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排序方式: 共有99条查询结果,搜索用时 31 毫秒
71.
一种黄绿光LED用荧光粉:Ga2S3∶Eu2+ 总被引:1,自引:0,他引:1
Eu2+-activated Ga2S3 phosphors were synthesized by solid-state reaction and their luminescence properties were studied with diffuse reflection spectroscopy, excitation spectra, emission spectra and fluorescence lifetime. The parameters of LED manufactured with phosphors Ga2S3∶Eu2+ were measured. The excitation spectra of these phosphors are broadband and can be matched with the emission wavelength of GaN chip. 相似文献
72.
应用量子化学电荷自洽离散变分Xα(SCC-DV-Xα)方法,研究了S-Al、S-Co复合掺杂增强尖晶石结构锂锰氧化物稳定性的作用机制.计算结果表明, S-Al复合掺杂锂锰尖晶石和S-Co复合掺杂锂锰尖晶石中的共价键强度均比未掺杂尖晶石LiMn2O4中的强,且与MnO2中的共价键强度相近; S-Al, S-Co复合掺杂尖晶石中Mn的电荷也与MnO2模型[Mn6O26]28-中十分接近. Mn原子的电荷密度次序是MnO2≈掺硫铝后锰锂尖晶石≈掺硫钴后的锂锰尖晶石< 锰锂尖晶石.即[LixMn3Co3O20S6]n-和[LixMn3Al3O20S6]n-中Mn的状态与MnO2中的Mn相似.上述结果揭示了S和非Jahn-Teller效应阳离子(Al3+,Co3+)复合掺杂尖晶石结构锂锰氧化物在电化学过程中不会发生Jahn-Teller畸变的内在原因. 相似文献
73.
Ya-Ping Zhang Wen Xu Na Li Hai-Yun Li Zi-Yin Shen Xin-Min Zhang Ming Yang Wei-Dong Zhang Chuan Zhang 《Chromatographia》2008,68(3-4):245-250
An LC-MS-MS method was revised and validated for simultaneous determination of icariin and its active metabolite icariside II in human plasma. The analytes and daidzein (IS) were extracted by liquid–liquid extraction and analyzed by LC-MS-MS. The separation was performed by a Zorbax SB-C18 column (3.5 μm, 2.1 × 100 mm) with an isocratic mobile phase consisting of methanol–water–formic acid (65:35:0.035, v/v/v) at a flow rate of 0.25 mL min?1. Detection was performed on a triple quadrupole tandem mass spectrum by multiple reaction monitoring mode using the electrospray ionization technique in positive mode. The method had lower limits of quantitation 0.2 and 0.1 ng mL?1 for icariin and icariside II, respectively, using 500 μL plasma sample. The linear calibration curves were obtained in the concentration range of 0.2–100 ng mL?1 for icariin and 0.1–100 ng mL?1 for icariside II. The RSD values of intra- and inter-day precision calculated from quality control (QC) samples were less than 7.2% for icariin and less than 6.5% for icariside II. The accuracy as determined from QC samples was within 3.8% for each analyte. The method has been applied to determine and evaluate the pharmacokinetic of icariin and its metabolite icariside II in volunteers following oral administration of icariin and extract of Epimedium, respectively. 相似文献
74.
Yan-Ting LI Xin-Min LIU Rui TIAN Wu-Quan DING Wei-Ning XIU Ling-Ling TANG Jing ZHANG Hang LI 《物理化学学报》2017,33(10):1998-2003
Ion exchange adsorption is an important physicochemical process at solid/liquid interfaces. In this study, an approach was established to estimate the activation energy of cation exchange reaction on the charged surface, considering Hofmeister effects. The experimental results showed that Hofmeister effects strongly affect the ionic adsorption equilibrium on the charged particle surface. The position of the adsorbed counterion in the diffuse layer was predicted according to the established model, and the ion exchange activation energies for different bivalent cations were estimated via the cation exchange experiments. The activation energy decreases with increasing ion concentration, and the adsorption saturation of cations is a function of the activation energy at different concentrations. The established model of cation exchange adsorption in the present study has universal applicability in solid/liquid interface reactions. 相似文献
75.
运用生物信息学软件对苏云金芽孢杆菌毒素Cry1Aa、Cry2Aa、Cry3Aa和Cry4Aa的
序列和基本参数、二级结构、三级结构、跨膜区和表面电势进行了预测比较。它们在一级
结构上有较大差异,但二级结构和跨膜区相似,三级结构中各毒素的结构域Ⅰ之间基本相
似,结构域Ⅱ之间差异较大,其中Cry2Aa为差异最大成员。4种毒素的表面电势分布不同。
毒素之间的结构相似性和差异性与其作用机理和杀虫特异性有关。 相似文献
76.
Cu含量对Ni-Cu-P化学镀层组织结构和性能影响 总被引:2,自引:0,他引:2
利用化学镀法制备出Ni-Cu-P合金镀层,研究了镀液中CuSO4·5H2O含量对合金镀层沉积速率和成分的影响. 通过XRD和SEM表征了不同CuSO4·5H2O质量浓度下Ni-Cu-P合金镀层的组织结构和表面形貌,运用极化曲线评价了合金镀层在质量分数为3.5%NaCl溶液中的耐蚀性能. 结果表明,随着镀液中CuSO4·5H2O质量浓度的增加,镀层沉积速率和P含量不断下降,Ni-P镀层中P的质量分数为14.98%. 当镀液中CuSO4·5H2O质量浓度为1.0 g/L时,P的质量分数为4.21%;镀层中Cu的含量随着镀液中CuSO4·5H2O含量的增加而增加. 当添加量为1.0 g/L时,镀层中Cu的质量分数达19.04%;镀层的结晶度随着Cu含量的上升不断增大,Cu的加入使镀层的表面形貌更加光滑;镀层的耐蚀性能随着镀液中CuSO4·5H2O含量的增加先上升后下降,当镀液中CuSO4·5H2O质量浓度为0.4 g/L时,Ni-Cu-P镀层表现出最优的耐蚀性能. 相似文献
77.
78.
An improved version of the grand unification composite model propose earlier is suggested. Under the hypothesis of partly broken global chiral symmetry, we give the four family of Fermions at low energies to realize unification of four family of Fermions. Neutrino may acquire naturally the Dirac mass. Proton lifetime and weak neutral current at low energy are consistent with experimental results. 相似文献
79.
Xin-Min Xiang & Jia-Dong Zheng 《计算数学(英文版)》1988,6(4):293-306
Because the nonlinear Schrödinger equation is met in many physical problems and is applied widely, The research on well-posedness for its solution and numerical methods has aroused more and more interest. The self-adjoint case has been considered by many authors. For a class of system of nonlinear and non-self-adjoint Schrodinger equations which refers to excitons occurring in one dimensional molecular crystals and in a spiral biomolecules, Guo Boling studied in [6], the pure initial and periodic initial value problems of this system and obtained the existence and uniqueness of its solution. In [7] we discuss the difference solution of this system and obtained its error estimate. In this paper, we shall study the finite element method for the periodic initial value problem of this system. Just as Guo pointed out in [6], since it has a non-self-adjoint term, it not only brings about trouble in mathematics, but also creates more difficulty in numerical analysis. Our analysis will show that for this system, in theoretically we can obtain the same results as when it has no non-self-adjoint term. 相似文献
80.
Hsu-Tung Ku Mei-Chin Ku Xin-Min Zhang 《Proceedings of the American Mathematical Society》1999,127(1):145-154
In this paper, we introduce a multi-parameter family of generalized power means, and use their special properties to provide a new method of interpolating inequalities. We give a different refinement of an inequality of Ky Fan as a particular application of our method.