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Various topological indices have been put forward in different studies, from biochemistry to pure mathematics. Among them, the Wiener index, the number of subtrees, and the Randi? index have received great attention from mathematicians. In the study of extremal problems regarding these indices among trees, one interesting phenomenon is that they share the same extremal tree structures. Much effort was devoted to the study of the correlations between these various indices. In this note we provide a common characteristic (the ‘semi-regular’ property) of these extremal structures, with respect to the above mentioned indices, among trees with a given maximum degree. This observation leads to a more unified approach for characterizing these extremal structures. As an application/example, we illustrate the idea by studying the extremal trees, regarding the sum of distances between all pairs of leaves of a tree, a new index, which recently appeared in phylogenetic tree reconstruction, and the study of the neighborhood of trees. 相似文献
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《Arabian Journal of Chemistry》2022,15(12):104308
This work aimed to identify the bioactive constituents of Ducrosia anethifolia Boiss eaves through cold methanolic extract. The GC–MS study of cold methanolic extract showed the presence of various pharmaceutically important bioactive compounds with unique peaks at specified retention time. The significant compounds are α-linoleic acid, α-sitosterol, n-hexadecanoic acid, palmitic acid β-monoglyceride, 2-methoxy-4-vinylphenol and benzoic acid, methyl ester. The FT-IR study showed them fingerprint region at 3326.80, 2943.53, 2831.74, 1450, 1110.67 and 1020.80 cm?1. The FT-IR study suggested the presence of glycosides, flavonoids, tannins, steroids, saponins, fatty acids and squalene. Oral administration of Ducrosia anethifolia Boiss leaves powder (DLP) (100 mg/kg body weight) was successfully reduced the blood sugar level after 14 d treatment in STZ (50 mg/kg bodyweight) induced diabetic rats significantly from 327.93 ± 24.5 to 171 0.03 ± 3.78 mg/dL. Furthermore, DLP (400 mg/kg body weight) was showed 74 ± 1.9 % inhibition of ulcer. The results of this study showed that DLP has both anti-diabetic and anti-ulcer characteristics when tested in vivo. 相似文献
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柱前衍生化高效液相色谱荧光检测法测定桑叶中的1-脱氧野尻霉素 总被引:10,自引:0,他引:10
建立了芴甲氧酰氯(FMOC—Cl)柱前荧光衍生一高效液相色谱法测定桑叶中1-脱氧野尻霉素(DNJ)的方法。桑叶经0.05mol/L,盐酸提取,在pH8.5的硼酸盐缓冲溶液条件下,DNJ反应生成荧光产物,然后用高效液相色谱-荧光检测器测定。流动相为乙腈-0.1%醋酸(55:45,V/V)。线性范围为0.567~34mg/L(相关系数r=0.9999);检出限为0.03mg/L。实验测得桑叶中DNJ含量为0.24%;平均回收率为97.1%,RSD为1.35%(n=6)。 相似文献
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The value of intrinsic chlorophyll fluorescence polarization, and the intensity in emission spectrum were investigated in
leaf segments of Alocasia macrorrhiza under several stress conditions including different temperatures (25–50°C), various concentrations of NaCl (0–250 mM), methyl
viologen (MV, 0–25 μM), SDS (0–1.0%) and NaHSO3 (0–80 μM). Fluorescence emission spectrum of leaves at wavelength regions of 500–800 nm was monitored by excitation at 436 nm.
The value of fluorescence polarization (P value), as result of energy transfer and mutual orientation between chlorophyll molecules, was determined by excitation at
436 nm and emission at 685 nm. The results showed that elevated temperature and concentrations of salt (NaCl), photooxidant
(MV), surfactant (SDS) and simulated SO2 (NaHSO3) treatments all induced a reduction of fluorescence polarization to various degrees. However, alteration of the fluorescence
spectrum and emission intensity of F685 and F731 depended on the individual treatment. Increase in temperature and concentration of NaHSO3 enhanced fluorescence intensity mainly at F685, while an increase in MV concentration led to a decrease at both F685 and F731. On the contrary, NaCl and SDS did not cause remarkable change in fluorescence spectrum. Among different treatments, the
negative correlation between polarization and fluorescence intensity was found with NaHSO3 treatments only. We concluded that P value being measured with intrinsic chlorophyll fluorescence as probe in leaves is a susceptible indicator responding to
changes in environmental conditions. The alteration of P value and fluorescence intensity might not always be shown a functional relation pattern. The possible reasons of differed
response to various treatments were discussed. 相似文献
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采用高效液相色谱法对我国东北地区茄科植物废弃物马铃薯、茄子、番茄和辣椒的叶片中茄尼醇进行了定性和定量分析。结果表明:马铃薯和茄子的叶片中茄尼醇质量分数较高,分别可达到0.331%和0.207%;番茄和辣椒的叶片中茄尼醇的质量分数分别为0.092%和0.089%。方法的线性范围为0.61~6.10μg,回收率为99.5%~103.3%。 相似文献
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We estimated internal CO2 conductance (gi ) for C3 plant species of different life forms (annual herbs, deciduous trees and evergreen trees) grown in a variety of environments to examine the effect of g i on their leaf carbon isotope ratio (i13C). The purpose of this study was to test the validity of using i13C as an index of photosynthetic water use efficiency (WUE). When comparing deciduous tree species grown in contrasting light environments, there was a strong positive relationship between i13C and WUE. Similarly, i13C was positively correlated to WUE when comparing the different species of evergreen trees. However, the difference in WUE between evergreen and deciduous tree species did not relate to that in leaf i13C. In addition, WUE was similar between highland and lowland herbaceous plants, although the former had a much higher i13C. The positive relationship between i13C and WUE did not hold across different life forms and different altitudes when differences in gi did not relate to those in stomatal conductance, resulting in independence of chloroplast CO2 partial pressure from intercellular CO2 partial pressure. 相似文献
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