174 resultados para 366.225


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Rapid eye movement (REM) is one of the most characteristic features of REM sleep, but the mechanisms underlying its regulation remain unclear. The present study aims to investigate whether the frontal eye field (FEF) is involved in the regulation of the r

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白马蝠蛾雌性生殖系统与鳞翅目其他昆虫不同: 无粘液腺器官; 成虫产卵行为特殊, 卵散产, 产后有用尾和足扫土盖卵的习性; 成虫交配授精以精包方式进行。交配除提供雌蛾精子外, 还能刺激产卵。最适宜成虫交配与产卵的温度为12.5—19.0℃, 相对湿度75—90%。图2表3参5

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记述采自广西西江水系河池地区的条鳅亚科鱼类二新种。后鳍岭鳅。(Oreonetes retrodorsalis) sp. nov与同属种的区别主要表现在其背鳍起点的位置较后, 背鳍和臀鳍分枝鳍条数目较少、尾鳍后缘凹入、头较小和尾柄较短等方面; 南丹高原鳅(Triplophysa nandanensis) sp. nov.则以头较大、吻较短、眼间距较狭、尾柄较短且高、背鳍分枝鳍条较多、尾鳍深叉形等易于与相近种相区别。

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Bamboo bats are a group of small bats with unique skull and morphology. They roost inside hollow bamboo stems in tropical and subtropical Asia and the Ambon Islands (Moluccas). We examined 53 specimens of Tylonycteris from southern and southwestern China. Comparisons of skull and external characteristics, pelage color, shapes of thumbpads and footpads, and statistical analysis of cranial measurements revealed that specimens from Damenglong, Jinghong County, Xishuang-banna, Yunnan, are distinctly different from the other two species of Tylonycteris described so far. The Yunnan specimens are the smallest in size; have dark blackish brown pelage color; and have larger upper premolars, smaller first lower premolars, and longer C-M-3. They are sympatric with the previously described species. Here we review the genus Tylonycteri and describe a new species, Tylonycteris pygmaeus, from the Yunnan material.

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水蛇亚科属于游蛇科,包含10个属。其中7个属为单型属。选取水蛇亚科14个形态学特征进行支序分析,并利用计算机软件Hennig86对水蛇亚科中8个属之间的系统发育关系进行初步探讨,结果显示水蛇亚科分为两支Gerarda和Fordonia两个属构成姊妹群,Cerberus、Erpeton和Homalopsis三个属也构成单系群,与Vorisetal(2002)的分子系统树相同,但Cantoria属的地位则与Vorisetal(2002)的明显不同。

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灵长类大脑前额皮质与感觉联合皮质和皮质下结构有广泛的纤维联系, 可广 泛接受来自体内外的感觉信息。前额皮质与注意和短时记忆过程都有关, 可能 主沟区与短时空间记忆的关系更为密切, 北区的去甲肾上腺素能系统参与短时记 忆过程, alpha-2Ⅰ去甲肾上腺素亚型受体与增强记忆有关。参23

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对68个外显子-内含子-外显子序列片段以及相应的外显子-外显子序列片段的二级结构进行分析后发现,内含子5^端和3^端的碱基G(剪接位点)中大约90%位于二级结构的环区或是茎区的端部并靠近环,而且位于环区的G也多靠近环的基部;92%的外显子拼接位点也有类似性质。约82%的分枝点A位于环区或环与茎的连接部位。折叠结构的形成使剪接位点和分枝点在空间上彼此靠近。

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1996年11月至1997年6月, 于雅砻江下游干流及其支流鳡鱼河中采获一批白鱼属 Anabarilius 鱼类标本, 经鉴定为西昌白鱼1新亚种。 命名为西昌白鱼雅砻亚种 Anabariliusliuiyalongensissubsp. nov. 与其它3个亚种的主要鉴别特征是: 第1鳃弓外侧鳃耙为7~10, 其余3个亚种分别为: 西昌指名亚种 A. liuiliui 为12~14, 程海亚种 A. liuichenghaiensis 15~16, 宜良亚种 A. liuiyiliangensis 10~12. 种内亚种分化主要是受到同域生态隔离和地理隔离作用的影响。

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A number of acrosome reaction (AR) initiators have been found to be effective in inducing AR of human, laboratory and domestic animal sperm. Using an improved simple fluorescence microscopy, effects of gamma-aminobutyric acid (GABA), progesterone and ionophore A23187 on sperm AR of tree shrew, a useful animal model in biomedical research, have been investigated. Spontaneous AR in 4.92-7.53% of viable sperm was observed. Complete AR in 10.31-18.25% of viable tree shrew sperm was obviously induced by 5 mu M and 10 mu M calcium ionophore A23187, 1 mM GABA, and 5 mu M progesterone, and there were no significant differences between their abilities to initiate complete AR. No significant differences of AR percentages between 1- and 2-h treatments with A23187, progesterone and/or GABA were observed. These results suggested that the responses of tree shrew sperm to these AR initiators are similar to that of human and other mammalian sperm. (C) 1997 Elsevier Science B.V.