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  • 1
    Electronic Resource
    Electronic Resource
    VARIATIONS IN CAPILLARY PERMEABILITY TO PLASMA PROTEINS DURING THE MENSTRUAL CYCLE (1966)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 73 (1966), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1966.tb15550.x
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  • 2
    Electronic Resource
    Electronic Resource
    Occurrence of Heterozygotes and Homozygotes for the α-Chain Haemoglobin Variant Hb-J(Tongariki) in New Guinea (1972)
    [s.l.] : Nature Publishing Group
    Nature 235 (1972), S. 46-47 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The haemoglobin variant Hb-J(Tongariki) was discovered1 in 1967 in Tongariki, an island in the New Hebrides, and shown to have an ?-chain substitution (all5 AlaAsp). An electro-phoretically similar variant was later shown2 to occur in a village in New Britain and its identity with the Tongariki ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/235046a0
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  • 3
    Electronic Resource
    Electronic Resource
    Field evaluation of several chemical indexes of soil nitrogen availability (1990)
    Springer
    Plant and soil 123 (1990), S. 83-88 
    Details
    ISSN: 1573-5036
    Keywords: maize ; nitrogen availability tests ; soil nitrate ; UV absorbance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The ability of several chemical soil N availability indexes to predict the N supplying capability (NSC) of soils to maize in the field was evaluated in 49 field experiments over 3 years in Pennsylvania. Two recently proposed indexes based on the amount of NH4 + released by treating soil with 2 M KCl at 100°C for 4 hr or with a pH 11.2 phosphate-borate buffer for 8 min were not good predictors of NSC (r=0.484 and 0.254, respectively). The absorbance of a 0.01 M NaHCO3 extract at 260 nm was also poorly correlated with field-measured NSC (r=0.412). The pre-sidedress soil NO3 − test (PSNT), the soil NO3 − concertration in the surface 20 cm of soil at planting, and the UV absorbance at 200 nm of a 0.01 M NaHCO3 extract of at planting soils were all moderately well correlated with NSC (r=0.672, 0.750, and 0.737, respectively). The latter two indexes are very simple, rapid, and inexpensive to perform and offer the possibility of improving the prediction of NSC in heavily manured fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009929
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  • 4
    Electronic Resource
    Electronic Resource
    The nitrogen mineralization rate of legume residues in soil as influenced by their polyphenol, lignin, and nitrogen contents (1990)
    Springer
    Plant and soil 129 (1990), S. 251-259 
    Details
    ISSN: 1573-5036
    Keywords: 15N recovery ; nitrogen release ; nitrogen availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A 12-week greenhouse experiment was conducted to determine the effect of the polyphenol, lignin and N contents of six legumes on their N mineralization rate in soil and to compare estimates of legume-N release by the difference and 15N-recovery methods. Mature tops of alfalfa (Medicago sativa L.), round leaf cassia (Cassia rotundifolia Pers., var. Wynn), leucaena (Leucaena leucocephala Lam., deWit), Fitzroy stylo (Stylosanthes scabra Vog., var Fitzroy), snail medic (Medicago scutellata L.), and vigna (Vigna trilobata L., var verde) were incorporated in soil at the rate of 100 mg legume N kg-1 soil. The medic and vigna were labeled with 15N. Sorghum-sudan hybrid (Sorghum bicolor, L. Moench) was used as the test crop. A non-amended treatment was used as a control. Net N mineralization after 12 weeks ranged from 11% of added N with cassia to 47% of added N for alfalfa. With the two legumes that contained less than 20 g kg-1 of N, stylo and cassia, there was net N immobilization for the first 6 weeks of the experiment. The legume (lignin + polyphenol):N ratio was significantly correlated with N mineralization at all sampling dates at the 0.05 level and at the 0.01 level at 6 weeks (r2=0.866). Legume N, lignin, or polyphenol concentrations or the lignin:N ratio were not significantly correlated with N mineralization at any time. The polyphenol:N ratio was only significantly correlated with N mineralization after 9 weeks (r2=0.692). The (lignin + polyphenol):N ratio appears to be a good predictor of N mineralization rates of incorporated legumes, but the method for analyzing plant polyphenol needs to be standardized. Estimates of legume-N mineralization by the difference and 15N recovery methods were significantly different at all sampling dates for both 15N-labeled legumes. After 12 weeks, estimates of legume-N mineralization averaged 20% more with the difference method than with the 15N recovery method. This finding suggests that estimates of legume N available to subsequent crops should not be based solely on results from 15N recovery experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032420
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of temperature and time of storage of dry soil samples on a chemical index of N availability (1982)
    Springer
    Plant and soil 66 (1982), S. 81-89 
    Details
    ISSN: 1573-5036
    Keywords: Extractable organic matter ; N availability index ; Organic matter ; Organic N ; Soil storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect was studied of storage temperature on the index of available soil N wich uses U.V. absorbance of a 0.01M NaHCO3 extract as an indicator. The U.V. absorbance was found to increase at a non-linear rate for four soils stored at temperatures of 50, 75, and 150°C. The change in extract absorbance due to extended soil storage at each of these temperatures was positively correlated to the percent organic matter, percent N, C/N value and concentration of humic substances in soils, but not to the extract absorbance prior to soil storage. These findings were not consistent with room temperature storage data which showed a linear increase in extract absorbance with soil storage time. The change in absorbance for the room temperature case was not related to any of the soil parameters mentioned above. Analysis of a soil stored at 105°C showed an increase in ninhydrin-detectable N, protein N and Kjeldahl N of the NaHCO3 extract, while the apparent molecular weight distribution of extracted organic matter (as determined by gel filtration) showed only a slight change. As a comparison to the NaHCO3 extract, a boiling CaCl2 extract of the same soil was also analyzed; and the absorbance at 260 nm was found to increase in a curvilinear fashion with starage time at 75°C but to less of an extent than was noted with the NaHCO3 extract. Nitrogen availability indexes based on the U.V. absorbance of these extracts, particularly those utilizing the NaHCO3 extract, would be significantly affected by soil storage at elevated temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02203405
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  • 6
    Electronic Resource
    Electronic Resource
    Using NCSWAP to simulate seasonal nitrogen dynamics in soil and corn (1995)
    Springer
    Plant and soil 177 (1995), S. 235-247 
    Details
    ISSN: 1573-5036
    Keywords: corn ; nitrogen availability ; N simulation ; soil ; tillage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this study was to determine if a re-calibrated version of the computer model NCSWAP (version 36) could accurately predict corn growth and soil N dynamics in conventionally tilled (CT) and no-till (NT) corn supplied with legume green manure or ammonium nitrate as N sources. We also attempted to ascertain the reasons for limitations in the model's ability to simulate corn growth and soil N dynamics found by our colleagues in a previous study and to propose potential improvements. The model was calibrated to accurately simulate total available N (N in plant above-ground biomass plus soil nitrate in the 0 to 45 cm profile) for a control and a fertilizer CT treatment in the 1992 growing season. To do so, input values defining the quantities of active soil organic N had to be reduced to 19% of the values proposed by the model developers and a solute transport factor defining the mobile vs. immobile fractions of soil nitrate adjusted from 0.8 to 0.2. The discrepancies between the proposed values and the lower values employed in this study might be due to the uncertainties in quantitatively describing soil N mineralization processes and the way they are handled in the model, as well as the lack of a component simulating macroporous-influenced water flow and solute transport in the model. With the current version, until one knows how to predict what these values are, the model needs to be re-calibrated for each experimental site and condition and thus is of limited value as a general model. With no further adjustment of input values, model validation success was mixed. The model accurately predicted total available N for treatments in the second year of the experiment that had the same N source and tillage as the treatments used for the calibration year but with the different weather and growing conditions. However, total available N was underpredicted where legume green manure was the N source and overpredicted with no-till cultivation. The model was accurate in simulating seasonal corn growth for nearly all the treatments, judged by nonsignificant mean difference (MD) values and highly significant correlation coefficients (r). Prediction of seasonal soil nitrate concentration was less accurate compared to total available N and corn growth variables. Potential improvements in the model's simulation of a no-till system as well as for predicting corn harvest yield and seasonal soil nitrate concentration where N deficiency occurs were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010130
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical characterization of two extracts used in the determination of available soil nitrogen (1982)
    Springer
    Plant and soil 64 (1982), S. 331-341 
    Details
    ISSN: 1573-5036
    Keywords: Humic substances ; Molecular weight distribution ; N availability index ; Ninhydrindetectable N ; Relative N uptake ; Soil proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two soil extracts used for chemical indexes for N availability, 0.01M NaHCO3 and boiling 0.01M CaCl2, were analyzed in effort to learn more about the nature of the extracted organic matter (O.M.). The two extracts appeared to remove different fractions of the soil O.M. A study of five soils showed that the C/N value of the NaHCO3 extract (following decarbonation) was significantly higher than that of the total soil O.M.; while the C/N value in the boiling CaCl2 extract was not significantly different from that in the soil O.M. There was also significant variation in C/N values among soils for the boiling CaCl2 extract. The extracts of three soils were analyzed for apparent molecular weight distribution using gel filtration and the results compared to those for base-extracted humic substances. Almost all the molecules in the extracts had apparent molecular weights less than 21,000 daltons while 21 to 47% of the humic substances from the same soils (extracted with 0.5M NaOH) had molecular weights greater than 21,000 daltons. In the boiling CaCl2 extract, 78 to 87% of the humic substances had apparent molecular weights less than 1,000 daltons, whereas with the NaHCO3 extract, 42 to 83% of the humic substances were in the 1,000 to 21,000 dalton range. Forty-three to 92% of the N extracted by the NaHCO3 was in protein form, and 8 to 30% was ninhydrin-detectable. In the boiling CaCl2 extract 25 to 30% of the extracted N was ninhydrin-detectable. For the same 10 soils, ninhydrin-detectable N values of the boiling CaCl2 extract appeared closely related to greenhouse and field relative N uptake, while the ninhydrin-detectable N values of the NaHCO3 extract appeared unrelated to both. The protein N and protein in plus ninhydrin-detectable N values of the NaHCO3 extract were closely related to greenhouse relative N uptake only. The results of this study indicated that specific fractions of the soil O.M. were being extracted by the two solutions and that significant differences existed in the chemical nature of the two extracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02372516
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  • 8
    Electronic Resource
    Electronic Resource
    Tillage effect on seasonal nitrogen availability in corn supplied with legume green manures (1994)
    Springer
    Plant and soil 162 (1994), S. 203-210 
    Details
    ISSN: 1573-5036
    Keywords: corn ; hairy vetch ; red clover ; nitrogen availability ; tillage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It has been shown that legume green manures have great potential for replacing a substantial amount of the N fertilizer required for corn (Zea mays L.) production. An experiment was conducted in central Pennsylvania (USA) to study seasonal fluctuation of nitrogen (N) availability in corn with conventional tillage (CT) and no-till (NT) following red clover (Trifolium pratense L.) and hairy vetch (Vicia villosa Roth) green manures double-cropped with winter wheat (Triticum aestivum L.). Samples of corn, weeds, and soil were taken periodically and analyzed for total N content in plant tissue and soil nitrate-N content. The sum of plant N (corn plus weed) and soil nitrate-N in the upper 45 cm profile was used as an indicator of total available N. Under CT, total available N increased rapidly upon legume incorporation and reached 80% of the maximum within 4 weeks. Under NT, total available N increased steadily after the legumes were killed with herbicides and reached a maximum within 7 to 8 weeks. Seasonal corn N accumulations with the legume N source were similar to those where corn followed fallow with 200 kg N ha−1 fertilizer with CT, but were less than those in the same fallow 200 kg N ha−1 treatment with no-till. Dry weather conditions together with weed competition reduced N availability to the no-till corn compared to the CT treatments. The seasonal fluctuations of total available N and corn N uptake suggest good synchronization between N availability from the legume green manures and N accumulation by corn plants in both tillage systems under the conditions of this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01347707
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