共查询到20条相似文献,搜索用时 109 毫秒
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IxchelN.Whitcher 《武汉植物学研究》1998,(4)
据报道,维西榛(Coryluswangii)仅分布在云南西北部。我们鉴定了中国科学院植牧研究所标本馆(PE)的标本,发现了该种在四川东部的新分布。该种与Corylusjacquemon-tii在形态学和分子水平上存在间断性。 相似文献
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四川分布的中国种子植物特有科属研究 总被引:9,自引:2,他引:7
对传统“特有”概念作了补充说明,确认四川有中国种子植物特有类群129属,12个特有科,在国产特有类群中占有较大比例。生活型虽然以草本为主,但高比例(近1/3)的木本类型以及木本类型多为原始的古特有成分却反映出植物区系的古老性和悠久发展历史。地理分布以盆地四周山地最丰富,西部高原和盆地中部缺乏或少有特有科、属。总体上可划分为3个分布中心区,包括西南区、东南区和东北区。新特有成分以西南区较多,而古特有成分大多集中中东南区和东北区。特有属与邻近地区的相似性还反映了四川植物区系和邻近地区植物区系的整体性。丰富的特有科、属同时也反映出四川种子植物区系的多样性。 相似文献
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据报道,维西榛(Corylus wangii)仅分布在云南西北部。我们鉴定了中国科学院植牧研究所标本馆(PE)的标本,发现了该种在四川东部的新分布。该种与Corylus jacquemon-tii在形态学和分子水平上存在间断性。 相似文献
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金叶子属分类、分布与演化趋势的研究 总被引:1,自引:0,他引:1
<正> 金叶子属(Craibiodendron W.W.Shmith)是杜鹃花科中的一个小属,含6种,分布于亚洲东南部,其现代分布中心在我国的云南南部。在杜鹃花科中,金叶子属与米饭花属(Lyonia Nutt.)、马醉木属(Pieris D.Don)有密切的关系。作者在完成(中国植物志)、(云南植物志)、(西藏植物志)该属工作过程中,查阅了近500号本属植物标本,并对分布于云南境内的本属植物进行了野外考察,认为有必要对本属的分类、分布及演化趋势进行讨论。现将研究心得发表如下。 相似文献
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中国四川阳蝇属五新种(双翅目:蝇科) 总被引:1,自引:0,他引:1
报告采自四川西部山区的蝇科阳蝇属HelinaR.-D.五新种,即:亚喜密阳蝇Helina subevecta sp.nov,阳阳蝇Helina solata sp.nov,用公山阳蝇Helina zhougongshanna sp.nov,康定阳蝇Helina kangdingen-sis sp.nov和赘脉阳蝇Helina appendicivena sp.nov。模式标本保存于中国军事医学科学院微生物流行病研究所医学昆虫标本馆。 相似文献
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The effects of python neuropeptide gamma (NPgamma) on hemodynamic parameters have been investigated in the anesthetized ball python (Python regius). Bolus intra-arterial injections of synthetic python NPgamma (1-300 pmol kg-1) produced a dose-dependent decrease in systemic arterial blood pressure (Psys) concomitant with increases in systemic vascular conductance (Gsys), total cardiac output and stroke volume, but only minor effects on heart rate. The peptide had no significant effect on pulmonary arterial blood pressure (Ppul) and caused only a small increase in pulmonary conductance (Gpul) at the highest dose. In the systemic circulation, the potency of the NK1 receptor-selective agonist [Sar9,Met(0(2))11] substance P was >100-fold greater than the NK2 receptor-selective agonist [betaAla8] neurokinin A-(4-10)-peptide suggesting that the python cardiovascular system is associated with a receptor that resembles the mammalian NK1 receptor more closely than the NK2 receptor. Administration of the inhibitor of nitric oxide synthesis, L-nitro-arginine-methylester (L-NAME; 150 mg kg-1), resulted in a significant (P<0.05) increase in Psys as well as a decrease in Gsys, but no effect on Ppul and Gpul. Conversely, the nitric oxide donor, sodium nitroprusside (SNP; 60 microg kg-1) produced a significant (P<0.05) decrease in Psys along with an increase in Gsys and pulmonary blood flow. However, neither L-NAME nor indomethacin (10 mg kg-1) reduced the cardiovascular responses to NPgamma. Thus, nitric oxide is involved in regulation of basal vascular tone in the python, but neither nitric oxide nor prostaglandins mediate the vasodilatory action of NPgamma. 相似文献
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Wang T Axelsson M Jensen J Conlon JM 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,279(2):R531-R538
The cardiovascular actions of python bradykinin (BK) and substance P (SP) have been investigated in the anesthetized ball python, Python regius. Bolus intra-arterial injections of python BK (0.03-3 nmol/kg) produced concentration-dependent increases in arterial blood pressure, heart rate (HR), and cardiac output concomitant with small decreases in systemic resistance and stroke volume. Intra-arterial injection of 3 nmol/kg python BK produced a tenfold increase in circulating concentration of norepinephrine, but epinephrine levels did not change. BK-induced tachycardia was attenuated (>90%) by the beta-adrenergic receptor antagonist sotalol, and the hypertensive response was attenuated (>70%) by the alpha-adrenergic receptor antagonist prazosin, indicating that effects of python BK are mediated at least in part by activation of the extensive network of adrenergic neurons present in vascular tissues. Bolus intra-arterial injections of python SP in the range 0. 01-30 pmol/kg produced concentration-dependent decreases in arterial blood pressure and systemic peripheral resistance concomitant with increases in cardiac output and stroke volume but with only minor effects on HR. The data suggest that kinins play a physiologically important role in cardiovascular regulation in the python. 相似文献
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A L Idowu R R Golding B O Ikede D H Hill J H Cunningham S B Akerelle 《Journal of wildlife diseases》1975,11(2):201-204
A massive growth in the lower jaw of an Indian python (Python molurus) was diagnosed from biopsy samples as a fibroma. Moderately satisfactory treatment was achieved by surgical excision. 相似文献
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Kuan Chung-Tian 《植物分类学报:英文版》1981,19(4):393-407
The abundance of Coniferae in Szechuan Province is a well-known fact, especially
of the Order Pinales. There are so far 19 genera 68 species and varieties belonging to
the Pinaceae, Taxodiaceae and Cupressaceae. This paper dealing with the fundamental
features in the distribution of these plant-groups may be not only of scientific interest but also of great importance to forestry.
According to an analysis of the influence of historic, geographic and ecological conditions on the distribution of plants, it is shown that the differantiation of geographical
distribution of genera and species in these 3 familias between the eastern and
the western areas is very evident. There are (Tab. 1) 18 genera and 27 species in the
eastern area, including 6 monotypic genera, they are Cathaya, Pseudolarix, Metosequoia,
Glyptostrobus, Fokienia and Platycladus. As the great concentration of the monotypic
and paleo-endemic genera is not found elsewhere, this area therefore distinctly indicates
the relic nature. It seems most probably that they came originally into existence in subtropical and warm-temperate climates of middle lalitudes in the northern hemisphere,
and most of them are in the lands bordering the Pacific Ocean.
On the other hand, there are 13 genera and 56 species in the western area with
only one monotypic genus (Platycladus) present, and most genera are polytypic with
wide ranges. The number of species in these genera here is larger than in any other
areas, for example, Abies and Picea are represented 12 species each (Fig. 1-4). There
are 10 species in Sabina (Fig. 5). It might be considered that each genus has developed into a great centre, In addition, it has been discussed in detail regarding the
vicarious distributions in geography, verticality, and ecology of ralated species in Abies,
Picea, Tsuga, Keteleeria, Larix, Pinus and Cupressus (Fig. 3-5), as well as the re lationship of these species. As shown above, these plants are also, without doubt, of
very old origin. Moreover, they are most likely very much closely related with Tethys
in the past, but the majority species apparently have arisen in relalively recent times.
They are due to the effect of mountain-making and glaciation, principally in consequence of the cooling process of the climatic vicissitude. 相似文献
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Transferrins play a major role in iron homeostasis and metabolism. In vertebrates, these proteins are synthesised in the liver and dispersed within the organism by the bloodstream. In oviparous vertebrates additional expression is observed in the oviduct and the synthesised protein is deposited in egg white as ovotransferrin. Most research on ovotransferrin has been performed on the chicken protein. There is a limited amount of information on other bird transferrins, and until our previous paper on red-eared turtle protein there was no data on the isolation, sequencing and biochemical properties of reptilian ovotransferrins. Recently our laboratory deposited ten new sequences of reptilian transferrins in the EMBL database. A comparative analysis of these sequences indicates a possibility of different mechanisms of iron release among crocodile and snake transferrin. In the present paper we follow with the purification and analysis of the basic biochemical properties of two crocodile (Crocodilus niloticus, C. rhombifer) and one snake (Python molurus bivittatus) ovotransferrins. The proteins were purified by anion exchange and hydrophobic chromatography, and their N-terminal amino-acid sequences, molecular mass and isoelectric points were determined. All three proteins are glycosylated and their N-glycan chromatographic profiles show the largest contribution of neutral oligosaccharides in crocodile and disialylated glycans in python ovotransferrin. The absorption spectra of iron-saturated transferrins were analysed. Iron release from these proteins is pH-dependent, showing a biphasic character in crocodile ovotransferrins and a monophasic type in the python protein. The reason for the different types of iron release is discussed. 相似文献
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Ontogenetic colour change is typically associated with changes in size, vulnerability or habitat, but assessment of its functional significance requires quantification of the colour signals from the receivers' perspective. The tropical python, Morelia viridis, is an ideal species to establish the functional significance of ontogenetic colour change. Neonates hatch either yellow or red and both the morphs change to green with age. Here, we show that colour change from red or yellow to green provides camouflage from visually oriented avian predators in the different habitats used by juveniles and adults. This reflects changes in foraging behaviour and vulnerability as individuals mature and provides a rare demonstration of the adaptive value of ontogenetic colour change. 相似文献