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161.
162.
建立了毛细管电泳-紫外检测同时测定血清中左旋多巴和甲基多巴的方法。以40 mmol/L硼砂(pH 9.5)为分离缓 冲溶液,在3.45 kPa(0.5 psi)压力下进样7 s、分离电压22 kV、检测波长200 nm、温度25 ℃的条件下进行测定,两 种物质获得了较好的分离。甲基多巴和左旋多巴分别为1.0~64.0 mg/L和1.0~71.0 mg/L时与峰面积呈良好的线性关系, 线性相关系数分别为0.9998和0.9994,检出限分别为0.6和0.8 mg/L(以信噪比为3计)。将该法用于血清中甲基多巴和左 旋多巴的测定,回收率为82.8%~88.8%,相对标准偏差为2.10%~2.63%。 相似文献
163.
REN Xiumin Department of Mathematics Shandong University Jinan China 《中国科学A辑(英文版)》2005,48(6):785-797
In this paper, we prove the following estimate on exponential sums over primes: Let κ≥1,βκ=1/2 log κ/log2, x≥2 and α=a/q λsubject to (a, q) = 1, 1≤a≤q, and λ∈R. Then As an application, we prove that with at most O(N2/8 ε) exceptions, all positive integers up to N satisfying some necessary congruence conditions are the sum of three squares of primes. This result is as strong as what has previously been established under the generalized Riemann hypothesis. 相似文献
164.
New lanthanide-based complexes constructed from cucurbit[6]uril: Synthesis,structures and properties
Three lanthanide-based complexes, {Gd2(H2O)10(CB[6])2}·CB[6]·6Cl·12H2O (1), {[Gd2(H2O)8CB[6]2]·(CuCl4)·4Cl·46H2O}n (2), and {Dy2(NO3)2(H2O)10(CB[6])}·4NO3·14H2O (3) (CB[6] = cucurbit[6]uril), were prepared with cucurbit[6]uril (CB[6]). These complexes were characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, UV–Vis spectroscopy, thermogravimetric analysis and magnetization measurements. Crystallographic results showed that 1 and 3 are dinuclear and crystallize in the triclinic space group Pī, whereas 2 is a 1-D zigzag supramolecular chain that crystallizes in the monoclinic system in C2/c. The results indicated that temperature has a big effect on the supramolecular assemblies and a different structure inducer also leads to the formation of different coordination polymers. Frequency dependence in the ac susceptibility signals was observed in 3. 相似文献
165.
The main purpose of this paper is to study the growth of meromorphic solutions of complex linear differential-difference equations L(z, f) =n∑i=0m∑j=0Aij(z)f(j)(z + ci) = 0 or F(z)with entire or meromorphic coefficients, and ci, i = 0,..., n being distinct complex numbers,where there is only one dominant coefficient. 相似文献
166.
Axisymmetric Bessel-modulated Gaussian beam with quadratic radial dependence (QBG beam) has attracted much attention recently. In this paper, the focal shift of the cylindrical vector QBG beam with radial variance phase wavefront is investigated theoretically by vector diffraction theory. Results show that focus shifts considerably by changing the phase parameter C that indicates the radial phase variance speed. Under condition of small beam parameter μ of cylindrical vector QBG beam, there is one focal peak that shifts far away from optical aperture on increasing C. When μ increases, there may occur two focal peaks that also shift remarkably on increasing C. And it was found that the dependence of focal shift distance on increasing phase parameter is linear. Phase parameter adjusts the focal shift distance, while, polarization angle does not affect focal shift obviously. 相似文献
167.
Xiumin Gao Qiufang Zhan Maojin Yun Hanming Guo Xiangmei Dong Songlin Zhuang 《Optical and Quantum Electronics》2011,42(14-15):827-840
Focusing properties of spirally polarized hollow Gaussian beam (HGB) are investigated theoretically by vector diffraction theory in this article. Results show that the optical intensity in focal region of spirally polarized HGB can be altered considerably by the beam order, numerical aperture of the focusing system, and spiral parameter that indicates the polarization spiral degree of the spirally polarized HGB. Spiral parameter can induce focal pattern change in axial direction remarkably, while beam order and numerical aperture affect radial foal pattern more obviously. The tunable principle of the focal pattern by spiral parameter differs very considerably under condition of different numerical aperture and beam order. Many novel focal patterns may occur in focal pattern evolution. It was also found that focal shift and focal depth can be altered significantly by spiral parameter and beam order. 相似文献
168.
贾秀敏 《浙江大学学报(理学版)》2018,45(4):427
利用导体曲面函数,将求解拉普拉斯方程转变为积分运算,从而得到了在无电荷区域普遍成立的电势表达式,再通过边界条件导出共焦抛物导体柱板间的电场分布,并给出了电场线方程. 相似文献