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51.
The study of the Lie groups with a left invariant flat pseudo-metric is equivalent to the study of the left-symmetric algebras
with a nondegenerate left invariant bilinear form. In this paper, we consider such a structure satisfying an additional condition
that there is a decomposition into a direct sum of the underlying vector spaces of two isotropic subalgebras. Moreover, there
is a new underlying algebraic structure, namely, a special L-dendriform algebra and then there is a bialgebra structure which
is equivalent to the above structure. The study of coboundary cases leads to a construction from an analogue of the classical
Yang–Baxter equation. 相似文献
52.
氟离子选择性电极法测定钍氟各级稳定常数 总被引:1,自引:0,他引:1
硫酸体系钍氟各级稳定常数对稀土冶炼生产实践具有重要的指导作用.采用溶解度法测定了室温(25 ℃)下不同酸度的钍氟共存区,采用氟离子选择电极测定不同浓度氟化氢溶液中的游离氟浓度,得到氢氟各级稳定常数.然后根据钍氟共存区图,配制一系列硫酸钍、氢氟酸和硫酸的混合液,测定各溶液中的游离氟浓度,从而得到钍氟各级稳定常数.结果表明,H与F的第1,2级稳定常数分别为k1=664.4,k2=47.9,Th和F的第1,2,3级稳定常数分别为k16.27×105,k2=9.68×104,k3=5.36×104. 相似文献
53.
54.
Lou Q Meng X Lao Z Xuan L Bai J Hou Q Hu G Luo R Tao L Li Z 《Molecules (Basel, Switzerland)》2012,17(1):884-896
Pirfenidone, a pyridone compound, is an effective and novel antifibrotic agent. In this article, we describe the design, synthesis and activity evaluation of novel antifibrotic agents, 1-(substituted aryl)-5-trifluoromethyl-2(1H) pyridones modified with carbohydrate. Most of the title compounds exhibited comparable or better inhibitory activity than fluorofenidone. Notably, compound 19a demonstrated the highest cell-based inhibitory activity against NIH 3T3 (IC(50) = 0.17 mM). 相似文献
55.
Iron(III) isoporphyrin, a tautomer of porphyrin with a saturated meso carbon, is one of the isoelectronic forms of oxoiron(IV) porphyrin π-cation radical, which is known as an important reactive intermediate of various heme enzymes. The isoporphyrin has been believed to be incapable of catalyzing oxygenation and oxidation reactions. Here, we report that an oxoiron(IV) porphyrin π-cation radical can be converted to iron(III) meso-chloro-isoporphyrin in the presence of trifluoroacetic acid and chloride ion. More importantly, this study shows the first evidence that iron(III) meso-chloro-isoporphyrin is an excellent reactive agent for chlorinating aromatic compounds and olefins. The results of this study suggest that the mechanism involves electrophilic chlorination of substrate with iron(III) meso-chloro-isoporphyrin. 相似文献
56.
There is a well-developed theory of weakly symmetric Riemannian manifolds. Here it is shown that several results in the Riemannian
case are also valid for weakly symmetric pseudo-Riemannian manifolds, but some require additional hypotheses. The topics discussed
are homogeneity, geodesic completeness, the geodesic orbit property, weak symmetries, and the structure of the nilradical
of the isometry group. Also, we give a number of examples of weakly symmetric pseudo-Riemannian manifolds, some mirroring
the Riemannian case and some indicating the problems in extending Riemannian results to weakly symmetric pseudo-Riemannian
spaces. 相似文献
57.
将离子液体1-丁基-3-甲基咪唑四氟硼酸盐([BMIM]BF4)作为流动相添加剂建立了同时测定复方苦参注射液中4种主要生物碱的HPLC分析方法。以Agilent TC-C18柱(250 mm×4.6 mm, 5 μm)为分离柱,甲醇-0.1%磷酸水溶液(含2.2×10-4mol/L [BMIM]BF4)(5:95, v/v)为流动相,流速1.0 mL/min,柱温30 ℃,进样量20 μL,在205 nm下检测。结果表明,苦参碱、槐定碱、氧化槐果碱以及氧化苦参碱的质量浓度分别在25.8~155.0 mg/L, 40.0~240.0 mg/L, 21.7~130.0 mg/L和37.5~225.0 mg/L范围内线性关系良好,相关系数均大于0.9990,平均回收率(n=9)在96.2%和98.9%之间。离子液体的加入能明显改善C18柱分离生物碱的色谱峰形并提高分离度。本法简便、快速、重复性好,可用于复方苦参注射液中生物碱的分离与测定。 相似文献
58.
Organo-soluble and transparent polyimides containing phenylphosphine oxide and trifluoromethyl moiety: Synthesis and characterization 总被引:1,自引:0,他引:1
A series of aromatic polyimides (PI-IIa-d) containing lateral phenylphosphine oxide (PPO) and trifluoromethyl (-CF3) moiety were prepared from an aromatic diamine, 2,5-bis[(4-amino-2-trifluoromethylphenoxy)phenyl]diphenyl-phosphine oxide (BATFDPO) and various aromatic dianhydrides via a two-step chemical imidization procedure. In parallel, for comparison, another series of polyimides (PI-Ia-d) without trifluoromethyl were synthesized from a diamine, 2,5-bis[(4-aminophenoxy)-phenyl]diphenylphosphine oxide (BADPO) and the same dianhydrides. It was found that both of the two series of polyimides (PIs) were soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidinone (NMP) and the solubility of PI-IIa-d was highly enhanced by the introduction of the bulky -CF3 group. Flexible and tough PI films with tensile strengths higher than 70 MPa were cast from the PI solution. The introduction of -CF3 moiety slightly sacrificed the thermal stability and mechanical properties of the PI films. For example, PI-IIa-d showed 5% weight loss at 472-476 °C, which was about 50 °C lower than those of their PI-Ia-d analogues. However, -CF3 group apparently improved the optical transparency and decreased the refractive indices of the PI films. PI-IId derived from BATFDPO and 4,4’-hexafluoroisopropylidenediphthalic anhydride (6FDA) exhibited the highest optical transparency with the transmittance of 90% at 400 nm and the refractive index as low as 1.5511 at 1310 nm. 相似文献
59.
Jin Wang Zhiqi Gu Bin Miao Lei Zhao Xinsheng Liu Jinrong Cheng Zhiqiang Zhang Jiadong Li 《Electroanalysis》2019,31(12):2404-2409
Semiconductor biochemical sensors are regarded as robust tools for the detection of various targets. However, re‐use of these sensors is one of the major obstacles hindering further development. To address this problem, a multi‐objective platform was developed based on magnetic beads and the AlGaN/GaN high electron mobility transistor (MBs AlGaN/GaN HEMT) device. Since the magnetic beads are capable of being fixed and released by inductance coils, the platform enables repeatability and multi‐objectivity during testing. To validate the advantages of the platform, metal ions and prostate specific antigen (PSA) were used. In this study, a platform sensing biochemical responses with a sensor was demonstrated to show the characteristics of reusability, multi‐target sensing, and simplicity, resulting in its promising prospects for widespread applications. 相似文献
60.
催化还原褪色光度法测定痕量铜的研究 总被引:13,自引:0,他引:13
本文在少量氯化钠存在下的磷酸-磷酸二氢钾缓冲溶液(pH=2.7)中,以铜(Ⅱ)催化次磷酸钠还原罗丹明B褪色为指示反应,建立了痕量铜的动力学光度分析新方法,在沸水浴中加热反应10min,测定的线性范围在0~0.40μg/25mL铜(Ⅱ)回归方程为△A=1.975c+0.003,相关系数为0.9999,以△A=0.01计算得测定下限为0.005μg/25mL。方法应用于铅基合金,纯铅粉和标准镁合金中铜 相似文献