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41.
A pressurized liquid extraction (PLE) and high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed for the qualitative determination of saponins in different parts of P. notoginseng, including rhizome, root, fibre root, seed, stem, leaf and flower. The samples were extracted using PLE. The analysis was achieved on a Zorbax SB-C18 column with gradient elution of acetonitrile and 8 mM aqueous ammonium acetate as mobile phase. The mass spectrometer was operated in the negative ion mode using the electrospray ionization, and a collision induced dissociation (CID) experiment was also carried out to aid the identification of compounds. Forty one saponins were identified in different parts of P. notoginseng according to the fragmentation patterns and literature reports, among them, 21 saponins were confirmed by comparing the retention time and ESI-MS data with those of standard compounds. The results showed that the chemical characteristics were obviously diverse in different parts of P. notoginseng, which is helpful for pharmacological evaluation and quality control of P. notoginseng. 相似文献
42.
In this article we establish necessary and sufficient conditions for the existence and the expressions of the general real solutions to the classical system of quaternion matrix equations A 1 XB 1 = C 1, A 2 XB 2 = C 2. Moreover, formulas of the maximal and minimal ranks of four real matrices X 1, X 2, X 3, and X 4 in solution X = X 1 + X 2 i + X 3 j + X 4 k to the system mentioned above are derived. As applications, we give necessary and sufficient conditions for the quaternion matrix equations A 1 XB 1 = C 1, A 2 XB 2 = C 2, A 3 XB 3 = C 3 to have common real solutions. In addition, the maximal and minimal ranks of four real matrices E, F, G, and H in the common generalized inverse of A 1 + B 1 i + C 1 j + D 1 k and A 2 + B 2 i + C 2 j + D 2 k, which can be expressed as E + Fi + Gj + Hk are also presented. 相似文献
43.
In this paper, we consider the linear parameterized inverse eigenvalue problem of bisymmetric matrices which is described as follows: 相似文献
44.
In this paper, we consider matrices with entries from a semiring S. We first discuss some generalized inverses of rectangular and square matrices. We establish necessary and sufficient conditions for the existence of the Moore–Penrose inverse of a regular matrix. For an m×n matrix A , an n×m matrix P and a square matrix Q of order m, we present necessary and sufficient conditions for the existence of the group inverse of QAP with the additional property that P(QAP)#Q is a {1,2} inverse of A . The matrix product used here is the usual matrix multiplication. The result provides a method for generating elements in the set of {1,2} inverses of an m×n matrix A starting from an initial {1} inverse of A . We also establish a criterion for the existence of the group inverse of a regular square matrix. We then consider a semiring structure (Mm×n(S),+,°) made up of m×n matrices with the addition defined entry-wise and the multiplication defined as in the case of the Hadamard product of complex matrices. In the semiring (Mm×n(S),+,°), we present criteria for the existence of the Drazin inverse and the Moore–Penrose inverse of an m×n matrix. When S is commutative, we show that the Hadamard product preserves the Hermitian property, and provide a Schur-type product theorem for the product A°(CC?) of a positive semidefinite n×n matrix A and an n×n matrix C. 相似文献
45.
Let S be a given set consisting of some Hermitian matrices with the same size. We say that a matrix A ∈ S is maximal if A − W is positive semidefinite for every matrix W ∈ S. In this paper, we consider the maximal and minimal inertias and ranks of the Hermitian matrix function f(X,Y) = P − QXQ* − TYT*, where * means the conjugate and transpose of a matrix, P = P*, Q, T are known matrices and for X and Y Hermitian solutions to the consistent matrix equations AX =B and YC = D respectively. As applications, we derive the necessary and sufficient conditions for the existence of maximal matrices of
H = { f(X,Y) = P - QXQ* - TYT* : AX = B,YC = D,X = X*, Y = Y*} .H = \{ f(X,Y) = P - QXQ* - TYT* : AX = B,YC = D,X = X*, Y = Y*\} . 相似文献
46.
47.
Investigation of 4H—SiC metal—insulation—semiconductor structure with Al2O3/SiO2 stacked dielectric
![]() Atomic layer deposited (ALD) Al2O3/dry-oxidized ultrathin SiO2 films as high-k gate dielectric grown on the 8° off-axis 4H-SiC (0001) epitaxial wafers are investigated in this paper. The metal-insulation-semiconductor (MIS) capacitors, respectively with different gate dielectric stacks (Al2O3/SiO2, Al2O3, and SiO2) are fabricated and compared with each other. The I-V measurements show that the Al2O3/SiO2 stack has a high breakdown field ( ≥ 12 MV/cm) comparable to SiO2, and a relatively low gate leakage current of 1× 10-7 A/cm2 at electric field of 4 MV/cm comparable to Al2O3. The 1-MHz high frequency C-V measurements exhibit that the Al2O3/SiO2 stack has a smaller positive flat-band voltage shift and hysteresis voltage, indicating less effective charge and slow-trap density near the interface. 相似文献
48.
Influence of geometrical parameters on the behaviour of SiC merged PiN Schottky rectifiers with junction termination extension
![]() This paper investigates the behaviours of 4H--SiC merged
PiN Schottky (MPS) rectifiers with junction termination extension
(JTE) by extensive numerical simulations. The simulated results show
that the present model matches the experimental data very well. The
influences of the JTE design parameters such as the doping
concentration and length of the JTE on the breakdown characteristics
are discussed in detail. Then the temperature sensitivity of the
forward behaviour is studied in terms of the different designs of
4H--SiC MPS with JTE, which provides a particularly useful guideline
for the optimal design of MPS rectifiers with JTE. 相似文献
49.
通过在稳定连续波运转的Yb:YAG 激光器中插入不同掺杂浓度的新型钠、镱共掺的氟化钙晶体的对比性实验,证明了镱、钠共掺的氟化钙晶体在1050nm具有明显的可饱和吸收作用,从而解释了该晶体作为增益介质在该波段总是趋于自调Q运转的原因.Yb3+离子是该晶体可饱和吸收作用的主要因素,但是共掺入适当的Na离子可以明显改善晶体的调Q效果.优化共掺镱、钠离子的浓度和比例后的氟化钙晶体能够作为1050nm波段激光器的被动Q开关.
关键词:
镱、钠共掺氟化钙
可饱和吸收体
调Q 相似文献
50.
Simulation research on offset field-plate used as edge termination in 4H-SiC merged PiN-Schottky diodes
![]() A new structure of 4H--silicon carbide (SiC) merged
PiN-Schottky (MPS) diodes with offset field-plate (FP) as edge
termination is developed. To understand the influences of 4H--SiC
MPS diodes with offset FP on the characteristics, simulations have
been done by using ISE TCAD. Related factors of offset FP have been
studied as well to optimise the reverse characteristics of 4H--SiC
MPS diodes. The simulation results show that the device using offset
FP can create a higher blocking voltage under reverse bias as
compared with that using field guard rings. Besides, the offset FP
does not cause any extra steps in the manufacture of MPS diodes. 相似文献
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