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961.
Yizhen Tang Jingyu Sun Xiujuan Jia Hao Sun Xiumei Pan Rongshun Wang 《Journal of computational chemistry》2010,31(7):1520-1527
The reaction of N2H4 with OH has been investigated by quantum chemical methods. The results show that hydrogen abstraction mechanism is more feasible than substitution mechanism thermodynamically. The calculated rate constants agree with the available experimental data. The calculated results show that the variational effect is small at lower temperature region, while it becomes significant at higher temperature region. On the other hand, the small‐curvature tunneling effect may play an important role in the temperature range 220?3000 K. Moreover, the calculated rate constants show negative temperature dependence at the temperatures below 500 K, which is in accordance with Vaghjiani's report that slightly negative temperature dependence is found over the temperature range of 258?637 K. The mechanism of the major product (N2H3) with OH has also been investigated theoretically to understand the title reaction thoroughly. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
962.
用于疾病诊断的Gd~Ⅲ/量子点多模态成像探针的构建 总被引:2,自引:0,他引:2
结合核磁共振成像(MRI)和荧光成像技术,以钆离子、近红外低毒量子点、二氧化硅和聚丙烯酸(PAA)等为原料,采用一系列纳米载体自组装技术,构建出MRI弛豫率/荧光效率高和生物相容性好的GdⅢ/量子点多模态纳米探针.结果表明,与未螯合GdⅢ的量子点纳米探针相比,GdⅢ/量子点多模态纳米探针具有更高的弛豫率;t1-加权MRI成像也证实了GdⅢ/量子点多模态纳米探针具有很好的阳性造影功效. 相似文献
963.
A simple and fast method of low-density extraction solvent-based solvent terminated dispersive liquid–liquid microextraction (ST-DLLME) was developed for the highly sensitive determination of carbamate pesticides in the water samples by gas chromatography-tandem mass spectrometry (GC-MSMS). After dispersing, the obtained emulsion cleared into two phases quickly when an aliquot of acetonitrile was introduced as a chemical demulsifier into the aqueous bulk. Therefore, the developed procedure does not need centrifugation to achieve phase separation. It was convenient for the usage of low-density extraction solvents in DLLME. Under the optimized conditions, the limits of detection for all target carbamate pesticides were in range of 0.001–0.50 ng mL−1 and the precisions were in the range of 2.3–6.8% (RSDs, 2 ng mL−1, n = 5). The proposed method has been successfully applied to the analysis of real water samples and good spiked recoveries over the range of 94.5–104% were obtained. 相似文献
964.
Breviscapine is a Traditional Chinese Medicine treating cardiovascular diseases by promoting blood circulation and removing blood stasis. The major active component of breviscapine has low aqueous solubility, poor chemical stability, short biological half-life and rapid elimination rate from the plasma. The use of a lipid emulsion formulation containing breviscapine might improve chemical stability, increase drug loading, exhibit sustained release profile. In the present study, we developed an optimized formulation and technological method for the preparation of sterile and stable breviscapine lipid emulsion (Bre-LE) for intravenous infusion. The average particle size, polydispersity index, zeta potential, stability constant (K(s)) value and content of final product were (225.3±8.8) nm, 0.221±0.020, (-29.6±1.5) mV, (24.3±2.9)% and (94.5±0.6)% respectively (n=3). The results of in vitro release experiment suggest that lipid emulsion as breviscapine carrier showed a desirable sustained release profile. Dilution stability and long-term stability were also researched in the present paper. The results show the carrier could protect drug from degradation after dilution by phosphate buffered saline and fetal calf serum. And Bre-LE was stable for up to 6 months at room temperature storage condition. The biodistribution of drug in heart of mice increased dramatically after encapsulation into lipid emulsion which was beneficial to heart disease therapy. 相似文献
965.
A series of iron(III) complexes ligated by 2-(benzimidazole)-6-(1-aryliminoethyl)pyridines was synthesized and examined by 1H NMR, ESI-MS, IR spectroscopic, elemental analysis and X-ray photoelectron spectroscopy (XPS). Activated with methylaluminoxane (MAO), all ferric complexes exhibited good activities (up to 5.38 × 106 g mol−1(Fe) h−1) of ethylene oligomerization and polymerization, and resultant oligomers and polyethylene waxes showed high α-olefin feature, meanwhile the distribution of oligomers mostly resembled Schulz-Flory rules. The various reaction parameters were investigated in detail, and the less bulky and electron-withdrawing substituents of ligands could enhance the catalytic activities of their ferric complexes. The observations explain the cause for unstable activities performed by stored iron(II) complexes. 相似文献
966.
967.
多壁碳纳米管修饰电极检测盐酸氯丙嗪的研究 总被引:1,自引:0,他引:1
制备了多壁碳纳米管修饰玻碳电极,采用循环伏安法(CV)研究了盐酸氯丙嗪在修饰电极上的电化学特性,发展了一种新的检测盐酸氯丙嗪的电化学分析方法。在最佳实验条件下,用循环伏安法检测盐酸氯丙嗪,其响应电流与盐酸氯丙嗪的浓度在8.0×10-5~1.0×10-3mol/L范围内有很好的线性关系,线性方程为Ip(A)=0.0106c(mol/L)-8×10-8(R2=0.999,n=6),检出限为6.2×10-6mol/L(S/N=3)。方法可用于盐酸氯丙嗪片的测定。 相似文献
968.
重质油胶体聚集结构的耗散粒子动力学模拟 总被引:1,自引:0,他引:1
重质油是以沥青质为胶核分散于饱和油分中形成的极其复杂的胶体体系.本文采用耗散粒子动力学(DPD)方法研究重质油的胶体结构及其影响因素.根据重质油各组分的分子结构特征,构建了描述重质油组分的粗粒化模型化合物.模拟结果表明,本文构建的粗粒化模型能很好地反映重质油的胶体聚集结构.沥青质分子结构对胶体聚集结构有序性有显著影响,较高稠合程度的芳香环结构将使胶束结构有较高的有序性,烷基侧链则表现出分散作用.重质油中的胶质具有胶溶作用,胶质与沥青质的浓度比存在一个极限,当小于这个极限时,重质油将出现聚沉. 相似文献
969.
By controlling the reflux time and the quantity of the shell materials, different sizes of thioglycollic acid (TGA) modified
CdTe/CdSe core/shell quantum dots were synthesized in aqueous solution. This type of QDs was used for sensitive and selective
determination of ascorbic acid in commercial tablets. Under optimal conditions, a good linearity was observed between the
relative fluorescence (FL) intensity and the concentration of ascorbic acid in the range of 4.0 to 64.0 μg/mL with a correlation
coefficient of 0.9968. The limit of detection was 2.4 μg/mL. This method was applied to the determination of the ascorbic
acid in Vitamin C tablets and Vitamin C Yinqiao pills, and satisfactory results were obtained. 相似文献
970.
Zhang C. P. Hao T. L. Chen P. Liang J. Wang C. Z. Kang H. X. Gao R. L. Fu X. B. 《Laser Physics》2011,21(12):2122-2127
The aim of this paper is to study the effect of low-level laser irradiation (LLLI) on proliferation of myoblasts in culture.
Myoblasts derived from rat skeletal muscle were irradiated by He-Ne laser with different doses. Compared with nonirradiated
control group, the number of myoblasts increased when the cells in normal culture conditions were exposed to the laser of
specific energy density. The amount of cells with proliferating cell nuclear antigen (PCNA) positive expression and the 5-bromo-2′-deoxyuridine
(BrdU) incorporation rate after laser irradiation were also higher than that of the control group, suggesting that LLLL at
certain doses can effectively enhance myoblasts growth activity in vitro. This study firstly demonstrated that stimulating
myoblasts to enter into proliferative stage from initial resting state was an important mechanism of regeneration and repair
of injured skeletal muscle promoted by LLLI in clinical treatment. 相似文献