排序方式: 共有53条查询结果,搜索用时 625 毫秒
41.
Meng Zhou XiaoHua Deng Song Fu RongXin Tang YunHui Hu ShiYou Li A. Vaivads M. Andre Xi Lin MingHui Lin XiaoMin Zhou 《中国科学G辑(英文版)》2009,52(4):626-630
Magnetic reconnection is a fundamental process in plasma, which is thought to play important roles both in laboratory and
natural plasmas through affecting magnetic topology, heating and accelerating particles. During an event on Oct. 1st, 2001,
the Cluster tetrahedron circled around the magnetic reconnection region several times, and Xiao et al. first identified the
null pair and found that the spectrum of the null-point oscillation shows the maximum power near the lower-hybrid frequency.
In this paper we report the observation of electromagnetic and electrostatic wave enhancements near lower hybrid frequency
associated with the reconnection process near the null pair. The lower hybrid waves (LHWs) with quasi-perpendicular propagation
were identified and also confirmed by the power law of the spectrum of electric and magnetic fields.
Supported by the National Natural Science Foundation of China (Grant Nos. 40325012, 40390151, 40574073, 40574074, and 40640420563),
the Research Foundation from Ministry of Education of China (Grant No. 40174043), and the China Plan on the International
Polar Year 相似文献
42.
The covariate-specific receiver operating characteristic (ROC) curve is an important tool for evaluating the classification accuracy of a diagnostic test when it is associated with certain covariates. In this paper, a weighted Wilcoxon estimator is constructed for estimating this curve under the framework of location-scale model for the test result. The asymptotic normality is established, both for the regression parameter estimator and the estimator for the covariate-specific ROC curve at a fixed false positive point. Simulation results show that the Wilcoxon estimator compares favorably to its main competitors in terms of the standard error, especially when outliers exist in the covariates. As an illustration, the new procedure is applied to the dementia data from the national Alzheimer’s coordinating center. 相似文献
43.
Reversible assembly and disassembly of rod-like large complex micelles have been achieved by applying photoswitching of supramolecular inclusion and exclusion of azobenzene-functionalized hyperbranched polyglycerol and α-cyclodextrin as driving force, promising a versatile system for self-assembly switched by light. Hydrogen-nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FT-IR) spectroscopy were applied to characterize the azobenzene-functionalized hyperbranched polyglycerol. Atomic force microscopy (AFM), transmission electron microscopy (TEM) and dynamic laser light scattering (DLS) were employed to investigate and track the morphology of the rod-like large complex micelles before and after irradiation of UV light. 相似文献
44.
21世纪以来,随着各学科之间的交叉渗透,化学工程的研究对象越来越复杂,界面传递对多相化工过程的影响越来越显示出它的重要性,传统的传递模型已经很难对界面复杂动态的传递行为进行定量描述.本文应用线性非平衡态热力学理论,对传统物质传递模型进行描述,分析界面传递过程速率,强化的三个因素:界面传质系数K、传递截面积A、界面化学位梯度△u.以含钾化合物作为模型体系,基于非平衡热力学原理建立了描述和预测固一液界面处介质传递速率的模型,并建立了描述其溶解速率的通用模型和测定钾离子动力学数据的实验方法,通过分析探讨了多相过程速率强化的途径. 相似文献
45.
Cao XueLei Jiang WeiChun Meng Bin Zhang WanChang Luo Tao Yang Sheng Zhang ChunLei Gu YuDong Sun Liang Liu XiaoJing Yang JiaWei Li Xian Tan Ying Liu ShaoZhen Du YuanYuan Lu FangJun Xu YuPeng Guan Ju Zhang ShuangNan Wang HuanYu Li TiPei Zhang ChengMo Wen XiangYang Qu JinLu Song LiMing Li XiaoBo Ge MingYu Zhou YuPeng Xiong ShaoLin Zhang Shu Zhang YongJie Cheng ZeHao Zhang Fei Li MaoShun Liang XiaoHua Gao Min Yang EnBo Liu XiaoHang Liu HongWei Yang YiJung Zhang Fan 《中国科学:物理学 力学 天文学(英文版)》2020,63(4):1-19
46.
47.
Separation and enrichment technology of cerium(Ⅲ) ions (Ce~(3+)) has always been of interest,especially in the latest decades,because cerium(Ⅲ) has been widely used as micro-additives in functional materials,gasolene catalysts,polishing powder,ceramic and metallurgical areas. 相似文献
48.
In the present work, we develop a method to derive the anomalous velocity of a spinning electron. From Dirac equation, the relationships among the expectation values of the Pryce’s mass-center operator, the position operator, the spin operator and the canonical momentum operator are investigated. By requiring that the center of mass for a classical spinning electron is related to the expectation value of Pryce’s mass-center operator, one can obtain a classical expression for the position of the electron. With the classical equations of motion, the anomalous velocity of a spinning electron can be easily obtained. It is shown that two factors contribute to the anomalous velocity: one is dependent on the selection of Pryce’s mass-center operators and the other is a type-independent velocity expressed by the rotational velocity and the Lorentz force. 相似文献
49.
三维荧光光谱结合二阶校正方法测定细胞培养基中阿霉素的含量 总被引:1,自引:0,他引:1
本文采用交替三线性分解(ATLD)和交替归一加权残差三线性分解(ANWE)两种二阶校正方法结合激发发射矩阵荧光光谱对完全不经任何预处理的细胞培养基中的阿霉素进行简单、快速、直接的定量测定.当算法选取组分数为2时,解析得到细胞培养基中阿霉素的平均回收率分别为(100.5±1.8)%和(100.3±1.9)%.在细胞培养基中加入烟酰胺腺嘌呤二核苷酸(NADH)、烟酰胺腺嘌呤二核苷酸磷酸(NADPH)、黄素腺嘌呤二核苷酸(FAD)和黄素单核苷酸(FMN)四种细胞内的自发荧光物后,选取组分数为4时,解析得到细胞培养基中阿霉素的平均回收率分别为(99.1±2.9)%和(99.2±3.1)%.结果表明该分析方法能够准确、快速地直接测定细胞培养基中阿霉素的含量,并且在模拟细胞内荧光干扰环境下可定量测定阿霉素,且能获得令人满意的结果. 相似文献
50.
He JianJun Hu Jun Xu ShiWei Chen ZhiQiang Zhang XueYing Wang JianSong Yu XiangQing Zhang LiYong Li Long Yang YanYun Ma Peng Zhang XueHeng Hu ZhengGuo Guo ZhongYan Xu Xing Yuan XiaoHua Lu Wan Yu YuHong Zang YongDong Tang ShuWen Ye RuiPing Chen JinDa Jin ShiLun Du ChengMing Wang ShiTao Ma JunBing Liu LongXiang Bai Zhen Lei XiangGuo Sun ZhiYu Zhang YuHu Zhou XiaoHong Xu HuShan Su Jun Li ErTao Wang HongWei Tian WenDong Li XiangQing 《中国科学:物理学 力学 天文学(英文版)》2011,54(1):32-36
The proton resonant properties in 18Ne, which determine the reaction rate of the key stellar 14O(α,p)17F reaction, have been studied by using a technique of proton resonant elastic scattering of 17F+p. A 4.22 MeV/nucleon 17F radioactive ion (RI) beam was produced via a projectile-fragmentation reaction, and separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL). By bombarding a thick (CH2) n target, the energy spectra of the recoiled protons were measured by two ΔE-E silicon telescopes at the center-of-mass scattering angles of θ c.m.≈175°±5°, θ c.m.≈152°±8°, respectively. Several proton resonances in 18Ne were observed clearly. A further R-matrix analysis of the experimental data is under way to determine the resonant parameters. The present work reports the preliminary results briefly. 相似文献