分光光度法测定氧氟沙星胶囊含量

采用分光光度法测定氧氟沙星胶囊的含量，线性范围1．6－15μg/ml(r=0.9999)平均回收率在99％以上，变异系数小于0．9％。本法简便、准确、稳定，适用于氧氟沙星胶囊含量的快速测定。

春风何以不度玉门关

释义 远远奔流而来的黄河，好像与白云连在一起，玉门关孤零零地耸峙在高山之中，显得孤峭冷寂。何必用羌笛吹起那哀怨曲调去埋怨杨柳迟迟不发芽呢，玉门关一带春风本来就是吹不到的啊!

Evaluation on Uncertainty of Determining Aspartame in Beverage by HPLC

[Objective] The aim was to evaluate the uncertainty of determining aspartame in beverage by high performance liquid chromatography （ HPLC）. [Method] The content of aspartame in beverage was determined by HPLC, then the source of uncertainty in the whole determination process was analyzed, and each component of uncertainty was evaluated and combined. [ Result] Through 6 repeated determinations by the method in GB/T 22254-2008 ＂Determination of Aspartame in Food＂, the average content of aspartame in beverage was （0.806 ±0.038） g/kg, and k =2. The main sources of uncertainty to affect the process were the sample weighting process, the preparation process of standard solution introduced by sample constant volume and the uncertainty introduced by fitting standard curve. ①The uncertainty of standard work-solution. The combined uncertainty of standard work-solution was 0.013 9, among them the uncertainty introduced by standard sample purity was 0.005 8, the standard uncertainty introduced by standard material weighting was 1.49 ×10^4, the relative uncertainty introduced by glass apparatus calibration in the preparation process of aspartame standard reserving solution was 0. 007 88, and the uncertainty introduced by glass apparatus calibration in the preparation process of standard work-solution was 0. 009 9. ②The uncertainty introduced by the preparation process of sample specimen. Among them the relative standard uncertainty introduced by sample weighting process was 0. 009, and the uncertainty introduced by sample constant volume was 0.000 78. ③The uncertainty introduced by the fitting process of standard curve. Among them the relative uncertainty of curve fitting was 0.002 46, the uncertainty introduced by the determined results of aspartame was 0.017 0, the total combined standard uncertainty was 0.023 9, and the expanded standard uncertainty was 0.019. [ Conclusion] The uncertainty components of standard solution, standard curve and repeatability are the main sources of uncertainty, while those of sample weighting and sample constant volume account for little proportion.

王之涣《凉州词》异文全面考辨

越是流传广泛的诗文,越是容易变形走样。王之涣的《凉州词》就是其中的一个典型。王之涣七绝《凉州词》的异文很多,"黄河远上"与"黄沙直上"之争备受关注,而"春风不度"与"春光不度"以及诗题和作者之异等却鲜有论及。通过对多达37种文献、50个版本的查证,尤其是对同一文献的多版本比较,不仅对《凉州词》进行了全面的考辨,而且校雠了前人论文论著中的一些讹误。综合考虑意境、版本等各种因素,《凉州词》的几处异文应该取"黄沙""直上"和"春光""不度"。

Study on Spatial Distribution Pattern of Thrip (Odentot hrips lati) on Alfalfa (Medicago sativa)

[Objective] The aim of this study was to reveal and analyze the spatial distribution pattern of thrip（Odentot hrips lati） on alfalfa（Medicago sativa）.[Method] Within alfalfa plantation areas,experimental plots with the sizes of 10×10,10×20,10×30,20×30,20×40,20×80,30×30,30×40,30×50,40×40,40×50,40×80 and 50×50 m2 respectively were set up in the randomly selected sampling sites of 1 m ×2 m in size.During bud-emerging period and florescence period of alfalfa in the experimental plots,the number of thrips was counted and their distribution pattern was measured using XU Ru-mei＇s method.[Result] During bud-emerging period of alfalfa,the spatial distribution of thrips assumed an elliptic shape sized of 40×30-40×40 cm2 at horizontal level and that presented an ascending-falling trend of tress density down from the top at vertical level.During the florescence period of alfalfa,it showed a homogeneous distribution or randomly distributed pattern at horizontal level and a falling trend of tress density from the top to the apex to the root at vertical level.[Conclusion] Our results provide theoretical basis for field selection of insect-resistant alfalfa varieties.

RBF neural network regression model based on fuzzy observations

A fuzzy observations-based radial basis function neural network （FORBFNN） is presented for modeling nonlinear systems in which the observations of response are imprecise but can be represented as fuzzy membership functions. In the FORBFNN model, the weight coefficients of nodes in the hidden layer are identified by using the fuzzy expectation-maximization （ EM ） algorithm, whereas the optimal number of these nodes as well as the centers and widths of radial basis functions are automatically constructed by using a data-driven method. Namely, the method starts with an initial node, and then a new node is added in a hidden layer according to some rules. This procedure is not terminated until the model meets the preset requirements. The method considers both the accuracy and complexity of the model. Numerical simulation results show that the modeling method is effective, and the established model has high prediction accuracy.

Calculation connectivity reliability of road networks based on recursive decomposition arithmetic

In order to decrease the calculation complexity of connectivity reliability of road networks, an improved recursive decomposition arithmetic is proposed. First, the basic theory of recursive decomposition arithmetic is reviewed. Then the characteristics of road networks, which are different from general networks, are analyzed. Under this condition, an improved recursive decomposition arithmetic is put forward which fits road networks better. Furthermore, detailed calculation steps are presented which are convenient for the computer, and the advantage of the approximate arithmetic is analyzed based on this improved arithmetic. This improved recursive decomposition arithmetic directly produces disjoint minipaths and avoids the non-polynomial increasing problems. And because the characteristics of road networks are considered, this arithmetic is greatly simplified. Finally, an example is given to prove its validity.

Characterizing heterogeneity in vehicular traffic speed using two-step cluster analysis

In order to analyze the heterogeneity in vehicular traffic speed, a new method that integrates cluster analysis and probability distribution function fitting is presented. First, for identifying the optimal number of clusters, the two-step cluster method is applied to analyze actual speed data, which suggests that dividing speed data into two clusters can best reflect the intrinsic patterns of traffic flows. Such information is then taken as guidance in probability distribution function fitting. The normal, skew-normal and skew-t distribution functions are used to fit the probability distribution of each cluster respectively, which suggests that the skew-t distribution has the highest fitting accuracy; the second is skew-normal distribution; the worst is normal distribution. Model analysis results demonstrate that the proposed mixture model has a better fitting and generalization capability than the conventional single model. In addition, the new method is more flexible in terms of data fitting and can provide a more accurate model of speed distribution.

SIMULATION ANALYSIS OF INFLUENCE OF ROAD SURFACE ROUGHNESS ON TYRE DYNAMIC PERFORMANCE IN AUTOMOTIVE BRAKING

Using a nonlinear time varying tyre model, this paper simulatively analyzes the influence of road surface roughness amplitude and road spatial frequency on automobile ground adhesion ability. The result shows that with the increase of road surface roughness, the tyre adhesion ability declines, and the automotive braking distance increases. Moreover, the reliability of the nonlinear time varying tyre model in reflecting the influence of the road surface roughness is validated. It is testified that this model is an effective dynamic one in the simulation of automotive braking performance on uneven road.

Viscous warm pressure bulging process of AZ31B magnesium alloy with different ellipticity dies

Based on the bulging principle of different ellipticity dies, the methyl vinyl silicone rubber with excellent thermal stability and heat transfer performance was chosen as the viscous medium. The finite element analysis and experiments of viscous warm pressure bulging （VWPB） of AZ31B magnesium alloy were conducted to analyze the influence of different ellipticity dies on the formability of AZ31B magnesium alloy. At the same time, based on the grid strain rule, the forming limit diagram （FLD） of VWPB of AZ31B magnesium alloy was obtained through measuring the strain of bulging specimens. The results showed that at the temperature range of viscous medium thermal stability, the viscous medium can fit the geometry variation of sheet and generate non-uniform pressure field, and as the die ellipticity increases, the difference value of non-uniform pressure reduces. Meanwhile, according to the FLD, the relationship between part complexity and ultimate deformation was investigated.

Research into Uncertainty in Measurement of Seawater Chemical Oxygen Demand by Potassium Iodide-Alkaline Potassium Permanganate Determination Method

Using the glucose and L-glutamic-acid to prepare the standard substance according to the ratio of 1：1, and the artificial seawater and the standard substance to prepare a series of standard solutions, the distribution pattern of uncertainty in measurement of seawater COD is obtained based on the measured results of the series of standard solutions by the potassium iodide-alkaline potassium permanganate determination method. The distribution pattern is as follows： Uncertainty in measurement is big and not constant at the high end, but small and constant at the low end.

ANALYSIS OF UN-COINCIDE COORDINATE ERROR IN SINGLE-AXIS ROTATING FIBER OPTIC STRAP-DOWN INERTIAL NAVIGATION SYSTEM

The un-coincide coordinate error in the single-axis rotating fiber optic strap-down inertial navigation system（SINS） is analyzed. Firstly, a rotating modulation technology is presented for SINS. The method provides the enhanced property of SINS when using the same-leveled inertial measurement units. Then, the rotating struc- ture modification is derived and augmented to resolve the un-modulated error-accumulated problem. As the insuf- ficient machine processing, the horizontal and the vertical errors on the machine surface are inevitable, and the in- volved coordinates are difficult to get the exact coincident. So, two major kinds of coordinate situation are stud- ied. The equivalent error models on gyro and acceleration outputs are built for each situation, and the impact is analyzed for compensation. The part of attitude and position error models caused by the built angle-rate error is established to calculate the un-eoincident impact. Considering these conditions of different gyro accuracy and mo- tion states simultaneously, numerical simulations are implemented. Results indicate that the SINS modulation ac- curacy is seriously affected by the combined factors on gyro accuracy and motion conditions.

An Uncertainty Assessment Approach for Measuring Flatness Error in Close Way

It is necessary for precise measurement to estimate the uncertainty of measurement result. When measuring flatness error in close way by pitch, usually the uncertainty of measurement result is independently estimated according to pitch points. By analyzing a concrete example, this paper proposed that the uncertainty should be evaluated by the correlation calculating method. This approach greatly improved the deficiencies of the assessment method according to independent measurement and enhanced measurement precision. It provides a reference value for uncertainty assessment in leveling a flat.

Changes in Violaxanthin Deepoxidase Activity and Unsaturation of Thylakoid Membrane Lipids in Indica and Japonica Rice Under Chilling Condition and Strong Light

To explore the differences of sensitivities to chilling and strong light in indica and japonica rice (Oryza sativa L), the changes in unsaturation of thylakoid membrane lipids and xanthophyll cycle were studied under chilling condition and strong light. The contents of unsaturated fatty acids of thylakoid membrane lipids decreased and that of the saturated ones increased with the time of chilling and strong light treatment, resulting in the reduction of the index of unsaturation of fatty acids (IUFA). The activity of violaxanthin deepoxidase (VDE), a key enzyme of xanthophyll cycle, also reduced. The content of violaxanthin (V) increased, and the contents of antheraxanthin (A) and zeaxanthin M decreased, the ratio of (A+Z)/ (A+Z+V) decreased correspondingly. Arrhenius analysis showed that VDE was sensitive to both chilling and unsaturation level of thylakoid membrane lipids. Correlation analysis showed that there was distinctly positive relationships between IUFA of thylakoid membrane lipids and the activity of VDE, Fv/Fm, and D, protein content. Lower IUFA values, less fluidity and stability of thylakoid membrane lipids, lower VDE activity and (A+Z)/(A+Z+V) ratio were found in indica rice cv. Shanyou 63 than in japonica rice cv. 9516 under chilling and strong light.

Determination of undrained shear strength using piezocone penetration test in clayey soil for bridge foundation

In order to obtain the reasonable undrained shear strength Su for geotechnical analyses of bridge foundations in Yangtze River floodplain clayey soils, a site-specific study is conducted using the imported piezocone penetration test （CPTu） with dissipation phases at the Fourth Nanjing Yangtze River Bridge construction sites. Taking the values of Su from laboratory tests as references, several existing Su-predicted methods based on CPTu are compared and evaluated. To verify the presented cone factor Nk, additional test sites are selected and examined. The results show that the values of cone factors such as Nkt, Nke, and Nau, depend on the shear test mode and disturbance. Generally, the values of Nke show more scattering than those of Nkt and N△u. For the stratified and layered sediments of the Yangtze River floodplain, it is recommended using the net cone resistance qT to estimate Su and the preliminary cone factor values Nkt are from 7 to 16, with an average of 11. It is also confirmed that the CPTu test, as a new technique in site characterization, can present reasonable parameters for bridge foundations.

A BEEM Study on Effects of Annealing Temperature on Barrier Height Inhomogeneity of CoSi_2/Si Contact Formed in Co-Ti-Si Systems

Ultra thin epitaxial CoSi 2 films are fabricated by solid state reaction of a deposited bilayer of Co(3nm)/Ti (1nm) on n Si(100) substrates at different temperatures.The local barrier heights of the CoSi 2/Si contacts are determined by using the ballistic electron emission microscopy (BEEM) and its spectroscopy (BEES) at low temperature.For CoSi 2/Si contact annealed at 800℃,the spatial distribution of barrier heights,which have mean barrier height of 599meV and a standard deviation of 21meV,obeys the Gaussian Function.However,for a sample that is annealed at 700℃,the barrier heights of it are more inhomogenous.Its local barrier heights range from 152meV to 870meV,which implies the large inhomogeneity of the CoSi 2 film.

Uncertainty in Measuring Construct-specific Fragments of Genetically Modified Maize MON863 by Real Time Quantitative PCR

[Objective] The study aimed at evaluating the uncertainty in measuring the construct-specific fragments of genetically modified maize MON863 by real time quantitative PCR.[Method] The content of construct-specific fragments in MON863 samples was determined by real time quantitative PCR,and then the uncertainty of measurement result was evaluated according to the sources of uncertainty like the PCR system,the data processing and the micropipette.[Result] Type A evaluation of uncertainty（uA） in the measurement was 1.7×10^-2;Type B evaluation of uncertainty（uB） was 9.0×10^-4;the combined standard uncertainty（uC） was 1.7×10^-2;the expanded uncertainty（U95） was 0.036 and the finally measured result was 1.08%±0.036.[Conclusion] The main uncertainty of the result measured by real time quantitative PCR came from the randomizing effect in the experimental process.

Analysis of Drought Changes and Drought Mitigation in Xiji County of Ningxia

[Objective] The aim was to study the characteristics of the changes of extreme weather climate incidents such as severe drought in northwest and rainstorm in Xiji County of Ningxia. [Method] Precipitation anomaly percentage was applied to divide drought level and for statistics analysis. Seasonal index, linear tendency, and 5-years gliding average were used to reflect the trend of drought changes. The circulation wave of temporal sequence used polynomial expression to simulate the interannual variation scale. The positive part of the polynomial expression used bar chart to simulate interannual variation scale. [Result] The index of drought season from November to June was large. The general trend of annual drought was increasing. The drought of interannual scale was most serious around 1977, about 15 and 20 years. The drought in recent years went up. The general situation of drought, interannual scale and changes of interannual scales from March to May and from September to October were discussed. Based on the weather at 500 hPa, the first rain in Xiji and the drought-turning-into-rain situation were classified. [Conclusion]These may provide reference value to the prevention and mitigation of drought.

Fractal Studies on Dielectric Ageing

A stochastic model of conducting crack propagation is presented to provide a conceptual framework dedicated to the study of the formation of fractal structure of dielectric ageing patterns as a result of a competition between random fluctuation growth and applied electric strength enhanced deterministic growth. The necessary and sufficient conditions resulting in fractal behaviour in dielectric ageing are found.

Uncertainty Evaluation of Preparation of Organophosphorus Pesticide Mixed Standard Solution

The uncertainty of standard solution plays an important role in detection of pesticide residues. It may affect the accuracy of detection results. In this study, the 14 organophosphorus pesticides mixed standard solution was used as the material to analyze all the influencing factors for the preparation of mixed standard solution with uncertainty as the only judging index. The preparation uncertainty of mixed standard solution was calculated with the top-down calculation method. In the end, the expanded uncertainty was presented. The results showed that the preparation of mixed standard solution from stock solution with precise pipettes had a relatively low uncertainty.