什麼是南猿屬
已滅絕的一屬人類,從上新世(約始於530萬年前)早期到更新世(約180萬年前)之初居住於非洲地區。大部分古人類學家相信南猿屬是現代人類的祖先。南猿與早期類人猿的區別在於體態直立和靠雙腳行走。他們的腦容量相當小,與現存類人猿差距不大,但他們的牙齒比較接近人類。人類學家依體型把南猿區分為二︰體型較小、較輕或所謂「纖細」型的阿法南猿(A. afarensis,375萬年前)和非洲南猿(A. africanus, 200~300萬年前);演化後較重、較「粗壯」型的粗壯南猿(A. robustus, 100~200萬年前)和鮑氏南猿(A. boisei, 175萬年前)。一般認為,粗壯南猿和鮑氏南猿從纖細型人種演化而來,最後因無演化的後繼者而滅絕。我們不清楚哪種纖細型南猿使人屬興起,雖然證據顯示是阿法南猿。亦請參閱Hadar remains、human evolution、Lucy、Olduvai Gorge、Sterkfontein。
Australopithecus
(“southern ape”) Genus of extinct hominids that lived in southern and eastern Africa from the early Pliocene Epoch (beginning c. 5.3 million years ago) to the beginning of the Pleistocene (c. 1.8 million years ago). It is believed to be ancestral to modern human beings. The australopithecines were distinguished from the apes by their upright posture and bipedal gait. Their brains were small, not very different from those of living apes, but their teeth were more human than apelike. Three species of gracile australopithecines, A. anamensis (4.2 million years ago), A. afarensis (3.75 million years ago) and A. africanus (3 million-2 million years ago), and two species of robust australopithecines, A. robustus (2 million-1 million years ago) and A. boisei (1.75 million years ago), have been identified. Both robust species apparently evolved from the gracile species and eventually became extinct without evolutionary successors. It is not known which gracile species gave rise to the genus Homo, though the evidence suggests it was the earlier A. afarensis. See also Hadar remains, human evolution, Laetoli footprints, Lucy, Olduvai Gorge, Sterkfontein.
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什麼是農業中毒
農業、林業、牧業、漁業與養殖業生產過程中,接觸有毒化學物質引起的中毒。農業從業人員接觸各種有毒化學物質的機會較多,因此容易中毒。中毒有急、慢性,嚴重的中毒可導致死亡。有些毒物還可以引起腫瘤或子代畸形。在生產過程中,加強安全防護措施,能夠有效地防止農業...
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什麼是浸潤
組織內侵入了異常的細胞或出現了正常情況下不應出現的機體細胞,以及某些病變組織向周圍擴充套件的現象。在細胞內或間質中出現異常的物質、或原有的某些物質的堆積過多也稱為浸潤。有的變性或沉積也稱為浸潤。浸潤大多為病理性的,但有時是為了治療目的而人為的。它們...
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什麼是羊水
充滿羊膜腔位於胎體周圍的液體。隨著妊娠時期的不同,其來源、容量與組成亦有變化。妊娠早期羊水主要是由母體血漿通過胎膜進入羊膜腔的漏出液,澄清透明。妊娠中期起,胎兒尿液可能成為羊水的重要來源,此時羊水略混濁,並有白色小片狀物質(脫落的毳毛、面板細胞、胎脂)懸...
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什麼是六淫
自然界風、寒、暑、溼、燥、火六種致病因素的合稱。“淫”有太過之意。風、寒、暑、溼、燥、火本指自然界六種不同的氣候或環境狀態,合稱六氣。若六氣太過、不及或與季節時間不符,超過人體所能適應的限度,則成為致病因素,這種情況下的六氣即成為六淫,或稱六邪。六淫...