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51.
Alessandro Ballio Renato Capasso Antonio Evidente Giuliano Grandolini Giacomino randazzo 《Phytochemistry》1982,21(7):1810-1811
The stereostructure of cotylenol, the aglycone of the cotylenins, has been confirmed by chemical correlation with the aglycone of fusicoccin A. 相似文献
52.
Paul Nieuwenhuysen Julius Clauwaert 《Journal of biochemical and biophysical methods》1981,5(5):279-286
It is impossible to measure the diffusion coefficient of macromolecules directly and accurately by quasi—elastic light scattering, when aggregates cannot be eliminated from the solutions to be investigated. Nevertheless, a simple method can be applied to overcome this problem in many cases. Aggregates are separated from the monomeric macromolecules by rate-zonal sedimentation in a CsCl density gradient in a transparent centrifugation tube; the monomers are then located by laser light scattering intensity measurements; photon correlation spectroscopy of the scattered light finally yields their diffusion coefficient. The viscosity of aqueous CsCl solutions at different temperatures and concentrations allows a good separation by centrifugation and a low uncertainty in the reduction of the measured diffusion coefficient to standard conditions.The application of the method to eukaryotic large ribosomal subunits is described as an example. 相似文献
53.
Catherine Richard Claude Delaude Louisette Le Men-Olivier Jean Le Men 《Phytochemistry》1978,17(3):539-541
The structure of a new bisindole alkaloid has been elucidated by chemical correlation and analysis of 13C NMR spectra. 相似文献
54.
本文根据湍流统计理论和野外观测数据,详细分析了林带背风面湍流自相关、空间相关和湍流积分尺度特征。在林带背风面的林缘附近,由于湍流尺度较小,使湍流相关系数不紧密。这时的时间尺度在2—3s(1.5m)和3—8s(5m),而空间尺度为10—20m左右。在远离林带以后,林带的作用减弱,随着湍流尺度增大,导致湍流相关系数增大。这时的时间尺度在15—20s,空间尺度在70—80m范围内,且湍流自相关系数服从2/3的指数定律。 相似文献
55.
56.
Nonparametric tests of the Markov model for survival data 总被引:1,自引:0,他引:1
57.
Breeding tomatoes for salt tolerance: inheritance of salt tolerance and related traits in interspecific populations 总被引:3,自引:0,他引:3
Y. Saranga A. Cahaner D. Zamir A. Marani J. Rudich 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,84(3-4):390-396
Summary Interspecific segregating populations derived from a cross between tomato (Lycopersicon esculentum) cv M82-1 -8 (M82) and the wild species L. pennellii accession LA-716 (Lpen716) were used to study the genetic basis of salt tolerance and its implications for breeding. BC1 (M82 x (M82 x Lpen716)) and BC1 S1 (progenies of selfed BC1 plants) populations were grown under arid field conditions and irrigated with water having electrical conductivities of 1.5 (control), 10 and 20 dSm-1. The evaluation of salt tolerance was based on total fruit yield (TY), total dry matter (TD) and TD under salinity relative to the control (RD). Sodium, potassium and chloride concentrations were measured in the leaves and stems. The methods for estimating heritability were adapted to BC1 plants and BC1S1 families. TY, TD and RD had heritability estimates of 0.3–0.45, indicating that salt tolerance can be improved by selection. Genetic correlations between traits indicated that high yield may be combined with salt tolerance and that ion contents are not likely to provide an efficient selection criteria for salt tolerance. Genetic correlations between performances under various salinity levels suggested that similar mechanisms affect the responses to salinity treatments of 10 and 20 dSm-1. Responses to paper selection confirmed that salt tolerance of the tomato may be improved by selection, and that this selection should be based on dry matter and yield parameters under salinity.Passed away May 1986 相似文献
58.
C. S. Wang B. S. Yandell J. J. Rutledge 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,85(1):79-88
Summary At least two common practices exist when a negative variance component estimate is obtained, either setting it to zero or not reporting the estimate. The consequences of these practices are investigated in the context of the intraclass correlation estimation in terms of bias, variance and mean squared error (MSE). For the one-way analysis of variance random effects model and its extension to the common correlation model, we compare five estimators: analysis of variance (ANOVA), concentrated ANOVA, truncated ANOVA and two maximum likelihood-like (ML) estimators. For the balanced case, the exact bias and MSE are calculated via numerical integration of the exact sample distributions, while a Monte Carlo simulation study is conducted for the unbalanced case. The results indicate that the ANOVA estimator performs well except for designs with family size n = 2. The two ML estimators are generally poor, and the concentrated and truncated ANOVA estimators have some advantages over the ANOVA in terms of MSE. However, the large biases may make the concentrated and truncated ANOVA estimators objectionable when intraclass correlation () is small. Bias should be a concern when a pooled estimate is obtained from the literature since <0.05 in many genetic studies. 相似文献
59.
Summary A technique is described for measuring the approximate exchange rates of the more labile amide protons in a protein. The technique relies on a comparison of the intensities in1H–15N correlation spectra recorded with and without presaturation of the water resonance. To distinguish resonance attenuation caused by hydrogen exchange from attenuation caused by cross relation, the experiment is repeated at several different pH values and the difference in attenuation of any particular amide resonance upon presaturation is used for calculating its exchange rate. The technique is demonstrated for calmodulin and for calmodulin complexed with its binding domain of skeletal muscle myosin light chain kinase. Upon complexation, increased amide exchange rates are observed for residues Lys75 through Thr79 located in the central helix of calmodulin, and for the C-terminal residues Ser147 and Lys148. In contrast, a decrease in amide exchange rate is observed at the C-terminal end of the F helix, from residues Thr110 through Glu114.Istituto Guido Donegani, Novara, Italy 相似文献
60.