| 释义 |
‖ corona|kɒˈrəʊnə|
Pl. coronæ |-niː|, rarely coronas.
[L. corōna crown, chaplet or wreath, fillet or circlet of gold or other material.]
1. A small circle or disc of light (usually prismatically coloured) appearing round the sun or moon. Also applied to a similar appearance opposite the sun, an anthelion; and more widely, to similar phenomena in optical instruments, etc.
1658in Phillips. 1670H. Stubbe The Plus Ultra 150 The reflexion of the glasses..did create a corona of several colours. 1783Barker in Phil. Trans. LXXIII. 245 There was a remarkable corona about the moon. 1807T. Young Nat. Philos. I. 466 The coloured circles or coronae, sometimes seen round the sun and moon. 1823W. Scoresby Jrnl. 273 A splendid display of five concentric coronæ, or prismatic circles, produced by the action of the sun on a low stratum of fog. 1849D. P. Thomson Introd. Meteorol. 227 In coronæ the blue prismatic colour is nearer the centre than the red; in halos this arrangement is reversed..the former arise from diffraction, the latter from refraction, of light.
2. Astron. The halo of radiating white light seen around the disc of the moon in a total eclipse of the sun; now known to belong to the sun.
1851–9Airy in Adm. Man. Sci. Enq. 3 If the eclipse be total attention should be paid..to the luminous corona surrounding the moon. 1879H. W. Warren Recr. Astron. v. 88 This region of discontinuous flame below the corona is called the chromosphere. 1890C. A. Young Elem. Astron. vi. §208 The corona is proved to be a true solar appendage and not a mere optical phenomenon.
3. A circular chandelier suspended from the roof of a church; more fully corona lucis (crown of light).
1825T. D. Fosbroke Encycl. Antiq. (1843) I. vi. 122/2 Pendent chandeliers, called Coronæ. 1844Ecclesiologist May 127 Two coronæ lucis to carry six lights. 1870F. R. Wilson Ch. Lindisf. 63 From the middle rib of the Chancel depends a corona.
attrib.1868Morn. Star 26 Mar., This staircase is lighted..by two corona gas chandeliers.
4. Arch. A member of the cornice, above the bed-moulding and below the cymatium, having a broad vertical face, usually of considerable projection; also called drip or larmier. [In Vitruvius corona is the cornice.]
1563Shute Archit. C j b, Coronix..you shall deuid into .4. partes. geue one part vnto Cimatium vnder Corona..geue likwise .2 parte vnto Corona..& the fourth part which remaineth, geue vnto Cymatium ouer Corona. 1712Addison Spect. No. 415 ⁋9. 1789 P. Smyth tr. Aldrich's Archit. (1818) 109 Reason forbids the corona to be omitted in the cornice. 1823P. Nicholson Pract. Build. 474 In the cornices of the entablatures, the coronas should not be ornamented. 1862Smiles Engineers II. 43 The last pieces of the corona were set [in the Eddystone Lighthouse].
5. R. C. Ch. The tonsure of a cleric. [med.L. corona clericalis, OF. corone, Godef.]
1846–7W. Maskell Mon. Rit. (1882) II. p. ci. note, The corona of the priesthood was distinguished from that of any lower order.
6. Anat., etc. Applied to various parts of the body resembling or likened to a crown; also to the upper portion or crown of any part, as of a tooth; cf. crown n.
spec. a. (in full corona glandis): see quot. 1753. b. Path. (in full corona veneris) ‘Term for syphilitic blotches on the forehead, which often extend around it like a crown’ (Syd. Soc. Lex.). c. Zool. The ‘test’ or body-wall of an echinoid. d. The trochal disc of a rotifer, etc.
1712Arbuthnot John Bull (1755) 46 The tokens were evident on him, blotches, scabs, and the corona. 1753Chambers Cycl. Supp., Corona, in anatomy, is that edge of the glans of the penis where the preputium begins. 1828Webster, Corona..2. In anatomy, the upper surface of the molar teeth or grinders. 1872Nicholson Palæont. 103 The ‘corona’ is the main element of the test. 1886C. T. Hudson Rotifera I. i. 6 Each side of the front of the head, or corona, is rounded into a nearly circular lobe. 1888Rolleston & Jackson Anim. Life 556 [In Echinoidea] The five ambulacral and interambulacral areæ make up the corona or test. 1898A. Sedgwick Text-bk. Zool. I. 299 Phylum Rotifera... It will be useful to use the word corona for the discoidal anterior end of the body. 1902Amer. Nat. Dec. 932 In Melo and some other genera the spines project upwards and are generally unclosed on the apertural side. This produces the spiral ‘corona’, so striking a feature in some shells. 1906Camb. Nat. Hist. I. 539 Echinidae in which the plates of the corona dovetail into each other. 1929Encycl. Brit. XIX. 575/1 Numerous cilia crowded upon a particular area of delicate skin close to or encircling the mouth... The whole area, including the mouth itself, as seen when the cilia are active, is called the corona. 1966H. G. S. Wright tr. Donner's Rotifers 23 This corona surrounds a cup-shaped enclosure.
e. corona radiata: (a) a mass of projection fibres in the brain which spread radially from the internal capsule to the cerebral cortex; (b) the layer of radially elongated follicular cells which surround an ovum and develop shortly before ovulation.
[1848Dunglison Med. Lex. (ed. 7) 222/2 Fasciculi of white fibres radiate in all directions from every part of the surface of the optic thalamus, excepting its inner side..; the anterior of these fibres pass directly forwards, the middle fibres outwards, and the posterior backwards, forming the corona radians.] 1869Gray Anat. (ed. 5) 482 Some of the diverging fibres..radiate into the anterior, middle, and posterior lobes of the hemisphere..before passing to the convolutions. These fibres have received the name of corona radiata. 1892C. S. Minot Human Embryol. i. iii. 53 The cells..next to the ovum are cylindroid, and radiate round the zona, constituting thus the so-called corona radiata. 1913A. Robinson Cunningham's Text-Bk. Anat. (ed. 4) 644 The fibres..spread out widely from each other in a radiating or fan-shaped manner, as they are followed to the various gyri of the cerebral hemisphere. This arrangement is termed the corona radiata. 1961Lancet 29 July 249/2 The lesions involved the pyramidal pathways at the level of the corona radiata, internal capsule, or pons. 1968H. Wang Outl. Human Embryol. i. 8 The liberated ovum, surrounded by the corona radiata, is expelled from the follicle.
7. Bot.
a. An appendage on the top of a seed, as the pappus on that of a dandelion or thistle.
b. A crown-like appendage on the inner side of the corolla in some flowers, as the daffodil and lychnis.
†c. The circle of florets surrounding the disc in a composite flower; the ‘ray’. Obs.
d. The medullary sheath, or innermost ring of woody tissue surrounding the pith in the stems of dicotyledons and gymnosperms.
e. The crown of the root, the junction of root and stem.
1753Chambers Cycl. Supp., Corona, among botanists, expresses anything growing on the head of the seed..Sometimes the coronæ are composed of simple filaments, and sometimes they are ramose. 1770Sir J. Hill Constr. Timber 57 The Corona is a ring..placed between the wood and the Pith. 1811A. T. Thomson Lond. Disp. ii. (1818) 401 It [wheat] has two set of roots; one set proceeding directly from the seed, and the other from what is denominated the corona of the plant, about two inches above the first: the coronal roots do not shoot till spring-time, and collect more nutriment than the seminal roots. 1828Webster, Corona..3. In botany, the circumference or margin of a radiated compound flower. Encycl. 1830Lindley Nat. Syst. Bot. 150 Petals..arising from without a short membranous rim or corona. 1875Bennett & Dyer Sachs' Bot. ii. v. 471 When the corolla itself is gamopetalous, the parts of the corona also coalesce, as in Narcissus, where it is very large. Ibid. 540 The corona of hairs which serves..for the dissemination of many seeds through the air.
8. Astron. Corona australis, C. borealis: two constellations, the Southern and Northern Crown, consisting of elliptical rings of stars.
9. Electr. A luminous appearance in the gas surrounding a conductor when the electric field at its surface is strong enough to ionize the gas but not strong enough to cause a spark. Also attrib., as corona discharge, the discharge causing a corona.
1906A. Russell Altern. Currents II. 475 When the potential difference between the mains is very high, each main is seen surrounded by a faintly luminous enveloping cloud of a bluish colour, which apparently does not touch the conductor it envelopes. This cloud is called the corona. Ibid., When coronae make their appearance it is found that the capacity between the mains and the loss of energy in distribution are increased. 1918Jrnl. Chem. Soc. CXIV. ii. 42 The corona discharge. 1926Encycl. Brit. 2nd Suppl. I. 949/1 In the case of high voltage aerial lines there is a notable loss of power due to the ionisation of the air. This is called the corona effect since it makes the lines appear luminous in the dark. 1937Discovery Aug. 248/2 Synthetic rubber compositions are used as a corona-proof sheath in high tension power cables. 1953Electronic Engin. XXV. 64 A corona stabilizer consists of a concentric anode and cathode in an envelope filled with a few millimetres pressure of a suitable gas, usually hydrogen. 1959R. E. Huschke Gloss. Meteorol. 138 Aircraft flying through active electrical storms often develop corona discharge streamers from antennas and propellers. |