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281.
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283.
A method is developed, based on word-searching, which provides a rapid test for the statistical significance of DNA sequence similarities for use in databank searching. The method makes allowance for the lengths and dinucleotide compositions of the sequences being compared. A way is also described to calculate the power of the test, i.e. the probability of detecting a given similarity as being statistically significant. The effects on the power of the test of the scoring method, word length, sequence length, and sequence composition are examined. A novel scoring method is shown to be superior to the method currently used in most word-searching algorithms. 相似文献
284.
The synthesis of hydrocarbons via hydrogenation of carbon monoxide was investigated over cobalt—nickel—zirconia catalysts of various compositions in combination with zeolite HZSM-5 in “mixed bed” and “follow bed” arrangements. These combinations resulted in the formation of aromatics in amounts as high as 30-35 wt% under relatively mild operating conditions (1 atm, 250–280°C). Although the olefinicity of C2 and C3 fractions in the product stream was higher in the mixed bed compared to the follow bed arrangement, the selectivities to aromatics were comparable in the two bed arrangements. The aromatic selectivity was found to be sensitive to operating conditions. The formation of aromatics was favored at high HZSM-5/metal catalyst ratios, low space velocities and high reaction temperatures. The product distributions obtained using various metal/zeolite bifunctional catalysts have been discussed. 相似文献
285.
286.
A new diffuser capable of scattering light in one direction (one-dimensional diffuser) has been developed and experimentally
tested. The diffuser is formed in a thick layer of dichromated gelatin. The scattering indicatrices of the diffuser measured
in two mutually perpendicular directions are presented. It is demonstrated that the indicatrix width in one direction is significantly
greater than that in the perpendicular direc-tion. However, no zero-order diffraction has been observed. The proposed one-dimensional
diffuser exhibits close scattering indicatrices for reading at a wavelength of 0.44 and 0.63 μm. 相似文献
287.
A method of measuring static and pulsed pressures using electrically conducting rubber sensors is proposed. The method is
based on a change in the volume resistivity of a filled rubber under the action of external pressure. The pressure-induced
change in resistance of the rubber sensor is proportional to the applied pressure and can be measured by a bridge circuit.
Using this method, it is possible to evaluate the degree of homogeneity of the pressure distribution over a solid surface.
This is achieved by distributing rubber sensors over the given surface. 相似文献
288.
Conclusions The chemical mutagenesis method is recommended for use in local purification installations for cleaning up of caprolactam-containing wastewater.Use of this method permits one to carry out a biochemical clean-up of wastewater having a caprolactam content up to 600 mg/liter while increasing the oxidative power of the aeration tank by a factor of two.Translated from Khimicheskie Volokna, No. 6, p. 46, November–December, 1985. 相似文献
289.
Research suggests that predictable electric shocks produce less stress than unpredictable shocks. In this experiment, predictability was manipulated by using fixed-time (FT, predictable) and variable-time (VT, unpredictable) schedules of shock delivery. Rats receiving 3-mA, 1-s electric shocks on a FT 45-s schedule developed less gastric pathology than another group that was administered identical shocks on a VT 45-s schedule. It is argued that this finding represents a more subtle effect of predictability than has been obtained heretofore. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
290.
Changes in the phase compositions and microstructures of magnesia-partially-stabilized zirconia (Mg-PSZ) were studied in water at 80–300 °C, 1 m HCl solutions at 80–140 °C and 1 m CH3COOH-CH3COONa buffer solutions at pH 3 and 80–140 °C for 10–40 days. The tetragonal to monoclinic phase transformation and the degradation of the fracture strength occurred in water above 200 °C. On the other hand, although no noticeable tetragonal to monoclinic phase transformation proceeded in 1 m HCl solutions and 1 m CH3COOH-CH3-COONa buffer solutions at pH 3 below 140 °C, the fracture strength of Mg-PSZ greatly degraded. The dissolution of Mg2+ ion was observed in water above 200 °C and in 1 m HCl solutions above 80 °C. 相似文献