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31.
32.
麻黄中伪麻黄碱在小鼠组织中的分布研究 总被引:1,自引:0,他引:1
为了解麻黄(Herba ephedrae,简称HE)中伪麻黄碱(Pseudoephedrine,简称PE)在小鼠脑、肺、心、肝、肾的分布变化,探讨HE的归经,用GC-MS/SIM法,分析了用药后30、60、120 min PE在小鼠脏器分布量。结果表明,PE于不同时间点在小鼠脏器的分布由多到少的顺序是:30 min时,肺脏(肾脏、肝脏、脑),心脏;60 min时,肾脏,心脏(肝脏),脑,肺脏;120 min时,脑,肾脏,心脏,肝脏(肺脏)。本试验从PE在小鼠体内脏器的分布量初步反映了HE的归经趋势。 相似文献
33.
A. Hazra K. Alexander D. Dollimore A. Riga 《Journal of Thermal Analysis and Calorimetry》2004,75(1):317-330
The present study was aimed at determining the kinetics of evaporation and establishing vapor pressure curves for both single and multi-component systems by thermogravimetry (TG) and differential scanning calorimetry (DSC). Essential oils (e.g. lavender oil, orange oil, clove oil and eucalyptus oil, etc.) are typically multi-component systems consisting of various volatile pure components (e.g. linalyl acetate, limonene, cinnamaldehyde, etc.) which resemble single component systems. In this study linalyl acetate was taken as the calibration compound for TG. The vapor pressure curves for the pure substances were plotted using TG and vapor pressure plots for clove oil and eucalyptus oil were constructed using DSC. The thermodynamic and kinetic parameters of the pure compounds were compared to that of the multi-component systems to quantitatively and qualitatively measure the influence of different compounds on each other. The k-value from the vapor pressure data for linalyl acetate was calculated as 112006 Pa kg0.5mol0.5s-1 m-2 K-0.5. The vapor pressure values were used to determine the Antoine constants using the SPSS 10.0 software.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
34.
Keller Hildegard Langer Elisabeth Lehner Harald Derflinger Gerhard 《Theoretical chemistry accounts》1978,49(2):93-100
The Algebraic Theory of Chirality Functions is derived by means of exclusively qualitative considerations. Hence, the significance of quantitative results is questionable. Moreover the construction of “Näherungsansätze” (”Approximation-Ansatz”), which may be interpreted as semiempirical methods, is achieved on the basis of plausibility and mathematical simplicity. Since physical arguments are not included, the consistency or inconsistency of “Näherungsansätze” with experimental results do not justify direct physical conclusions. 相似文献
35.
The inhibitory effect of a series of neutral lipophilic solutes (methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-amylalcohol, n-hexanol, diethylether, nitrobenzene, and pyridine) on the diffusional water permeability (Pd, tot) of bovine erythrocyte membrane at 25 degrees C was studied in comparison to that of p-chloromercuri benzoate (pCMB). Permeability data were obtained by measuring the transmembrane diffusional water exchange time tau(exch) using an 1H-T2 NMR technique. Maximal inhibition by approximately 50% of Pd, tot was produced by 2 mM pCMB which completely blocked the membrane water channels in 20 min, hence suggesting the channel-to-lipid diffusional water permeability ratio of about 1:1. Furthermore, the maximal inhibitory effect of pCMB in combination with the lipophilic solutes was lower than that of pCMB alone. As pCMB does not interfere with the lipid bilayer, and provided that it blocks the water channels in solute presence as well, this confirms that the solutes induce an increase in the lipid-mediated background water permeability contribution (Pd, lipid) by the formation of aqueous leaks in the membrane hydrophobic barrier. However, faster but less efficient in permeability inhibition than pCMB (either alone or combined with solutes) were the lipophilic solutes alone. Taken together, the results indicate that the lipophilic solutes suppress the membrane total permeability Pd, tot by two opposing effects: a reduction of its channel-mediated part (Pd, channel) to the extent exceeding that of a simultaneous Pd, lipid increase. The inhibitory potency of the solutes tested appears to be correlated with their solubility in the membrane medium. 相似文献
36.
K. H. C. Baser H. R. Nuriddinov T. Ozek B. Demirci N. Azcan A. M. Nigmatullaev 《Chemistry of Natural Compounds》2002,38(1):51-53
The herbal parts of Arischrada korolkowii (Regel et Schmalh.) Pobed. (Lamiaceae) growing in Uzbekistan were hydrodistillated to yield 1.1% of essential oil. The essential oil was analyzed by GC/MS. Eighty eight compounds were characterized representing 98% of the essential oil with 1,8-cineole (29.3%), camphor (9.8%), -caryophyllene (8.5%), bornyl acetate (7.7%), caryophyllene oxide (7.2%), and borneol (5.6%) as the main constituents. 相似文献
37.
38.
The structural and magnetic properties of a new ternary Ir-Mn-Ge phase, Mn3IrGe, as well as the solid solution Mn3Ir(Si1−xGex), 0?x?1, have been investigated by means of X-ray and neutron powder diffraction, magnetization measurements and first principles calculations. The crystal structure is cubic, of the AlAu4-type (an ordered form of the β-Mn structure), Z=4, space group P213, and the unit-cell dimension varies linearly with the silicon content. For all compositions, antiferromagnetic ordering is found below a critical temperature of about 225 K. The magnetic structure is noncollinear, as a result of frustrated magnetic interactions on a triangular network of Mn atoms, on which the moments rotate 120° around the triangle axes. The magnitude of the magnetic moment at 10 K is 3.39(4) μB for Mn3IrGe. The theoretical calculations reproduce with very good accuracy the magnitudes as well as the directions of the experimentally observed magnetic moments. 相似文献
39.
We study the two-dimensional first passage problem in which bonds have zero and unit passage times with probabilityp and 1–p, respectively. We prove that as the zero-time bonds approach the percolation thresholdp
c, the first passage time exhibits the same critical behavior as the correlation function of the underlying percolation problem. In particular, if the correlation length obeys(p) ¦p–p
c¦–v, then the first passage time constant satisfies(p)¦p–p
c¦v. At pc, where it has been asserted that the first passage time from 0 tox scales as ¦x¦ to a power with 0<<1, we show that the passage times grow like log ¦x¦, i.e., the fluid spreads exponentially rapidly. 相似文献
40.