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排序方式: 共有619条查询结果,搜索用时 15 毫秒
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目的研究不同时间间隔经眼眶静脉丛多次采血后,对雄性Wistar大鼠重要脏器系数的影响。方法实验组分别间隔3 d、7 d、10 d,经眼眶静脉丛采血,每次采血1 mL,共采3次。对照组于实验组最后一次采血时采血一次,采血1 mL。每次采血前称量体重,于最后一次采血后将大鼠处死,取心脏、肝脏、肾脏、脾脏、胸腺,称量脏器重量,计算脏器系数。结果间隔3 d多次采血,大鼠的肝、肾系数差异具有显著性(P〈0.05),间隔7 d、10 d多次采血,大鼠的各脏器系数差异无显著性。结论间隔3 d多次采血对大鼠的肝、肾系数有影响,间隔7 d、10 d多次采血对各脏器系数均无影响。 相似文献
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Advances in sequencing technology have led to a sharp decrease in the cost of ''data generation''. But is this sufficient to ensure cost-effective and efficient ''knowledge generation''? 相似文献
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In the genus Petunia, distinct pollination syndromes may have evolved in association with bee-visitation (P. integrifolia spp.) or hawk moth-visitation (P. axillaris spp). We investigated the extent of congruence between floral fragrance and olfactory perception of the hawk moth Manduca sexta. Hawk moth pollinated P. axillaris releases high levels of several compounds compared to the bee-pollinated P. integrifolia that releases benzaldehyde almost exclusively. The three dominating compounds in P. axillaris were benzaldehyde, benzyl alcohol and methyl benzoate. In P. axillaris, benzenoids showed a circadian rhythm with an emission peak at night, which was absent from P. integrifolia. These characters were highly conserved among different P. axillaris subspecies and P. axillaris accessions, with some differences in fragrance composition. Electroantennogram (EAG) recordings using flower-blends of different wild Petunia species on female M. sexta antennae showed that P. axillaris odours elicited stronger responses than P. integrifolia odours. EAG responses were highest to the three dominating compounds in the P. axillaris flower odours. Further, EAG responses to odour-samples collected from P. axillaris flowers confirmed that odours collected at night evoked stronger responses from M. sexta than odours collected during the day. These results show that timing of odour emissions by P. axillaris is in tune with nocturnal hawk moth activity and that flower-volatile composition is adapted to the antennal perception of these pollinators. 相似文献
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Dauter Z 《Progress in biophysics and molecular biology》2005,89(2):153-172
In recent years, number of X-ray synchrotron beam lines dedicated to collecting diffraction data from macromolecular crystals has exceeded 50. Indeed, today most protein and nucleic acid crystal structures are solved and refined based on the synchrotron data. Collecting diffraction data on a synchrotron beam line involves many technical points, but it is not a mere technicality. Even though the available hardware and software have become more advanced and user-friendly, it is always beneficial if the experimenter is aware of the problems involved in the data collection process and can make informed decisions leading to the highest possible quality of the acquired diffraction data. Various factors, important for the success of data collection experiments and their relevance for different kinds of applications, are discussed. 相似文献
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Sfanos K Harmody D Dang P Ledger A Pomponi S McCarthy P Lopez J 《Systematic and applied microbiology》2005,28(3):242-264
A taxonomic survey was conducted to determine the microbial diversity held within the Harbor Branch Oceanographic Marine Microbial Culture Collection (HBMMCC). The collection consists of approximately 17,000 microbial isolates, with 11,000 from a depth of greater than 150 ft seawater. A total of 2273 heterotrophic bacterial isolates were inventoried using the DNA fingerprinting technique amplified rDNA restriction analysis on approximately 750-800 base pairs (bp) encompassing hypervariable regions in the 5' portion of the small subunit (SSU) 16S rRNA gene. Restriction fragment length polymorphism patterns obtained from restriction digests with RsaI, HaeIII, and HhaI were used to infer taxonomic similarity. SSU 16S rDNA fragments were sequenced from a total of 356 isolates for more definitive taxonomic analysis. Sequence results show that this subset of the HBMMCC contains 224 different phylotypes from six major bacterial clades (Proteobacteria (Alpha, Beta, Gamma), Cytophaga, Flavobacteria, and Bacteroides (CFB), Gram + high GC content, Gram + low GC content). The 2273 microorganisms surveyed encompass 834 alpha-Proteobacteria (representing 60 different phylotypes), 25 beta-Proteobacteria (3 phylotypes), 767 gamma-Proteobacteria (77 phylotypes), 122 CFB (17 phylotypes), 327 Gram + high GC content (43 phylotypes), and 198 Gram + low GC content isolates (24 phylotypes). Notably, 11 phylotypes were < or =93% similar to the closest sequence match in the GenBank database even after sequencing a larger portion of the 16S rRNA gene (approximately 1400 bp), indicating the likely discovery of novel microbial taxa. Furthermore, previously reported "uncultured" microbes, such as sponge-specific isolates, are part of the HBMMCC. The results of this research will be available online as a searchable taxonomic database (www.hboi.edu/dbmr/dbmr_hbmmd.html). 相似文献
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Frank D. Steinheimer 《Journal of Ornithology》2004,145(4):300-320
This paper analyses Charles Darwins bird collection and the ornithological knowledge he derived from it during the voyage of H.M.S. Beagle. Darwin collected 468 bird skins, 10 detached parts of the lesser rhea, and the nests and eggs of 16 different taxa as well as 14 whole birds and 4 parts of birds which he preserved in spirit. He labelled these specimens with a number tag only, cross-referring the number to a notebook entry. Partly because of his limited ornithological knowledge and partly because he was confronted at times with entirely unknown birds, Darwin was often unable to apply the correct generic designations and gave his South American specimens English and Spanish names from literature and the local tongues, as well as the scientific generic names of European birds. Back home, it was John Gould, the prominent ornithologist of the Zoological Society of London, who made sense of Darwins collection, among his many other scientific achievements correctly identifying the Galápagos finches as a group of closely related birds. Darwins bird collection did not receive much attention in the latter part of the 19th century. Most of the specimens had their original labels removed and replaced by ones of the custodian institution. Today, original Darwin specimens stemming from the Beagle voyage are to be found in at least eight different institutions, but almost half of the bird specimens Darwin collected on the Beagle voyage are not accounted for. The appendix to this paper lists for the first time all the birds which Darwin collected during the voyage. Darwins famous book On the origin of species hardly draws upon any ornithological examples from his voyage on the Beagle. Nevertheless, Darwin contributed much to ornithology. His collection contained 39 new species and subspecies of birds, mainly described by Gould, and some birds from populations now extinct, and he also made a few very good field observations, published in the sections of The Zoology of the Voyage of H.M.S. Beagle dedicated to birds.
相似文献
Frank D. SteinheimerSylter Strasse 18, 90425 Nuremberg, GermanyEmail: Phone: +49-30-20938512Fax: +49-30-20938528 |
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夜间收集趋光性昆虫的方法 总被引:3,自引:1,他引:2
在昆虫种类和多样性调查时,需要简便快捷地收集昆虫标本,尤其要保证其完整性。为此目的现介绍1种收集灯下趋光性昆虫的方法。在收集桶内的底部放上1cm厚的泡沫塑料,滴入乙酸乙酯到泡沫塑料上吸附适量即可。在收集桶口蒙盖1块白布,用手压白布的中心至桶底部药液上方2~3cm处,并把露在桶外部的白布用皮筋勒紧在桶的外壁上,使桶中的白布不能自由升降。然后把收集桶与引诱装置结合,趋光性昆虫一旦落入桶中的白布里,就会被乙酸乙酯熏醉,渐渐行动力减弱,直至醉死。该方法相对于以往方法,收集到的昆虫标本完整度高、可利用性好,并且操作过程的安全性、效率性、简便性、经济性等方面都有所改进。 相似文献