| 释义 |
reversible, a. and n.|rɪˈvɜːsɪb(ə)l|
[f. reverse v. + -ible. Cf. F. réversible, Sp. reversible, Pg. reversivel, It. riversibile.]
A. adj.
1. a. Admitting of being reversed; capable of reversing.
1648Hammond Wks. (1683) I. 81 The fate and state of this Kingdom might be a reversible mutable state. 1685J. Dunton Lett. fr. New-Eng. (1867) 18 If it was not Fate, and so might be reversible, then there was nothing certain in his Art. 1828Stark Elem. Nat. Hist. I. 247 Tarsus short, the hind toe reversible. 1861C. F. Bromley Woman's Wand. in West. World 20 These benches have reversible backs; so that you may sit fronting the engine or not as you prefer. 1899T. Eaton & Co. Catal. Spring & Summer 116/1 Men's reversible coats, made of napa tan leather, lined with heavy drab corduroy. 1910F. Yeigh Through Heart of Canada ii. 36 The famous reversible falls of the St. John River..are best viewed from the suspension bridge. 1921A. W. Grabau Textbk. Geol. I. xvii. 525 A reversible fall is produced, facing inward when the ocean is highest and outward when it is lowest. 1926Daily Colonist (Victoria, B.C.) 9 Jan. 18/1 (Advt.), Reversible Rugs, shown in Oriental designs and colorings. They are made of hard-wearing jute and have the appearance of wool rugs. 1957Encycl. Brit. XXIII. 459/1 Reversible fabrics may have..two series of differently coloured welts or warps to one of the other series, in which event they may be similarly figured on both sides by causing the threads of the double series to change places. 1974Times 14 Apr. 7/2 The coats and capes..are all reversible with soft knitted mohair on the outside and a sort of super deluxe dishcloth knitting inside.
b. Of a propeller: capable of providing reverse thrust, usu. by reversal of the pitch of the blades while the direction of rotation remains unchanged. So reversible-pitch attrib. phr.
1907H. Chatley Problem of Flight vii. 86 Reversal of motion can be obtained by the use of change speed gearing, which is altered for the backward motion, so that its torque is reversed... Reversible wings to the helices can also be used for this purpose, but the rigidity would probably be impaired. 1922Flight XIV. 657/2 An airscrew..has been produced by..one of the first airscrew making firms in America... It comprises a system of special blades, and a mechanism for varying the pitch of same.. but the airscrew is reversible as well. 1923Rep. Internat. Air. Congr. 588 This propeller is reversible as well as adjustable, and can be used as a brake in landing on rough terrain. 1930F. E. Weick Aircraft Propeller Design xi. 188 The effectiveness of the reversible-pitch propeller as an air-brake..has been experimented with by both the Army and the Navy. 1935J. W. Anderson Diesel Engines xv. 347 On reversible propellers the blades are twisted by suitable mechanism to give the proper angle for the desired direction of motion of the boat. 1951P. Du Cane High-Speed Small Craft xi. 131 Variable (controllable) reversible-pitch propellers have so far been fitted in relatively few experimental craft built in Great Britain. 1965C. N. Van Deventer Introd. Gen. Aeronaut. viii. 197/2 Towards the end of WW II the final refinement to propellers was perfected with the reversible pitch propeller. 1967Jane's Surface Skimmer Syst. 1967–68 12/1 A 230 hp flat-six aero-engine drives a reversible-airscrew for propulsion.
2. Physics and Chem.
a. Thermodynamics. Of a change or process: that is capable of reversal, completely and in detail; strictly, applicable to an ideal change in which the system is in equilibrium at all times. Also applied to a system undergoing such changes.
1856Phil. Mag. XI. 216 The temperatures of two bodies are proportional to the quantities of heat respectively taken in and given out in localities at one temperature and at the other, respectively, by a material system subjected to a complete cycle of perfectly reversible thermo-dynamic operations, and not allowed to part with or take in heat at any other temperature. 1878Stewart & Tait Unseen Univ. iii. §106. 118 That an engine whose cycle of operations is reversible is a perfect engine. 1922Glazebrook Dict. Appl. Physics I. 929/1 The expansions and compressions and the transfers of heat that occur in a real engine are never strictly reversible, some of them indeed are far from being reversible. 1950W. J. Moore Physical Chem. i. 22 Reversible processes are never realizable in actuality since they must be carried out infinitely slowly. 1958Condon & Odishaw Handbk. Physics v. 5/1 All reversible engines working between the same two heat reservoirs must have the same efficiency. 1963A. E. J. Hayes Appl. Thermodynamics v. 53 When a fluid undergoes a reversible process it passes through a series of equilibrium states, i.e. states in which the fluid properties are uniform throughout. The term reversible does not merely imply ability to operate in the reverse direction, but also that the process must be able to retrace its path through the same sequence of equilibrium states. 1978P. W. Atkins Physical Chem. ii. 62 In thermodynamics a reversible change is one that can be reversed by an infinitesimal modification of a variable.
b. Applied to chemical reactions which in normal circumstances also take place in the opposite direction, and hence yield an equilibrium mixture of reactants and products.
1885Jrnl. Chem. Soc. XLVIII. i. 117 Reversible chemical changes are thus brought into the class of reciprocal phenomena. 1899J. McCrae tr. A. Reychler's Outl. Physical Chem. 241 The reversible reaction BaSO4+K2CO3{equil}K2SO4+BaCO3. 1912J. W. Mellor Mod. Inorg. Chem. vi. 99 Opposing reactions are also called incomplete or reversible reactions in contradistinction to irreversible or complete reactions typified by the action of zinc on sulphuric acid, where the reaction is completed in one direction and is not opposed by a counter reaction. 1950N. V. Sidgwick Chem. Elements II. 1213 These acids..are formed by the action of water on the elementary halogen, which leads..to a reversible hydrolysis of the type X2+H2O{equil}HX+HOX. 1972R. A. Jackson Mechanism iv. 85 When aliphatic fluorides are dissolved in antimony pentafluoride, a reversible reaction leads to the formation of carbonium ions.
c. Applied to an electrochemical cell in which the chemical reaction can be reversed by the application of a sufficiently large opposing e.m.f.; hence to quantities measured under, or pertaining to, conditions in which the e.m.f. of the cell is balanced by an applied e.m.f. and no current is flowing.
1895C. S. Palmer tr. Nernst's Theoret. Chem. iv. vi. 599 Strictly speaking, all reversible batteries can be used as accumulators. 1936R. W. Gurney Ions in Solution viii. 90 Under these circumstances it is found that the processes in each half-cell..are now simply taking place in the reverse direction. Such a cell is called a reversible cell—meaning reversible both in its mechanism and in the thermodynamic sense. 1957G. E. Hutchinson Treat. Limnol. I. xi. 693 It is usual to term the actual potential measured the irreversible oxygen potential, while the theoretical value calculated may be termed the reversible oxygen potential. 1977N. J. Selley Exper. Approach to Electrochem. iv. 63 The value of the applied p.d. for which the current is zero is the ‘reversible cell potential’..for the back reaction. 1978P. W. Atkins Physical Chem. xii. 346 A cell that is not truly reversible will respond to a small imbalance by supplying appreciable currents in one direction or the other, and it may be very difficult to detect its true balance point.
d. Physical Chem. Of a colloid or colloidal system: capable of being changed from a gelatinous state into a sol by a reversal of the treatment which turns the sol into a gel or gelatinous precipitate. Of a change of state: characterized by this property.
1899Jrnl. Physiol. XXIV. 175 (heading) Heat-reversible colloidal mixtures. 1915[see irreversible a. 3]. 1930Engineering 4 July 6/2 The power of absorption [of clay] being due to its containing a large proportion of matter in a state of fine division, forming a ‘non-rigid reversible gel’.. composed of colloidal matter. 1955J. Osborne Dental Mech. (ed. 4) i. 18 The cooling process is relatively slow, since all reversible hydrocolloids are bad conductors of heat. 1970Encycl. Polymer Sci. & Technol. IV. 27 To redissolve reversible colloids, none of those drastic measures are required which are so characteristic of irreversible colloids.
B. n. A cloth which is faced on both sides, so as to allow of its being turned; a garment faced on both sides, so that it may be worn with either outside.
1863Cornh. Mag. Jan. 89 The housebreakers' wives and children, maybe, take their turn during the day: at night, the men themselves watch. On such occasions they often wear ‘reversibles’, or coats which may be worn inside out; one side being of a bright, the other of a dark colour. 1892Daily News 10 Aug. 2/7 For the country districts tweeds, serges, reversibles, and cheap ladies' materials are the most wanted. 1905Eng. Dial. Dict. V. 93/1 Reversible, a double cloth with a face, gen. made of better quality than the back. w. Yks. 1964McCall's Sewing ii. 31/2 Reversible, fabric that has been finished so that either side may be used or a garment finished so that it may be turned and worn on either side. |