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排序方式: 共有3185条查询结果,搜索用时 18 毫秒
811.
812.
一种新颖的实现冷原子或冷分子囚禁的可控制光学四阱及其二维光学晶格 总被引:3,自引:3,他引:0
原子光学晶格为精确操控中性原子和研究某些基本物理问题提供了一种方法。提出了一种利用单光束照明余弦型振幅光栅与透镜组合系统实现冷原子或冷分子囚禁的可控制光学四阱新方案,计算了四阱的光强分布,讨论了从光学四阱到双阱或单阱的演化过程,并导出了光学四阱的几何参量、光强分布、强度梯度及其曲率与光学透镜系统参量间的解析关系,获得了四阱间距与光栅空间频率的关系。研究表明通过改变余弦光栅的空间频率即可实现从光学四阱到双阱或单阱的连续双向演化。 相似文献
813.
采用绝热近拟和绝热变分近似两种方法,计算了均匀强磁场(10≤β≤1000)中H2^+的σg,πu,δg,Φu,γg,ηu态的能有有原子核间的平衡距离,并与前人的结果进行了比较。 相似文献
814.
The O-demethylation of lignin monomers, which has drawn substantial attention recently, is critical for the formation of phenols from aromatic ethers. The P450BM3 peroxygenase system was recently found to enable the O-demethylation of different aromatic ethers with the assistance of dual-functional small molecules (DFSM), but these prepared mutants only have either moderate O-demethylation activity or moderate selectivity, which hinders their further application. In this study, we improve the system by introducing different amino acids into the active site of P450BM3, and these amino acids with different side chains impacted the catalytic ability of enzymes due to their differences in size, polarity, and hydrophobicity. Among the prepared mutants, the combination of V78A/F87A/T268I/A264G and Im-C6-Phe efficiently catalyzed the O-demethylation of guaiacol (TON = 839) with 100% selectivity. Compared with NADPH-dependent systems, we offer an economical and practical bioconversion avenue. 相似文献
815.
Federica Aiello Gloria Uccello-Barretta Claudio Picchi Samuele Nazzi Alessandra Recchimurzo Federica Balzano 《Molecules (Basel, Switzerland)》2022,27(19)
The understanding of the interaction between non-steroidal anti-inflammatory drugs and human serum albumin plays a fundamental role in the development of new drugs and new therapeutic strategies. Several studies have been performed, nevertheless, the interaction phenomena are still not fully understood. In this work, high-field solution Nuclear Magnetic Resonance (NMR) spectroscopy was applied to compare the strength of the interaction of diclofenac sodium salt, ketorolac tris salt and flurbiprofen sodium salt toward albumin. To this aim, mono- and bi-selective relaxation rate measurements were performed by applying selective π-pulses at the selected frequencies and by following magnetization recovery. On the basis of the dependence of relaxation parameters on albumin concentration, normalized affinity indexes were calculated for several protons of the drugs. Affinity indexes for diclofenac were about five-fold higher in comparison with ketorolac and flurbiprofen. Aromatic moieties of the three drugs and methine protons at the chiral centers of ketorolac and flurbiprofen were more involved in the interaction with albumin. In conclusion, NMR spectroscopy allows not only for the comparison of drug-to-protein affinities but also points out the nature of the drug sites that are more extensively involved in the interaction. 相似文献
816.
Shengxia Duan Jian Liu Yanling Pang Feng Lin Xiangyan Meng Ke Tang Jiaxing Li 《Molecules (Basel, Switzerland)》2022,27(20)
In this paper, a simple and environmentally friendly method was developed for the preparation of highly stable C@Fe3O4 composites with controllable morphologies using sodium alginate as the carbon source and the easily obtained α-Fe2O3 as the precursors. The morphologies of the as-prepared C@Fe3O4 composites, inherited from their corresponding precursors of α-Fe2O3, survived from the annealing treatments, were characterized by the field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The C@Fe3O4 composites resisted to oxidation, acidification and aggregation, exhibiting porous structures and ferromagnetic properties at room temperature. Moreover, the adsorption performance of the C@Fe3O4 composites was evaluated by absorbing MB (methylene blue) in liquid environment. Experiments indicated that the C@Fe3O4 composites exhibited highly enhanced adsorption capacities and efficiencies as compared with their corresponding precursors of α-Fe2O3. This generalized method for the synthesis of C@Fe3O4 composites provides promising applications for the highly efficient removal of MB from industrial effluents. 相似文献
817.
Marianna Nalli Domiziana Masci Andrea Urbani Giuseppe La Regina Romano Silvestri 《Molecules (Basel, Switzerland)》2022,27(22)
Aberrant accumulation of β-catenin in the cell nucleus as a result of deregulation of the Wnt/β-catenin pathway is found in various types of cancer. Direct β-catenin targeting agents are being researched despite obstacles; however, specific β-catenin drugs for clinical treatments have not been approved so far. We focused on direct β-catenin targeting of potential therapeutic value as anticancer agents. This review provides recent advances on small molecule β-catenin agents. Structure-activity relationships and biological activities of reported inhibitors are discussed. This work provides useful knowledge in the discovery of β-catenin agents. 相似文献
818.
819.
采用密度矩阵方法来处理长脉冲光与钠原子的相互作用,求解24能级钠精细结构的布洛赫方程,给出参与跃迁的每个态密度随时间的演化曲线。对于圆偏振情形,发现在长脉冲(大于100 ns)的持续时间内,最终的原子通过转移只在3S1/2(2,2)到3P/3/2(3,3)之间进行泵浦并且激发态达到稳态。进一步的2能级模型计算与24能级计算结果的对比表明:用2能级近似的速率方程方法取代24能级密度矩阵方法具有合理性,由此简化了模型,节约了后续研究的计算量。 相似文献
820.
Can Xie Kun Luo Libin Tan Qiaomei Yang Xiongjie Zhao Liyi Zhou 《Molecules (Basel, Switzerland)》2022,27(24)
Carbon monoxide (CO) is a vital endogenous gaseous transmitter molecule involved in the regulation of various physiological and pathological processes in living biosystems. In order to investigate the biological function of CO, many technologies have been developed to monitor the level of endogenous CO in biosystems. Among them, the fluorescence detection technology based on the fluorescent probe has the advantages of high sensitivity, excellent selectivity, simple operation, especially non-invasive damage to biological samples, and the possibility of real-time in situ detection, etc., which is considered to be one of the most effective and applicable detection techniques. Therefore, in the last few years, a lot of work has been carried out on the design, synthesis and in vivo fluorescence imaging studies of CO fluorescent probes. Furthermore, using fluorescent probes to detect the changes in CO concentrations in living cells and tissues as well as in organisms has been one of the hot research topics in recent years. However, it is still a challenge to rationally design CO fluorescent probe with excellent optical performance, structural stability, low background interference, good biocompatibility, and excellent water solubility. Therefore, this review focuses on the research progress of CO fluorescent probes in the detection mechanism and biological applications in recent years. However, this popular and leading topic has rarely been summarized comprehensively to date. Thus, the research progress of CO fluorescent probes in recent years is reviewed in terms of their design concept, detection mechanism, and their biological applications. In addition, the relationship between the structure and performance of the probes was also discussed. More significantly, we hope that more excellent optical properties fluorescent probes for gaseous transmitter molecule CO detection and imaging will overcome the current problems of high biotoxicity and limited water solubility in future. 相似文献