查询词典 marginal density

The main research work of this dissertation is as follows: Based on the chemical reaction engineering theory and the nitrobenzene electroreduction mechanism, the plate and frame electrolyzer was designed and applied to the process of electroreduction nitrobenzene to p-aminophenol. This dissertation measured the residence time distribution data of the electrolyzer by means of the pulse response method and studied the rule of flow pattern along with the current capacity change. Under different conditions ,this dissertation studied the cyclic voltammetry properties of nitrobenzene on different electrodes by means of the dynamic cyclic voltammetry method and the electrode materials applied to the NB electroreduction have been selected primarily.Baseed on the results of cyclic voltammetry tests, this dissertation used p-electrode systems to measure the steady-state- polarization curves of nitrobenzene on different electrodes in H-type diaphragm cell, and obtained each primary factor s influence rule and the exchange current density value of each electrode.And then on the basis of the conclusions of fundamental researchs upword, the effects of influence factors on the the yield of p-aminophenol and the current efficiency,such as electrode material, current density, quantity of electricity circulated, nitrobenzene concentration . sulpuric acid concentration and so on, have been studied in detail in the systems of hign temperature , strong acidity and oxygen-poorthrough a series of electrolysis experiments in this paper.After all using Pb as anode Monel metal as cathode Dupont Nafion 417 cation-exchange membrane as membrane, this dissertation obtained the optimum technological condition: reaction temperature about 85C, current density 500A m-2, sulphuric acid concentration 20%wt.

论文的主要研究工作为：运用化学反应工程理论，结合硝基苯的电还原机理，设计出用于硝基苯直接电还原合成对氨基苯酚实验的板框式电解槽，并利用脉冲响应法测定了该板框式电解槽的停留时间分布数据，研究了流型随流量变化的规律；通过动态循环伏安法研究了硝基苯在不同电极上、不同条件下的循环伏安特性，初步评选出了用于硝基苯电还原的电极材料；结合循环伏安的测定结果，在H型隔膜电解槽中采用三电极体系测定了硝基苯在不同电极上、不同条件下的稳态极化曲线，得到了各主要因素的影响规律及硝基苯在各个电极上电还原的交换电流密度数值；在基础研究结论指导下，采用板框式电解槽，在高温、强酸、贫氧系统中，进行了一系列的电解实验，分别考察了电极材料、电流密度、通电量、硝基苯浓度、硫酸浓度等因素对收率及电流效率的影响，最终选择以蒙乃尔合金电极作为阴极、铅合金为阳极、Dupont Nofion 417阳离子交换膜为隔膜，得到由硝基苯直接电还原制对氨基苯酚的最佳电解工艺条件：反应温度85℃，电流密度500A·m~(-2)，硫酸浓度20％wt。

In this paper, the multivariate archimedean copula is used to analyze the asymmetric dependence structure among financial asset returns, whose marginal processes are captured by nonparametric kernel density estimation.

在研究金融资产的组合风险分析中，描述多个金融资产间的相关结构是选择最优组合权重的关键因素之一，如何准确地刻画金融资产间的非对称尾部相关结构，在定量研究组合资产的风险分析中尤其重要。

Furthermore, some new conclusions were drawn for a particular general form, and the general form was extended to the n-dimensional general marginal density function.

针对具体的广义形式，得出了多个新结果，并将密度函数广义形式推广到n维，最后讨论了这一广义形式在舍选抽样中的应用。

We discuss the mechanism of wave beam forming for the phase array vibrators, give a definition of the marginal energy density for the seismic wave field, and make some quantitative analyses to the energy intensity along each direction on the snapshot of the wave field.

本文讨论这种相控阵震源的波束形成机制。引入了地震波场的边际能量密度的概念，利用地震波场的时间切片技术，对模型空间各个方向上的能量强度进行了定量分析。

The structure and heterogeneity of urban green space in the five districts in Fuzhou , which included the main tree species with diameter at breast height distribution, height class, health class, importance value, relation and the green space patches with areas distribution, perimeter distribution, porosity, connectivity, marginal density, dominance, the characteristics of geo-statistics and so on, were studied in quantification by the use of the principle of landscape ecology combining with the method of studying porosity and connectivity and geo-statistics.

本研究应用景观生态学的原理结合孔性、连通性研究方法和地统计方法对福州市五个行政区的绿地结构和异质性进行了量化研究，包括：城市绿地主要树种、树种的胸径分布、树高等级、健康等级、重要值和多样性、主要树种间的关联度以及绿地斑块大小分布、周长分布、斑块的孔性、连通性、边缘密度、优势度、斑块的地统计学特性等。

objective the aim of this study is to investigate the expression and the distribution of the nerve growth factor during the period of neural tube development of human embryo.method early development of neural tube was studied in human embryos about 35 gestational days by using immunocytochemical abc technique.result there were ngf immuno-positive substances in the cytoplasm and nuclei of neuroepithelial cells in the ventricular zones of neural tube.in the intermediate zone of neural tube,ngf immunoreactivity was detected in the nuclei of some neurons,or the processes of other neurons which contained no ngf-immunoreactive substances in their nuclei;the expression pattern of ngf in the marginal zone of neural tube was similar to that of the intermediate zone.the density of ngf-immunorecative particles was higher on the rostrum side of neural tube than on the caudal side.the ngf immuno-positive cells were also observed among the somites of embryo under the neural tube.conclusion these results suggest that ngf was an important signal molecule to induce neural tube differentiation,and that ngf may play a significant role in regulation of the biological function of neurons in developing neural tube.

目的 研究捷安肽素的抗真菌作用机理。方法采用形态学方法和同位素标记法。显微形态观察经捷安肽素处理后的供试真菌的形态学变化。进一步采用14c同位素标记的特异底物&尿苷二磷酸-（14c）-葡萄糖&示踪，研究捷安肽素对真菌(1，3)-β-d-葡聚糖合成酶活性反应的影响。结果研究神经生长因子在早期人胚神经管发育过程中的定位表达。方法采用免疫细胞化学 abc法染色，研究35天人胚的发育情况。结果在人胚神经管的室管带中，神经元的细胞质和细胞核ngf免疫反应阳性；在中间带，一部分神经元的细胞核ngf免疫反应阳性，另外一部分神经元的细胞核ngf免疫反应阴性，而其突起ngf免疫反应阳性；在边缘带ngf的表达与中间带相似。在神经管的头侧ngf阳性反应较强，神经管的尾侧ngf阳性反应较弱。结论 ngf在人胚神经管免疫反应阳性，表明ngf可能是诱导神经管分化发育的重要信号分子，提示ngf可能在人胚神经管的发育中具有十分重要的作用。神经生长因子；人胚；神经管；发育

Extract information based on the instantaneous features : In the center is one of the instantaneous rate of the power spectral density of the maximum, is a center to the absolute value of the instantaneous rate of the standard deviation, Non-zero weak signal instantaneous phase of the nonlinear component absolute standard deviation, Non-zero weak signal instantaneous phase of the nonlinear component standard deviation, In the center is one of the non-weak signal of the absolute value of the instantaneous frequency standard deviation, a signal to one of the instantaneous frequency of the power spectral density of the maximum, According to 16QAM and QPSK signals XI axis projection in the different performance parameters raised.

提取信号七个基于瞬时信息的特征：零中心归一化瞬时幅度功率谱密度的最大值，零中心归一化瞬时幅度绝对值的标准偏差，零中心非弱信号段瞬时相位非线性分量绝对值标准偏差，零中心非弱信号段瞬时相位非线性分量标准偏差，零中心归一化的非弱信号段瞬时频率绝对值的标准偏差，一个信号段的归一化瞬时频率功率谱密度的最大值，根据信号 QPSK 和16QAM在 XI 轴投影的不同表现，提出特征参数。

By analyzing and calculating work on the spectroscopic diagnostic results, the quantitative relationship between the electron density of laser induced plasma and linear heat input as well as the relationship between electron density and factor of absorption are deduced.

通过对激光等离子体光谱诊断结果的分析、计算，定量地得到了等离子体粒子密度与焊接线能量之间的函数关系以及粒子密度与吸收系数的函数关系。

Replacing complete concentrated feed with mixed concentrated feeds of dwarf elephant grass, brachiaria hybrid Ⅰ and brachiaria hybri Ⅱ, there was no significant effect on the growth and acetone body quality of young goose. The three acids glyceride and high density lipoprotein of serum from 80 day-old geese had no significant difference, but the total cholesterin and low density lipoprotein of geese fed with dwarf elephant grass, brachiaria hybrid Ⅰ and brachiaria hybri Ⅱ were all lower than that fed with concentrated feed to some extent.

用矮象草、臂型草杂种Ⅰ、臂型草杂种Ⅱ混合精料代替全精料养鹅并不会显著影响仔鹅的发育和酮体品质。80日龄鹅的血清TG和HDL差异不显著，但矮象草、臂型草杂种Ⅱ和臂型草杂种Ⅰ饲养的鹅，TC和LDL都一定程度上低于精料组的鹅。

The changes of population density of Rhizosphere bacteria, fungi and actinomyces, and the types and population density of nitrogen-fixing bacteria, phosphobacteria and potassium-bacteria in different types of soils were studied.

研究了不同肥力烟区根际细菌、真菌和根际放线菌的数量变化，以及固氮细菌、磷细菌和钾细菌的数量和种类的变化。

We are forbidden from giving money to these shoeless, skinny children, as this will perpetuate begging.

向光着脚，骨瘦如柴的孩子施舍是不可以的，因为要招来无休无止的乞讨。

It would be hard not to fall victim to some sharpeyed policeman.

要想不被某个目光锐利的警察抓到，谈何容易。