Inhabiting the portion of the oceandeeper than 2000 m and shallower than6000 m. The abyssal realm is the largest en-vironment on earth. Abyssal fauna tend to beblack or gray,unstreamlined,and delicatelystructured.栖息于海洋中水平面2 000m以下、6 000m以上的。深海海域是地球上最大...[继续阅读]

    One of anumber of specialized epidermal cells of aplant that are found adjacent to the guardcells,and may help in opening and closing the stomata.位于植物内保卫细胞近旁的特异化的表皮细胞,可协助打开或关闭气孔。...[继续阅读]

    One ofthe pair of nerves that arises from the posteri-or region of the medulla oblongata in thebrain of higher vertebrates. It carries motornerve fibers and merges with the adjacent va-gus nerve close to its root. In fishes and am-phibians it is considere...[继续阅读]

    See photosynthetic pig-ments.参阅626页photosyn-thetic pigments。...[继续阅读]

    1. The reflex process inthe eye by which an image is focused on theretina. In humans,the eye at rest is focusedon infinity,with the lens and cornea flat-tened,To focus on a near object the ciliarymuscles contract,and the lens,being elas-tic,becomes more c...[继续阅读]

    Denoting relatively large tissuesor organisms that are not composed of dis-crete cells and are,in effect,unicellular.Examples are aseptate fungal hyphae andmuscle fibers. The term is used in preferenceto unicellular to distinguish such structures(which ar...[继续阅读]

    Denoting a chromosome or frag-ment of a chromosome that lacks a cen-tromere指缺少着丝粒的染色体或染色体片段。...[继续阅读]

    A cup-shaped socket on eachside of the pelvic girdle in tetrapods thatholds the rounded head of the thigh bone (fe-mur) to form the hip joint. This ball-and-socket arrangement allows for great stabilityand a wide range of movement.四足动物腰带四周的杯状的窝形结构,连接大腿骨(股...[继续阅读]

    A carboxylicacid,CH_3COOH,obtained by the oxidationof ethyl alcohol. Acetic acid is a componentof vinegar (which is obtained by bacterial ox-idation of wine waste).乙醇氧化后形成的一种羧酸 CH_3COOH。乙酸是细菌氧化酿酒废料获得的醋中的一种成分。...[继续阅读]

    Aneurotransmitterfound at the majority of synapses,which oc-cur where one nerve cell meets another.Nerves that produce acetylcholine are calledcholinergic nerves ; they form the parasympa-thetic nervous system and also supply thevoluntary muscles. See neu...[继续阅读]