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991.
992.
Mutual precipitates of poly (N, N-dimethyl acrylamide) and poly (4-hydroxystyrene) were collected from dioxane, methanol, or acetone. The glass transition (Tg) temperatures of the precipitates are higher than the weight-average values. Clear films cast from dimethylformamide solutions have lower Tg values. Complexation also occurred between poly (ethyl oxazoline) and poly (4-hydroxystyrene) in dioxane and between poly (vinyl pyrrolidone) and poly (4-hydroxystyrene) in methanol. Again, the glass transition temperatures of the precipitates are higher than the values for the blend films. The ΔCp values associated with the glass transitions of the complexes are smaller than those of the blends having the same compositions. Negative excess heat capacities of mixing have been observed for several precipitates. 相似文献
993.
A simple High performance liquid chromatographic (HPLC) method for the specific determination of the molecular weight and concentration of hyaluronic acid (HA) in complex mixtures has been developed. Hyaluronate-binding proteins isolated from bovine cartilage labelled by 125I or fluoresceinisothiocyanate were used as specific markers. The specific binding affinities of the markers were compared and were found to have association constants of 1.6 x 10(7) M-1 and 1.2 x 10(7) M-1 respectively. The HA levels and molecular weight distributions can be easily determined in the range 10-500 ng/mL in complex mixtures by the use of markers, molecular sieving HPLC columns and appropriate detectors. It has been demonstrated clearly that the method is useful for the highly specific determination of the parameters in complex biological samples such as serum and synovial fluids and is recommended for clinical applications. 相似文献
994.
995.
A three-phase model of a hybrid chiral quark bag is proposed. In addition to the phases of asymptotically free current quarks
and of totally colorless mesons, the model contains the intermediate phase of massive constituent quarks. A self-consistent
solution with an account for the “Dirac sea” contribution is found in the (1+1)-dimensional case. The dependence of the bag
parameters on the parameters of the theory is investigated analytically and numerically.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 117, No. 2, pp. 263–299, November, 1998. 相似文献
996.
Studies of breakdown threshold intensity for air at various pressures in the range of 24–760 torr using 0.355, 0.532 and 1.06
μm radiation are reported. We observep
−0.8 scaling ofI
th at 1.06 μm and a weak scaling ofp
−0.4 at 0.532 and 0.355 μm radiation. Strong dependence of breakdown spot size on laser power but weak dependence on air pressure
is observed. 相似文献
997.
The new olefinic substituted aminodisilanes, which are obtained from the reaction of organometallic reagents with aminochlorodisilanes, are converted into the chlorodisilanes by equilibration reactions or treatment with HCI. The resulting olefinic functionalized disilanes are identified by means of 29Si, 13C, 1H NMR and GC MS measurements. 相似文献
998.
L. A. Chetkina V. E. Zavodnik A. N. Sobolev V. K. Bel'skii B. P. Bespalov A. G. Abolin 《Journal of Structural Chemistry》1991,32(3):442-445
L. Ya. Karpov Physical Chemical Research Institute. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 3, pp. 141–144, May–June, 1991. 相似文献
999.
The use of a direct liquid introduction type liquid chromatographic-mass spectrometric interface to study highly thermally labile rifamycin antibiotics is described. Using negative ionization, abundant molecular ions were observed, and the spectra, also contained structurally significant fragments. Variation of the high-performance liquid chromatographic parameters did not change the spectra, thus making it easy to change chromatographic conditions. In quantitative studies, a surprising correlation was found, indicating that the mass spectrometric signal was proportional to the square of the sample concentration. 相似文献
1000.