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951.
Several Polygonatum species are important medicinal materials as tonic to cure disorders in China. Because of their different medical effects, it is desired to distinguish them at species level. In addition, to ensure and control their medical quality, it is also important to monitor their chemical changes associated with traditional process. Taking the advantages of Fourier transform infrared spectroscopy (FT-IR) and multivariate analysis, we developed a convenient, fast and reliable approach to discriminate and quality control these materials. Despite similar absorption patterns, each species also presented spectral differences, especially on the FT-IR fingerprint range of 1800-600 cm−1. Second derivative method obviously enlarged those differences and then showed more species-specific features. These spectral differences could be used as powerful discriminating points to distinguish them. PCA results showed that each species separated clearly with their biological replicates grouped together, which indicated that the variance between species is greater than within species, therefore, these species could be distinguishable. Using this approach, the five herbal materials were discriminated successfully in their raw, processed and ethanol extracted formats. On the other hand, visual inspecting infrared spectra of samples from 1 to 9 process steps, absorbance near 1737, 1259, 817 and 780 cm-1 increased gradually but decreased gradually at 927 cm−1. Besides, spectral contour near 1050 cm−1 changed sharply with process treatment. These spectral changes indicated that hydrolyzing polysaccharides into oligo- and mono-saccharides, especially glucose and fructose, are the main chemical changes associated with traditional process. This is consistent with the traditional experience that the processed materials are dark as night and sweet as malt sugar. Meanwhile, our results also indicated that their chemical constituents changed profoundly after process, which might be the chemical basis for raw and processed materials have different medical effects. Based on absorbance at 817 and 780 cm−1 and the color, taste, smell of processed materials followed by energy efficacy, raw materials had to be processed more than 21 h to ensure their quality. This research shows the potential of FT-IR spectroscopy coupled with multivariate analysis to discriminate different herbs and to monitor chemical changes with process and then control their quality. This could be very helpful to ensure the quality, safety, and efficacy of herbs on clinical practices. 相似文献
952.
A general reduction method for periodic solutions in conservative and reversible systems 总被引:1,自引:0,他引:1
Jürgen Knobloch André Vanderbauwhede 《Journal of Dynamics and Differential Equations》1996,8(1):71-102
We introduce a general reduction method for the study of periodic solutions near equilibria in autonomous systems which are either conservative or reversible. We impose no restrictions on the linearization at the equilibrium, allowing higher multiplicities and all kinds of resonances. It is shown that the problem reduces to a similar problem for a reduced system, which is itself conservative or reversible, but also has an additionalS
1-symmetry. This symmetry allows to immediately write down the bifurcation equations. Moreover, the reduced system can be calculated up to any order by a normal form reduction on the original system. The method of proof combines normal forms with the Liapunov-Schmidt method. A similar approach was already introduced for Hamiltonian systems in [9], and for equivariant systems in [3]; this paper extends the results of these papers to the cases of conservative and reversible systems.The research in this paper was supported by the EEC Science Project on Bifurcation Theory and Its Applications. 相似文献
953.
L. Brian Lawrence 《Transactions of the American Mathematical Society》1996,348(1):187-203
We prove in ZFC that the box product of many copies of is neither normal nor collectionwise Hausdorff. As an addendum to the proof, we show that if the cardinality of the continuum is , then these properties also fail in the closed subspace consisting of all functions which assume the value on all but countably many indices.
954.
Osamu Saeki Kazuhiro Sakuma 《Transactions of the American Mathematical Society》1996,348(7):2585-2606
We give two congruence formulas concerning the number of non-trivial double point circles and arcs of a smooth map with generic singularities --- the Whitney umbrellas --- of an -manifold into , which generalize the formulas by Szücs for an immersion with normal crossings. Then they are applied to give a new geometric proof of the congruence formula due to Mahowald and Lannes concerning the normal Euler number of an immersed -manifold in . We also study generic projections of an embedded -manifold in into and prove an elimination theorem of Whitney umbrella points of opposite signs, which is a direct generalization of a recent result of Carter and Saito concerning embedded surfaces in . The problem of lifting a map into to an embedding into is also studied.
955.
Mohamed Sifi 《Journal of Theoretical Probability》1995,8(3):475-499
We provide
相似文献
956.
The basic theorem presented shows that the product of a linearly ordered space and a countable (regular) space is normal. We prove that the countable space can be replaced by any of a rather large class of countably tight spaces. Examples are given to prove that monotone normality cannot replace linearly ordered in the base theorem. However, it is shown that the product of a monotonically normal space and a monotonically normal countable space is normal.
957.
Chunlan Jiang Shunhua Sun Zongyao Wang 《Transactions of the American Mathematical Society》1997,349(1):217-233
It is shown that given an essentially normal operator with connected spectrum, there exists a compact operator such that is strongly irreducible.
958.
M. D. Buhmann 《Constructive Approximation》1990,6(1):21-34
Let
or
. Givenf:
n
, we establish convergence orders of interpolation where the cardinal functionx withx(j)=0j
is a linear combination of integer shifts, of a fast decaying function
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