Definition:中央孔zhōng yāng kǒng在顆石的中央?yún)^(qū),大部分類型有一個空洞。central: in,near,or forming the middle of something中心的zhōng xīn deopening: vacancy空缺kòng quē...[繼續(xù)閱讀]

    Definition:An order of extinct fishes in the class acanthodii having scales of acellular boneand dentine,one dorsal fin,and no teeth.棘魚目jí yú mù棘魚類中最晚出現(xiàn)并最晚滅絕的種類,早泥盆世至早二疊世。沒有牙齒或肩帶腹面的膜質(zhì)板,僅具一個背鰭,具棘魚型...[繼續(xù)閱讀]

    Definition:The common name for four extinct classes of primitive echinoderms that have aflattened theca or body lacking radial symmetry. These enigmatic fossils were originallyclassified together in the class Carpoidea,but more recent echinoderm researche...[繼續(xù)閱讀]

    Definition:Any of a group (genus Aepyornis or order Aepyornithiformes)of giganticflightless ratite birds known only from remains found in Madagascar.象鳥 xiàng niǎo 生活于馬達加斯加第四紀(jì)的巨型植食性平胸鳥類,翼退化,無飛行能力。至少在16世紀(jì)以前已滅絕。Origi...[繼續(xù)閱讀]

    Definition:The midsection of a long bone;diaphysis.錨干máo gàn錨形骨片的組成部分,指錨臂與柄端之間的干狀部分。Origin:From Old English sceaft....[繼續(xù)閱讀]

    Definition:一級隔壁yī jí gé bì發(fā)生在次級隔膜內(nèi)腔中的隔壁,常與原生隔壁等長。major: greater than others in importance or rank主要的z hǔ yào deseptum: a thin partition or membrane that divides two cavities or soft masses of tissue in anorganism隔壁gé bì...[繼續(xù)閱讀]

    Definition: In population genetics,the founder effect is the loss of genetic variation thatoccurs when a new population is established by a very small number of individuals from a largerpopulation. It was first fully outlined by Ernst Mayr in 1952,using e...[繼續(xù)閱讀]

    Definition:The vein which often has cross-connections that form closed “cells”in themembrane.縱脈zòng mài從翅基部伸向翅邊緣的脈。...[繼續(xù)閱讀]

    Definition:側(cè)部cè bù中間板表面的部分,在兩側(cè)呈三角形。lateral:situated on one side or other of the body or of an organ,especially in the region furthestfrom the median plane外側(cè)的wài cè deExample:Cheek is the whole of the lateral area below and posterior to the eyes on each si...[繼續(xù)閱讀]

    Definition:Having a single whorl,as certain flowers and the shells of certain invertebrates.單環(huán)式dān huán shìOrigin:International Scientific VocabularyExample:This toxin is a class of monocyclic heptapeptides with many different isomerides.該毒素是一類具有多種異構(gòu)體的環(huán)狀多...[繼續(xù)閱讀]