Recent progress in the synthesisof C60 derivatives is reviewed according to the mechanism of organic chemical reaction, such as addition,oxidation-reduction, ionic reaction, pericyclic reaction, radical reaction, and so on.
The secretory canals,mainly distributing in the pericyclic parenchymna and secondary phloem,and occurring in a spallation-produced manner,were secondary ones and did not appeared in the primary structure.
The review is devoted to the photochromism of pericyclic reactions of crown-containing photochromic systems.
Cation-dependent pericyclic reactions of crown-containing photochromic compounds
Energetic, structural, and orbital criteria indicate the heteroelectric mechanism for the cyclization of compound E-3 and the pericyclic mechanism for the cyclization of compounds 1 and Z-3.
Pericyclic and Heteroelectrocyclic Mechanisms for the Cyclization of 1,3,5-Hexatrien-1-one and Its 6-Aza Analog
Expression was never detected in vascular tissue and was poorly correlated with lignification except in the cells surrounding primary xylem and pericyclic fibers in N.
Chang Shan, the subterranean portion of Dichroa febrifuga Lour. (family Hydrangeaceae), and Shu Chi, the leafy tops of the same plant, have been used in Chinese medicine more than two thousand years, but their antimalarial action has been scientifically proved and constituents investigated only in recent years. A brief account of their history, botanical source, plant habit, cultiva-tion and collection and a detailed description of their sensory, macroscopical and microscopical characters are given. The important...
Chang Shan, the subterranean portion of Dichroa febrifuga Lour. (family Hydrangeaceae), and Shu Chi, the leafy tops of the same plant, have been used in Chinese medicine more than two thousand years, but their antimalarial action has been scientifically proved and constituents investigated only in recent years. A brief account of their history, botanical source, plant habit, cultiva-tion and collection and a detailed description of their sensory, macroscopical and microscopical characters are given. The important diagnostic features of Chang Shan are:-vessels with long oblique end-plates having well-marked scalariform perforations and often containing tyloses; septate xylem-fibres; idioblasts containing bundles of acicular crystals embedded in mucilage; thick-walled pericyclic fibres; the deep-seated origin of the cork. A well-marked medullary sheath of thick-walled, lignified and pitted parenchyma occurs in the pith of both the stem and rhizome. The important diagnostic features of Shu Chi are:-thick-walled, warty, unicellular trichomes; paracytic (rubiaceous) stomata; epidermal cells with pitted anticlinal walls and finely striated cuticle; water-pores in the teeth of the leaf; idioblasts with bundles of acicular crystals em-bedded in mucilage; droplets of fixed oil in most of the cells of the leaf; thick-walled pericyclic fibers from the stem as well as deep-seated cork and characteristic vessels as seen in the subterranean organs. The significance of some of the microscopical findings as a further illustration of the connexion between anatomy and taxonomy is also discussed.
1). Rauwolfia verticillata (Lour.) Baill. (family Apocyanaceae) is an erect evergreen shrub growing wild in Kwangtung, Yunnan, and the islands of Taiwan and Hainan. An alkaloid, named Rauwolfia A (C_(25)H_(28)N_2O_2) was isolated recently from root and stem by Chao (赵承嘏) and proved to possess sedative and hypo- tensive activity. 2). The macroscopical, microscopical and sensory characters of the root and of rhizome were studied. The principal differences in microscopic structure between roots of R. verticillata...
1). Rauwolfia verticillata (Lour.) Baill. (family Apocyanaceae) is an erect evergreen shrub growing wild in Kwangtung, Yunnan, and the islands of Taiwan and Hainan. An alkaloid, named Rauwolfia A (C_(25)H_(28)N_2O_2) was isolated recently from root and stem by Chao (赵承嘏) and proved to possess sedative and hypo- tensive activity. 2). The macroscopical, microscopical and sensory characters of the root and of rhizome were studied. The principal differences in microscopic structure between roots of R. verticillata and R. serpentina, compared in a table, were also pre- sented. 3). The root is cylindrical, more or less branched, curved or slightly torturous slowly tapering toward the end. Externally, it shows a grayish-brown cork and many irregular longitudinal ridges and furrows. The fracture of thin pieces is short and irregular, that of thick pieces is irregular and splintery; the freshly frac- tured surface exhibits a grayish-brown cork, white to dark brown phelloderm and phloem which are easily peeled off, and a pale yellow central core of hard and com- pact wood, occupies about 3/4 to 4/5 part of the root in diameter, it possesses 1 to 4 growth rings and numerous, almost straight-arranged medullary rays. Odour indistinct, and taste bitter. 4). The important microscopical features of the root: The transverse section shows a stratified cork consisting of 3 to 16 alternating tangential bands of larger and smaller cork cells, both of them possess thin, lignified wall. Phelloderm con- sists up to about 10 layers of tangentially elongated parenchymatous cells, most of which contain starch grains and calcium oxalate crystals. Secondary phloem shows starch- and crystal-bearing phloem parenchyma and sieve tubes traversed by phloem rays, the latter being of mostly from 1 to 2 cells, occasionally up to 4 cells in width containing abundant starch grains and a few calcium oxalate crystals and from 7 to 16 cells high in the tangential-longitudinal sections; selerenchymatous fibres which measure 330-670μlong and 13-30μ wide and stone cells which measure up to 70 μ in diameter are scantily scattered singly or in small groups of 2 in the outer part of the secondary phloem and the inner part of phelloderm of the older thick parts of the root, both possess pitted lignified wall. Wood wedges consist of wood fibres, wood parenchyma cells, vessels, tracheids and shorter rays, the cell walls of all these elements are lignified; vessel elements varied greatly in shape and size, from isodiametric or irregular circular, oval, spindle shape, polygonal to cylindrical, up to 760 μ long and 70 μ wide, some of the vessels exhibit tylosis or gummy lignin in the cavity; tracheids measuring up to shout 290 μ long, and 35μ wide with moderately thick end and pitted walls; wood fibres up to 1520μ long and 30 μ wide possess tapered to abruptly tapered ends, and rarely bifurcate, walls with simple and obligue pits: 5). The chief microscopical characters of the rhizome are as follows: the cork shows a similar stratification to that of the root. Inside is a outer narrow zone of phelloderm followed by an inner broad zone of starch- and crystal-bearing par- enchyma in which numerous isodiametric or irregular, elongated stone cells, scle- renehymatous fibres, and latex cells are scattered; stone cells with lignified wall are arranged singly or in groups of 2 to 3, and measure up to 270 μ long, and 115μ wide; selerenchymatous fibres with tapered ends and lignified wall are more longer than that of the root and measure up to 860 μ long, 60 μ wide; pericycle, usually broad, contains a few thick, non-lignified pericyclic fibres which are scattered singly and measure up to 2850 μ long, 20μ wide; the fibres show taping and often lobed ends, with alternate, constricted and enlarged portions having thin wall and broad lumen which measure up to 30μ wide and concentrically zoned in cross, section. The bundles are of bicollateral type, constituted of external phloem, xylem, and internal phloem; vessels are shorter than that of the root, up to 690 μ long, 50 μ wi- de; wood fibres are longer than that of the root, up to 1610μ long, 30μ wide; in- ternal phloem forms a ring at the margin of the pith containing starch grains, calcium oxalate crystals and a few selerenchymatous fibres which are similar to that of the cortex; numerous irregular amorphous masses of brownish colour also occur in the root and rhizome. 6). The starch grains are mostly simple, with a few 2 to 3-compound grains, the individual grains are spheridal, ovoid, elliptical, and possess a centric point or clift hilium, measuring up to 17μ in diameter; no distinet polarization and strati- fications are visible. 7). The monoclinic prisms, tabular crystals, clusters, and a number of twin crystals of ealeium oxalate were found in the root and the rhizome measuring up to 43μ long; they are often arranged in longitudinal rows.
The root barks of Aralia mandshurica Rupr. et Maxim. and A. elata (Miq.) Seem. are known as "Ci-Lao-Yia" in the indigenous medicine of northeastern China and have long been used as a general tonic. In this paper the pharmacognostical features of the bark of A. mandshurica are described and illustrated. The drug consists mostly of root bark with a few rootlets attached and some barks of the rhizome and of the lower part of stem are also present. The principal microscopical features of the drug are: (1) the...
The root barks of Aralia mandshurica Rupr. et Maxim. and A. elata (Miq.) Seem. are known as "Ci-Lao-Yia" in the indigenous medicine of northeastern China and have long been used as a general tonic. In this paper the pharmacognostical features of the bark of A. mandshurica are described and illustrated. The drug consists mostly of root bark with a few rootlets attached and some barks of the rhizome and of the lower part of stem are also present. The principal microscopical features of the drug are: (1) the secretory canals arranged in 4 to 11 rings occuring only in the cortex and phloem; (2) the crystal-bearing parenchyma cells occuring more abundantly in the cortex than in the phloem; (3) the pericyclic fibres are found only in the barks of rhizome and stem, other sclerenchymatous cells are absent; (4) the crystals mostly in clusters measuring about 20 to 56μ in diameter; (5) the starch grains mostly simple with a few 2 to 4-compound grains measuring about 2 to 9μ in diameter; (6) the rays being 1 to 6 cells wide filled with starch grains and amorphous resin-like substance. Fluorescent analysis and chemical tests have been made. The percentage contents of the water, total ashes, water and alcohol extractives of the drug have also been determined.
pericyclic
周环
查询“pericyclic”译词为用户自定义的双语例句
相关查询
2008 CNKI－中国知网