Yahoo奇摩 網頁搜尋

  1. 論文門 相關
  1. List of Chinese classifiers - Wikipedia › wiki › List_of_Chinese_classifiers

    List of Chinese classifiers. In the tables, the first two columns contain the Chinese character representing the classifier, in traditional and simplified versions when they differ. The next four columns give pronunciations in Standard ...

  2. Logic gate - Wikipedia › wiki › Logic_gate
    • Electronic Gates
    • History and Development
    • Symbols
    • Universal Logic Gates
    • de Morgan Equivalent Symbols
    • Data Storage
    • Three-State Logic Gates
    • Manufacturing
    • Further Reading

    A functionally complete logic system may be composed of relays, valves (vacuum tubes), or transistors. The simplest family of logic gates uses bipolar transistors, and is called resistor–transistor logic (RTL). Unlike simple diode logic gates (which do not have a gain element), RTL gates can be cascaded indefinitely to produce more complex logic functions. RTL gates were used in early integrated circuits. For higher speed and better density, the resistors used in RTL were replaced by diodes resulting in diode–transistor logic (DTL). Transistor–transistor logic (TTL) then supplanted DTL. As integrated circuits became more complex, bipolar transistors were replaced with smaller field-effect transistors (MOSFETs); see PMOS and NMOS. To reduce power consumption still further, most contemporary chip implementations of digital systems now use CMOSlogic. CMOS uses complementary (both n-channel and p-channel) MOSFET devices to achieve a high speed with low power dissipation. For small-scale...

    The binary number system was refined by Gottfried Wilhelm Leibniz (published in 1705), influenced by the ancient I Ching's binary system. Leibniz established that using the binary system combined the principles of arithmetic and logic. In an 1886 letter, Charles Sanders Peirce described how logical operations could be carried out by electrical switching circuits. Eventually, vacuum tubes replaced relays for logic operations. Lee De Forest's modification, in 1907, of the Fleming valve can be used as a logic gate. Ludwig Wittgenstein introduced a version of the 16-row truth table as proposition 5.101 of Tractatus Logico-Philosophicus (1921). Walther Bothe, inventor of the coincidence circuit, got part of the 1954 Nobel Prize in physics, for the first modern electronic AND gate in 1924. Konrad Zuse designed and built electromechanical logic gates for his computer Z1(from 1935 to 1938). From 1934 to 1936, NEC engineer Akira Nakashima, Claude Shannon and Viktor Shetakov introduced switch...

    There are two sets of symbols for elementary logic gates in common use, both defined in ANSI/IEEE Std 91-1984 and its supplement ANSI/IEEE Std 91a-1991. The "distinctive shape" set, based on traditional schematics, is used for simple drawings and derives from United States Military Standard MIL-STD-806 of the 1950s and 1960s. It is sometimes unofficially described as "military", reflecting its origin. The "rectangular shape" set, based on ANSI Y32.14 and other early industry standards as later refined by IEEE and IEC, has rectangular outlines for all types of gate and allows representation of a much wider range of devices than is possible with the traditional symbols. The IEC standard, IEC 60617-12, has been adopted by other standards, such as EN 60617-12:1999 in Europe, BS EN 60617-12:1999 in the United Kingdom, and DINEN 60617-12:1998 in Germany. The mutual goal of IEEE Std 91-1984 and IEC 60617-12 was to provide a uniform method of describing the complex logic functions of digita...

    Charles Sanders Peirce (during 1880–81) showed that NOR gates alone (or alternatively NAND gates alone) can be used to reproduce the functions of all the other logic gates, but his work on it was unpublished until 1933. The first published proof was by Henry M. Sheffer in 1913, so the NAND logical operation is sometimes called Sheffer stroke; the logical NOR is sometimes called Peirce's arrow. Consequently, these gates are sometimes called universal logic gates.

    By use of De Morgan's laws, an AND function is identical to an OR function with negated inputs and outputs. Likewise, an OR function is identical to an ANDfunction with negated inputs and outputs. A NAND gate is equivalent to an OR gate with negated inputs, and a NOR gate is equivalent to an AND gate with negated inputs. This leads to an alternative set of symbols for basic gates that use the opposite core symbol (AND or OR) but with the inputs and outputs negated. Use of these alternative symbols can make logic circuit diagrams much clearer and help to show accidental connection of an active high output to an active low input or vice versa. Any connection that has logic negations at both ends can be replaced by a negationless connection and a suitable change of gate or vice versa. Any connection that has a negation at one end and no negation at the other can be made easier to interpret by instead using the De Morgan equivalent symbol at either of the two ends. When negation or pola...

    Logic gates can also be used to store data. A storage element can be constructed by connecting several gates in a "latch" circuit. More complicated designs that use clock signals and that change only on a rising or falling edge of the clock are called edge-triggered "flip-flops". Formally, a flip-flop is called a bistable circuit, because it has two stable states which it can maintain indefinitely. The combination of multiple flip-flops in parallel, to store a multiple-bit value, is known as a register. When using any of these gate setups the overall system has memory; it is then called a sequential logic system since its output can be influenced by its previous state(s), i.e. by the sequence of input states. In contrast, the output from combinational logicis purely a combination of its present inputs, unaffected by the previous input and output states. These logic circuits are known as computer memory. They vary in performance, based on factors of speed, complexity, and reliability...

    A three-state logic gate is a type of logic gate that can have three different outputs: high (H), low (L) and high-impedance (Z). The high-impedance state plays no role in the logic, which is strictly binary. These devices are used on buses of the CPU to allow multiple chips to send data. A group of three-states driving a line with a suitable control circuit is basically equivalent to a multiplexer, which may be physically distributed over separate devices or plug-in cards. In electronics, a high output would mean the output is sourcing current from the positive power terminal (positive voltage). A low output would mean the output is sinking current to the negative power terminal (zero voltage). High impedance would mean that the output is effectively disconnected from the circuit.

    Since the 1990s, most logic gates are made in CMOS (complementary metal oxide semiconductor) technology that uses both NMOS and PMOS transistors. Often millions of logic gates are packaged in a single integrated circuit.

    Awschalom, D.D.; Loss, D.; Samarth, N. (5 August 2002). Semiconductor Spintronics and Quantum Computation. Berlin, Germany: Springer-Verlag. ISBN 978-3-540-42176-4. Retrieved 28 November 2012.
    Bostock, Geoff (1988). Programmable logic devices: technology and applications. New York: McGraw-Hill. ISBN 978-0-07-006611-3. Retrieved 28 November 2012.
    Brown, Stephen D.; Francis, Robert J.; Rose, Jonathan; Vranesic, Zvonko G. (1992). Field Programmable Gate Arrays. Boston, MA: Kluwer Academic Publishers. ISBN 978-0-7923-9248-4. Retrieved 28 Novem...
  3. Philosophical Association of Japan - Wikipedia › wiki › Philosophical_Association_of_Japan
    • History
    • Activities
    • External Links

    The PAJ was founded in 1949 by Japanese philosophers, with Amano Teiyū being elected its first president. Beginning in 1952, mainly through the efforts of presidents Amano, Ide Takashi (March 10, 1892 – March 9, 1980), Shimomura Toratarō (August 17, 1902 – January 22, 1995), Mutai Risaku (August 8, 1880 – July 5, 1974), and Watsuji Tetsurō (1889 – 1960)[citation needed], the first edition of the association's journal Philosophy(哲学, Tetsugaku)was published "with the primary purpose of offering occasions for the exchange of opinions and information about research in philosophy inside and outside of Japan".

    Annual conference
  4. Facebook - Wikipedia › wiki › Facebook

    Facebook's initial public offering came on May 17, 2012, at a share price of US$38. The company was valued at $104 billion, the largest valuation to that date. The IPO raised $16 billion, the third-largest in U.S. history, after Visa Inc. in ...

  5. Jennifer Lawrence - Wikipedia › wiki › Jennifer_Lawrence

    Jennifer Shrader Lawrence (born August 15, 1990) is an American actress. She was the world's highest-paid actress in 2015 and 2016, with her films grossing over $6 billion worldwide to date. She appeared in Time ' s 100 most influential ...

  6. Semiconductor - Wikipedia › wiki › Semiconductor
    • Properties
    • Materials
    • Physics of Semiconductors
    • Early History of Semiconductors
    • See Also
    • Further Reading
    • External Links

    Variable electrical conductivity

    Semiconductors in their natural state are poor conductors because a current requires the flow of electrons, and semiconductors have their valence bands filled, preventing the entire flow of new electrons. Several developed techniques allow semiconducting materials to behave like conducting materials, such as doping or gating. These modifications have two outcomes: n-type and p-type. These refer to the excess or shortage of electrons, respectively. An unbalanced number of electrons would cause...


    Heterojunctions occur when two differently doped semiconducting materials are joined. For example, a configuration could consist of p-doped and n-doped germanium. This results in an exchange of electrons and holes between the differently doped semiconducting materials. The n-doped germanium would have an excess of electrons, and the p-doped germanium would have an excess of holes. The transfer occurs until an equilibrium is reached by a process called recombination, which causes the migrating...

    Excited electrons

    A difference in electric potential on a semiconducting material would cause it to leave thermal equilibrium and create a non-equilibrium situation. This introduces electrons and holes to the system, which interact via a process called ambipolar diffusion. Whenever thermal equilibrium is disturbed in a semiconducting material, the number of holes and electrons changes. Such disruptions can occur as a result of a temperature difference or photons, which can enter the system and create electrons...

    A large number of elements and compounds have semiconducting properties, including: 1. Certain pure elements are found in group 14 of the periodic table; the most commercially important of these elements are silicon and germanium. Silicon and germanium are used here effectively because they have 4 valence electrons in their outermost shell, which gives them the ability to gain or lose electrons equally at the same time. 2. Binary compounds, particularly between elements in groups 13 and 15, such as gallium arsenide, groups 12 and 16, groups 14 and 16, and between different group-14 elements, e.g. silicon carbide. 3. Certain ternary compounds, oxides, and alloys. 4. Organic semiconductors, made of organic compounds. 5. Semiconducting metal–organic frameworks. The most common semiconducting materials are crystalline solids, but amorphous and liquid semiconductors are also known. These include hydrogenated amorphous silicon and mixtures of arsenic, selenium and tellurium in a variety o...

    Energy bands and electrical conduction

    Semiconductors are defined by their unique electric conductive behavior, somewhere between that of a conductor and an insulator. The differences between these materials can be understood in terms of the quantum states for electrons, each of which may contain zero or one electron (by the Pauli exclusion principle). These states are associated with the electronic band structure of the material. Electrical conductivity arises due to the presence of electrons in states that are delocalized (exten...

    Charge carriers

    The partial filling of the states at the bottom of the conduction band can be understood as adding electrons to that band. The electrons do not stay indefinitely (due to the natural thermal recombination) but they can move around for some time. The actual concentration of electrons is typically very dilute, and so (unlike in metals) it is possible to think of the electrons in the conduction band of a semiconductor as a sort of classical ideal gas, where the electrons fly around freely without...


    The conductivity of semiconductors may easily be modified by introducing impurities into their crystal lattice. The process of adding controlled impurities to a semiconductor is known as doping. The amount of impurity, or dopant, added to an intrinsic (pure) semiconductor varies its level of conductivity. Doped semiconductors are referred to as extrinsic.By adding impurity to the pure semiconductors, the electrical conductivity may be varied by factors of thousands or millions. A 1 cm3 specim...

    The history of the understanding of semiconductors begins with experiments on the electrical properties of materials. The properties of the time-temperature coefficient of resistance, rectification, and light-sensitivity were observed starting in the early 19th century. Thomas Johann Seebeck was the first to notice an effect due to semiconductors, in 1821. In 1833, Michael Faraday reported that the resistance of specimens of silver sulfide decreases, when they are heated. This is contrary to the behavior of metallic substances such as copper. In 1839, Alexandre Edmond Becquerel reported observation of a voltage between a solid and a liquid electrolyte, when struck by light, the photovoltaic effect. In 1873, Willoughby Smith observed that selenium resistors exhibit decreasing resistance, when light falls on them. In 1874, Karl Ferdinand Braun observed conduction and rectification in metallic sulfides, although this effect had been discovered much earlier by Peter Munck af Rosenschold...

    A. A. Balandin & K. L. Wang (2006). Handbook of Semiconductor Nanostructures and Nanodevices (5-Volume Set). American Scientific Publishers. ISBN 978-1-58883-073-9.
    Sze, Simon M. (1981). Physics of Semiconductor Devices (2nd ed.). John Wiley and Sons (WIE). ISBN 978-0-471-05661-4.
    Turley, Jim (2002). The Essential Guide to Semiconductors. Prentice Hall PTR. ISBN 978-0-13-046404-0.
    Yu, Peter Y.; Cardona, Manuel (2004). Fundamentals of Semiconductors : Physics and Materials Properties. Springer. ISBN 978-3-540-41323-3.
    Calculator for the intrinsic carrier concentrationin silicon
    Semiconductor OneSource Hall of Fame, Glossary
  7. Poly(methyl methacrylate) - Wikipedia › wiki › Poly(methyl_methacrylate)

    Poly(methyl methacrylate) (PMMA) belongs to a group of materials called engineering plastics.It is a transparent thermoplastic.PMMA is also known as acrylic, acrylic glass, perspex, or plexiglass, as well as by the trade names and brands Crylux, ...

  8. Koryo-saram - Wikipedia › wiki › Koryo-saram
    • Autonym
    • Origins
    • Post-Deportation
    • Culture
    • See Also
    • Further Reading
    • External Links

    The word Koryo in "Koryo-saram" originated from the name of the Goryeo (Koryŏ) Dynasty from which "Korea" was also derived. The name Soviet Korean was also used, more frequently before the collapse of the Soviet Union. Russians may also lump Koryo-saram under the general label koreytsy (корейцы); however, this usage makes no distinctions between ethnic Koreans of the local nationality and the Korean nationals (citizens of North Korea or South Korea). In Standard Korean, the term "Koryo-saram" is typically used to refer to historical figures from the Goryeo dynasty; to avoid ambiguity, Korean speakers use a word Goryeoin (Korean: 고려인, Hanja: 高麗人, meaning the same as "Koryo-saram") to refer to ethnic Koreans in the post-Soviet states. However, the Sino-Korean morpheme "-in" (인) is not productive in Koryo-mal, the dialect spoken by Koryo-saram and as a result, only a few (mainly those who have studied Standard Korean) refer to themselves by this name; instead, "Koryo-saram" has come to...

    Immigration to the Russian Far East and Siberia

    The early 19th century saw the decline of the Joseon Dynasty of Korea. A small population of wealthy elite owned the farmlands in the country, and poor peasants found it difficult to survive. Koreans leaving the country in this period were obliged to move toward Russia, as the border with China was sealed by the Qing Dynasty. However, the first Koreans in the Russian Empire, 761 families totalling 5,310 people, had actually migrated to Qing territory; the land they had settled on was ceded to...

    Deportation to Central Asia

    In 1937, facing reports from the People's Commissariat for Internal Affairs (NKVD) that there were possibilities that Japanese would have infiltrate the Russian Far East by means of ethnic Korean spies, Joseph Stalin and Vyacheslav Molotov signed Resolution 1428-326 ss, "On the Exile of the Korean Population from border Raions of the Far East Kray", on 21 August. According to the report of Nikolai Yezhov, 36,442 Korean families totalling 171,781 persons were deported by 25 October. The deport...

    Scholars estimated that, roughly 470,000 Koryo-saram were living in the Commonwealth of Independent States.

    After their arrival in Central Asia, the Koryo-saram quickly established a way of life different from that of neighbouring peoples. They set up irrigation works and became known throughout the region as rice farmers. They interacted little with the nomadic peoples around them and focused on education. Although they soon ceased to wear traditional Korean clothing, they adapted Western-style dress rather than the clothing worn by the Central Asian peoples. The ritual life of the Koryo-saram community has changed in various respects. Marriages have taken on the Russian style. At Korean traditional funerals, the coffin is taken out of the house either through the window or a single door threshold; however, if there is more than one door threshold on the way out (e.g. in modern multi-stories buildings), three notches are made on each threshold. The name of the dead is traditionally written in hanja; however, as hardly anyone is left among the Koryo-saram who can write in hanja, the name...

    Alekseenko, Aleksandr Nikolaevich (2000). Республика в зеркале переписей населения [Republic in the Mirror of the Population Censuses] (PDF). Population and Society: Newsletter of the Centre for De...
    Back, Tae-Hyun (2004). "The social reality faced by ethnic Koreans in Central Asia". Korean and Korean American Studies Bulletin. 12(2–3): 45–88.
    Chang, Jon (February 2005). "Central Asia or Bust". KoreAm Journal. Archived from the original on 7 October 2008. Retrieved 26 February 2009.
    Dong, Xiaoyang; Su, Chang (August 2005), "Strategic Adjustments and Countermeasures against Extremist Forces of Central Asian Countries after 9/11", in Charles Hawkins; Robert Love (eds.), Proceedi...
    (in Russian) Association of Scientific and Technological Societies Koreans (ANTOK)
    (in Russian) CIS Koreans Information Web-Site of ARIRANG.RU
    (in Russian) Lib.Ru: the Koreans
    (in Russian) Tashkent Representation of the Institute of Asian Culture and Development (TP IAKR) — an Association of Koreans in Karakalpakstan.
  9. Aluminium alloy - Wikipedia › wiki › Aluminium_alloy

    Aluminium alloy. Welded aluminium alloy bicycle frame, made in the 1990s. Aluminium alloys (or aluminum alloys; see spelling differences) are alloys in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, ...

  10. Old Man (song) - Wikipedia › wiki › Old_Man_(song)

    "Old Man" is a song written and performed by Canadian rock singer-songwriter and guitarist Neil Young from his 1972 album Harvest. "Old Man" was released as a single on Reprise Records in the spring of 1972, reaching number 4 ...

  11. 其他人也搜尋了
  1. 論文門 相關