变分原理与非线性水波的Hamilton描述

本文用全变分方法导出水波动力学问题的基本方程组,再用平均势函数Ｆ（Ｘ,ｔ）渐近表示速度势函数（Ｘ,ｙ,ｔ）和Ｌａｇｒａｎｇｅ函数Ｌ（Ｘ,ｙ,ｔ）,导出具有Ｂｏｕｓｉｎｅｓｑ形式的方程．研究了Ｈａｍｉｌｔｏｎ正则方程的简单推导问题．     

锂离子电池SiAg复合材料研究

应用机械合金化法制备了两种不同组分的Si-Ag复合材料.扫描电镜(SEM)、X射线衍射(XRD)、充放电测试和循环伏安法对该材料的微观形貌、相组成及电化学性能.研究表明,组成原子比为1∶1的复合材料具有很好的循环稳定性和可逆性,在0.2mA·cm-2的电流密度下,经50周循环后可逆容量仍保持300mAh·g-1.实验发现,借助充放电控制,即可有效提高合金材料的循环性能.     

减速电势法测量功函数变化的实验方法

功函数（ｗｏｒｋｆｕｎｃｔｉｏｎ）定义为使电子脱离固体进入周围空间（真空）所必须给与电子的最低能量,有时也称为逸出功．它是表征固体表面宏观性质的重要物理量之一,一般随温度缓变,但随表面状况（如表面清洁度、晶向、结构、反应、化学组成、电荷转移等）变化灵敏,变化幅度一般从几十到几百毫电子伏（ｍｅＶ）．对于Ｏ／Ｗ（１００）系统,变化可大于１ｅＶ［１］．因此获取功函数随时间变化的信息对于各种瞬态表面?...     

Optical state selection process with optical pumping in a cesium atomic fountain clock

We propose and realize a new optical state selection method on a cesium atomic fountain clock by applying a two-laser 3-3' optical pumping configuration to spin polarize atoms. The atoms are prepared in |F=3, m_F=0> clock state with optical pumping directly after being launched up, followed by a pushing beam to push away the atoms remaining in the |F=4> state. With a state selection efficiency exceeding 92%, this optical method can substitute the traditional microwave state selection, and helps to develop a more compact physical package. A Ramsey fringe has been achieved with this optical state selection method, and a contrast of 90% is obtained with a full width half maximum of 0.92 Hz. The short-term frequency stability of 6.8×10^-14 (τ/s)^-1/2 is acquired. In addition, the number of detected atoms is increased by a factor of 1.7 with the optical state selection.     

三维无界区域上弱阻尼非线性Schrodinger方程的指数吸引子

文［１］中证明了弱阻尼非线性Ｓｃｈｒｄｉｎｇｅｒ方程在无界区域ＲＮ（Ｎ≤３）上存在一个最大的紧吸引子．本文在此基础上得到了Ｒ３上指数吸引子的存在性     

Exponential attractors of the ginzburg-landau-BBM equations in an unbounded domain

1. IntroductionThe infinite dimensional dynamical systems which are defined by nonlinear evolutionequations have a lot of properties sindlar to what the differential dynamical system8 havehad, such as attractor and inertia1 manifold. However, because of spectral barriers and spec-tra1 gap conditions, for many dissipative evolution equations such as the 2D Navior-Stokesequations, the existence of an inertial manifOld still remains to be a precarious question. Themajor difference between inert…     

可吸收抗菌胆道支架的制备及其生物相容性研究

胆道梗阻是临床上高发病率和高死亡率的疾病之一, 而植入可吸收支架以替代或扩张梗阻病灶是理想的治疗方法之一. 以聚(L-丙交酯-co-ε-己内酯)(Poly (L-lactide-co-ε-caprolactone), PLCL) (丙交酯与己内酯的质量比为8020)和聚L-丙交酯(Poly (L-lactide), PLLA)为基质制备了管状支架, 然后以聚六亚甲基胍盐酸盐(Polyhexamethylene Guanidine Hydrochloride, PHMG)涂覆于支架表面制备抗菌涂层, 研究该支架的理化性质、抗菌活性以及在动物体内的生物相容性和十二指肠的通畅性. 结果表明 PLCLPLLA=5050(P50-50)材料的力学性能在所有配比材料中最好. 经PHMG包覆后的PP50-50皮下植入时, 具有良好的抗菌活性和体内良好的生物相容性. 用PP50-50膜制成的支架在28d内在小鼠十二指肠内具有良好的通畅性和支撑性. 组织学和免疫荧光染色显示, 炎症反应发生在早期, 随后消退. 这些结果表明, PP50-50支架可能是治疗胆道狭窄的一种良好选择.     

大海马昼夜活动节律与缠绕物偏好的观察

对大海马的昼夜活动规律及缠绕物偏好等行为进行了观察．大海马白天活动,晚上休息（Q≥3．59,P〈0．05）．成熟类群以游泳（S）或身体快速运动（Af）摄食,光弱时,游动少,仅头部运动（Ah）、身体缓慢摆动（As）或休息（R）;未成熟类群白天活动强烈,表现为2次摄食活动．大海马对细竹丝、聚乙烯绳、聚乙烯充气管等缠绕物类型偏好无差异（P〉0．05）,与规格无关（P〉0．05）;较喜好垂直或倾斜的缠绕物,喜好程度相似（P〉0．05）,而不喜水平放置缠绕物,也与规格无关（P〉0．05）;成熟个体喜欢在容器底部活动,未成熟个体以中上层活动为主（P〈0．01）．     

Frequency Upconversion Fluorescence Emission of Er^3＋-Doped Oxychloride Germanate Glass

Frequency upconversion fluorescence property of Er^3 -doped oxychloride germanate glass is investigated. Intense green and red emissions centred at 525, 546, and 657nm, corresponding to the transitions ^2H11/2→4I15/2,^4S3/2→^4I15/2, and ^4F9/2→^4I15/2, respectively, were simultaneously observed at room temperature. The quadratic dependence of the 525, 546, and 657nm emissions on excitation power indicates that a two-photon absorption process occurs under 975 nm laser diode (LD) excitation. The Raman spectrum investigation indicates that oxychloride germanate glass has the maximum phonon energy at-805cm^-1. The thermal stability of this oxychloride germanate glass is evaluated by differential scanning calorimetry, and thermal stability factor AT(△T = Tx -Tg) is 187℃. Intense upconversion luminescence and good thermal stability indicate that Er^3 -doped oxychloride germanate glass is a promising upconversion laser material.