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941.
Sandra Cruz Sylvain Bernès Pankaj Sharma Rosa Vazquez Guadalupe Hernández Roberto Portillo René Gutiérrez 《应用有机金属化学》2010,24(1):8-11
Optically pure α‐diimines quantitatively obtained in solvent‐free conditions starting from 2,3‐butanedione and (S)‐(?)‐1‐phenylethylamine and (S)‐(?)‐1‐(4‐methylphenyl)ethylamine, respectively, yielded the new chiral mono‐Pd complexes 2a–b, which have been partly characterized by IR, 1H‐ and 13C‐NMR spectroscopies along with MS‐FAB+ spectrometry. The crystal and molecular structure for palladacycle 2a has been fully confirmed by single‐crystal X‐ray studies. Studies in vitro of 2a–b have displayed growth inhibition against different classes of cancer: leukemia (K‐562 CML), colon cancer (HCT‐15), breast cancer (MCF‐7), central nervous system (U‐251 Glio) and prostate cancer (PC‐3) cell lines. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
942.
GMM-based Wald tests tend to overreject when used for small samples, mainly due to inaccurate estimation of the weighting matrix. This article proposes applying the shrinkage method to address this problem. Using a possibly-misspecified factor model, the shrinkage method can provide a good estimator for the weighting matrix, and hence improve the finite-sample performance of the GMM-based Wald tests. 相似文献
943.
944.
945.
S. Shanmuga Sundara Raj Hoong‐Kun Fun Jing Zhang Ren‐Geng Xiong Xiao‐Zeng You 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):e274-e275
In the crystal structure of the title compound, C12H10N4, the pyridine ring makes a dihedral angle of 1.12 (9)° with the mean plane of the complete almost planar and crystallographically centrosymmetric molecule. There are stacks of parallel molecules along the a‐axis direction, with alternate stacks having a herring‐bone arrangement relative to each other and an interplanar spacing of 3.551 Å. 相似文献
946.
We begin with proposing a unitary operator responsible for diagonalizing the Hamiltonian with kinetic couplings in particle
physics to get a new form of Hamiltonian which has no coupling terms. By virtue of the invariant eigen-operator (IEO) method
we search for the invariant eigen-operators for the new Hamiltonian. In this way the energy-gap of the Hamiltonians can be
naturally obtained. This method may be generalized to N-mode Hamiltonian with kinetic couplings case.
Work supported by the National Natural Science Foundation of China under grant 10475056 and Foundation of President of Chinese
Academy of Science. 相似文献
947.
High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its
bright parent star. A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error
of an optical system. We derive an algorithm for the wave-front measurement directly from 3 focal plane images. The 3 images
are achieved through a deformable mirror to provide specific phases for the optics system. We introduce an extra amplitude
modulation on one deformable mirror configuration to create an uncorrelated wave-front, which is a critical procedure for
wave-front sensing. The simulation shows that the reconstructed wave-front is consistent with the original wave-front theoretically,
which indicates that such an algorithm is a promising technique for the wave-front measurement for the high-contrast imaging.
Supported by the National Natural Science Foundation of China (Grant No. 10873024) 相似文献
948.
In this paper, an optimal criterion is presented for adaptive Kalman filter in a control system with unknown variances of
stochastic vibration by constructing a function of noise variances and minimizing the function. We solve the model and measure
variances by using DFP optimal method to guarantee the results of Kalman filter to be optimized. Finally, the control of vibration
can be implemented by LQG method. 相似文献
949.
Yun Long ZHANG Liang Ren ZHANG* Zhen Jun YANG Ji Mei MIN Li He ZHANG* Yang LU Ning Bo GONG Qi Tai ZHENG National Research Laboratory of Natural Biomimetic Drugs Peking University Beijing Institue of Materia Medica Chinese 《中国化学快报》2001,(5)
Tubercidin (4-amino-7--D-riobofuranosyl-7-H-pyrrolo[2,3-d]pyrimidine) 1, an antibio-tic substance produced in the culture broth of Streptomyces tubericidus1, is an adenosine analog in which N-7 is replaced by a carbon atom. It has attracted much attention due to the biological activities for the growth inhibition of certain tumors, and many derivatives of tubercidin have been synthesized2-5.For the synthesis of tubercidin analogs, 4-chloro-7-H-pyrrolo[2,3-d]pyrimidine-2,3,5-tri-O-acetyl--D-r… 相似文献
950.
This paper presents a family of High‐order finite volume schemes applicable on unstructured grids. The k‐exact reconstruction is performed on every control volume as the primary reconstruction. On a cell of interest, besides the primary reconstruction, additional candidate reconstruction polynomials are provided by means of very simple and efficient ‘secondary’ reconstructions. The weighted average procedure of the WENO scheme is then applied to the primary and secondary reconstructions to ensure the shock‐capturing capability of the scheme. This procedure combines the simplicity of the k‐exact reconstruction with the robustness of the WENO schemes and represents a systematic and unified way to construct High‐order accurate shock capturing schemes. To further improve the efficiency, an efficient problem‐independent shock detector is introduced. Several test cases are presented to demonstrate the accuracy and non‐oscillation property of the proposed schemes. The results show that the proposed schemes can predict the smooth solutions with uniformly High‐order accuracy and can capture the shock waves and contact discontinuities in high resolution. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献