| 释义 |
▪ I. absciss, abscisse, n.|ˈæbsɪs|
Pl. -es; more commonly in the L. form abscissa |æbˈsɪsə|, pl. abscissae; also Eng. abscissas.
[L. abscissa (sc. linea a line) cut off; pa. pple. of abscindere: see abscind.]
1. Geom. Literally, a line or distance cut off; spec. the portion of a given line intercepted between a fixed point within it, and an ordinate drawn to it from a given point without it.
In Conic Sections: the segment (or segments) of a diameter (or in a hyperbola, a diameter produced), intercepted between the point where it is cut by an ordinate, and the bounding curve. In Rectilineal Coördinates, the segment of a given line, x, intercepted between the point where it is cut by another line, y, and that in which it is cut by a line parallel to the latter drawn from a given point without it, and called the ordinate.
1698De Moivre in Phil. Trans. XX. 192 The Abscisse corresponding to a certain Area in any Curve. 1748Hartley Observ. on Man i. iii. §2. 339 The Ordinates & Points of the Absciss being given, in the unknown Curve. 1798in Phil. Trans. LXXXVIII. 7 It was found to be a very accurate parabola, the abscissa of which was 13·85 in. 1841Young Math. Dissert. i. 10 In what directions the positive abscissas and the positive ordinates are usually taken. 1871B. Stewart Heat §141 Let us..reckon the temperatures along a line of abscissae after the manner represented in the figure.
2. Bot. absciss layer, a layer of cells across the base of the petiole in deciduous leaves.
1893in Funk's Stand. Dict. 1898H. C. Porter tr. Strasburger's Text-bk. Bot. i. §1. 143 Preparatory to the falling of leaves an absciss layer is formed, by means of which the separation of the leaves from the stem is effected. 1924Holman & Robbins Textbk. Gen. Bot. vi. 180 The conditions which favor leaf fall cause the cells near the lower end of the leaf stalk to become meristematic and to give rise to a zone of delicate, thin-walled cells extending clear across the base of the petiole. This is called the absciss layer (ed. 3, 1934, vi. 198 abscission layer). 1940Bot. Gaz. CII. 323 (title) Effect of growth substances on the absciss layer in leaves of Coleus.
▪ II. abˈsciss, v.
[Back-formation f. abscission.]
trans. and intr. To cut off; to abscind; to abscise. Hence abˈscissed ppl. a.
1869G. Lawson Dis. & Injuries of Eye ii. 51 The Staphyloma may be abscissed. Ibid. 52 Another way of abscissing the staphyloma is to transfix its base with a Beer's knife. 1918Bot. Gaz. LXVI. 36 The numbers refer to the total number of abscissed petioles at the corresponding dates. Ibid. 41 The lower leaves began to absciss. 1938Priestley & Scott Introd. Bot x. 140 (caption) Naturally abscissed branches of oak. Ibid. xxxviii. 554 These twigs..may be abscissed after many years of growth. |