| 释义 |
‖ annulus|ˈænjʊləs|
Pl. -i.
[L., erroneous mediæval spelling of ānulus a ring, dim. of rare ānus a rounding, a circular form (see Lewis and Short).]
1. A ring, or ring-like body (in various technical applications).
1563J. Shute Archit. C j a, Thre of them ye shal geue to Echinus..the fourth part geue to Annulus. 1713Derham Phys. Theol. iv. xii. 223 These Rings have a Curious Apparatus of Muscles enabling those creatures..to dilate or contract their Annuli. 1761Sterne Tr. Shandy (1802) III. x. 275 By the return of the two ends of the strings thro' the annulus or noose made by the second implication of them. 1794Sullivan View Nat. II, There is a prodigious annulus encompassing Saturn. 1853Kane Grinnell Exp. xix. (1856) 143 An annulus of Arctic shrubs and trees.
2. Geom. ‘The name of a ring, or solid formed by the revolution of a circle about a straight line exterior to its circumference as an axis, and in the plane of the said circle.’ Penny Cycl. 1834.
1802Playfair Illustr. Hutton. The. 508 If..the ring is a solid annulus..it may be so constituted that the attraction of Saturn..may produce a force perpendicular to its surface.
3. Bot.
a. In ferns: The ring of cells which partially surrounds the sporangia.
b. In mosses: The elastic external ring of epidermal cells with which the brim of the sporangium is furnished.
c. In fungi: Sometimes applied to the portion of the veil, which remains like a collar round the stalk.
1830Lindley Nat. Syst. Bot. 313 The resemblance between the midrib of one of these scales and the annulus of a Polypodium. 1863Berkeley Brit. Mosses 311 Annulus, a little ring, which is often elastic, at the rim of the mouth of the sporangium. 1871M. C. Cooke Fungi (1874) 19 The collar adherent to the stem falls back, and thenceforth is known as the annulus or ring.
4. Astr. A ring of light, as in an annular eclipse.
1871Schellen Spectrum Anal. §54. 256 Forming an annulus around the moon of about 8′ in diameter.
▸ Anat. A ring of dense fibrous tissue surrounding each of the valvular orifices of the heart, forming a point of attachment for the valve leaflets and for myocardial fibres. Also called annulus fibrosus.
1923Heart 10 22 We have been unable to find a description of the annulus and its limits, sufficient for our purposes. 1971Ann. Thoracic Surg. 11 336 (title) Unusual complications during mitral valve replacement in the presence of calcification of the annulus. 2005Ann. Thoracic Surg. 79 1662 At follow-up, there was no evidence of [pulmonary] valve failure or tissue growth within the valve annulus. |