| 词汇 | alkaloid |
| 释义 | alkaloid noun[ C ] chemistry specializeduk /ˈæl.kə.lɔɪd/ us /ˈæl.kə.lɔɪd/ a type of chemical found in plants that often acts as a drug or poison, or is used in medicines: 生物碱（植物中的化学物质，常用于制药或作为毒物） Morphine and cocaine are powerful alkaloids.吗啡和可卡因是强力的生物碱。 Chemistry: types of chemical acid salt aerogel albumin alkali metal alkaline antioxidant carbohydrate homologous series inorganic isopropanol ketone lectin melamine monosaccharide mothball propellant saline soluble sulphide weak base Examples of alkaloidalkaloid In many leaves, alkaloid concentrations range from 100 to 500 g g-1 fresh weight. Most of the alkaloids and flavonoids are present in the flowers and in the ripe fruits. The administered doses of alkaloid and flavonoid fractions correspond to the proportion of these components in the crude extract used in the experiment. Coffee plants contain alkaloid compounds that discourage herbivory. This equation was also used to quantify consumption of saponins, cyanogenic glycosides and alkaloids. A colour change from white to orange indicates presence of alkaloid or related amines. No differences were detected between lipid-poor and -rich seasons in levels of alkaloids, fibre or saponins. It is not known whether disproportionately higher levels of alkaloids in other tissues, principally the phloem, contribute to this aphid resistance. Table 3 shows the binding capacities of the soils from data set 1 for four alkaloids. However, there is a difference because unexpectedly no changes in enzyme activity of cauda treated with crude and alkaloid extracts were noticeable. The toxin adsorption capacities of soils in the first sample set were determined by capillary gas liquid chromatography using the alkaloids lupanine, sparteine, quinine and atropine. All the ergot alkaloids increase the motor activity of the uterus, by producing persistent contractions in the inner zone of myometrium through a calcium channel mechanism. There were no alkaloids or triterpenes. The crude extract was obtained from plants collected at the beginning of the vegetative cycle, when they contained 0.095 g alkaloids and 1.50 g flavonoids per 100 g dry plant. The working party on naturally occurring toxicants in food has completed its study of pyrrolizidine alkaloids in milk. From the Hansard archive Example from the Hansard archive. Contains Parliamentary information licensed under the Open Parliament Licence v3.0 See all examples of alkaloid These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. |
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