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排序方式: 共有307条查询结果,搜索用时 31 毫秒
81.
Shi  Yuguang  Wang  Wenlong  Yu  Haobin 《Mathematische Zeitschrift》2019,291(1-2):569-589
Mathematische Zeitschrift - In this paper we prove a rigidity result for the equality case of the Penrose inequality on 3-dimensional asymptotically flat manifolds with nonnegative scalar curvature...  相似文献   
82.
A new solid acid, based on tantalum hydroxide, was used to catalyze saccharide dehydration into 5-hydroxymethylfurfural (HMF) with high catalytic activity and excellent stability in a water-2-butanol biphasic system. Furthermore, good results were also obtained from Jerusalem artichoke juice with the catalyst under the same conditions.  相似文献   
83.
Li4Ti5O12 (LTO) was synthesized with two different cooling methods by solid-state method, namely fast cooling and air cooling. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), galvanostatic charge–discharge test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), respectively. XRD revealed that the basic LTO structure was not changed. FESEM images showed that fast cooling effectively reduced the particle sizes and the agglomeration of particles. Galvanostatic charge–discharge test showed that the air cooling sample exhibited a mediocre performance, having an initial discharge capacity of 136.3mAh?·?g?1 at 0.5 C; however, the fast cooling sample demonstrated noticeable improvement in both of its discharge capacity and rate capability, with a high initial capacity value of 142.7 mAh?·?g?1 at 0.5 C. CV measurements also revealed that fast cooling enhanced the reversibility of the LTO. EIS confirmed that fast cooling resulted in lower electrochemical polarization and a higher lithium-ion diffusion coefficient. Therefore, fast cooling have a great impact on discharge capacity, rate capability, and cycling performance of LTO anode materials for lithium-ion batteries.  相似文献   
84.
A simple and sensitive ultra-high performance liquid chromatography–tandem mass spectrometric (UHPLC–MS/MS) method was developed and validated for the determination of ARQ531, a Bruton’s tyrosine kinase inhibitor in rat plasma. After protein precipitation with acetonitrile, the samples were separated on a UPLC BEH C18 column with 0.1% formic acid in water and acetonitrile as mobile phase at a flow rate of 0.4 ml/min. The mass detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring with precursor-to-product ion transitions of m/z 479.1 > 365.1 and m/z 441.2 > 138.1 for ARQ531 and internal standard, respectively. Good linearity (correlation coefficient > 0.9988) was achieved over the concentration range of 0.5–1,000 ng/ml and the lower limit of quantitation was 0.5 ng/ml. The accuracy ranged from −13.50 to 11.35% and the precision was <8.87%. The extraction recovery was >85.56%. ARQ531 was demonstrated to be stable under the tested conditions. The validated method was further applied to a pharmacokinetic study of ARQ531 in rats after intravenous (1 mg/kg) and oral (1, 3 and 10 mg/kg) administration. The results demonstrated that ARQ531 displayed linear pharmacokinetic profiles over the oral dose range of 1–10 mg/kg and good oral bioavailability (>50%).  相似文献   
85.
Determination of SARS-coronavirus by a microfluidic chip system   总被引:4,自引:0,他引:4  
Zhou X  Liu D  Zhong R  Dai Z  Wu D  Wang H  Du Y  Xia Z  Zhang L  Mei X  Lin B 《Electrophoresis》2004,25(17):3032-3039
  相似文献   
86.
合成了系列铕铽双核稀土有机稀土配合物Tb1-xEux(TTA)3Phen,通过差热.热重分析、XRD、红外光谱、紫外光谱和荧光光谱等测试手段研究了配合物的组成、结构和发光性质。由紫外可见光谱可以看出,稀土有机配合物的吸收峰主要来自有机配体HTrA和1,10-Phen;差热-热重分析证明,稀土有机配合物热稳定性较好。荧光光谱和电致发光表明,铽对铕配合物的发光有协同作用。在该系列配合物中,不仅有机配体可以将吸收的能量传递给发光的铕离子使其发光,而且铽离子也可将其吸收的能量通过分子内能量传递给铕离子,增强铕的发光强度。同时就双核稀土有机配合物光致发光和电致发光的特性及掺杂体系的能量传递过程进行了讨论。  相似文献   
87.
Li M  Tang S  Shen F  Liu M  Xie W  Xia H  Liu L  Tian L  Xie Z  Lu P  Hanif M  Lu D  Cheng G  Ma Y 《The journal of physical chemistry. B》2006,110(36):17784-17789
The electropolymerization behaviors of an electroactive and luminescent compound TCPC as precursor are studied. The resultant electrochemical deposition (ED) films are characterized by cyclic voltammetry (CV), UV-vis, fluorescence spectra, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Under the CV mode with potential range of -0.5 to 0.85 V vs Ag/Ag(+), the coupling reactions between the carbazole units of TCPC are very efficient, while the fluorescent trifluorene segment in TCPC is chemically inert in this potential range, which results in a highly fluorescent film formation on indium tin oxide (ITO) electrode. The deposition parameters for preparing the TCPC-based ED films are optimized, and the best ED film gives the fluorescence efficiency of 45.5% with surface roughness of 2.8 nm and morphologic stability as heating to 180 degrees C. The light-emitting devices (LEDs) using this ED film as light emitting layer with structure ITO/ED film (approximately 100 nm)/Ba/Al achieve maximum luminescence and external quantum efficiency of 4224 cd/m(2) at 17 V and 0.72% at 11.5 V, respectively, which are better than the device using TCPC spin-coating films as emitting layer. The technique provides a facile route toward a patternable luminescent film and device because such luminescent ED films can be manipulatively deposited on the electrified electrode.  相似文献   
88.
The interactions between granulocyte-macrophage colony-stimulating factor (GM-CSF) and heparin or low-molecular weight heparin (LMWH) were studied by CZE. It was found that GM-CSF could bind to both heparin and LMWH. The binding constants were calculated from Scatchard regression to be (6.5 +/- 0.8) x 10(5)/M and (11.2 +/- 0.7) x 10(5)/M, respectively. The specificity of the interaction between GM-CSF and heparin was also studied by employing another sulfated K carrageenan oligosaccharide as a control. Results showed that K carrageenan oligosaccharide could not interact with GM-CSF, indicating that GM-CSF could specifically interact with heparin.  相似文献   
89.
石英砂中甲烷水合物稳定条件研究   总被引:3,自引:0,他引:3  
采用不同粒径(160~200目、200~300目、300~400目、400~600目)细颗粒石英砂模拟自然界中沉积物实验合成甲烷水合物, 采用多步升温分解法测定了甲烷水合物的稳定温度-压力(p~T)条件. 结果发现细颗粒石英砂对甲烷水合物的稳定条件有明显影响, 温度最大下降1.5 K. 其中160~200目的石英砂是实验测试条件下石英砂对甲烷水合物稳定条件有无影响的分界目数. 每一种石英砂在不同的温度压力下甲烷水合物p-T数据点较为离散, 并且不同石英砂中p-T数据曲线出现交叉, 这与文献中采用规则的硅胶、玻璃球等测得的结果有所不同. 文献中测定的甲烷水合物p-T数据点温度相对于纯水中甲烷水合物p-T数据点温度向左偏移量相同.  相似文献   
90.
The electrochemical polymerization (EP) method to fabricate highly luminescent films and devices is rarely reported. It is typically believed that the organic light-emitting devices (OLEDs) made by EP method behave low performance because of the structural defects, doped electrolytes, and rough morphology in EP films. Here we present a new strategy to fabricate high-quality EP films including the special molecular design for EP precursors and the electrochemical control for EP processes. The resulting EP films exhibit high fluorescence, low doping levels, and smooth surface morphology. The efficiency of EP film devices arrive a level of >10 cd A?1 (green-emission). Moreover, the full-color micropatterned EP films with sharp edge and high resolution have been achieved, demonstrating a new simple method for fabricating micropatterned luminescent polymers and devices compared with currently used techniques.  相似文献   
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