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991.
R. C. Roverud E. R. Rabitoy 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,174(5):567-573
Big brown bats, Eptesicus fuscus, were presented with artificial frequency modulated (FM) echoes that simulated an object becoming progressively closer to the bat. A stereotyped approach phase behavioral response of the bat to the virtual approaching target was used to determine the ability of the bat to analyze FM signals for target distance information. The degree to which the bats responded with approach phase behavior to a virtual approaching target was similar when they were presented with either a naturally structured artificial FM echo or an artificial FM echo constructed from a series of brief pure tone steps. The ability of the bats to respond to an FM signal structured from a sequence of pure tone elements depended on the number of pure tone steps in the series; the bats required the presentation of tone-step FM signals containing about 83 or greater pure tone elements. Moreover, the duration of the individual tone steps of the tone-step FM signals could not exceed a specific upper limit of about 0.05 ms. Finally, it appears that the bats were able to independently resolve individual tone steps within the tone-step FM signals that were separated by about 450 Hz or more.Abbreviations CF
constant frequency
- FM
frequency modulation 相似文献
992.
从中国发病鸡中分离的鸡减蛋综合征病毒(EggDropSyndromVirus,EDSV)弱毒株(AA-2),其基因组全长约为33kb。用限制性内切酶HindⅢ水解EDSV全基因组,构建了以pBluescriptⅡ(KS+)为载体的右末端片段的克隆(约4.2kb),对其进行了序列测定和结构分析。该片段全长4183个碱基对(bp),位于基因组右末端87.3m.u.-100m.u.。结果显示,该片段与哺乳动物腺病毒右末端E4区结构不同,与禽Ⅰ型腺病毒代表株CELO右末端片段亦无同源性。本文为深入了解EDSV基因组结构特点,EDSV与其他腺病毒基因结构与功能的进化关系和EDSV载体的构建奠定了分子生物学基础 相似文献
993.
Membranes of adjacent cells form intercellular junctional complexes to mechanically anchor neighbour cells (anchoring junctions), to seal the paracellular space and to prevent diffusion of integral proteins within the plasma membrane (tight junctions) and to allow cell-to-cell diffusion of small ions and molecules (gap junctions). These different types of specialised plasma membrane microdomains, sharing common adaptor molecules, particularly zonula occludens proteins, frequently present intermingled relationships where the different proteins co-assemble into macromolecular complexes and their expressions are co-ordinately regulated. Proteins forming gap junction channels (connexins, particularly) and proteins fulfilling cell attachment or forming tight junction strands mutually influence expression and functions of one another. 相似文献
994.
995.
Yuzuru Hamada Toshifumi Udono Migaku Teramoto Ikuo Hayasaka 《Primates; journal of primatology》1998,39(2):157-169
Skeletal developmental of chimpanzees was studied cross-sectionally. By application of the TW2 method, we described the skeletal
development of chimpanzees and compared their skeletal development with humans'. A development pattern of chimpanzees repeated
accelerations and decelerations displaying “early-juvenile trough,” “pre-adolescent peak,” “mid-adolescent trough,” and “post-adolescent
peak” in incremental curves. Sex differences in skeletal development are slower development in males during infant and early
juvenile phases, and greater increment around the adolescent phase in males. Females are fully mature at younger ages than
males, e.g. about one and a half years. In comparison with chimpanzees, humans have such characteristics as a longer slower
period of juvenile development and a shorter spurt-like adolescent fast period which ends with full maturity. 相似文献
996.
997.
Estimating the uptake of traffic-derived NO2 from 15N abundance in Norway spruce needles 总被引:1,自引:0,他引:1
The 15N ratio of nitrogen oxides (NOx) emitted from vehicles, measured in the air adjacent to a highway in the Swiss Middle Land, was very high [δ15N(NO2) = +5.7‰]. This high 15N abundance was used to estimate long-term NO2 dry deposition into a forest ecosystem by measuring δ15N in the needles and the soil of potted and autochthonous spruce trees [Picea abies (L.) Karst] exposed to NO2 in a transect orthogonal to the highway. δ15N in the current-year needles of potted trees was 2.0‰ higher than that of the control after 4 months of exposure close to
the highway, suggesting a 25% contribution to the N-nutrition of these needles. Needle fall into the pots was prevented by
grids placed above the soil, while the continuous decomposition of needle litter below the autochthonous trees over previous
years has increased δ15N values in the soil, resulting in parallel gradients of δ15N in soil and needles with distance from the highway. Estimates of NO2 uptake into needles obtained from the δ15N data were significantly correlated with the inputs calculated with a shoot gas exchange model based on a parameterisation
widely used in deposition modelling. Therefore, we provide an indication of estimated N inputs to forest ecosystems via dry
deposition of NO2 at the receptor level under field conditions.
Received: 7 November 1997 / Accepted: 16 September 1998 相似文献
998.
Daxu Li Jie Zhang Jian Zhao Yi Zhang Fei Chen Jingqiu Zhu Shujun Liu Zhirong Yang 《Plant Cell, Tissue and Organ Culture》2006,84(3):285-292
The mature seeds, mesocotyls, and young leaf tips of Elymus sibiricus L. cv. ‘chuancao No. 2’ were cultured on Murashige and Skoog (MS) medium supplemented with 5.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-d) and 0.05 mg/L kinetin in the dark at 26°C, the calluses were produced. The rate of callus regeneration depended on the explants
source and plant growth regulators. Plants regenerated from whitish-yellow-coloured compact nodular callus formed after subculturing
for 8 weeks. Higher frequency (54%) of shoot differentiation was obtained from the embryo tissues of mature seed than from
either mesocotyls (24%) or young leaf tip tissues (6%) when these calluses from different types of explants were cultured
on plant regeneration medium containing half strength MS salts supplemented with 0.1 mg/L kinetin, 1.5 mg/L 2,4-D and 20 g/L sucrose. The green plants were rooted within 6 weeks in the root regeneration medium, and over 97% of these soil-established
plants were obtained in the greenhouse when potted in a sand and peat mixture medium. 相似文献
999.
In this study, the role of Toll‐like receptor 2 (TLR2) in immune responses of murine peritoneal mesothelial cells against Bacteroides fragilis was investigated. Enzyme linked immunosorbent assay was used to measure cytokines and chemokines. Activation of nuclear factor κB (NF‐κB‐α) and mitogen‐activated protein kinases (MAP kinases) was investigated by western blot analysis. B. fragilis induced production of interleukin‐6, chemokine (C‐X‐C motif) ligand 1 (CXCL1) and chemokine (C‐C motif) ligand 2 (CCL2) in wild type peritoneal mesothelial cells; this was impaired in TLR2‐deficient cells. In addition, in response to B. fragilis, phosphorylation of inhibitory NF‐κB‐α and c‐Jun N‐terminal kinase mitogen‐activated protein kinase (MAPK) was induced in wild type mesothelial cells, but not in TLR2‐deficient cells,. Inhibitor assay revealed that NF‐κB and MAPKs are essential for B. fragilis‐induced production of CXCL1 and CCL2 in mesothelial cells. These findings suggest that TLR2 mediates immune responses in peritoneal mesothelial cells in response to B. fragilis. 相似文献
1000.
水牛精子蛋白质组双向电泳体系的建立和优化 总被引:1,自引:0,他引:1
建立和优化一种适合水牛精子蛋白质组学研究的双向电泳技术。以水牛精子为研究对象,比较两种不同配方的裂解液,以及不同上样量对其2-DE图谱质量的影响。结果显示,以7 mol/L尿素、2 mol/L硫脲、4%CHAPS、1%DTT、0.5%Cocktail of protease inhibitors为裂解液,24 cm胶条上样量200μg时,可获得较好的精子总蛋白质2-DE图谱。运用ImageMaster 2-Dplatinum分析软件检测出约500个蛋白质点,蛋白质大部分分布在等电点5-7之间,分子量范围约40-90 kD。 相似文献