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991.
Xue Bai Wan Qi Shi Hua Feng Chen Ping Zhang Ying Li Shu Fan Yin 《Chemistry of Natural Compounds》2012,48(1):60-65
New 4-chalcone ursolate and 1-acetyl-3-(4-phenyl)-4,5-dihydro-2-pyrazoline-5-phenyl ursolate derivatives were synthesized
by esterification of UA and chalcone or pyrazoline. The compounds were structurally confirmed by IR, 1H NMR, 13C NMR, and HR-MS spectroscopy. The cytotoxicity of ten derivatives was evaluated against A549, SKOV3, and HepG2 cell lines
by MTT assay. The result showed that several compounds were more potent than UA against A549 and SKOV3 cells; however, none
of them were more potent than UA against HepG2. 相似文献
992.
A series of novel bis-pyrazole/pyridine complexes, [Zn(2)(HL(1))(2)(μ(2)-SO(4))](2)·EtOH·H(2)O (1), [Co(2)(HL(1))(2)(μ(2)-SO(4))](2)·2DMF·6H(2)O (2), [Zn(4)(HL(1))(4)(μ(4)-SO(4))][OH](2) (3), [Zn(2)(HL(2))(2)(μ(2)-SO(4))]·2H(2)O (4), [Zn(H(2)L(2))(H(2)O)(2)](SO(4))·0.87H(2)O (5) (H(2)L(1) = 2,6-di-(5-phenyl-1H-pyrazol-3-yl)pyridine, H(2)L(2) = 2,6-di-(5-methyl-1H-pyrazol-3-yl)pyridine), were synthesized hydrothermally from the self-assembly of Zn(II) or Co(II) with different types of bipyrazolyl/pyridine derivative ligands. All the complexes were characterized by elemental analysis, IR and UV-vis spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction. Structural analyses revealed that metal atoms (Zn and Co) in complexes 1-5 are five-coordination modes, forming slightly distorted trigonal bipyramidal geometries. In complexes 1-3, H(2)L(1) ligand connected the two metal centers via the tetradentate fashion, and the same form of connection was found in complex 4 with H(2)L(2) ligand. While in complex 5, H(2)L(2) only connected with one metal center via the tridentate fashion, which was different from those in complexes 1-4. Additionally, there are abundant hydrogen bonding interactions in complexes 1-4. Interestingly, for hydrogen bonding connecting fashions being different, the molecules for the complexes 1 and 4 are held together by the hydrogen bond to form a 1D supramolecular structure, whereas complexes 2 and 3 are a hydrogen bonded dimer. In addition, quantum chemical calculations for 1, 3, and 4, thermal behaviors and photoluminescent properties for 1 and 3-5 were performed and discussed in detail. In the mean time, we found that these complexes had potential catalytic activity for the oxidation reaction of cyclohexane. 相似文献
993.
We investigate the electronic transport properties for a molecular device model constructed by a phenylene ethynylene oligomer molecular with different side groups embedding in a carbon chain between two graphene electrodes. Using the first-principles method, the unusual dual conductance, negative differential resistance (NDR) behavior with large peak to valley ratio, and obvious rectifying performance are numerically observed in such proposed molecular device. The analysis of the molecular projected self-consistent Hamiltonian and the evolution of the frontier molecular orbitals (MOs) as well as transmission coefficients under various external voltage biases gives an inside view of the observed results, which suggests that the dual conductance behavior and rectifying performance are due to the asymmetry distribution of the frontier MOs as well as the corresponding coupling between the molecule and electrodes. But the NDR behavior comes from the conduction orbital being suppressed at certain bias. Interestingly, the conduction properties can be tuned by introducing side groups to the molecule and the rectification as well as the NDR behavior (peak to valley ratio) can be improved by adding different side groups in the device model. 相似文献
994.
An efficient rhodium/olefin-sulfoxide catalyzed asymmetric conjugate addition of organoboronic acids to a variety of nitroalkenes has been developed, where 2-methoxy-1-naphthyl sulfinyl functionalized olefin ligands have shown to be highly effective and are applicable to a broad scope of aryl, alkyl, and heteroaryl nitroalkenes. 相似文献
995.
996.
Porous polycaprolactone/chitosan blend scaffolds with various compositional proportions were prepared using a particulate‐leaching method. The pore parameters of resultant scaffolds were found to be mainly modulated by porogen. The compressive mechanical properties and hydrophilicity of scaffolds were examined by measuring their compressive modulus and stress strength as well as swelling index. Selected chondrocytes isolated from articular cartilage of knee joints of rabbits were seeded on these scaffolds, and further in vitro cultured for various periods. The growth and activity of seeded cells were estimated by counting numbers of cells proliferated on scaffolds and measuring the amounts of proteoglycans and type II collagen synthesized by the seeded cells. It was found that some scaffolds composed of proper component ratios and having appropriate pore parameters exhibited promising characteristics for the adhesion and proliferation of seeded cells while maintaining the phenotype and activity of the cells. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
997.
Wan‐Ling Liu Yi‐Fen Hsu Yu‐Wei Liu Brenda Singco Ssu‐Wei Chen Hsi‐Ya Huang Ting‐Yu Chin 《Electrophoresis》2012,33(19-20):3008-3011
In this study, a rapid and sensitive method is described for the catecholamines detection in rat brain. CE with LIF detection for the determination of FITC derivatized catecholamines (dopamine, epinephrine, and norepinephrine) was demonstrated. Conventional water bath and microwave‐assisted derivatization methods were employed and a significant reduction in the derivatization time from 2 h for the conventional water bath at room temperature (ca. 25°C) to 2 min for the microwave‐assisted derivatization was achieved. Online sample concentration of field‐amplified sample stacking (FASS) method was employed to achieve higher sensitivities (the detection limits obtained in the normal injection mode ranged from 2.6 to 4.5 ng L?1 and in the FASS mode ranged from 22 to 34 pg L?1). Furthermore, this microwave‐assisted derivatization CE–LIF method successfully determined catecholamines in rat brain with as low as 100 ng L?1 (FASS mode) to 10 μg L?1 (normal injection mode). This CE–LIF method provided better detection ability when compared to the best reports on catecholamines analyses. 相似文献
998.
Zal U’yun Wan Mahmood Nik Azlin Nik Ariffin Abdul Kadir Ishak Norfaizal Mohamed Mei Wo Yii Kamaruzaman Ishak Zainab Pa’wan 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):901-906
A method is described for the determination of 90Sr in environmental samples using combination of developed in-house method, Eichrom Sr resin and Beta Counter. Strontium was
efficiently, rapidly and simply separated from Ca and other interfering matrix components by Eichrom Sr resin. All the results
in general showed good accuracy, high precision, reliable and in good agreement between these two measured and certified value
of SRM (i.e. IAEA-375, IAEA-326, IAEA-152 and IAEA-414). As a whole, the procedure described in this work notably improves
conventional methods in particular concerning the time needed, sample volume, safer and others. Thus, the introduced method
was successfully performed and will be applied to actual sample for the determination of 90Sr in different environmental materials such as soil, sediments, milk, biological sample, water etc. 相似文献
999.
研究了广义Ekeland变分原理在拟度量空间中的一些重要应用.利用广义Ekeland变分原理证明了函数f满足关于α的Takahashi ε-条件当且仅当f满足关于相同α的Hamel ε-条件.此外,利用关于α的Takahashi ε-条件得到了一些重要结论. 相似文献
1000.
We study the structure of a metric n-Lie algebra G over the complex field C. Let G = SR be the Levi decomposition, where R is the radical of G and S is a strong semisimple subalgebra of G. Denote by m(G) the number of all minimal ideals of an indecomposable metric n-Lie algebra and R ⊥ the orthogonal complement of R. We obtain the following results. As S-modules, R ⊥ is isomorphic to the dual module of G/R. The dimension of the vector space spanned by all nondegenerate invariant symmetric bilinear forms on G is equal to that of the vector space of certain linear transformations on G; this dimension is greater than or equal to m(G) + 1. The centralizer of R in G is equal to the sum of all minimal ideals; it is the direct sum of R ⊥ and the center of G. Finally, G has no strong semisimple ideals if and only if R⊥■R. 相似文献