement of the usual polar angle of spherical coordinates. (Geographic and magnetic north coincide…

  • dip circle (scientific instrument)

    Dip circle, instrument for measuring the inclination, or dip, of the Earth’s magnetic field. It consists essentially of a magnetic needle pivoted at the centre of a graduated circle. The assembly is mounted such that the needle swings vertically rather than horizontally, as does a compass needle.

  • dip meter (scientific instrument)

    Dip circle, instrument for measuring the inclination, or dip, of the Earth’s magnetic field. It consists essentially of a magnetic needle pivoted at the centre of a graduated circle. The assembly is mounted such that the needle swings vertically rather than horizontally, as does a compass needle.

  • dip needle (scientific instrument)

    Dip circle, instrument for measuring the inclination, or dip, of the Earth’s magnetic field. It consists essentially of a magnetic needle pivoted at the centre of a graduated circle. The assembly is mounted such that the needle swings vertically rather than horizontally, as does a compass needle.

  • dip pole (geophysics)

    Dip pole, any point on the Earth’s surface where the dip (magnetic inclination; i.e., the angle between the Earth’s surface and the total magnetic field vector) of the Earth’s magnetic field is 90 degrees—that is, perpendicular to the surface. There are two main dip poles, one on the Antarctic

  • Dip Singh (Sikh military leader)

    Sikhism: The 18th and 19th centuries: …the Harmandir Sahib in 1757, Dip Singh, a member of the Shahid misl, pledged to free the shrine or die in the attempt. His small army was met by a much larger one several kilometres from Amritsar, and in the ensuing battle Dip Singh’s head was cut off. According to…

  • dip stream (hydrology)

    valley: Drainage patterns: …of the cuesta are called dip streams because they parallel the structural dip of the strata. Streams draining the cuesta scarp into longitudinal valleys flowing opposite to the structural dip are called antidip streams.

  • dip, angle of (geophysics)

    geomagnetic field: Representation of the field: The dip angle, I (for inclination), is the angle that the total field vector makes with respect to the horizontal plane and is positive for vectors below the plane. It is the complement of the usual polar angle of spherical coordinates. (Geographic and magnetic north coincide…

  • dip-slip fault (geology)

    fault: Normal dip-slip faults are produced by vertical compression as Earth’s crust lengthens. The hanging wall slides down relative to the footwall. Normal faults are common; they bound many of the mountain ranges of the world and many of the rift valleys found along spreading margins…

  • Dīpa?kara (Buddhist religious reformer)

    Atī?a, Indian Buddhist reformer whose teachings formed the basis of the Tibetan Bka’-gdams-pa (“Those Bound by Command”) sect of Buddhism, founded by his disciple ’Brom-ston. Traveling to Tibet in 1038 or 1042 from Nālandā, a centre of Buddhist studies in India, Atī?a established monasteries t

  • Dīpāvali (Hindu festival)

    Diwali, one of the major religious festivals in Hinduism, lasting for five days from the 13th day of the dark half of the lunar month Ashvina to the second day of the light half of Karttika. (The corresponding dates in the Gregorian calendar usually fall in late October and November.) The name is

  • Dīpava?sa (Sinhalese historical record)

    Dīpava?sa, (Pāli: “History of the Island”), oldest extant historical record of Sri Lanka, compiled in the 4th century. It is considered to be one of the main sources drawn upon by the author of the later and more comprehensive historical chronicle the Mahāva?sa. In its emphasis on ecclesiastical

  • Dipelta (plant genus)
  • Dipendra (prince of Nepal)

    Gyanendra: …subsequent suicide of Crown Prince Dipendra, who had committed the murder.

  • diphenhydramine (drug)

    Diphenhydramine, synthetic drug used in the treatment of various conditions including hay fever, acute skin reactions (such as hives), contact dermatitis (such as from poison ivy), and motion sickness. Diphenhydramine counteracts the histamine reaction. Introduced into medicine in 1945 and marketed

  • diphenoxylate (drug)

    antidiarrheal drug: The opiate derivative diphenoxylate typically is given with atropine in a combination marketed as Lomotil. Although opioids carry a risk of dependency and addiction, codeine and the synthetic analogs diphenoxylate and loperamide produce little dependence, and they have been used successfully for diarrhea.

  • diphenyl (chemical compound)

    Biphenyl, an aromatic hydrocarbon, used alone or with diphenyl ether as a heat-transfer fluid; chemical formula, C6H5C6H5. It may be isolated from coal tar; in the United States, it is manufactured on a large scale by the thermal dehydrogenation of benzene. Biphenyl is slightly less reactive c

  • diphenylcarbazone (chemical compound)

    chemical indicator: 08 volts; and diphenylcarbazone, an indicator for mercuric ion, changes from yellow to violet when the mercuric ion concentration is increased from 0.000001 to 0.00001 mole per litre. Each of these indicators thus has a relatively narrow transition range, and each is capable of giving a sensitive, sharp…

  • diphenylnitrogen oxide (chemical radical)

    radical: Stable radicals.: An example is diphenylnitrogen oxide, (C6H5)2NO, which is obtained by the oxidation of diphenylhydroxylamine, (C6H5)2NOH.

  • Diphilus (Greek poet)

    Diphilus, major poet of Greek New Comedy and a significant influence on the Roman playwrights Plautus and Terence. Diphilus lived most of his life in Athens, and his death was commemorated there with a funerary epitaph. He is believed to have written more than 100 comedies, of which 137 fragments

  • diphosgene (poison gas)

    Diphosgene, in chemical warfare, poison gas widely used by Germany during World War I. Its chemical name is trichloromethyl chloroformate, and it is a colourless, moderately persistent, poisonous, organic compound, the odour of which is likened to that of newly mown hay. It is easily condensable

  • diphosphopyridine nucleotide (biochemistry)

    Arthur Kornberg: …flavine adenine dinucleotide (FAD) and diphosphopyridine nucleotide (DPN), coenzymes that are important hydrogen-carrying intermediaries in biological oxidations and reductions.

  • diphosphorus pentoxide (chemical compound)

    nitrile: …formed by heating amides with phosphorous pentoxide. They can be reduced to primary amines through the action of lithium aluminum hydride or hydrolyzed to carboxylic acids in the presence of either an acid or a base.

  • diphros (furniture)

    furniture: Greece: The diphros was a stool standing on four crossed, turned legs, sometimes connected by stretcher bars and sometimes terminating in hoofs or claw feet. The convenience of folding stools was realized at an early date, and the diphros was popular.

  • diphtheria (disease)

    Diphtheria, acute infectious disease caused by the bacillus Corynebacterium diphtheriae and characterized by a primary lesion, usually in the upper respiratory tract, and more generalized symptoms resulting from the spread of the bacterial toxin throughout the body. Diphtheria was a serious

  • diphtheria antitoxin (biochemistry)

    infectious disease: Antitoxins: Diphtheria antitoxin of animal origin remains the principal treatment, along with antibiotics.

  • diphtheria toxoid (biochemistry)

    diphtheria: The diphtheria toxoid is usually first given in several successive doses during the first few months of life, with booster doses within one or two years and again at five or six years of age.

  • diphtheritic laryngitis (disease)

    laryngitis: Diphtheritic laryngitis is caused by the spread of diphtheria from the region of the upper throat down to the larynx. It may cause a membrane of white blood cells, fibrin (blood clotting protein), and diseased skin cells to attach to and infiltrate the surface mucous…

  • diphtheritic stomatitis (disease)

    yellow-eyed penguin: Conservation status: …changes in seawater temperature and diphtheritic stomatitis (a disease caused by bacteria that produces mouth lesions in chicks that hinder swallowing and respiration). In addition, the species is limited to small habitat patches, many of which have declined in quality as a result of residential development and other human activities.…

  • diphthong (phonetics)

    Diphthong, in phonetics, a gliding vowel in the articulation of which there is a continuous transition from one position to another. Diphthongs are to be contrasted in this respect with so-called pure vowels—i.e., unchanging, or steady state, vowels. Though they are single speech sounds,

  • diphyletic theory (phylogeny)

    phylogeny: Animal evolution: The alternative diphyletic theory has been proposed by many zoologists. It contends that the higher metazoans had two lines of descent; one led to annelids, arthropods, and mollusks, and the other led to echinoderms and chordates. Both groups emanated from an ancient flatworm.

  • Diphylla ecaudata (mammal)

    vampire bat: …or Desmodus, youngi) and the hairy-legged vampire bat (Diphylla ecaudata) are the only sanguivorous (blood-eating) bats. The common vampire bat thrives in agricultural areas and feeds on livestock such as cattle, pigs, and chickens. The other two vampires are primarily restricted to intact forests, where they feed on birds, reptiles,…

  • Diphyllidea (tapeworm order)

    flatworm: Annotated classification: Order Diphyllidea Two bothridia, each sometimes bisected by a median longitudinal ridge; large rostellum (cone-shaped or cylindrical projection) armed with dorsal and ventral groups of large hooks; cephalic peduncle (fleshy stalk on head) with longitudinal rows of T-shaped hooks; genital pore median, parasitic in elasmobranchs; 1…

  • Diphyllobothrium latum (flatworm)

    digestive system disease: Tapeworms: Diphyllobothrium latum, a fish tapeworm, may cause a severe anemia similar to pernicious anemia, because it consumes most of the vitamin B12 in the diet of the host.

  • Diphyllodes magnificus (bird)

    bird-of-paradise: The magnificent bird-of-paradise (Diphyllodes magnificus) and Wilson’s bird-of-paradise (D. respublica) are caped and have two wirelike tail feathers curving outward; in Wilson’s the crown is bare and has a “cross of Christ” pattern. The king bird-of-paradise (Cicinnurus regius), only 13 to 17 cm long, has similar…

  • Diphyllodes respublica

    bird-of-paradise: magnificent bird-of-paradise (Diphyllodes magnificus) and Wilson’s bird-of-paradise (D. respublica) are caped and have two wirelike tail feathers curving outward; in Wilson’s the crown is bare and has a “cross of Christ” pattern. The king bird-of-paradise (Cicinnurus regius), only 13 to 17 cm long, has similar but flag-tipped tailwires and fanlike…

  • diplacusis (physiology)

    sound: Binaural perception: …between the two ears, called diplacusis, is generally not a problem. A type of beating known as binaural beats can sometimes be observed when the two tones are presented binaurally.

  • diplegia (pathology)

    cerebral palsy: …or on both sides (diplegia). In spastic diplegia, spastic contractions and paralysis are usually more prominent in the lower extremities than in the arms and hands (Little diplegia), or only the legs may be affected (paraplegia). The cerebral damage causing spastic cerebral palsy primarily affects the neurons and connections…

  • dipleurula larva (zoology)

    echinoderm: Development: …basic larval type called a dipleurula larva, characterized by bilateral symmetry; hence the name, which means “little two sides.” A single band of hairlike projections, or cilia, is found on each side of the body and in front of the mouth and anus. The characteristic larvae found among the living…

  • diploblastic cell system (biology)

    circulatory system: General features of circulation: …anemones, jellyfish, and corals—has a diploblastic level of organization (i.e., its members have two layers of cells). The outer layer, called the ectoderm, and the inner layer, called the endoderm, are separated by an amorphous, acellular layer called the mesoglea; for these animals, bathing both cellular surfaces with environmental fluid…

  • Diplocarpon rosae (fungus)

    black spot: …disease caused by the fungus Diplocarpon rosae. On rose plants, the spots are roundish and up to 1 cm (0.5 inch) in diameter with fringed margins. Leaves on susceptible varieties turn yellow and drop early. Affected plants may defoliate twice in a season, are greatly weakened, produce fewer and inferior…

  • diplocentrid (scorpion)

    scorpion: Annotated classification: Family Diplocentridae 85 species found in warm regions of the Middle East, Mexico southward to northern South America, and the Antilles islands. Tubercular spine under stinger. Family Euscorpiidae 56 species absent from Australia and most of Africa. Family Liochelidae

  • Diplocentridae (scorpion)

    scorpion: Annotated classification: Family Diplocentridae 85 species found in warm regions of the Middle East, Mexico southward to northern South America, and the Antilles islands. Tubercular spine under stinger. Family Euscorpiidae 56 species absent from Australia and most of Africa. Family Liochelidae

  • Diplocladon hasseltii (invertebrate)

    bioluminescence: The range and variety of bioluminescent organisms: …Diplocladon hasseltii, called starworm, or diamond worm, gives off a continuous greenish blue luminescence from three spots on each segment of the body, forming three longitudinal rows of light, the appearance of which inspired the common name night train. Phrixothrix, the railroad worm, possesses two longitudinal rows, with a red…

  • diplococci (bacteria)

    coccus: Pairs of cocci are called diplococci; rows or chains of such cells are called streptococci; grapelike clusters of cells, staphylococci; packets of eight or more cells, sarcinae; and groups of four cells in a square arrangement, tetrads. These characteristic groupings occur as a result of variations in the reproduction process…

  • diplococcus (bacteria)

    coccus: Pairs of cocci are called diplococci; rows or chains of such cells are called streptococci; grapelike clusters of cells, staphylococci; packets of eight or more cells, sarcinae; and groups of four cells in a square arrangement, tetrads. These characteristic groupings occur as a result of variations in the reproduction process…

  • Diplococcus pneumoniae (bacterium)

    Pneumococcus, (Streptococcus pneumoniae), spheroidal bacterium in the family Streptococcaceae that causes human diseases such as pneumonia, sinusitis, otitis media, and meningitis. It is microbiologically characterized as a gram-positive coccus, 0.5 to 1.25 μm (micrometre; 1 μm = 10-6 metre) in

  • Diplodocidae (dinosaur family)

    sauropod: Diplodocidae (including Diplodocus and Apatosaurus), and Titanosauridae. The smaller sauropods reached a length of up to 15 metres (50 feet), while larger species such as Apatosaurus routinely reached lengths of 21 metres. Brachiosaurus was one of the largest and most massive of all known dinosaurs,…

  • Diplodocus (dinosaur genus)

    Diplodocus, (genus Diplodocus), gigantic dinosaurs found in North America as fossils from the Late Jurassic Period (161 million to 146 million years ago). Diplodocus is perhaps the most commonly displayed dinosaur. It, along with sauropods such as Apatosaurus (formerly Brontosaurus), belong to a

  • Diplodus holbrooki (fish)

    pinfish: …rhomboides; Diplodus holbrooki is called spottail pinfish. The name is derived from the presence of numerous spines on the front portion of the dorsal fin. The pinfish characteristically has yellow fins, gold stripes down the body, and a dark spot on the upper rear margin of the operculum. The spotted…

  • Diplograptus (graptolite genus)

    Diplograptus, genus of graptolites, small, extinct colonial marine animals thought to be related to the primitive chordates and restricted to ancient marine environments. Forms or species of Diplograptus are useful index, or guide, fossils for the Ordovician period (which occurred from 505 to 438

  • diplohaplontic cycle (biology)

    Alternation of generations, in biology, the alternation of a sexual phase and an asexual phase in the life cycle of an organism. The two phases, or generations, are often morphologically, and sometimes chromosomally, distinct. In algae, fungi, and plants, alternation of generations is common. It is

  • diplohaplontic life cycle (biology)

    Alternation of generations, in biology, the alternation of a sexual phase and an asexual phase in the life cycle of an organism. The two phases, or generations, are often morphologically, and sometimes chromosomally, distinct. In algae, fungi, and plants, alternation of generations is common. It is

  • diploid parthenogenesis (biology)

    animal reproductive system: Parthenogenesis: …from a male gamete (diploid parthenogenesis). Even if males were present, sperm could not fertilize the eggs because the latter are already diploid. Under conditions of environmental stress such as seasonal changes, some females form eggs that undergo reductional division, resulting in eggs with the haploid number of chromosomes;…

  • diploid phase (biology)

    algae: Reproduction and life histories: …of chromosomes and is called diploid. When one haploid gamete fuses with another haploid gamete during fertilization, the resulting combination, with two sets of chromosomes, is called a zygote. Either immediately or at some later time, a diploid cell directly or indirectly undergoes a special reductive cell-division process (meiosis). Diploid…

  • diploidy (biology)

    ploidy: The condition is called diploidy. During meiosis the cell produces gametes, or germ cells, each containing half the normal or somatic number of chromosomes. This condition is called haploidy. When two germ cells (e.g., egg and sperm) unite, the diploid condition is restored.

  • Diplolepis rosae (insect)

    gall wasp: …caused by the gall wasp Diplolepis rosae.

  • diploma (document)

    diplomatics: Classification of documents: …documents can be classified as diplomas or mandates. Privileges and diplomas give evidence of legal transactions designed to be of long duration or even of permanent effect, while mandates and many papal letters contain commands.

  • Diploma Leopoldinum (Transylvanian history)

    Diploma Leopoldinum, (English: “Leopold’s Diploma”) decree issued in October 1690 by Leopold I, Holy Roman emperor and king of Hungary (1658–1705), after the Ottoman Turks had been driven from central Hungary in 1686. The decree established the political status and the freedoms of Transylvania,

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