Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Chemical and biological characteristics of alkaline saline soils from the former Lake Texcoco as affected by artificial drainage (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 102-108 
    Details
    ISSN: 1432-0789
    Keywords: Key words Alkaline saline soils ; Micro-organisms ; Characteristics ; C and N mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soils from the former Lake Texcoco are alkaline saline and were artificially drained and irrigated with sewage effluents since the late 1980s. Undrained soil and soil drained for 1, 5 and 8 years were sampled, characterized and incubated aerobically for 90 days at 22±1  °C while production of CO2, available P and concentrations of NH4 +, NO2 – and NO3 – were monitored. Artificial drainage decreased pHH2O, water holding capacity, organic C, total N, and Na+, K+, Mg2+, B, Cl– and SO4 2– concentrations, increased inorganic C and Ca2+ concentrations more than 5-fold while total P was not affected. Microbial biomass C decreased with increased length of drainage but bacteria, actinomycetes, denitrifiers and cellulose-utilizing bacteria tended to show opposite trends. CO2 production was less in soils drained ≥5 years compared to undrained soil but more than in soils drained for 1 year. Emission of NH3 was negligible and concentrations of NH4 + remained constant over time in each soil. Nitrification, as witnessed by increases in NO3 – concentrations, occurred in soil drained for 8 years. NO2 – concentrations decreased in soils drained ≤1 year in the first 7 days of the incubation and remained constant thereafter. It was found that artificial drainage of soils from the former Lake Texcoco profoundly affected soil characteristics. Decreases in pH and Na+, K+, Cl– and SO4 2– concentrations made conditions more favourable for plant growth, although low concentrations of inorganic N and available P might be limiting factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000223
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Soil processes as affected by replacement of natural mesquite ecosystem with maize crop (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 274-278 
    Details
    ISSN: 1432-0789
    Keywords: Key words Mesquite ; Carbon dioxide production ; Nitrogen mineralization ; Microbial biomass carbon ; Nitrous oxide production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In the central highlands of Mexico, the vegetation is dominated by mesquite (Prosopis spp.), a leguminous tree or shrub. An experiment was carried out to investigate how cultivating the land and the disappearance of the natural ecosystem affected the biological functioning of the soil. Soil was sampled from under the canopy of isolated (MESQ treatment) and densely growing mesquite trees (DENS treatment), from the surrounding soil not covered by the canopies of the trees (BARE treatment) and from adjacent land cultivated with maize (ARABLE treatment). Soil was characterized and then incubated aerobically for 39 days at 22±1  °C and CO2, N2O production, microbial biomass C and inorganic N concentrations were monitored. The organic C content was 2.3 times and 1.1 times greater in the MESQ and the BARE treatments, respectively, than in the ARABLE treatment, while microbial biomass C was 3.5 times and 1.3 times greater. The microbial biomass activity as expressed by CO2 production was 5.9 times and 3.9 times greater in the MESQ and the BARE treatments, respectively, than in the ARABLE treatment, while N mineralization, as witnessed by the increase in NO3 – concentrations, was 3.4 times and 1.7 times greater. No significant amounts of N2O were produced in any of the treatments. It was found that cultivating land characterized by the presence of mesquite changed its characteristics profoundly, and even soil not covered by tree canopies had higher microbial biomass C, and C and N mineralization than soil cultivated with maize and beans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050433
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    H-reflexes in masseter and temporalis muscles in man (1995)
    Springer
    Experimental brain research 107 (1995), S. 315-320 
    Details
    ISSN: 1432-1106
    Keywords: Trigeminal reflexes ; M. masseter ; M. temporalis ; H-reflexes ; M-responses ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In contrast with limb muscles, studies on H-reflexes in the trigeminal system are scarce. The present report aimed at reevaluating the responses obtained in the masseter and temporalis muscles after electrical stimulation of their nerves. Twenty-four subjects participated in the experiments. The reflexes were elicited in the masseter and temporal muscles by monopolar stimulation and recorded using surface electrodes. Stimulation of the masseteric nerve evoked an M-response in the masseter and an H-reflex in both the masseter and the temporal muscles. In contrast with the masseter muscle, where the homonymous H-reflex disappeared at higher stimulation intensities, the heteronymous temporal H-reflex remained and reached a plateau. Simultaneous stimulation of the masseteric and deep temporal nerves resulted in an M-response and an H-reflex in both the masseter and temporal muscles. Increasing stimulus intensitites led to disappearance of the H-reflex in both muscles. The results were compared with those obtained by others on limb muscles. As in these muscles, the presence of heteronymous H-reflexes in the jaw muscles can be used in future studies of motoneuronal excitability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230051
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Relations among motor unit types, generated forces and muscle length in single motor units of anaesthetized cat peroneus longus muscle (1994)
    Springer
    Experimental brain research 101 (1994), S. 406-414 
    Details
    ISSN: 1432-1106
    Keywords: Muscles ; Muscle contraction ; Motor unit ; Contractile properties ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The active length-tension curves of identified single motor units (MUs) belonging to peroneus longus muscle (PL) of anaesthetized adult cats were obtained by eliciting isometric single twitches and tetani. The recorded responses were evaluated by measuring the peak tension amplitude and the tension-time area at muscle lengths extending throughout the physiological length range of the muscle (mean 5.5 mm, standard deviation ±0.8). The muscle lengths at which each tested MU developed its maximal twitch (L tw) and tetanic (L te) tensions were determined and compared with the muscle length (L o) at which the stimulation of all the α-axons, innervating PL and contained in L7 ventral root, developed their maximal twitch tension. The mean of single MU L tw values was at L o+1.08±1.1 mm. Slow MUs showed the longest values of L tw(L o+1.6±1.0 mm). Single MUs stimulated at tetanic frequencies presented their L te at values shorter than L o (L o−2.8±1.7 mm). Slow MUs had the shortest L te (L o−3.4±1.5 mm). For all the units L te was shorter than L tw. L tw and L te were, respectively, negatively and positively correlated with the developed tension. Optimal length values also appeared to be related to the MU types. The possibility is discussed that the muscle and tendon compliances and the high non-linearities to the applied forces are the main factors which can determine the differences among L o, L tw and L te values. The relationships between MU type and optimal length values are suggested to be, at least partly, an epiphenomenon due to the different contraction strengths of the various MU types. However, the heterogeneous distribution of the MU types is brought into account to explain the dependence of L tw and L te values on MU type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227334
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Photic driving response in primary headache: diagnostic value tested by discriminant analysis and artificial neural network classifiers (1999)
    Springer
    Italian journal of neurological sciences 20 (1999), S. 23-28 
    Details
    ISSN: 1126-5442
    Keywords: Key words EEG ; Photic driving response ; Headache ; Discriminant analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to discriminate migraine patients (MWoA) from tension-type headache (TTH) patients and normals in order to confirm that the photic driv-ing response in the medium frequency range is a marker of migraine and to test the hypothesis that MWoA and TTH are separate disorders based on electrophysiological pattern. We recruited 120 MWoA patients, 64 TTH patients, and 51 healthy controls without any history of headache or of migraine inheritance, according to International Headache Society (IHS) criteria. The classification method was discriminant analysis using both linear discriminant analysis with a stepwise selection of predictors and an artificial neural network classifier (NNs). The mean amplitude of the first harmonic elicited by flash stimulation in the 15–27 Hz range was significantly increased over Fp1, C3, C4, P4, O2, and O1 electrodes in MWoA and TTH patients in comparison with normal subjects. Using both classification methods, only the control subjects were correctly distinguished. When only the patient groups were matched, no significant difference was detectable. The increased brain response to visual stimulation detected in both migraine and TTH suggests a common neuronal dysfunction in the two headache subtypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100720050006
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Dissociation energies of the intermetallic molecules CuIn, AgIn, and AuIn (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 406-412 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The gaseous diatomic intermetallic molecules of the IA-IIIB groups, elements CuIn, AgIn, and AuIn, were investigated in a Knudsen cell-mass spectrometric study of the vapors over the respective alloys. From a number of all-gas equilibria their dissociation energies have been derived: Do0(CuIn) =183.7±7.9, Do0(AgIn) =162.8±4.9, Do0(AuIn) =282.3±5.7 kJ/mol. These values were compared to the values calculated from empirical models of bond. Of particular interest is the strikingly high dissociation energy of AuIn which was interpreted in terms of relativistic effects rather than due to multiple bond. The implications in the indium electronegativity value and the mode of formation of AuIn(g) are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456489
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Mass spectrometric study of the thermochemistry of gaseous EuTiO3 and TiO2 (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 1909-1912 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The gaseous molecule EuTiO3 has been investigated in a high temperature mass spectrometric study of vapors over the europium–titanium–oxygen system. From the enthalpy of reaction: EuTiO3(g)=EuO(g)+TiO2(g) and proper ancillary data, the atomization energy of this molecule has been determined. In addition, from the study of the gaseous exchange reaction: TiO2(g)+Eu(g)=TiO(g)+EuO(g) the dissociation energy of TiO2(g) has been derived and compared with previous results. The dissociation energies proposed are: D(open circle)0,at(EuTiO3) =2278±28 kJ mol−1 and D(open circle)0,at(TiO2) =1260±12 kJ mol−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449377
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Identification and stability determinations for the gaseous titanium oxide molecules Ti2O3 and Ti2O4 (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 1913-1916 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The gaseous titanium oxides molecules Ti2O3 and Ti2O4 were observed for the first time by high temperature mass spectrometry in the vapors over a cobalt–titanium–oxygen system. From the study of three all-gas reaction equilibria, the stabilities of these molecules have been derived: D(open circle)0,at(Ti2O3) =2312±56 kJ mol−1 and D(open circle)0,at (Ti2O4)=3017±47 kJ mol−1. The appearance potentials were measured to be 8.3±0.5 and 10.5±0.5 eV for Ti2O+3 and Ti2O+4, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449378
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Determination of the atomization energies of the gaseous molecules Nb2O4, Nb2O5, Nb4O9, and Nb4O10 (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5955-5960 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The complex gaseous niobium oxide molecules Nb2O4, Nb2O5, Nb4O9, and Nb4O10 were identified for the first time in a Knudsen cell-mass spectrometric study of the vapors in equilibrium over a condensed phase resulting from extensive vaporization of lithium niobate with lithium depletion. These molecules were characterized thermochemically from the study of several all-gas equilibria. The resulting atomization energies are ΔH00,at(Nb2O4) =3322±45 kJ mol−1; ΔH00,at(Nb2O5) =3910±59 kJ mol−1; ΔH00,at(Nb4O9) =7958±82 kJ mol−1; ΔH00,at(Nb4O10) =8595±71 kJ mol−1. The corresponding standard heats of formation are ΔH0f,298(Nb2O4,g) =−909±45 kJ mol−1; ΔH0f,298(Nb2O5,g) =−1252±59 kJ mol−1; ΔH0f,298(Nb4O9,g) =−2889±82 kJ mol−1; ΔH0f,298(Nb4O10,g) =−3281±71 kJ mol−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451507
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Labeling of Retina and Optic Tectum Phospholipids in Chickens Exposed to Light or Dark (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The labeling of retina ganglion cell and optic tectum phospholipids was determined in chickens given an intraocular injection of 32P and then either exposed to light or maintained in the dark. Significantly higher labeling was found in the optic tectum phospholipids of light-exposed compared with dark-maintained animals after 3–24 h of labeling. In the ganglion cells, the labeling of phospholipids increased in dark with respect to light at 15 and 30 min of labeling; from 60 min to 24 h, the labeling of phospholipids was significantly higher in light with respect to dark, even if the precursor pool showed a higher labeling in dark at all times studied. When labeling was allowed to proceed in the dark for 30 min and then half of the animals were exposed to light for 15 min, the labeling of ganglion cell phospholipids of light-exposed animals was significantly higher than those of animals kept in the dark. No individual phospholipid accounted for the differences observed in the labeling of the total phospholipid pool. These results are interpreted as an increase in the biosynthesis of phospholipids in the ganglion cell somas in light with respect to dark.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb05768.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...