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An endemic brackish water faunule consisting of three taxa of bivalves,Hudsonella sinensis (Chen) n. gen.,Hudsonella sp., andProtocardia hepingxiangensis Chen & Lin occurs in the Bajocian of the southern Qinghai province, China.Hudsonella sinensis is a very variable species with a hinge structure characteristic of the subfamily Pachydontinae of the family Corbulidae. According to both geochemical data (stable carbon isotopes and the strontium/barium ratio) and ecological data the faunule lived in a brackish water embayment of mesohaline salinity (5#x2013;18 per mil) burrowing in soft substrate. 相似文献
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将四组豚鼠在125dBSPL,1KHz强声中暴露3小时。一组动物于声暴露前后吸空气作为对照组。其余三组动物吸2ATA高压氧(HBO),每次30分钟。其中于声暴露前吸1次者为预防组;于声暴露后连续吸14天次者为治疗组;于声暴露前吸1次,声后吸14天次者为HBO防治组。声暴露后,各组动物短声诱发皮层听区电位听阈上升。对照组听力损失最重,达70dB;预防组和防治组仅损失53dB和51dB(同对照组比P<0.01);治疗组损失68.5dB。短纯音测昕结果与此类似。对照组耳蜗病理损伤长度平均为527μm;预防组和防治组分别为142μm和106μm(P<0.05);治疗组为295μm。由此可以认为HBO对声损伤具有显著的预防作用。 文中讨论了高压氧的预防机理及其治疗作用 相似文献
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瓜子金皂甙丙和丁的化学结构研究 总被引:1,自引:0,他引:1
自草药瓜子金(Polygala japonica Houtt)地上部分又分离得到两种皂甙,即瓜子金皂甙丙和皂甙丁,它们的分子式均为 C_(42)H_(68)O_(15),为同分异构物。两者酸水解均得瓜子金皂甙元和 D-葡萄糖,但碱水解时,只有皂甙丁可被水解,产物和酸水解相同。经~1HNMR,~(13)CNMR,MS 推定它们的结构式,瓜子金皂甙丙为3-O-[β-D-葡萄吡喃糖(1→2)-β-D-葡萄吡喃糖]瓜子金皂甙元;而瓜子金皂甙丁为28-O-[β-D-葡萄吡喃糖(1→2)-β-D-葡萄吡喃糖]瓜子金皂甙元。上述两种皂甙均为新化合物。 相似文献
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We have constructed a luc reporter vector for Dictyostelium discoideum using a 626-bp fragment from the nuclear-associated plasmid Ddp2. The ori from Ddp2 is localized within this fragment and was used to provide an autonomous replication sequence for the reporter vector. This reporter vector was stably retained in D. discoideum AX3K cells without alteration. The vector molecule was also found to exist in relatively low copy number compared to other Dictyostelium vectors in the transformed cells. We demonstrated the utility of this vector as a reporter vector with glycogen synthase promoter/luc fusions of varying sizes. 相似文献
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While the majority of sympathetic neurons are noradrenergic, a minority population are cholinergic. At least one population of cholinergic sympathetic neurons arises during development by a target-dependent conversion from an initial noradrenergic phenotype. Evidence for retrograde specification has been obtained from transplantation studies in which sympathetic neurons that normally express a noradrenergic phenotype throughout life were induced to innervate sweat glands, a target normally innervated by cholinergic sympathetic neurons. This was accomplished by transplanting footpad skin containing sweat gland primordia from early postnatal donor rats to the hairy skin region of host rats. The sympathetic neurons innervating the novel target decreased their expression of noradrenergif traints and developed choline acetyltransferase (ChAT) activity. In addition, many sweat gland-associated fibers acquired acetylcholinesterase (AChE) staining and VIP immunoreactivity. These studies indicated that sympathetic neurons in vivo alter their neurotransmitter phenotype in response to novel envronmental signals and that sweat glands play a critical role in the cholinergic and peptidergic differentiation of the sympathetic neurons that innervate them. The sweat gland-derived cholinergic differentiation factor is distinct from leukemia inhibitory factor and ciliary neurotrophic factor, two well-characterized cytokines that alter the neurotransmitter properties of cultured sympathetic neurons in a similar fashion. Recent studies indicate that anterograde signalling is also important for the establishment of functional synapses in this system. We have found that the production of cholinergic differentiation activity by sweat glands required sympathetic innervation, and the acquisition and maintenance of secretory competence by sweat glands depends upon functional cholinergic innervation. 1994 John Wiley & Sons, Inc. 相似文献
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报道了我国园蛛科7新种,即:云南园蛛Araneus yunnanensis、景洪金蛛Argiopejing hongensis、长垂驼蛛Cyphalonolus elongalus、石门壮头蛛Chorizopes shimenensis、勐海曲腹蛛Cyrlarachne menghaiensis 、文山肥蛛Larinia wenshanensis 和十字亮腹蛛Singa cruciformis。 相似文献
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渗透胁迫对高粱根K~+吸收的影响 总被引:4,自引:0,他引:4
以CaSO40.5mmolL-1溶液培养高粱得到低钾植株,在渗透胁迫下当PEG-1000使外界渗透势下降时,刺激了高粱根高K+亲和系统的净K+积累,其表观Km值和Tmax值分别为18μmolL-1和49.6μmolg-1DWh-1。此高亲和系统不受可渗物质乙二醇和外界pH变化的影响,为蛋白质合成抑制剂环己酰亚胺抑制。 相似文献
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