查询词典 f ratio

The direct incorporation of U-13C glucose was estimated by the intensity increase of m/z to F(F was parent fragment, and n was the carbon number in the fragment), while the total isotope incorporation from the added 13C could be calculated according to the abundance ratio increment summation from m/z (Fa+1) through (Fa was the fragment containing all original skeleton carbons, and T was the carbon number in the amino acid molecule). The 13C enrichment in the target compound was expressed as atom percentage excess, and that of D-amino acid needed to be corrected by the coefficient of hydrolysis-induced racemization. The 13C enrichment reflected the carbon turnover velocity of individual amino acid enantiomers, and was powerful to investigate the dynamics of soil amino acids.

外加葡萄糖直接合成氨基酸的比例可利用质谱碎片的相对强度变化来评价（n为质谱碎片F中含有的碳原子数目）；而源于葡萄糖的13C同位素在氨基酸分子中的富集程度是所有同位素峰相对强度变化的总和。13C在目标化合物中的富集比例用原子百分超评价，D氨－基酸的APE还需进一步利用水解诱导的外消旋化系数校正。13C在目标化合物中的富集程度可反映各氨基酸手性异构体的碳循环速率大小，是研究土壤氨基酸动态变化的有力工具。

The common method, that all strong-correlation terms of the model are eliminated, can bring the loss in the engineering application, so the new method is proposed that the identified model reserves some correlation. The augmented matrix A is constructed by the outputΔW and the matrix S. The"determinating order based on ratio of determinant"is brought out to screen the strong-correlation terms in the structure identification. The latent root estimation is improved in screening the eigenvalues and eigenvectors. Thus the estimation precision is improved greatly.The consistence check of guidance instrument error coefficients of flight test and ground test is the purpose of flight experiment. The causes of inconsistency of the two models are analyzed. The hypothesis test of linear regression model based on F statistics is proposed to check the consistence.Finally, the instability of error coefficients is probably caused by the change of the flight environments, therefore, the relation between the error coefficients and flight environment is analyzed. The approach is presented to identify SINS guidance instrument error models and compensate the error in the segmented sections corresponding to the change of vertical acceleration of aircraft.

在结构辨识中，常用的方法由于将模型中的强相关项全部剔除而给工程应用带来损失，因此，本文提出了新的有益思想，即在保留一定相关性的基础上进行辨识：将输出向量ΔW与环境函数矩阵S构成增广矩阵A，然后采用"比定阶行列式"来剔除相关向量的方法，这样既可以尽可能多地保留了对落点影响大的强相关参数，又可以对落点影响小的强相关参数给予剔除；在参数估计中，改进了特征根估计中特征根和特征向量的筛选方法，提出"近零"准则，从而大大提高了参数估计的精度；再者，鉴于天地模型"一致性"检验是飞行试验和SINS制导工具误差系数分离的主要目的，因此，本文又深入分析了造成天地模型不一致的原因，提出了采用基于F统计的线性回归模型假设检验方法来进行捷联制导工具误差模型的天地"一致性"检验；最后，鉴于飞行环境剧烈变化可能会对惯性仪表误差系数稳定性带来一定的影响，因此本文深入地分析了SINS制导工具误差系数与外界环境的关系，提出了基于过载变化大小的分段辨识和分段实时补偿的算法。

The river patterns of the study area were analyzed by the latest channel pattern discrimination in the last glacial maximum and deglaciation of the Late Pleistocene. The hydrology, sediment, environment parameters of the ancient channel in the study area, width-depth ratio F =22.22, suspended sediment concentration M =10.10%, channel curvature P =1.52, meander wavelength L =

然后应用最新河型判别方法，分析判别晚更新世末次盛冰期和冰消期研究区埋藏古河道的河流类型为辫状型；并分析得到研究区古河道的宽深比（ F ＝22.22）、悬移质含量（ M ＝10.10％）、河道弯曲率（ P ＝1.52）、河曲波长（ L ＝1 647 m）等古水文泥沙环境参数分类指标。

Thereby F/T-PSA ratio may be useful for the differentiation between BPH and prostate cancer.

因而，F/T-PSA测定可有助于BPH与前列腺癌的鉴别诊断。

In this paper, the relationship between the fatigue crack front straightness S t and fatigue loading ratio f were explored.

通过实验，研究了疲劳裂纹前沿平直度 St与疲劳载荷比 f 之间的关系，发现两者高度正相关，为预制具有平直裂纹前沿的疲劳裂纹提供了有效的途径和方

The reason for this is that ratio F/D determines the angle the edges of the parabola are seen from the focus.

原因就是F/D的比率限定了抛物线焦点到边缘的角度。

His first camera had an aperture of about 360mm or 14.5 in diameter, and a focal ratio of f/1.75. It is now housed in a museum at the Hamburg Observatory .

他的第一个相机的光圈约三百六十零毫米或14.5 ，直径，和一个焦点的比例f/1.75 ，这是现在住在一个博物馆在汉堡天文台。

The ratio F/D is also crucial in determining the characteristics of the feed that will illuminate the dish.

在决定典型照射馈源时，F/D的比率也是决定性因素。

ABSTRACT:The half-power bandwidth method is the commonly used method at home and abroad, the authors discover that factors, such as the sampling frequency, the frequency resolution, the ratio of the sampling frequency to the signal frequency, the analyzed width and the damping ratio, make the estimated damping ratio fluctuate vastly. Mostly the result is incredible except for some conditions, the error is sometime amazing, which is not acceptable.

半功率带宽法是国内外常用的测试阻尼的方法，笔者发现半功率带宽法由于受到信号处理中的①采样频率SF②频率分辨率△f③采样频率与信号频率之比K ④采样分析的长度T和⑤阻尼比D的大小等因素的影响使得测得的阻尼比值波动很大，除少数状态是可信的外，多数状态是不稳定的，有时误差惊人，得到的测试数据不能使用，易导致错误的结论。

As prepared sample were characterized by FTIR and XRD, Results showed that the C-H bonds disappeared and the C-F bonds gradually increased in the process of reaction, the plane structure of mesophase pitch molecule was destroyed and distortion molecule construction of pitch fluoride took place it, moreover, the average distance between layers gradually increased with the enhancement of the F/C atomic ratio of pitch fluoride.

红外测试表明：随着氟化反应的进行，C-H键消失，C-F键形成并逐渐增加；XRD测试表明：中间相沥青中原有的大分子平面芳烃结构被破坏。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。