|
Ansai District
Ansai () is a district of the city of Yan'an, Shaanxi province, China. It has a total area of and a population of 172,900 people. Part of the Loess Plateau, the district has an average elevation of . Its postal code is 717400, and its Serial Number is 610624. Administrative divisions Ansai District administers three subdistricts and eight towns. Subdistricts Ansai has jurisdiction over the following 3 subdistricts: * () * Jinming Subdistrict () * Baiping Subdistrict () Towns Ansai has jurisdiction over the following 8 towns: * () * Yanhewan () * () * () * () * () * () * () Geography The district, located in the Loess Plateau, is largely hilly, with its elevation ranging from to in height. The main rivers of the district are the Yan River, the Xingzi River, the Xichuan River, the Xiaochuan River, the Xiaogou River, and the Shuangyang River. Climate The district has an average temperature of , an average annual rainfall of , and experiences an avera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
District (People's Republic Of China)
The term ''district'', in the context of China, is used to refer to several unrelated political divisions in both ancient and modern China. In the modern context, district (), formally city-governed district, city-controlled district, or municipal district (), are subdivisions of a Municipality of China, municipality or a prefecture-level city. The rank of a district derives from the rank of its city. Districts of a municipality are Prefecture (China), prefecture-level; districts of a sub-provincial city are sub-prefecture-level; and districts of a prefecture-level city are Counties of China, county-level. The term was also formerly used to refer to obsolete District (China)#County-controlled districts (obsolete), county-controlled districts (also known as district public office). However, if the word ''district'' is encountered in the context of ancient History of China, Chinese history, then it is a translation for ''History of the administrative divisions of China, xian'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Clay
Fire clay is a range of refractory clays used in the manufacture of ceramics, especially fire brick. The United States Environmental Protection Agency defines fire clay very generally as a "mineral aggregate composed of hydrous silicates of aluminium (Al2O3·2SiO2·2H2O) with or without free silica." Properties High-grade fire clays can withstand temperatures of 1,775 °C (3,227 °F), but to be referred to as a "fire clay" the material must withstand a minimum temperature of .Minerals Zone, World Mineral Exchange. Retrieved 2011-6-23. Fire clays range from ''s'' to ''plastic fire clays'', but there are ''semi-flint'' and ''semi-plastic'' fire clays as well. Fire clays consist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kerogen
Kerogen is solid, insoluble organic matter in sedimentary rocks. Comprising an estimated 1016 tons of carbon, it is the most abundant source of organic compounds on earth, exceeding the total organic content of living matter 10,000-fold. It is insoluble in normal organic solvents and it does not have a specific chemical formula. Upon heating, kerogen converts in part to liquid and gaseous hydrocarbons. Petroleum and natural gas form from kerogen. Kerogen may be classified by its origin: lacustrine (e.g., algal), marine (e.g., planktonic), and terrestrial (e.g., pollen and spores). The name "kerogen" was introduced by the Scottish organic chemist Alexander Crum Brown in 1906,''Oxford English Dictionary'' 3rd Ed. (2003) derived from the Greek for "wax birth" (Greek: κηρός "wax" and -gen, γένεση "birth"). The increased production of hydrocarbons from shale has motivated a revival of research into the composition, structure, and properties of kerogen. Many studies have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. Alabaster, a fine-grained white or lightly tinted variety of gypsum, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England. Gypsum also crystallizes as translucent crystals of selenite. It forms as an evaporite mineral and as a hydration product of anhydrite. The Mohs scale of mineral hardness defines gypsum as hardness value 2 based on scratch hardness comparison. Etymology and history The word ''gypsum'' is derived from the Greek word (), "plaster". Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon dioxide, nitrogen, hydrogen sulfide, and helium are also usually present. Natural gas is colorless and odorless, so odorizers such as mercaptan (which smells like sulfur or rotten eggs) are commonly added to natural gas supplies for safety so that leaks can be readily detected. Natural gas is a fossil fuel and non-renewable resource that is formed when layers of organic matter (primarily marine microorganisms) decompose under anaerobic conditions and are subjected to intense heat and pressure underground over millions of years. The energy that the decayed organisms originally obtained from the sun via photosynthesis is stored as chemical energy within the molecules of methane and other hydrocarbons. Natural gas can be burned fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude oil and petroleum products that consist of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, mostly zooplankton and algae, are buried underneath sedimentary rock and subjected to both prolonged heat and pressure. Petroleum is primarily recovered by oil drilling. Drilling is carried out after studies of structural geology, sedimentary basin analysis, and reservoir characterisation. Recent developments in technologies have also led to exploitation of other unconventional reserves such as oil sands and oil shale. Once extracted, oil is refined and separated, most easily by distillation, into innumerable products for direct use or use in manufacturing. Products include fuels such as gasol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apricot
An apricot (, ) is a fruit, or the tree that bears the fruit, of several species in the genus ''Prunus''. Usually, an apricot is from the species '' P. armeniaca'', but the fruits of the other species in ''Prunus'' sect. ''Armeniaca'' are also called apricots. Etymology ''Apricot'' first appeared in English in the 16th century as ''abrecock'' from the Middle French ''aubercot'' or later ''abricot'', from Spanish '' albaricoque'' and Catalan ''a(l)bercoc'', in turn from Arabic الْبَرْقُوق (al-barqūq, "the plums"), from Byzantine Greek βερικοκκίᾱ (berikokkíā, "apricot tree"), derived from late Greek ''πραικόκιον'' (''praikókion'', "apricot") from Latin '' ersica ("peach")praecocia'' (''praecoquus'', "early ripening"). Species Apricots are species belonging to ''Prunus'' sect. ''Armeniaca''. The taxonomic position of '' P. brigantina'' is disputed. It is grouped with plum species according to chloroplast DNA sequences, but more closely r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apple
An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, where its wild ancestor, ''Malus sieversii'', is still found today. Apples have been grown for thousands of years in Asia and Europe and were brought to North America by European colonization of the Americas, European colonists. Apples have Religion, religious and mythology, mythological significance in many cultures, including Norse mythology, Norse, Greek mythology, Greek, and Christianity in Europe, European Christian tradition. Apples grown from seed tend to be very different from those of their parents, and the resultant fruit frequently lacks desired characteristics. Generally, apple cultivars are propagated by clonal grafting onto rootstocks. Apple trees grown without rootstocks tend to be larger and much slower to fruit after plantin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals who are raised for consumption, and sometimes used to refer solely to farmed ruminants, such as cattle, sheep, goats and pigs. Horses are considered livestock in the United States. The USDA classifies pork, veal, beef, and lamb (mutton) as livestock, and all livestock as red meat. Poultry and fish are not included in the category. The breeding, maintenance, slaughter and general subjugation of livestock, called '' animal husbandry'', is a part of modern agriculture and has been practiced in many cultures since humanity's transition to farming from hunter-gatherer lifestyles. Animal husbandry practices have varied widely across cultures and time periods. It continues to play a major economic and cultural role in numerous communities. Lives ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
