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991.
992.
Isolation and identification of new prenylated acetophenone derivatives from Acronychia oligophlebia
Qian-Wen Niu Neng-Hua Chen Zhong-Nan Wu Ding Luo Ying-Ying Li Yu-Bo Zhang 《Natural product research》2019,33(15):2230-2235
Three new prenylated acetophenone derivatives, acronyculatin P (1), acronyculatin Q (2), and acronyculatin R (3) were isolated from the leaves of Acronychia oligophlebia. Their structures were identified by extensive analyses of spectroscopic data (IR, UV, ESI-HRMS, 1D and 2D NMR) and comparison with the literatures. In addition, the cytotoxic activity against MCF-7 cells of the compounds were evaluated by the MTT assay and the IC50 values were 56.8, 40.4 and 69.1?μM, respectively. 相似文献
993.
A novel kinetic spectrophotometric method is described for the determination of rutin. The method is based on the inhibitory effect of rutin on the oxidation reaction of amaranth by potassium periodate in acidic media at 100 degrees C. The linear range for the determination of rutin is 0.02 - 0.50 microg/ml, and the detection limit is 0.014 microg/ml. The method has been successfully applied to the determination of rutin in medicine of rutin tablet and traditional Chinese medicine. 相似文献
994.
Copper-zinc heterometallic 1D chain coordination polymer has been synthesized and characterized by elemental analysis, and
IR spectra etc. The crystal structure was determined by single-crystal X-ray diffraction analyses. The title complex is 1D
chain coordination polymer with the chemical formula {[CuLZn·CuLZn(H2O)]·H2O}n, where H4L=N-(2-hydroxybenzamido)-N′-(3-carboxylsalicylidene)ethylenediamine. Its structural unit is comprosed of two tetranuclear
cycles formed by two dissymmetrical tetranuclear units. These units polymerized each other to form 1D chain coordination polymer. 相似文献
995.
De-Zhong Niu Lai-Long Mu Shou-Zheng Yu Jiu-Tong Chen 《Journal of chemical crystallography》2003,33(1):27-31
The synthesis as well as crystal and molecular structure of [Bi(C5H4NOS)3] are reported. The complex crystallizes in the monoclinic system, space group P21/n with lattice parameters a = 9.6521(3) Å, b = 10.0659(4) Å, c = 18.4484(7) Å, = 102.13(6)°, and D
calc = 2.227 Mg · m–3 for Z = 4. It is clear from the packing diagram that the title compound is a dimer via the secondary coordination. Surrounding Bi atom, three five-membered ring planes (Bi,O,N,C,S) make a dihedral angle of 55.91, 54.72, and 26.13° respectively. The whole crystal presents a three-dimensional network structure as each molecule produces four weak C–H O hydrogen bonds and a weak C–H S hydrogen bond. 相似文献
996.
997.
Reading the primary sequence directly using nanopores remains challenging due to the complex building blocks of 20 proteinogenic amino acids and the corresponding sophisticated structures. Compared to the uniformly negatively charged polynucleotides, biological nanopores hardly provide effective ionic current responses to all heterogeneously charged peptides under nearly physiological pH conditions. Herein, we precisely design a N226Q/S228K mutant aerolysin which creates a new electrostatic constriction named R3 in-between two natural sensing regions for controlling the capture and translocation of heterogeneously charged peptides. At nearly physiological pH, the decoration of positive charges at this constriction gives a large velocity of electroosmotic flow (EOF), leading to a maximum 8-fold increase in frequency for the heterogeneously charged peptides with the net charge from +1 to −3. Even the duration time of the negatively charged peptide Aβ35-25D4 in N226Q/S228K AeL also rises from 0.07 ± 0.01 ms to 0.63 ± 0.01 ms after introducing the third electrostatic constriction. Therefore, the N226Q/S228K aerolysin nanopore with three electrostatic constrictions realizes the dual goals of both capturing and decelerating heterogeneously charged peptides without labelling, even for the folded peptides.An engineered aerolysin nanopore captures all types of peptides despite the charges and folded structure, which facilitate the achievement of nanopore protein sequencing. 相似文献
998.
Zifang Zhao Yue Liu Fang Wan Shuai Wang Nannan Zhang Lili Liu Anyuan Cao Zhiqiang Niu 《中国化学快报》2021,32(2):594-597
The recent boom in large-scale energy storage system promotes the development of lithium-oxygen batteries because of their high theo retical energy density.However,their applications are still limited by the sluggish kinetic,insoluble discharge product deposition and the undesired parasitic reaction.Herein,the free-standing nitrogen doped reduced graphene oxide/Co(OH)_2(NRGO/Co(OH)_2) composite films were prepared by a facile hydrothermal method,The NRGO/Co(OH)_2 composite films display interconnected three-dimensional conductive network,which can not only promote the diffusion of O_2 and the transport of electrolyte ions,but also provide abundant storage space for discharge products.Moreover,the introduction of nitrogen-containing functional groups results in improved conductivity and electron adsorption ability,which can facilitate electron transport and enhance the surface catalytic activity.Combining with excellent catalytic performance,the lithium-oxygen batteries with NRGO/Co(OH)_2 composite film cathodes deliver low charge overpotential and excellent cycling performance. 相似文献
999.
A new method based on Lie-B(a)cklund symmetry method to solve the perturbed nonlinear evolution equations is presented. New approximate solutions of perturbed nonlinear evolution equations stemming from the exact solutions of unperturbed equations are obtained.This method is a generalization of Burde's Lie point symmetry technique. 相似文献
1000.
Xi‐Rui Zeng Xiao‐Niu Fang Shie‐Ming Peng Hsiu‐Mei Lin 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(11):m497-m498
The crystal structure of the title compound, [Cu2(C2F3O2)2(C10H8N3O)2]·2CH3CN, contains discrete [Cu2(CF3COO)2(O‐dpa)2] molecules (O‐dpaH is di‐2‐pyridylamine 1‐oxide) which have imposed crystallographic twofold symmetry and an acetonitrile molecule of solvation. The O‐dpa− ligand is both bidentate and bridging, linking two Cu atoms with a separation of 3.4270 (11) Å. Each Cu atom is surrounded by four coordinated atoms that are almost coplanar, with dimensions Cu—N = 1.940 (2) and 1.984 (3) Å, and Cu—O = 1.912 (2) and 1.945 (2) Å. 相似文献