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1.
In order to shorten the difference between the raw silk size grading standards of the world and that of China, to quicken the step of the electronic raw silk testing process, the distribution of the coefficient of variation (CV50m%) of the raw silk size in the electronic testing and the development of the new standards are studied according to the sampling and grading theory. By the theoretical deduction and the simulating experiments, the distribution of the coefficient of variation of the raw silk size is given, and the grading scheme whose quality index is the coefficient of variation(CV50m%)of the raw silk size and the grading precisions of all grades are proposed. Moreover, the rightness and the feasibility of the grading scheme are testified by the sampling and grading simulation.  相似文献   

2.
Based on studies of the water content of the early Cretaceous Feixian high-magnesium basalts in the eastern part of the North China Craton (NCC), it has been suggested that the early Cretaceous lithospheric mantle of the eastern NCC was highly hydrous (〉1,000 ppm, HeO wt.) and that this high water content had significantly reduced the vis- cosity of the lithospheric mantle and provided a prerequisite for the destruction of the NCC. The eastern part of the NCC had undergone multistage subduction of oceanic plates from the south, north, and east sides since the early Paleozoic, and these events may have caused the strong hydration of the NCC lithospheric mantle. To determine which subduction had contributed most to this hydration, we measured the water contents of the peridotite xenoliths hosted by the early Cretaceous high-magnesium diorites of Fushan in the south- central part of the Taihang Mountains. Our results demon- strate that the water content of the early Cretaceous litho- spheric mantle beneath the south part of the Taihang Mountains was ~ 40 ppm and significantly lower than that of the contemporary lithospheric mantle beneath the eastern part of the NCC. Thus, the hydration of the early Cretaceous lithospheric mantle of the eastern part of the NCC can be ascribed to the subduction of the Pacific plate from the west side. Thus, the main dynamic factor in the destruction of the NCC was likely the subduction of the Pacific plate.  相似文献   

3.
The type of pinion and rack vertical shiplifts has been developed in recent a couple of years in the construction of dams. But the design methods and methodologies have rarely been discussed in literature. The Xiangjiaba shiplift is the second shiplift of this type following the Three Gorges shiplift. Being aimed at the technological rationality of the design in synthetically considering security, economy and applicability, this paper presents the research results of some vital issues relating the design of the Xiangjiaba shiplift, including the determination of design water depth of ship chamber based on fluid numeral computation and physical model test, the optimum design of general layout of main equipments and the civil structure of the Xiangjiaba shiplift, the finite element method (FEM) analysis of stress, vibration modes and the buckling of ship chamber, antiseismic research and the design of structures and mechanisms of the shiplift and the optimum design of driving mechanisms. This research provides the theoretical basis for the design of the Xiangjiaba shiplift. The design principles and research methods are valuable for the design of the same type of shiplifts.  相似文献   

4.
5.
We studied the resonant tunneling properties of one-dimensional photonic crystals consisting of single-negative permittivity and single-negative permeability media using transfer matrix methods. The results show that there exists a pair of resonant tunneling modes in this structure. The separation of the pair of tunneling modes can be tuned by varying the ratio of thicknesses of the two single-negative layers or the thickness of the defect layer. The electric field intensity of the resonant tunneling modes increases rapidly with the increase of the ratio of thicknesses of the two single-negative layers. The peak value of the field intensity of the resonant tunneling modes is enhanced by one order of magnitude when the ratio of thicknesses of the two single-negative layers increases by 0.4. This property will be applied widely in the field of nonlinearity optics. With the increase of the ratio of thicknesses of the two single-negative layers, the electric field of the tunneling modes becomes more localized, and the full width at half maximum of the tunneling modes becomes narrower. Besides, the pair of tunneling modes is insensitive to incident angle and thickness fluctuation. These properties will be used for the design of tunable omnidirectional double-channel filter with high quality factor.  相似文献   

6.
Based on the features of the serious deformation of coal roadway, many random variables of the mechanics of the surrounding rocks and the influence of mining, the reliability analysis model of the support structure of coal roadway under the influence of mining is established, and the calculating formulas of reliability of the support structure is obtained with the engineering structure reliability theory. And the reliability is calculated based on the method of Monte Carlo to the coal roadway which is exampled on the influence of mining or not. The relationship between support parameters and reliability, the mining influence coefficients and reliability is established, which provides theory foundations for the design of the coal roadway bolt support.  相似文献   

7.
The finite element method is one of the typical methods that are used for numerical water quality modeling of the topographically complicated river. In this paper, based on the principle of probability theory the probability density of pollutants is introduced. A new model for the grid size optimization based on the finite element method is developed with the incorporation of the maximum information entropy theory when the length of the grid is given. Combined with the experiential evaluation approach of the flow discharge per unit river width, this model can be used to determine the grid size of the finite element method applied to water quality modeling of the topographically complicated river when the velocity field of the river is not given. The calculating results of the application of the model to an ideal river testified the correctness of the model. In a practical case-the application of the model to the Xingjian River (the Hengyang section of the Xiangjiang River), the optimized width of the grid of the finite element method was gained and the influence of parameters was studied, which demonstrated that the model reflected the real situation of the pollutants in the river, and that the model had many excellent characteristics such as stabilization, credibility and high applicability in practical applications.  相似文献   

8.
This paper introduces the Hua construction and presents the holomorphic automorphism group of the Hua construction of the fourth type. Utilizing the Bergman kernel function, under the condition of holomorphic automorphism and the standard complete orthonormal system of the semi-Reinhardt domain, the infinite series form of the Bergman kernel function is derived. By applying the properties of polynomial and Γ functions, various identification relations of the aforementioned form are developed and the explicit formula of the Bergman kernel function for the Hua construction of the fourth type is obtained, which suggest that many of the previously-reported results are only the special cases of our findings.  相似文献   

9.
This paper introduces the Hua construction and presents the holomorphic automorphism group of the Hua construction of the fourth type.Utilizing the Bergman kernel function,under the condition of holomorphie automorphism and the standard complete or- thonormal system of the semi-Reinhardt domain,the infinite series form of the Bergman kernel function is derived.By applying the prop- erties of polynomial andΓfunctions,various identification relations of the aforementioned form are developed and the explicit formula of the Bergman kernel function for the Hua construction of the fourth type is obtained,which suggest that many of the previously-reported results are only the special cases of our findings.  相似文献   

10.
In order to ascertain the distribution of flow depth and veloctiy of debris flow,the the combination of numerical modeling and the GIS technology has been used to simulate the movement process of debris flow out of the outlet .The main model of momentum classification of risk zoning of debris flow is Z=Khv,Based on the distribution of the veloctiy and depth of debris flow ,the ditribution of momentum can be ascertained.Thereby the classification of risk zoning of debris flow can be worked out ,A case study of Chacatio Valley in Caracas,Venezuela,is presented to illus-trate the application of the method.  相似文献   

11.
谷氨酰胺转胺酶发酵培养基的响应面分析优化   总被引:2,自引:0,他引:2  
利用SAS(Statistical Analysis System)软件中二水平设计的Plackett-Burman设计和响应面分析法(Response Surface Analysis,简称RSA),研究了链霉菌(Streptomyces sp.)HS-1摇瓶发酵生产谷氨酰胺转胺酶的发酵培养基.通过二水平设计实验考察了八种因素对发酵生产谷氨酰胺转胺酶的影响,利用极差分析确定其中以豆饼粉水解物、甘油以及硫酸铵为影响链霉菌发酵生产谷氨酰胺转胺酶的重要因素.通过响应面分析法建立了这三个重要因素的二次回归模型,应用规范分析找到最优点,分别为豆饼粉水解物24.0 g &;#8226; L-1,甘油24.4 g &;#8226; L-1,硫酸铵5.40g &;#8226; L-1.摇瓶实验表明,应用优化培养基谷氨酰胺转胺酶酶活由6.27 μ &;#8226; mL-1提高到7.30μ &;#8226;mL-1,提高了16.4%.  相似文献   

12.
Degradation of organic matter in the sediments of Hongfeng Reservoir   总被引:1,自引:0,他引:1  
In this work, the distribution of organic carbon, DNA and lipids in the sediments of Hongfeng Reservoir were described in addition to SO4^2- profile in pore water. The contents of organic carbon in the sediments range from 23.3 to 76.8 mg·g^-1, with the peak value appearing at the depth of 8 cm bellow the sediments water interface (SWI), and tend to decrease gradually with sedimentation depth. The concentrations of SO4^2- decreased from 40.50 mg·L^-1 to 12.00 mg·L^-1 at SWI in top 4 cm sediment, and was kept at 12.0 mg·L^-1 bellow that depth. Newly produced organic carbon can be conserved as long as 14 years in the sediments. The contents of DNA were relatively high in top 9 cm surface sediments, as revealed by agarose gel images, close to those of organic carbon and sulphate reduction index (SRI). This study shows that bacteria played an important role in organic matter degradation; SO4^2- is the primary electron acceptor under anaerobic condition in this reservoir; DNA in the lake sediments can provide important information for the study of cycling of nutrient elements in the lake.  相似文献   

13.
Fluorescence study on the interaction between apoCopC and cupric   总被引:2,自引:0,他引:2  
The interaction between apoCopC and cupric was investigated by fluorescence spectra, in phosphate (20 mmol/L) buffer at pH 6.0. Results suggest that the environment is measured to be hydrophobic completely around tryptophan (83). At the same time, apoCopC fluorescence at 320 nm was significantly quenched with the addition of cupric and the 1:1 stoichiometric ratio of apoCopC to cupric was confirmed by fluorescence. In addition, the conditional binding constants were calculated to be Kcu-copc=(1.8±0.58)×10^13 mol^-1 L on the basis of the results of fluorescence titration curves. The apoCopC has the ability to bind specifically cupric ion.  相似文献   

14.
α-硫辛酸和二氢硫辛酸的抗氧化作用   总被引:5,自引:0,他引:5  
采用多种化学发光体系和比色体系研究了氧化型硫辛酸——α-硫辛酸(α-lipoic acid, LA)和还原型硫辛酸——二氢硫辛酸(dihydrolipoic acid, DHLA)直接清除活性氧、抗脂质过氧化以及对&;#8226;OH引起的DNA氧化损伤的保护作用.实验发现,LA和DHLA能有效清除相应体系中的活性氧过氧化氢(H2O2)、羟自由基(&;#8226;OH)、过氧亚硝基阴离子(ONOO-)和二苯代苦味肼基自由基(DPPH&;#8226; ),能显著抑制脂质过氧化,并对&;#8226;OH引起的DNA氧化损伤有良好的保护作用,而DHLA还可以有效清除超氧阴离子自由基(O&;#8226;2-).这些结果提示,LA和DHLA都是良好的抗氧化剂,但相比之下DHLA的抗氧化能力要显著强于LA.本研究为LA和DHLA保健和药用价值的进一步开发,提供了自由基生物学方面的依据.  相似文献   

15.
Proton transfer in carbonic anhydrase Ⅱ has been studied at the B3LYP/6-31G(D) level. The active site model consists of the zinc ion, four histidine residues, two threonine residues, and three water molecules. Our calculations showed that the proton of the zinc-bound water molecule could be transferred to the nearest water molecule and an intermediate containing H3O^+ is then formed. The intermediate is only 1.3 kJ·mol^-1 above the reactant complex, whereas the barrier height for the proton transfer is about 8.1 kJ·mol^-1.  相似文献   

16.
在低温下对高氯酸银-苯配合物AgClO4&;#8226;C6H6的晶体结构进行了重新测定,晶体属斜方晶系,空间群Cmcm(#63).晶胞参数:a=8.154 0(6)×10-10 m, b=7.918(4)×10-10 m, c=11.717(1)×10-10 m,V=756.4(4)×10-30m3, Z = 4, 精度偏离因子R=0.023, Rw =0.050.根据该配合物晶体结构特征和从头计算的研究结果, 与前人报道的结构数据进行了对比, 指出两次测定在结构上的差异.据此, 提出了目前在中外教科书中有关苯在与银离子配位时发生严重变形的描述有待更正的必要性.  相似文献   

17.
The detailed electrical conductivity measuremerit (ECM), trace chemical compositions and microparticles concentration analysis are performed for BH8 ice core from the depth of 126.0m to 130.0m at Vostok Station. At depth 128.7m, a volcanic signal 4726 a B.P. is detected. The volcanic sulphate flux is 95.8 kg·km^-2, sulphate peak concentration 1352.8 ng·g^-1, duration time about 10.1 years, comparable with some well-known volcanic events. The results indicate that it seems to be a relatively large scale, long lasting volcanic signal with farther volcanic origin.  相似文献   

18.
农田氮素非点源污染模型及年负荷估算研究   总被引:1,自引:0,他引:1  
研究了农田中氮素随径流动力输出的过程,并依据径流特征和农田氮肥施用情况,将全年区分为水田施肥期、水田生长期和非水田期.按试验时的天气条件,分别采用人工模拟降雨或农田实测降雨的资料,分析农田非点源污染回归模型.水田施肥期采用人工模拟集中降雨情形,降雨强度为2 mm&;#8226;min-1,模型氮素浓度范围为28~45 mg&;#8226;L-1;水田生长期和非水田期采用天然降雨,降雨强度为0.037 6~0.075 1 mm&;#8226;min-1,模型氮素浓度为0.2~4.0 mg&;#8226;L-1.在分析长系列降雨资料的基础上,综合运用修正SCS(Soil Conservation Service)法、单位线法和相关分析法,估算得到农田径流过程排放的氮素量,再加上地下水渗漏流失的氮素量,取得上海地区一般降水年份农田的氮素非点源污染年负荷量为26.5 kg&;#8226;ha-1.  相似文献   

19.
Enzyme-catalytic fluorescence determination of artemisinin (qinghaosu, QHS) was developed using pyronine B (PB) as substrate of horseradish peroxidase (HRP). The interaction between HRP and QHS was an enzyme-substrate model. The catalytic characteristic of HRP in the oxidation reaction, in which the fluorescence of PB was decreased in the presence of QHS, was studied. The steady-state catalytic rate depended upon enzyme and substrate concentrations, and the Michaelis-Menten parameters Km, Vmax and Kcat were 8.4×10^-5mol·L^-1, 7.4×10^-6mol·L^-1s^-1 and 50.23s^-1. The catalytic activity of enzyme was inhibited in the presence of deactivated agents and at high temperature, respectively. Under optimum conditions, linear relationship between fluorescence intensity change (F0-F) of pyronine B and concen- tration of QHS was in the range of 1.41×10^-7-1.27×10^-6mol·L^-1. The detection limit (3σ) was determined to be 2.7×10^-8mol·L^-1. The proposed method was applied to the concentration determination of QHS in the media of plasma or urine samples.  相似文献   

20.
 研究了时标上三阶非线性p-Laplacian三点边值问题[Φp(p(t)u Δ∆ (t))]Δ+a(t)f(t,u(t))=0,t∈[0,T],βu(0)-γuΔ(0)=0,uΔ(T)=αu(η),u Δ∆(0)=0借助于锥上的五泛函不动点定理,得到了边值问题至少有三个正解的一些新的结果,同时给出了例子验证了主要结果。  相似文献   

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