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  • Springer  (890)
  • American Institute of Physics  (116)
  • 1995-1999  (1,006)
  • 1925-1929
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  • 1
    Electronic Resource
    Electronic Resource
    9-(2-Methylphenyl)-3,4,5,6,9,10-hexa- hydroxanthene-1,8(2H,7H)-dione (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 759-763 
    Details
    ISSN: 1572-8854
    Keywords: X-ray diffraction ; xanthenedione ; heterocyclic fused rings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Several 9-(2-R phenyl)xanthenediones have been synthesized and the x-ray diffraction structure for the 2-methylphenyl derivative (4b) has been determined. This compound crystallizes in the monoclinic system, space group P21/n, with a = 11.729 (3), b = 9.674 (3), c = 14.628 (4) Å, and β = 106.30°. It presents a partially hydrogenated xanthene system in distorted boat conformation for the heterocyclic central ring, and an almost ideal envelope conformation for the outer rings. The aromatic substituent at the ninth position is at 84° in angle with the xanthene system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009583417391
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Skeletal Site of Origin and Donor Age on Osteoblastic Cell Growth and Differentiation (1999)
    Springer
    Calcified tissue international 64 (1999), S. 280-286 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Human osteoblastic cells — Skeletal site — Aging.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Bone loss with aging may be due, at least in part, to inadequate bone formation. Moreover, the process of bone aging is known to follow a different pattern throughout the skeleton. In this study, we examined the cell proliferation rate (area under the cell growth curve, AUC) and the secretion of C-terminal type I procollagen (PICP), alkaline phosphatase (ALP), and osteocalcin (OC) in primary cultures of osteoblastic cells from human trabecular bone. Osteoblastic cells were obtained for 168 donors (100 women and 68 men). Ninety-eight bone samples were obtained from subjects undergoing knee arthroplastia, 52 aged 50–70 years (64 ± 5) and 46 over age 70 (73 ± 2). Another 70 bone samples were obtained from subjects undergoing hip arthroplastia; 51 were 50–70 years old (64 ± 4) and 19 were over 70 (75 ± 5). Osteoblastic cells from the older donors had a lower proliferation rate and OC secretion than those from younger subjects. However, ALP secretion was higher in the former subjects, whereas PICP secretion was unchanged. Osteoblastic cells from hip had a lower proliferation rate than those from knee. PICP secretion was also lower and ALP secretion was higher in the former cells. In age-matched cell cultures, osteoblastic cells from the knee had higher proliferation rate and PICP secretion than osteoblastic cells from the hip. However, ALP secretion was lower in knee osteoblastic cells than those from hip only in the younger group. With aging, ALP secretion was found to increase in knee osteoblactic cells, whereas OC secretion decreased in osteoblastic cell cultures from the hip. Our findings suggest that bone loss with aging may be accounted for, at least in part, by a decreased osteoblastic cell proliferation and an increased osteoblastic maturation. In addition, our data indicate that these changes with aging do not occur similarly at different skeletal sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900619
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of carbon source and pH of the growth medium on spore germination in Phycomyces blakesleeanus (1995)
    Springer
    Archives of microbiology 164 (1995), S. 231-234 
    Details
    ISSN: 1432-072X
    Keywords: Key words Spore activation ; Phycomyces ; Carbon source ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phycomyces blakesleeanus sporangiospores responded differently to activation by physical and chemical stimuli. Spores that were physically (heat shock) activated or chemically (ammonium acetate) activated germinated and grew at pH 4.5 with the hexoses glucose, fructose, galactose, and N-acetylglucosamine, and with glycerol and amino acids. Under these conditions, physically activated spores showed a lower, although significant growth with the hexoses fructose, galactose, N-acetylglucosamine and with glycerol. On the other hand, physically activated spores incubated at alkaline pH (pH 7.3) required glucose to germinate; a requirement not observed with chemically activated spores, which showed significant growth in the other hexoses tested. Both physically and chemically activated spores incubated at pH 7.3 were unable to germinate and grow with amino acids and glycerol. These results suggest that there are different targets for activation of the spores by physical and chemical treatments. The levels of the fermentative enzymes alcohol dehydrogenase and lactate dehydrogenase and of the oxidative enzyme NAD+-isocitrate dehydrogenase were higher in cells grown at pH 4.5 in medium containing glucose; however, alcohol dehydrogenase and lactate dehydrogenase appear not to be affected by a change in the pH of the growth medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050259
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  • 4
    Electronic Resource
    Electronic Resource
    Persistent behavior in a phase-shift sequence of periodical biochemical oscillations (1998)
    Springer
    Bulletin of mathematical biology 60 (1998), S. 689-702 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We present the analysis of a phase-shift sequence obtained from random transitions between periodic solutions of a biochemical dynamical model, formed by a system of three differential equations and which represent an instability-generating multienzymatic mechanism. The phase-shift series was studied in terms of Hurst’s rescaled range analysis. We found that the data were characterized by a Hurst exponent H = 0.69, which was clearly indicative of long-term trends. This result had a high significance level, as was confirmed through Monte Carlo simulations in which the data were scrambled in the series, destroying its original ordering. For these series we obtained a Hurst exponent which was consistent with the expectation of H = 0.5 for a random independent process. This clearly showed that, although the transitions between the periodic solutions were provoked randomly, the stochastic process obtained exhibited long-term persistence. The fractal dimension was also estimated and found to be consistent with the value of the Hurst exponent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1006/bulm.1997.0036
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  • 5
    Electronic Resource
    Electronic Resource
    Mutational analysis of the MPZ, PMP22 and Cx32 genes in patients of Spanish ancestry with Charcot-Marie-Tooth disease and hereditary neuropathy with liability to pressure palsies (1997)
    Springer
    Human genetics 〈Berlin〉 99 (1997), S. 746-754 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Charcot-Marie-Tooth disease (CMT) and hereditary neuropathy with liability to pressure palsies (HNPP) are two inherited peripheral neuropathies. The most prevalent mutations are a reciprocal 1.5-Mb duplication and 1.5-Mb deletion, respectively, at the CMT1A/HNPP locus on chromosome 17p11.2. Point mutations in the coding region of the myelin genes, peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ) or connexin 32 (Cx32) have been reported in CMT patients, including CMT type 1 (CMT1), CMT type 2 (CMT2) and Déjérine-Sottas neuropathy (DS) patients, and only in the coding region of PMP22 in HNPP families lacking a deletion. We have investigated point and small mutations in the MPZ, PMP22 and Cx32 genes in a series of patients of Spanish ancestry: 47 CMT patients without duplications, and 5 HNPP patients without deletions. We found 15 different mutations in 16 CMT patients (34%). Nine different mutations in ten patients were detected in the Cx32 gene, this being the most frequently involved gene in this series, whereas five mutations involved the MPZ gene and only one the PMP22 gene. Six out of nine nucleotide substitutions in the Cx32 gene involved two codons encoding arginine at positions 164 and 183, suggesting that these two codons may constitute two Cx32 regions prone to mutate in the Spanish population. Analysis of HNPP patients revealed a 5′ splicing mutation in intron 1 of the PMP22 gene in a family with autosomal dominance, which confirms allelic heterogeneity in HNPP. Ectopic mRNA analysis on leukocytes suggests that this mutation might behave as a null allele.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050442
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  • 6
    Electronic Resource
    Electronic Resource
    Leishmania infantum Nicolle, 1908 from southern Spain: Characterisation of the strains from human visceral and cutaneous leishmaniasis and from sandflies; with a numerical analysis of the isoenzymatic data (1996)
    Springer
    Systematic parasitology 33 (1996), S. 177-182 
    Details
    ISSN: 1573-5192
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This study presents the results of the characterisation of 17 strains ofLeishmania by isoenzyme electrophoresis from a focus of leishmaniasis in southern Spain: two from human visceral leishmaniasis, four from human cutaneous leishmaniasis and 11 from sandflies. The 17 strains are grouped in 6 zymodemes characterised by their variability as regards to the electrophoretic mobility of the enzymes MDH, G6PD, NP and ME. Thus, we confirm the high intraspecific variability ofLeishmania (L.) infantum in a focus of southern Spain, as already suggested by previous studies. Zymodemes GR-15 and GR-17 are also described for the first time in Spain, and they characteristically possess the same relative electrophoretic mobility in the enzyme ME (93). Sixteen zymodemes of theL. infantum complex found in southern Spain were numerically analysed on the basis of the enzymatic profiles of 122Leishmania strains characterised from this area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01531198
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  • 7
    Electronic Resource
    Electronic Resource
    Cubic CdS thin films studied by spectroscopic ellipsometry (1997)
    Springer
    Journal of materials science 8 (1997), S. 399-403 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract CdS polycrystalline films were grown onto glass substrates by chemical bath deposition (CBD) and characterized by spectroellipsometry, X-ray diffraction and transmission electron microscopy. The X-ray diffraction patterns of the samples showed the presence of a CdS cubic phase (β-CdS) and of Cd2SiO4 as interfacial material. Using electron diffraction it was possible to index the films as cubic CdS. From effective dielectric function measurements and from reported optical data for the dielectric function of cubic CdS crystals, grown by vapour phase epitaxy, it was possible to fit the experimental data to an effective medium approximation, and to deduce the film thickness, the void fraction and the field screening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018555826924
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  • 8
    Electronic Resource
    Electronic Resource
    Gamma radiation and radon levels in Mexico City dwellings (1995)
    Springer
    Journal of radioanalytical and nuclear chemistry 193 (1995), S. 259-268 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Gamma exposure rate and radon levels were measured in 75 single-family dwellings in Mexico City in order to correlate them with local environment. Radon monitoring was performed both indoors and outdoors using a continuous working level monitor for short-lived radon decay products; the gamma exposure rate was measured using CaSO4: Dy+PTFE. The results obtained show a log-normal distribution. The mean indoor radon concentration is lower than 45 Bq/m3 and the mean indoor gamma exposure rate was 11.29 μR/h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02039883
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of 2,4-D in aqueous solution by neutron activation analysis (1999)
    Springer
    Journal of radioanalytical and nuclear chemistry 241 (1999), S. 323-325 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A method based on neutron activation analysis was developed for the determination of fractions of milligrams of 2,4-D (2,4-dichlorophenoxy acetic acid) in aqueous solution in laboratory tests. The indirect determination of 2,4-D was based on the quantification of chlorine,38Cl, produced by neutron activation. The range of application was 0.01–100 mg l−1. No loss of38Cl by chemical effects of the nuclear reaction was found. The advantages of the proposed method include high precision and sensitivity of determination. Results were compared with those obtained by UV-Vis spectrophotometry, where concentrations less than 1 mg·l−1 were not detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02347468
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  • 10
    Electronic Resource
    Electronic Resource
    Preparation, spectral studies, and X-ray crystal structures of (16S, 17R, 20S)-3-oxo-16-hydroxy-25-nor-lanostan-24-oic lactone (II) and (16S, 17R, 20S)-4,16-dihydroxy-25-nor-3,4-seco-lanostan-3,24-dioic acid dilactone (III) (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 331-337 
    Details
    ISSN: 1572-8854
    Keywords: Guayule ; Parthenium ; triterpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structures of the title compounds have been determined by direct methods, and refined to a finalR of 0.059 forII and 0.046 forIII. Both molecules crystallize in space group P212121. The cell dimensions forII area=10.096(5),b=11.255(3),c=20.300(7) Å;Z=4,D x=1.188 g cm−3, μ(MoKα)=0.70 cm−1, while the cell dimensions forIII area=7.346(1),b=10.470(3),c=30.546(5) Å;Z=4,D x=1.212 g cm−3, μ(MoKα)=0.74 cm−1. The rings of the triterpene skeletons aretrans-cis-trans-cis connected. The conformations of both molecules are discussed. Also the preparation and the spectral data of (17R, 20S)-3,16-dioxo-25-nor-lanostan-24-oic acid (V) and (17R, 20S)-3,16,24-trioxo-25-hydroxy-16,24-seco-lanostan-25-acetate (VI) are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01796059
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