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排序方式: 共有274条查询结果,搜索用时 195 毫秒
101.
Fused perylenebisimide-carbazole: new ladder chromophores with enhanced third-order nonlinear optical activities 总被引:1,自引:0,他引:1
Yang Y Wang Y Xie Y Xiong T Yuan Z Zhang Y Qian S Xiao Y 《Chemical communications (Cambridge, England)》2011,47(38):10749-10751
A series of ladder chromophores featuring planar structures of fused perylenebisimide and carbazole have been efficiently synthesized via photocyclization under sun light. Compared to N,N'-bis(3-pentyl) perylenebisimide (PBI-1), they show remarkably enhanced nonlinear properties. 相似文献
102.
采用共沉淀法制备了Ru-Zn催化剂,考察了二乙醇胺的添加对Ru-Zn催化剂上苯选择加氢制环己烯性能的影响,并采用N2物理吸附、透射电镜、X射线衍射、X射线荧光、傅里叶变换红外和程序升温还原等手段对催化剂进行了表征.结果表明,二乙醇胺可以与浆液中ZnSO4反应生成(Zn(OH)2)3(ZnSO4)(H2O)3和硫酸二乙醇胺盐.随着二乙醇胺用量的增加,化学吸附在催化剂表面的(Zn(OH)2)3(ZnSO4)(H2O)3增多,它与硫酸二乙醇胺盐的协同作用提高了Ru-Zn(4.9%)催化剂上苯选择加氢生成环己烯的选择性.当二乙醇胺用量为0.3g时,(Zn(OH)2)3(ZnSO4)(H2O)3在Ru-Zn(4.9%)催化剂加氢后样品的表面高度分散,反应性能最佳,循环使用第3次时苯转化率为84.3%,环己烯选择性和收率分别达75.5%和63.6%;使用至第4次时,反应25min时苯转化率和环己烯选择性仍可达75%以上,环己烯收率为58%以上. 相似文献
103.
Abstract By the improved high-pressure DTA, we have determined the high-pressure vertical phase diagrams of the Cd-Pb-Sn ternary system up to 2.5 GPa. A complete method of calculating high-pressure phase diagrams has been devised, in which the special attention has been paid to the effecs of high prssure on the partial molar free energy of each component in equilibrium phases. The high-pressure phase diagrams of Cd-Pb-Sn and Cd-Sn-Zn ternary systems up to 2.5 GPa were calculated successfully. The agreement between the observed and the calculated resuts is satisfactory. 相似文献
104.
105.
Xueying Zheng Wing Kam Fung Zhongyi Zhu 《Annals of the Institute of Statistical Mathematics》2013,65(4):617-638
In this paper, we develop robust estimation for the mean and covariance jointly for the regression model of longitudinal data within the framework of generalized estimating equations (GEE). The proposed approach integrates the robust method and joint mean–covariance regression modeling. Robust generalized estimating equations using bounded scores and leverage-based weights are employed for the mean and covariance to achieve robustness against outliers. The resulting estimators are shown to be consistent and asymptotically normally distributed. Simulation studies are conducted to investigate the effectiveness of the proposed method. As expected, the robust method outperforms its non-robust version under contaminations. Finally, we illustrate by analyzing a hormone data set. By downweighing the potential outliers, the proposed method not only shifts the estimation in the mean model, but also shrinks the range of the innovation variance, leading to a more reliable estimation in the covariance matrix. 相似文献
106.
In this paper, we propose a robust empirical likelihood (REL) inference for the parametric component in a generalized partial linear model (GPLM) with longitudinal data. We make use of bounded scores and leverage-based weights in the auxiliary random vectors to achieve robustness against outliers in both the response and covariates. Simulation studies demonstrate the good performance of our proposed REL method, which is more accurate and efficient than the robust generalized estimating equation (GEE) method (X. He, W.K. Fung, Z.Y. Zhu, Robust estimation in generalized partial linear models for clustered data, Journal of the American Statistical Association 100 (2005) 1176-1184). The proposed robust method is also illustrated by analyzing a real data set. 相似文献
107.
Chuang Liu Dong Yang Yuangui Wang Jiafu Shi Zhongyi Jiang 《Journal of nanoparticle research》2012,14(8):1-12
In recent years, the search for environmentally friendly alternative energy sources with reduced carbon footprints has increased. The coupling of photovoltaic power sources with advanced electrolysis systems for hydrogen production via water splitting using organic contaminants as sacrificial electron donors has been considered to a be viable alternative. In this report, we demonstrated the feasibility of a scaled-up rooftop prototype of the proposed hybrid photovoltaic-electrolysis system, which utilizes semiconductor nanoparticles coated on to metal substrates as electrodes for the generation of hydrogen coupled with the oxidation of wastewater. Application of an anodic bias of >2.0?V to bismuth-doped TiO2 (BiO x ?CTiO2) on Ti metal anodes with a sequential under-coatings of nanoparticulate SnO2, IrO2, Ta2O5, and Bi2O3 results in the electrochemical degradation of a variety of organic chemical contaminants in water (i.e., rhodamine B (Rh.B), methylene blue (MB), salicylic acid, triclosan, and phenol) and actual wastewater from a chemical manufacturing plant, while at the same time, molecular hydrogen is produced at stainless steel (SS) cathodes. The kinetics of the anodic substrates oxidation is investigated as a function of the cell current (I cell), substrate concentration, and background electrolyte composition (e.g., NaCl, Na2SO4, or seawater). Average current efficiencies were found to be in the range of 4?C22?%, while the cathodic current and energy efficiencies for hydrogen production were found to be in the range of 50?C70?% and 20?C40?%, respectively. 相似文献
108.
109.
全二维液相色谱的初步构建及其在山羊血清分离中的应用 总被引:4,自引:0,他引:4
以GFC/RP模式构建全二维液相色谱系统,第一维凝胶过滤色谱柱使用ShodexProteinKW 802. 5(300mm×8mmi.d. ),以0. 2mol/LNaH2PO4 (pH7. 0)的流动相在0. 15mL/min的流速下等度洗脱,第二维反相色谱柱使用HypersilBDSC18 (35mm×4. 6mmi.d. ),在3mL/min的流速下梯度洗脱。采用平行柱交替分析的形式作切换接口, 2. 5min切换一次,两个反相柱交替富集、分析第一维洗脱产物。以5个标准蛋白混合物的分离评价该系统,在单独一维模式中不能分离的样品在全二维液相色谱中得到了较好的分离,二维系统的总峰容量为225。与一维色谱相比,系统的总峰容量、分辨率得到较大提高。并用于山羊血清的纯化分析,对一维分离中的重合谱峰进行验证,对制备纯化有一定的实际意义。 相似文献
110.
This paper proposes an infeasible interior-point algorithm with full-Newton step for linear programming, which is an extension
of the work of Roos (SIAM J. Optim. 16(4):1110–1136, 2006). The main iteration of the algorithm consists of a feasibility step and several centrality steps. We introduce a kernel
function in the algorithm to induce the feasibility step. For parameter p∈[0,1], the polynomial complexity can be proved and the result coincides with the best result for infeasible interior-point
methods, that is, O(nlog n/ε).
This work was supported in part by the National Natural Science Foundation of China under Grant No. 10871098. 相似文献