伪狂犬病毒糖蛋白H基因片段的克隆、序列测定和分析

对伪狂犬病毒湖北地方株(PRVHB株)糖蛋白H基因片段进行了扩增、克隆、序列测定和分析,比较了该序列与PRVKa株及NIA-3株三者之间的同源性.结果显示,克隆片段长1396bp,G+c含量75.6%,包括糖蛋白H(gH)N端283个氨基酸编码区及上游调控序列和胸苷激酶(TK)C端136个氨基酸编码区.gH基因ORF上游调控区存在有TATA框和CAT框的真核启动子特征结构.PRVHB株gH基因片段序列与PRVKa株和N1A-3株相应序列的核苷酸同源性相同,为99.6%.推导的gH多肽N端第1～30位氨基酸组成的肽段富含疏水性氨基酸,具有真核信号肽的序列特征.     

Improvement of laser damage thresholds of fused silica by ultrasonic-assisted hydrofluoric acid etching

Polished fused silica samples were etched for different durations by using hydrofluoric(HF) acid solution with HF concentrations in an ultrasonic field. Surface and subsurface polishing residues and molecular structure parameters before and after the etching process were characterized by using a fluorescence microscope and infrared(IR) spectrometer, respectively. The laser induced damage thresholds(LIDTs) of the samples were measured by using pulsed nanosecond laser with wavelength of 355 nm. The results showed that surface and subsurface polishing residues can be effectively reduced by the acid etching process, and the LIDTs of fused silica are significantly improved. The etching effects increased with the increase of the HF concentration from 5 wt.% to 40 wt.%. The amount of polishing residues decreased with the increase of the etching duration and then kept stable. Simultaneously, with the increase of the etching time, the mechanical strength and molecular structure were improved.     

A new ignition hohlraum design for indirect-drive inertial confinement fusion

In this paper,a six-cylinder-port hohlraum is proposed to provide high symmetry flux on capsule.It is designed to ignite a capsule with 1.2-mm radius in indirect-drive inertial confinement fusion(ICF).Flux symmetry and laser energy are calculated by using three-dimensional view factor method and laser energy balance in hohlraum.Plasma conditions are analyzed based on the two-dimensional radiation-hydrodynamic simulations.There is no Y_(lm)(l≤4) asymmetry in the six-cylinder-port hohlraum when the influences of laser entrance holes(LEHs) and laser spots cancel each other out with suitable target parameters.A radiation drive with 300 eV and good flux symmetry can be achieved by using a laser energy of 2.3 MJ and peak power of 500 TW.According to the simulations,the electron temperature and the electron density on the wall of laser cone are high and low,respectively,which are similar to those of outer cones in the hohlraums on National Ignition Facility(NTF).And the laser intensity is also as low as those of NIF outer cones.So the backscattering due to laser plasma interaction(LPI) is considered to be negligible.The six-cyliner-port hohlraum could be superior to the traditional cylindrical hohlraum and the octahedral hohlraum in both higher symmetry and lower backscattering without supplementary technology at an acceptable laser energy level.It is undoubted that the hohlraum will add to the diversity of ICF approaches.     

基于EMD和数学形态学的多环芳烃光谱去噪EI北大核心CSCD

基于多环芳烃中苯并[k]荧蒽(BkF)的强荧光特性,构建了荧光检测实验系统,并制备了10个不同浓度的BkF甲醇溶液样品,分析了样品荧光特性。为了更好地进行定性和定量分析,采用经验模态分解(EMD)改进阈值法结合数学形态学对荧光光谱信号进行去噪处理,并与EMD阈值去噪法进行对比。结果表明,提出的方法使去噪后的荧光光谱更加平滑,荧光强度与样品浓度的线性相关系数更高,达到0.99746;信噪比有所提高;原始信号与去噪后信号的均方误差由0.0053降低至0.0012。提出的方法去噪效果显著,有效地提高了光谱的分析精度,为荧光光谱预处理提供了一种新方法。     

fs激光在靶背表面产生的质子束成丝

 介绍了利用3TW/60fs钛宝石超短超强激光与20μm铜薄膜靶相互作用的实验。实验观测到质子束的角分布随激光功率密度有所变化。在较高的功率密度（～1×10¹⁸ W/cm²）时，观测到环状的质子束分布，发散角较大。在较低的激光功率密度（～2×10¹⁷ W/cm²）时，质子束发散角减小，质子束出现成丝现象。质子束的角分布实际上反映了从靶前输运到靶背的超热电子电流横向分布。在输运过程中，由于Weibel不稳定性会使超热电子电流出现空心化并最后破裂成丝。     

应用荧光定量PCR技术快速定量检测猪瘟病毒

采用荧光定量PCR技术对猪瘟病毒进行快速定量检测．实验证明,该方法的检测灵敏度可达10拷贝/μL,对于不同毒株以及各种组织样品检测结果均为阳性,通过该方法与RT-PCR、nPCR的比较,发现该方法检测灵敏度比RT-PCR高100倍．与nPCR具有相同的灵敏度,并且该方法避免了常规PCR电泳检测所带来的高污染率,因此,该方法以其快速、灵敏、低污染率的优点,会在猪瘟的早期检测及预防、控制上起到重要作用。     

Y2(Fe1-xSix)14B的中子衍射研究

Nd₂Fe₁₄B是一种磁能积很高的优良的永磁材料,但在实用上稍嫌它的居里温度低了一点。为了提高它的居里温度,人们曾用某些元素替代其中的一些铁作了尝试。文献[9]及我们最近的实验表明:用硅代替部分铁之后,材料的居里点都获得了提高。本文用中子衍射法研究了Si在Y₂Fe₁₄B中的占位情况,以了解Si对磁性能产生的影响。中子衍射的结果表明:Si择优地占据c,j₁及k₂晶位。最后,用磁交换作用对结果进行了讨论。 关键词：     

初中物理形成的思维定势对高中物理教学的影响

学生具有扎实的初中物理知识基础对高中物理的学习大有帮助，这毋庸置疑．然而，如果一个学生对初中的部分知识掌握得过死，形成了思维定势，就会对高中物理的学习造成不良影响．     

Ho2Fe17Cx的结构与磁性

用快速急冷方法制备了Ho₂Fe₁₇C_x化合物,研究了它们的形成、结构与磁性。这些化合物在高温下是稳定的,随C含量的增加,晶体结构由六角Th₂Ni₁₇型转变为菱形Th₂Zn₁₇型。测量了Ho₂Fe₁₇C_x化合物在1.5K和室温下的饱和磁化强度,得到每个Fe原子磁矩近似与C含量无关。C原子的引 关键词：     

二氧化碲非同向声光可调谐滤波器的设计分析

在分析非同向声光可调谐滤波器器件设计理论的基础上，同时考虑声光晶体的双折射和旋光特征，分析和计算了二氧化碲声光可调谐滤波器的超声波极角θａ和入射光波极角θｉ之间的关系以及超声波频率ｆａ和光波波长λ０之间的调谐关系。