新疆野生甘草与栽培甘草的质量特征比较

为比较新疆野生甘草与栽培甘草的质量差异,本文采用粉末X射线衍射(XRD)全谱分析法和紫外分光光度法对二者进行对比分析。结果表明:野生甘草和栽培甘草在2θ值2°～30°低角度范围内指纹图谱无较大特征差异;野生甘草中主要化学成分和Fe、Mg、Ca三种微量元素的含量均高于栽培甘草,且成份比例也不同——野生甘草中三种微量元素的含量比例是1.00:6.67:107.84,而栽培甘草中为1.00:8.70:36.42。     

Localization of calmodulin and calmodulin-like protein and their functions in biomineralization in P. fucata

Calmodulin (CaM) and calmodulin-like protein (CaLP) are two proteins involved in biomineralization. Their localizations in Pinctada fucata mantle epithelia were studied by Western blot (WB) analysis of the nuclear/cytosol fraction of primary cultured Pinctada fucata mantle cells and immunogold electron microscopy. The results showed a completely different distribution of these two proteins at the subcellular level. CaM was distributed throughout both the nucleus and cytoplasm of the mantle epithelium but CaLP was distributed only in the cytoplasm. The functions of these two proteins in biomineralization were investigated by shell regeneration. During this process, the expressions of CaM and CaLP were greatly enhanced in different organelles of the mantle epithelium. Overexpression of these two proteins and a mutant of calmodulin-like protein (M-CaLP) that lacks an extra C-terminal tail in MC3T3-E1 promoted the mRNA expression of osteopontin, a biomineralization marker for osteoblasts. All of the results indicated that CaM and CaLP have completely different distributions in the mantle epithelium and affect the biomineralization process at different levels. The extra C-terminal tail of CaLP is important for its functions in biomineralization in Pinctada fucata.     

面向移动目标的WSN单个检测模式覆盖问题

基于能量暴露模型,分析了环境噪声、传感器和被测移动目标物理参数节点检测半径的影响,提出了一种大规模无线传感器网络(WSN)在二维平面上节点归一化密度的三角形分析模型(TAM).以检测概率为覆盖性能评价指标,采用归一化分析方法,用TAM分析了归一化路径长度小于1时归一化密度与单个检测模式的检测概率关系,得到了最坏情况下节点归一化临界密度上限.仿真实验结果表明归一化临界密度可较为准确地由检测概率和归一化路径长度确定,可为大规模无线传感器网络的传感器参数选择和部署提供参考.     

外语教学中调动学生积极性的策略

随着外语教学和研究的不断发展,外语教学也从以前的"以教师为中心"的传统教学法向"以学生为中心"的交际教学法转变。认识到语言学习不仅仅是靠教师教出来的,教并不意味着学。所以,学生的积极性和主动性的发挥对教学的效果起着不可低估的作用。     

斜面两点悬挂物体运动控制研究

如何控制两点悬挂斜面上的物体进行二维运动,其实质是以两个相关的极坐转换成平面坐标的运动控制系统。本文通过一个单片机控制两个减速同步电机正反转和一个斜板组成的实验模型,对悬挂物体实现定点定位和规定运动的方案论证、算法分析、控制实现等方面进行了论证和实现。     

度在无向图中的简单应用

在已有文献基础上,计论度在判断无向图的圈、连通性、Euler图以及Hamilton图等方面的一些运用．     

利用分层分类法进行厦门岛城市地表分类研究

利用分层分类法把厦门岛城市土地类型分为七类,并对分类结果进行了验证．在TM图像光谱特征分析和归一化差异型指数分析结论上,提出分层分类法的分类步骤．利用ERDAS的专家分类器逐类地提取土地类型,并利用掩膜法将原图像上新提取地类所对应区域掩膜掉,使得分类过程越来越容易．分层分类法避免了一次划分多种类别方法在选择波段组合上的矛盾．精度评价结果表明,总分类精度达到90．9％,达到分类要求标准．     

圆分布双跳无线传感器网络配置及拓扑发现修复算法与仿真

指出了无线传感器网络在从战场到环境监测的许多领域都表现得越来越重要,给出了一类圆分布双跳无线传感器网络,并提出其安全性要求和模型．对于其面临的威胁,在权衡网络资源局限性的基础上,提出了相应解决方案,包括拓扑发现算法、网络配置协议和网络修复算法（TDNSR）。仿真结果表明：和SPIN算法相比,TDNSR能迅速实现网络拓扑发现和配置并修复,能有效减少资源开销。     

R—L模型的参数估计及其影响分析

基于EM算法和Laplace逼近,首先给出了R-L模型的参数估计,然后应用完全数据对数似然函数的条件期望以及相应的Q距离函数,对R-L模型数据进行了数据删除影响分析和局部影响分析,并通过实际数据验证了所得诊断统计量的有效性.     

Crystal structure of the neurotrophin-3 and p75NTR symmetrical complex

Neurotrophins (NTs) are important regulators for the survival, differentiation and maintenance of different peripheral and central neurons. NTs bind to two distinct classes of glycosylated receptor: the p75 neurotrophin receptor (p75(NTR)) and tyrosine kinase receptors (Trks). Whereas p75(NTR) binds to all NTs, the Trk subtypes are specific for each NT. The question of whether NTs stimulate p75(NTR) by inducing receptor homodimerization is still under debate. Here we report the 2.6-A resolution crystal structure of neurotrophin-3 (NT-3) complexed to the ectodomain of glycosylated p75(NTR). In contrast to the previously reported asymmetric complex structure, which contains a dimer of nerve growth factor (NGF) bound to a single ectodomain of deglycosylated p75(NTR) (ref. 3), we show that NT-3 forms a central homodimer around which two glycosylated p75(NTR) molecules bind symmetrically. Symmetrical binding occurs along the NT-3 interfaces, resulting in a 2:2 ligand-receptor cluster. A comparison of the symmetrical and asymmetric structures reveals significant differences in ligand-receptor interactions and p75(NTR) conformations. Biochemical experiments indicate that both NT-3 and NGF bind to p75(NTR) with 2:2 stoichiometry in solution, whereas the 2:1 complexes are the result of artificial deglycosylation. We therefore propose that the symmetrical 2:2 complex reflects a native state of p75(NTR) activation at the cell surface. These results provide a model for NTs-p75(NTR) recognition and signal generation, as well as insights into coordination between p75(NTR) and Trks.