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1.
In this paper, we study vanishing and splitting results on a complete smooth metric measure space \((M^n,g,\mathrm {e}^{-f}\mathrm {d}v)\) with various negative m-Bakry-Émery Ricci curvature lower bounds in terms of the first eigenvalue \(\lambda _1(\Delta _f)\) of the weighted Laplacian \(\Delta _f\), i.e., \(\mathrm {Ric}_{m,n}\ge -a\lambda _1(\Delta _f)-b\) for \(0<a\le \dfrac{m}{m-1}, b\ge 0\). In particular, we consider three main cases for different a and b with or without conditions on \(\lambda _1(\Delta _f)\). These results are extensions of Dung and Vieira, and weighted generalizations of Li-Wang, Dung-Sung, and Vieira.
相似文献2.
YB叶片泵降噪途径的探讨 总被引:1,自引:0,他引:1
林九如 《宁波大学学报(理工版)》1995,(2)
通过对YB型叶片泵的固体振动、液压冲击与脉动的噪声测定与分析,确定噪声源并探讨了对该类泵行之有效的降噪途径。文章对新颖的高次方程定子曲线特性进行了数学模拟,并确定其特征方程各系数,同时,文章又探讨了对减振槽的优化设计,以其最小压差、最低液压冲击作为目标函数,确定了减振槽最佳几何尺寸。 相似文献
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An improved adaptive-threshold burst assembly algorithm is proposed to alleviate the limitation of conventional assembly schemes on data loss and delay. The algorithm will adjust the values of assembly factors according to variant traffic regions. And the simulation results show that, by using the adaptive-factor adaptive assembly scheme, the performance of networks is extensively enhanced in terms of burst loss probability and average queuing delay. 相似文献
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本文报道了锌、镉、汞、铅硒化物、碲化物半导体超微粒子的制备以及它们的光谱性质 ,比较了它们的粗、细粒子的吸收光谱和荧光光谱的差异 ,以及与硫化物超微粒子的相似性 ,同时讨论了上述物质的超微粒子在老化过程中的行为及其原因. 相似文献
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本文采用装有Jones柱的流动注射系统,研究了钒(Ⅱ)-光泽精体系的化学发光反应。在此基础上建立了痕量钒测定的新方法。方法的检出限3×10 ̄(-10)g·mL ̄(-1);对于1.0×10 ̄(-7)g·mL ̄(-1)钒标准溶液测定的相对标准偏差为2%(n=11);线性范围1.0×10 ̄(-9)~9.0×10 ̄(-5)g·mL ̄(-1),相关系数大于0.9980。该方法已用于水样中痕量钒的测定。对于反应机理,本文也进行了探讨。 相似文献
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超细碳酸钙的制备与表征 总被引:1,自引:0,他引:1
本文探讨了乳液法制备油溶性超细碳酸钙的最佳实验条件,并对获得的超细碳酸钙进行了表征.实验结果表明:超细碳酸钙形状呈球形,粒度均匀,粒径分布在。. O1 ^-0. 03}m之间,在许多有机溶剂中具有良好的分散性. 相似文献
8.
A new post-chemiluminescence (PCL) phenomenon was observed when phenothiazine medications were injected into the reaction
mixture after the chemiluminescence (CL) reaction of luminol and potassium ferricyanide had finished. A possible reaction
mechanism was proposed based on studies of the kinetic characteristics of the CL, CL spectra, fluorescence spectra, and on
other experiments. The feasibility of determining various phenothiazine medications by utilizing these PCL reactions was examined.
A molecular imprinting–post-chemiluminescence (MI-PCL) method was established for the determination of chlorpromazine hydrochloride
using a chlorpromazine hydrochloride-imprinted polymer (MIP) as the recognition material. The method displayed high selectivity
and high sensitivity. The linear range of the method was 1.0×10−8∼1.0×10−6, with a linear correlation coefficient of 0.9985. The detection limit was 3×10−9 g/ml chlorpromazine hydrochloride, and the relative standard deviation for a 1.0×10−7 g/ml chlorpromazine hydrochloride solution was 4.0% (n=11). The method has been applied to the determination of chlorpromazine hydrochloride in urine and animal drinking water
with satisfactory results.
相似文献
9.
A simple, rapid and sensitive flow injection chemiluminescence (CL) method is described for the determination of naproxen. It was found that strong CL signal was generated when naproxen was mixed with KMnO4 and Na2SO3 in neutral aqueous medium. Under the optimum experimental conditions, the CL intensity was linearly related to the concentration of naproxen from 4.0 × 10−9 to 1.0 × 10−6 g mL−1 (r = 0.9993). The detection limit was 2 × 10−9 g mL−1 naproxen, the relative standard deviation for 1.0 × 10−7 g mL−1 naproxen solution was 1.5% (n = 11) and the sampling frequency was 120 h−1. The method was applied to the determination of naproxen in pharmaceutical preparation with satisfactory results. The mechanism of CL reaction was discussed briefly. 相似文献
10.
A simple flow injection chemiluminescence (FI-CL) method was proposed for the determination of nitrofurazone. Strong CL signal was generated during the reaction of nitrofurazone with H2O2 and N-bromosuccinimide (NBS) in alkaline condition. The CL signal was proportional to the nitrofurazone concentration in the range 1.0 × 10−7 to 1.0 × 10−5 g mL−1. The detection limit was 2 × 10−8 g mL−1 nitrofurazone and the relative standard deviation was less than 4% (6.0 × 10−6 g mL−1 nitrofurazone, n = 11). The proposed method was successfully applied to the determination of nitrofurazone in compound furacillin nasal drops, human plasma and urine samples. The CL reaction mechanism was also discussed briefly. Singlet oxygen generated in the reaction between H2O2 and NBS was suggested to be participated in the CL reaction. 相似文献