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  • 1
    Electronic Resource
    Electronic Resource
    Input synchrony and spike-timing dependent plasticity (2003)
    Springer
    The European physical journal 31 (2003), S. 385-390 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 87.18.Sn Neural networks – 87.16.Xa Signal transduction – 87.17.Aa Theory and modeling; computer simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The influence of a weight-dependent spike-timing dependent plasticity (STDP) rule on the temporal evolution and equilibrium state of a certain synapse is investigated. We show that under certain conditions, a spike-induced rate-learning scheme could be achieved. Through studying the situation when a single Hodgkin-Huxley neuron is driven by a large ensemble of input neurons, we find that synchronized firing of a sub population of input neurons may be important to information processing in the nervous system. Using simulations, we show that the temporal structure of the spike trains of these synchronized input neurons can be transmitted reliably; further, synapses from these neurons will increase stably due to the STDP rule and this may provide a mechanism for learning and information storage in biologically plausible network models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00046-2
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  • 2
    Electronic Resource
    Electronic Resource
    Elastic buckling of honeycomb structure under out-of-plane pressure (1991)
    Springer
    Acta mechanica solida Sinica 4 (1991), S. 449-455 
    Details
    ISSN: 0894-9166
    Keywords: out-of-plane ; honeycomb structure ; elastic buckling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A theoretical model and an analytical method, which are suitable for initial elastic buckling analysis of two-dimensional honeycomb structures including hexagonal honeycombs with walls of equal or unequal thickness, rectangular and triangular honeycombs etc., are developed in this paper. The results given in present paper agree well with the experimental data of hexagonal honeycombs with walls of unequal thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02207593
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  • 3
    Electronic Resource
    Electronic Resource
    Optical fiber sensor for berberine based on fluorescence quenching of 2-(4-diphenylyl)-6-phenylbenzoxazole (1998)
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 702-706 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new optical fiber sensor was prepared for the determination of berberine in aqueous solution using a micrometer-sized flow-cell and a bifurcated optical fiber. The sensing is based on fluorescence quenching of 2-(4-diphenylyl)-6-phenylbenzoxazole (PBBO) in the PVC membrane. This process is accompanied by non-fluorescent ground-state complex formation. With this sensor, berberine can be determined in sample solutions from 2.42 × 10–5 mol L–1 to 6.04 × 10–7 mol L–1. Satisfactory reproducibility, reversibility, and short response times of less than 1 min are realized. The sensor also shows good selectivity over some common pharmaceutical species and alkali and alkali-earth metal salts, and can be used for the direct assay of berberine in commercial tablets. The results are in correspondence with those obtained by the pharmacopoeia method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050785
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  • 4
    Electronic Resource
    Electronic Resource
    Optosensing of hydrochloric acid based on the fluorescence quenching of a flavone copolymer (1998)
    Springer
    Fresenius' journal of analytical chemistry 362 (1998), S. 387-390 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An optical fiber sensor for the continuous determination of hydrochloric acid is presented. It is based on the fluorescence quenching of a flavone containing copolymer membrane by hydrochloric acid. The quenching efficiency is greatly enhanced in the presence of Fe(III). This enhancement is attributed to the primary inner filter effect, as well as the formation of a complex between the 4′-N,N-dimethylaminoflavone group in the copolymer and the Fe(III) species extracted from hydrochloric acid solution. The optical response is linear and reversible for 0.10–6.00 mol L–1 HCl with a response time of the order of a second. The standard deviations for repeated alternative measurements of 0.20 and 2.00 mol L–1 hydrochloric acid are 0.32% and 0.46% (n = 10), respectively, indicating a good reproducibility. Because of the covalently bonding of the dye to polymer, the sensor exhibits also a good stability. Selectivity has also been evaluated for some potential interferents. The sensor in conjunction with a flow-injection system can be used for on-line determination of hydrochloric acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051090
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of Bcl-2 protein in the epiphyseal plate cartilage and trabecular bone of growing rats (1997)
    Springer
    Histochemistry and cell biology 108 (1997), S. 45-55 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The protooncogene protein, Bcl-2, protects cells from apoptosis and ensures their survival in vitro by inhibiting the action of the apoptosis-inducer, Bax. Its expression in proliferative and long-lived cells in vivo also indicates that it protects against cell death. The chondrocytes of the epiphyseal plate cartilage undergo a series of maturation steps and deposit mineral in the cartilage matrix before dying. The possibility that Bcl-2 helps protect chondrocytes until mineral deposition is completed was investigated by determining the distribution of Bcl-2 immunoreactivity in the epiphyseal plate cartilage of growing rats and its subcellular localization, using a specific antibody. The involvement of Bax in the triggering of chondrocyte death was checked by immunocytochemistry. Bcl-2 expression in the osteoblasts and the final result of their evolution, the osteocytes, was also examined in trabecular bone. Bcl-2 immunoreactivity was non-uniformly distributed throughout the epiphyseal cartilage. It was maximal in proliferative chondrocytes, decreased in mature chondrocytes, and low in hypertrophic chondrocytes, whereas there was Bax immunoreactivity in all chondrocytes examined. Immunolabeling was intense in osteoblasts but considerably lower in fully differentiated osteocytes. Bcl-2 immunoreactivity was mainly in the cytoplasm of chondrocytes, osteoblasts, and early osteocytes; the nuclei appeared clear. The subcellular distribution of Bcl-2 immunolabeling in chondrocytes, revealed by gold particles in the electron microscope, showed that gold particles were frequently concentrated in the mitochondria in all the cartilage zones and lay mainly within the organelles, not at their periphery. The endoplasmic reticulum contained moderate immunoreactivity and there were few gold particles in the cytoplasm and nuclei. The number of gold particles decreased in all the subcellular compartments from proliferative to hypertrophic chondrocytes. In contrast, Bax immunoreactivity changed little during chondrocyte terminal evolution, and its subcellular distribution mirrored that of Bcl-2. These immunocytochemical data indicate that Bcl-2 helps maintain chondrocytes and osteoblasts until their terminal maturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050145
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and properties of undecatungstozirconates with a transition metal (1995)
    Springer
    Transition metal chemistry 20 (1995), S. 81-83 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary K n [ZrW11O39M(H2O)]·xH2O complexes were prepared and characterized by elemental analysis, u.v.-vis., i.r. spectroscopy and electrochemistry. The title heteropolyanions catalyse olefin epoxidation by iodosylbenzene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00135408
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  • 7
    Electronic Resource
    Electronic Resource
    Genetic diversity in the Chinese pangolin (Manis pentadactyla) inferred from protein electrophoresis (1994)
    Springer
    Biochemical genetics 32 (1994), S. 343-349 
    Details
    ISSN: 1573-4927
    Keywords: Manis pentadactyla ; protein electrophoresis ; genetic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We examined protein polymorphism of Chinese pangolins (Manis pentadactyla) from Yunnan Province of China, including two forms of three brown and nine dusky Chinese pangolins. Sixty-two genetic loci were screened; 12 loci were found to be polymorphic. The percentage of polymorphic loci (P) is 0.194, the mean individual heterozygosity (H) is 0.078, and the mean number of alleles (A) is 1.258. Furthermore, we calculated the genetic distance (D) between the two forms and found a low level of genetic divergence (D=0.0206) between them, which indicates an almost-indistinguishable divergence at the level of proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00554181
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic diversity in the Chinese pangolin (Manis pentadactyla) inferred from protein electrophoresis (1994)
    Springer
    Biochemical genetics 32 (1994), S. 343-349 
    Details
    ISSN: 1573-4927
    Keywords: Manis pentadactyla ; protein electrophoresis ; genetic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We examined protein polymorphism of Chinese pangolins (Manis pentadactyla) from Yunnan Province of China, including two forms of three brown and nine dusky Chinese pangolins. Sixty-two genetic loci were screened; 12 loci were found to be polymorphic. The percentage of polymorphic loci (P) is 0.194, the mean individual heterozygosity (H) is 0.078, and the mean number of alleles (A) is 1.258. Furthermore, we calculated the genetic distance (D) between the two forms and found a low level of genetic divergence (D=0.0206) between them, which indicates an almost-indistinguishable divergence at the level of proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426896
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  • 9
    Electronic Resource
    Electronic Resource
    Biosynthesis and Characterization of 4-Fluorotryptophan-Labeled Escherichia coli Arginyl-tRNA Synthetase (1999)
    Springer
    The protein journal 18 (1999), S. 187-192 
    Details
    ISSN: 1573-4943
    Keywords: Arginyl-tRNA synthetase ; 4-fluorotryptophan ; 19F NMR ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Escherichia coli 4-fluorotryptophan-substituted arginyl-tRNA synthetase was biosynthetically prepared and purified from a tryptophan auxotroph which could overproduce this enzyme. A method was developed to separate 4-fluorotryptophan from tryptophan and to determine accurately their contents in the 4-fluorotryptophan-containing proteins. It was confirmed that more than 95% of the tryptophan residues in the purified 4-fluorotryptophan-substituted arginyl-tRNA synthetase were replaced by 4-fluorotryptophan. Studies on the effect of the 4-fluorotryptophan replacement on properties of the enzyme showed that, when compared with the native enzyme, both the specific activity and the first-order rate constant of the fluorinated enzyme decreased by approximately 20% with just slightly higher K m values. CD studies, however, did not reveal any difference between the secondary structure of the native and fluorinated enzymes. In addition, thermal unfolding studies showed that the 4-fluorotryptophan replacement did not significantly affect the thermal stability of the enzyme. We may conclude that the substitution of 4-fluorotryptophan in arginyl-tRNA synthetase had no substantial effect on the structure and function of the enzyme. Finally, a preliminary study of 19F nuclear magnetic resonance spectroscopy of the fluorinated enzyme has shown promising prospect for further investigation of its structure and function with NMR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020675922382
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization of a genomic clone of Erwinia carotovora subsp. carotovora TG3 encoding a pectolytic enzyme of apparent molecular weight 78 kDa (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 294-298 
    Details
    ISSN: 1617-4623
    Keywords: Erwinia carotovora subsp. carotovora ; Pectolytic enzyme ; Gene cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A clone containing the gene encoding a pectolytic enzyme of Erwinia carotovora subsp. carotovora was selected as the one that showed maceration on a solid medium containing sodium polypectate. The gene was located on a 3.2-kb DNA fragment flanked by a BglII site and a Hin-dIII site. Via mini-Mudlac mutagenesis, a possible promoter site was located within the gene between the BglII site and the EcoRI site. The mRNA transcribed from the promoter was directed from the BglII site toward the EcoRI site, determined from the orientation of the inserted mini-Mudlac. The probable gene product was identified as a 78 kDa protein. The enzyme activity of the Escherichia coli clone was detected mainly in the periplasmic space. Potato tuber slices were not macerated by the E. coli clone and synthesis of the enzyme in E. coli was not regulated by the enzyme substrate, sodium polypectate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325697
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