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41.
42.
用振幅比之方法计算了中性粲介子衰变到CP本征态的CP不对称性. 计算了时间相关和时间积分的CP不对称性. 结果表明, 时间积分的CP不对称参数约为千分之一的量级. 还讨论了在BESⅢ和B工厂上实验检验的可能性. 相似文献
43.
Priyanka Trivedi Jonnala Kotesh Kumar Arvind Singh Negi Karuna Shanker 《Biomedical chromatography : BMC》2011,25(6):697-706
Extraction and pre‐concentration of a bioactive marker compound, phenyl‐1,3,5‐heptatriyne from Bidens pilosa, prior to HPLC has been demonstrated using both organic and ecofriendly solvents. Non‐ionic surfactants, viz. Triton X‐100, Triton X‐114 and Genapol X‐80, were used for extraction. No back‐extraction or liquid chromatographic steps were required to remove the target phytochemical from the surfactant‐rich extractant phase. The optimized cloud point extraction procedure has been shown to be a potentially useful methodology for the preconcentration of the target analyte, with a preconcentration factor of 4–99. Moreover, the method is simple, sensitive, rapid and consumes lesser solvent than traditional methods. An isocratic chromatographic separation and quantitation was accomplished on a C18 column with acetonitrile–acidified aqueous as mobile phase at a flow rate of 1.0 mL/min, UV detection at 254 nm and specificity with photo diode‐array detector (PDA) and MS. Under the optimum experimental conditions recovery was satisfactory (99.18–100.33%) without interference from the surfactant. The method seems to be reliable with intraday precision and interday precision below 2.0%. Good linearity was obtained in the working range from 7.5 to 30 µg/mL with correlation coefficient >0.99. The limits of detection and quantitation were 1.84 and 6.13 µg/mL, respectively. The method was validated following international guidelines and successfully applied for quantitative assays of cytotoxic compound phenyl‐1,3,5‐heptatriyne in Bidens pilosa. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
44.
We calculate the branching ratio of B→J/ψπ0 with a mixed formalism that combines the QCD-improved factorization and the perturbative QCD approaches. The result is consistent with experimental data.The quite small penguin contribution in B→J/ψπ0 decay can be calculated with this method. We suggest two methods to extract the weak phase β. One is through the dependence of the mixing induced CP asymmetry SJ/ψπ0 on the weak phase β, the other is from the relation of the total asymmetry ACP with the weak phase β. Our results show that the deviation △SJ/ψπ0 of the mixing induced CP asymmetry from sin(-2β) is of O(10-3) and has much less uncertainty. The above O(10-3) deviation can provide a good reference for identifying new physics. 相似文献
45.
Simon J. Holder Geraldine G. Durand Chert‐Tsun Yeoh Elodie Illi Nicholas J. Hardy Tim H. Richardson 《Journal of polymer science. Part A, Polymer chemistry》2008,46(23):7739-7756
A series of ABA amphiphilic triblock copolymers possessing polystyrene (PS) central hydrophobic blocks, one group with “short” PS blocks (DP = 54–86) and one with “long” PS blocks (DP = 183–204) were synthesized by atom transfer radical polymerization. The outer hydrophilic blocks were various lengths of poly(oligoethylene glycol methyl ether) methacrylate, a comb‐like polymer. The critical aggregation concentrations were recorded for certain block copolymer samples and were found to be in the range circa 10−9 mol L−1 for short PS blocks and circa 10−12 mol L−1 for long PS blocks. Dilute aqueous solutions were analyzed by transmission electron microscopy (TEM) and demonstrated that the short PS block copolymers formed spherical micelles and the long PS block copolymers formed predominantly spherical micelles with smaller proportions of cylindrical and Y‐branched cylindrical micelles. Dynamic light scattering analysis results agreed with the TEM observations demonstrating variations in micelle size with PS and POEGMA chain length: the hydrodynamic diameters (DH) of the shorter PS block copolymer micelles increased with increasing POEGMA block lengths while maintaining similar PS micellar core diameters (DC); in contrast the values of DH and DC for the longer PS block copolymer micelles decreased. Surface‐pressure isotherms were recorded for two of the samples and these indicated close packing of a short PS block copolymer at the air–water interface. The aggregate solutions were demonstrated to be stable over a 38‐day period with no change in aggregate size or noticeable precipitation. The cloud point temperatures of certain block copolymer aggregate solutions were measured and found to be in the range 76–93 °C; significantly these were ∼11 °C higher in temperature than those of POEGMA homopolymer samples with similar chain lengths. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7739–7756, 2008 相似文献
46.
A. Sibirtsev J. Haidenbauer H. -W. Hammer U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2006,29(3):363-367
We show that the recently measured asymmetry in helicity-angle spectra of the Λ-hyperons, produced in the reaction pp → K
+Λp reaction, and the energy dependence of the total pp → K
+Λp cross-section can be explained consistently by the same Λp final-state interaction. Assuming that there is no final-state interaction in the Σ0
p channel, as suggested by the available data for the reaction pp → K
+Σ0
p, we can also reproduce the energy dependence of the Λ/Σ0 production ratio and, in particular, the rather large ratio observed near the reaction thresholds. The nominal ratio of the
Λ and Σ0 production amplitudes squared, i.e. when disregarding the final-state interaction, turns out to be about 3, which is in line with hyperon production data from
proton and nuclear targets available at high energies. 相似文献
47.
Jian Dong Yun Wang Xu Tang Wenli Zhang 《Journal of Dispersion Science and Technology》2017,38(10):1388-1395
The cloud points (CPs) of the copolymers 17R4 and L64 were first measured, and then the effects of salts ((NH4)3C6H5O7, K3C6H5O7) on 17R4 and L64 were researched. After finishing the work described above, the temperature (278.15, 283.15, and 288.15) K of aqueous two-phase systems was determined, which consist of 17R4-(NH4)3C6H5O7, 17R4-K3C6H5O7, L64-(NH4)3C6H5O7, and L64-K3C6H5O7. Finally, the liquid–liquid equilibrium (LLE) data of binodal curve and the tie line for 17R4-(NH4)3C6H5O7 aqueous two- phase systems (ATPSs) 17R4-K3C6H5O7 ATPSs, L64-(NH4)3C6H5O7 ATPSs, and L64-K3C6H5O7 ATPSs were obtained. Nonlinear fitting of the empirical equation was used for making the diagram. The results showed that the change in the size of the two-phase areas increases with the increase of temperature. The capacity of the salts to induce phase segregation follows the Hofmeister series, that is, K3C6H5O7?>?(NH4)3C6H5O7. In addition, the findings also showed that the phase separation ability of 17R4 is better than that of L64. 相似文献
48.
新工科的人才培养目标使混合式教学模式成为高校教学改革的重要趋势。云教材是与混合式教学模式相契合的教学资源。工程力学云教材的建设贯彻以成果为导向的教育理念,明确学习目标,集成富媒体数字出版、云服务和移动学习三大领域的前沿技术,为工程力学混合式教学提供配套的教学资源。实践应用表明,工程力学云教材提高了学生的学习兴趣和自主学习能力,助力新工科的建设。 相似文献
49.
50.
以1-(2-噻唑偶氮)-2-萘酚(TAN)为络合试剂,非离子表面活性剂Triton X-114为萃取剂,浊点萃取同时富集Cr(Ⅲ)和Cr(Ⅵ),并于RP-C18柱上,用含4.5 mmol/L十六烷基三甲基溴化铵(CTMAB)和0.03mol/L HAc-NaAc缓冲溶液(pH5.5)的甲醇-水(体积比69∶31)溶液为流动相,对富集的Cr(Ⅲ)和Cr(Ⅵ)进行高效液相色谱快速分离、测定。对浊点萃取时溶液的pH值、TAN和Triton X-114的用量等影响因素进行了考察。在优化实验条件下,对100μg/L的Cr(Ⅲ)和Cr(Ⅵ)进行7次平行测定,保留时间的相对标准偏差分别为1.2%和0.9%,峰面积的相对标准偏差分别为4.7%和2.7%。Cr(Ⅲ)和Cr(Ⅵ)的线性范围均为50~5 000μg/L,检出限分别为7.5、3.5μg/L。大部分离子不干扰测定,该方法具有较高的灵敏度,可用于湖泊表层沉积物中铬形态的分析。 相似文献