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Levin变换应用于欧拉常数数列及连分式数列改进算法的加速收敛
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作者 姚清照 贺黎明 《大学数学》 2021年第1期5-9,共5页
利用Lu等人通过连分式修正更快收敛的欧拉常数数列及其相关余项式,进一步采用Levin变换进行二次加速,特别是在克服舍入误差的情况下,就能更有效地计算出欧拉常数的高精度数值结果.
关键词 加速收敛 通用Levin变换 连分式 欧拉常数 舍入误差
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Synthesis, Crystal Structures, Hirshfeld Surfaces, Thermo Characteristics and Solubility of Co-crystal of Buprofezin with Hydrofluoric Acid
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作者 MA Liang yao qing-zhao +4 位作者 ZHOU Yu-Ming WANG Ming-Liang SUN Bai-Wang XUE Yi GUO Chang 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2020年第3期500-510,378,共12页
A new kind of co-crystal of buprofezin(C(16)H(24)FN3OS) with hydrofluoric acid has been prepared through evaporation technique. It crystallizes in the triclinic space group P1, with a = 9.9733(8), b = 10.3460(9), c = ... A new kind of co-crystal of buprofezin(C(16)H(24)FN3OS) with hydrofluoric acid has been prepared through evaporation technique. It crystallizes in the triclinic space group P1, with a = 9.9733(8), b = 10.3460(9), c = 10.5739(12) ?, a = 68.655(9), b = 73.291(9), g = 66.738(8)o, V = 920.34(17) ?~3, Mr = 325.44, Dc = 1.174 g/cm^3, Z = 2, F(000) = 348, m = 0.190 mm^(-1), the final GOOF = 1.042, R = 0.0485 and wR = 0.1167. Single-crystal X-ray diffraction, XRPD, DSC, TGA, Hirshfeld surface analysis, Raman spectroscopy and FT-IR were used to characterize the co-crystal. It has a twodimensional plane structure, and the intermolecular interactions of co-crystal are mainly H–F×××H, H–O×××H and H–O×××H. Thermology study further confirmed that co-crystal has stronger thermal stability and higher melting point than buprofezin, and it has stronger water solubility. The results show that this co-crystal is valuable for the study of residual activity and application effects of buprofezin. 展开更多
关键词 CO-CRYSTAL BUPROFEZIN X-RAY thermal stability
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