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(单词翻译:双击或拖选)
Fatty acids - long straight chains of carbon and hydrogen ending with an acid group at one end. Saturated1 fatty acids have no capacity to absorb more hydrogen atoms. Animal fats are mostly of this type and are considered less healthy as they end to accumulate in the linings2 of arteries3.
Feedback - a system of control, where work being done is modified by the product. For example the blood pressure is maintained by the strength of the heart beat and the muscle tone of the arterioles. In the walls of the large arteries are receptors sensitive to the degree of stretch in the muscle wall. As the blood pressure increases, the wall are stretched, and the receptor sends signals via the brain to the sympathetic nervous system back to the heart and blood vessels5, causing decreased pumping effort and more relaxed muscle tone in the arteries. In chemical reactions the accumulated product slows down the rate of production. For example if the oxygen level of the body falls, the rate of respiration6.increases to restore the levels to normal. These control system are thus circular; what is produced returns to control the further production. They are examples of negative feedback, and are common in maintaining stability or homeostasis. Positive feedback is less common as it tends to be unstable7. An example is the release by platelets of thrompotaxin. When the levels of thrombotaxin are high, they do not inhibit8 further production as occurs in a negative feedback system but actually stimulate9 more platelets to produce more thrombotaxin and so on until there is an explosive increase in the number of sticky platelets. This is useful in an emergency to s bleeding, but very dangerous when a clot10 forms inside a blood vessel4.
Fibre - a long thin string-like structure constructed of smaller fibrils and even smaller microfibrils. Examples are collagen, elastic11 and keratin fibres. Collagen fibres are arranged parallel to each other in a tendon, to give it great resistance to tension (pulling).
Fibrinogen - a large soluble12 protein found in blood which is converted into fibrin during blood clotting13.
Fibroblasts - cell of connective tissue which form both the intercellular matrix and fibres.
Fibronectin - a glycoprotein which is found in the extracellular matrix and is important for the attachments14, and therefore the movement of cells.
Filamentous15 - long, thin, hair-like.
Fluorapatite- an apatite crystal in which fluoride has replaced hydroxyl ions.
Fluorosis - mottling of the teeth caused by an excess of fluoride in the drinking water. A fluorosis index recognises 4 stages of severity.
Foramina - the plural16 of foramen, which is a hole, for example Foramen Ovale.
Fossils - dead plant or animal remains17 whichhave become infused with minerals over many millions of years and are now hard and rock -like. The original shape of the animal or plant may be very well preserved.
Fractal dimension - a dimension which is some fraction in between a line(1) and a plane(2), or a plane and a solid (3). These fractal dimensions are useful in describing the quality of natural lines and surfaces, such as coastlines, trees, vascular18 branching and the patterns of trabecula bone
Freeway space - the space between the teeth when the jaw19 is in a rest position.
1 saturated | |
a.饱和的,充满的 | |
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2 linings | |
n.衬里( lining的名词复数 );里子;衬料;组织 | |
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3 arteries | |
n.动脉( artery的名词复数 );干线,要道 | |
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4 vessel | |
n.船舶;容器,器皿;管,导管,血管 | |
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5 vessels | |
n.血管( vessel的名词复数 );船;容器;(具有特殊品质或接受特殊品质的)人 | |
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6 respiration | |
n.呼吸作用;一次呼吸;植物光合作用 | |
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7 unstable | |
adj.不稳定的,易变的 | |
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8 inhibit | |
vt.阻止,妨碍,抑制 | |
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9 stimulate | |
vt.刺激,使兴奋;激励,使…振奋 | |
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10 clot | |
n.凝块;v.使凝成块 | |
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11 elastic | |
n.橡皮圈,松紧带;adj.有弹性的;灵活的 | |
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12 soluble | |
adj.可溶的;可以解决的 | |
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13 clotting | |
v.凝固( clot的现在分词 );烧结 | |
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14 attachments | |
n.(用电子邮件发送的)附件( attachment的名词复数 );附着;连接;附属物 | |
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15 filamentous | |
adj. 细丝状的,如丝的,纤维状的 | |
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16 plural | |
n.复数;复数形式;adj.复数的 | |
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17 remains | |
n.剩余物,残留物;遗体,遗迹 | |
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18 vascular | |
adj.血管的,脉管的 | |
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19 jaw | |
n.颚,颌,说教,流言蜚语;v.喋喋不休,教训 | |
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