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521.
We study the sensitivity of energy eigenstates to small perturbation in quantum integrable and chaotic systems.It is shown that the distribution of rescaled components of perturbed states in unperturbed basis exhibits qualitative difference in these two types of systems:being close to the Gaussian form in quantum chaotic systems,while,far from the Gaussian form in integrable systems.  相似文献   
522.
This communication describes a simple sensitive one-step potentiometric aptasensing method for quantitative detection of a referenced therapeutic biomarker (programmed death-ligand 1, PD−L1). The aptasensor is constructed by modifying PD−L1-specific aptamer on Ti3C2-MXene nanosheets-functionalized electrode. Introduction of PD−L1 induces the specific reaction between PD−L1 and aptamer, thereby resulting in the change of spatial structures. The surface electric potential of modified electrode is shifted upon addition of PD−L1 proteins before and after the reaction of aptamer with the analyte. Interestingly, potentiometric aptamer with Ti3C2-MXene nanosheets can achieve a higher sensitivity and a lower detection limit toward target PD−L1 relative to aptamer-modified electrode. Experimental results indicated that the linear range and detection limit of using Ti3C2-MXene nanosheets were 0.01–100 ng mL−1 and 7.8 pg mL−1 PD−L1, respectively. Meanwhile, the specificity, reproducibility, storing stability and accuracy of potentiometric aptasensor are acceptable for the screening of PD−L1 in human serum samples.  相似文献   
523.
The key to the efficient use of biomass resources is the rational design and preparation of lignin-based fine chemicals. In this investigation, the colloidal self-assembly structure formed by lignin in good solvents is used as the module, magnetic Fe3O4 nanoparticles are taken as the carrier, and magnetic composite lignin nanoparticles are prepared in batches by a rapid and convenient surficial grafting (patching) process. The varying amphiphilicity and wettability of lignin are influenced by the various types of wetting solvents. Its wetting behavior can be regulated to achieve oil–water separation in different adsorption or/and emulsification processes. This study provides a novel tool for industrial oil–water separation and, thus, general oily wastewater treatment.  相似文献   
524.
研究相空间中有二阶线性单面约束的非完整系统的Lie对称性与守恒量.首先根据微分方程在无限小变换下的不变性建立Lie对称性所满足的确定方程和限制方程,给出结构方程和守恒量;其次讨论系统的Lie对称性逆问题;最后举一实例说明结果的应用.  相似文献   
525.
多自由度振动系统的一类凸集响应   总被引:5,自引:0,他引:5  
何彩英  张景绘 《力学学报》1997,29(5):530-539
对激励用凸集合建模的线性时不变振动系统定义了响应集的概念,将多自由度振动系统的凸集响应问题转化成寻求响应集的问题,从而降低了求解的难度.并提出了求解一类凸集载荷的响应集的支撑超平面法.对有限时刻的响应集,导出了求任意方向边界点的解析解,而对无限时刻的响应集,建议了一种求任意精度的凸多胞形近似的方法.最后给出了一个实例,得到了不同时刻的响应集,并将凸集响应与谐波响应及非平稳随机响应作了对照  相似文献   
526.
地震响应的凸集分析*   总被引:3,自引:0,他引:3  
本文提出了一种用于表示地震动不确定性的椭球傅立叶界限凸集模型.从数学上严格推出了这种模型对单自由度系统的最坏响应.并给出了模型参数的几种选取方法.通过合理地选取模型界限参数,将椭球傅立叶界限凸集模型与模拟的地震波结果进行比较,证实了基于标准地震波的抗震设计的危险性.  相似文献   
527.
Silk possesses excellent mechanical properties and biocompatibility due to its unique protein sequences and hierarchical structures. Thus, it has been widely used as a biomaterial in a broad spectrum of biomedical applications. In this study, an in-depth investigation of glycerol-plasticized silk films was carried out to understand the processing-structure-properties relationships. A series of glycerol-plasticized silk films with glycerol contents in the range of 0 to 30% (w/w) were prepared. The molecular structures and organizations of silk proteins and the interactions between glycerol and proteins were studied using FTIR, XRD, and DSC. At a low glycerol content (<12%), DSC revealed that the glass transition temperature and thermally induced crystallization temperature decreased as the glycerol content increased, implying that glycerol mainly interacts with silk proteins through hydrogen bonding. As the glycerol content further increased, the chain mobility of the silk proteins was promoted, leading to the formation of β-sheet structures, water insolubility, and increased crystallinity. In addition, the stretchability and toughness of the films were significantly enhanced. The role of glycerol as a plasticizer in regulating the silk protein structures and determining the properties of the films was thoroughly discussed.  相似文献   
528.
紫外光度法分析了萘、联苯和氧化联苯,采用偏最小二乘法(PLS)。用计算机对测定信息进行处理,不经掩蔽和分离同时测定了混合体系中的萘、联苯和氧化联苯。试验结果表明,萘、联苯和氧化联苯的浓度分别在0~30mg.L^-1,0~50mg.L^-1、0~50mg.L^-1内呈线性关系,对合成样品中这三种组分进行分析,结果满意。  相似文献   
529.
In this paper, we study topological dynamics of high-dimensional systems which are perturbed from a continuous map on Rm×Rk of the form (f(x),g(x,y)). Assume that f has covering relations determined by a transition matrix A. If g is locally trapping, we show that any small C0 perturbed system has a compact positively invariant set restricted to which the system is topologically semi-conjugate to the one-sided subshift of finite type induced by A. In addition, if the covering relations satisfy a strong Liapunov condition and g is a contraction, we show that any small C1 perturbed homeomorphism has a compact invariant set restricted to which the system is topologically conjugate to the two-sided subshift of finite type induced by A. Some other results about multidimensional perturbations of f are also obtained. The strong Liapunov condition for covering relations is adapted with modification from the cone condition in Zgliczyński (2009) [11]. Our results extend those in Juang et al. (2008) [1], Li et al. (2008) [2], Li and Malkin (2006) [3], Misiurewicz and Zgliczyński (2001) [4] by considering a larger class of maps f and their multidimensional perturbations, and by concluding conjugacy rather than entropy. Our results are applicable to both the logistic and Hénon families.  相似文献   
530.
通过微波辅助法快速合成NaGdF4∶Yb,Er上转换发光材料,合成时间仅25 min.利用X射线衍射(XRD)、场发射扫描电镜(FE-SEM)和能谱仪(EDS)对合成的样品进行了表征,并研究了样品的上转换发光性能.结果表明,材料的晶体结构为六方晶系;颗粒形貌为球形,分散性好,粒径约为200 nm;980 nm激光二极管...  相似文献   
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