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991.
鹅生长激素基因外显子单核苷酸多态性分析 总被引:1,自引:0,他引:1
以莱茵鹅、四川白鹅、豁眼鹅、皖西白鹅和朗德鹅5个鹅品种为试验材料,根据鸭、鹅生长激素基因序列设计了3对引物扩增第2、第3、第5外显子,用PCR-SSCP方法进行单核苷酸多态性分析,并对不同鹅品种进行群体遗传学分析。结果显示:在鹅GH基因第2外显子上共发现2个单碱基突变位点,第39个碱基处的T→C突变未发生氨基酸变化,为沉默突变;第74个碱基处T→C单碱基突变导致第25个氨基酸由缬氨酸(V)变为丙氨酸(A);鹅群中表现出10种基因型(AA、AB、AC、AD、BB、BC、BD、CC、CD、DD)。统计结果发现:10种基因型在鹅品种间分布存在极显著差异(P0.01);所有鹅品种均处于Hardy-W e inberg平衡状态。群体遗传分析显示:杂合度、有效等位基因数朗德鹅最低,豁眼鹅最高;朗德鹅PIC为0,四川白鹅为中度多态外,其他品种均为高度多态。表明鹅GH基因在不同鹅品种中具有丰富的单核苷酸多态性,可以进一步作为候选基因来分析其与生产性状的相关性。 相似文献
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Based on the discussion of the simulation for the cable prestress, the rigidity theory was used to identify the geometrical dimensions of semi-rigid structures in zero state. When the structural geometry in initial state is given, the geometrical dimension in zero state is determined by the initial prestress distribution. The contribution-matrix method is firstly applied to get the initial lack of fit. However, the influencing factor of initial lack of fit on the displacement of control point is linear superposition, that is, the structural response is linear, and it is irreconcilable with the geometry nonlinear of semi-rigid structure. In order to reduce the error of nonlinear structural response, the influencing factor in the contribution-matrix method is revised, and modified contribution-matrix method is put forward. Programs by ANSYS parameter design language APDL are worked out for the form-finding analysis of beam-string structure of a practical project. The numerical results show that the modified contribution-matrix method reduces the errors of the assumption of structural linear response. And it can be applied to the form-finding of semi-rigid structures with small stiffness. 相似文献
996.
The differential equation which governs the behavior of the gear transmission system of 1.5 MW wind turbine is established. The external excitation caused by wind speed fluctuation is discussed and the internal excitation due to time varying mesh stiffness and comprehensive error is also analyzed. The calculating formulations of the harmonic balance method of nonlinear dynamic equations are presented. Then, the multi objective dynamic optimization model is developed to minimize the value of vibration acceleration and the overall volume. The optimization of a practical example using mixed discrete combined programming is performed. The result shows that the proposed method of modeling and optimization design can effectively reduce the wind turbines gearbox vibration levels and weight. 相似文献
997.
It is important to utilize coal bed methane to achieve the safe, environmental and economic benefits. The authors simulate the processes of multi jet diffusion combustion of low concentration coal bed methane using k ε turbulence model,non premixed combustion model and P1 radiation model. The influences of different geometrical structures and operating parameters on the combustion process are compared with each other. The results show that the distance between the gas nozzles and central axis,the angle of gas deflected from air ,the velocity ratio of air to gas have important impacts on the combustion. When the distance, the deflection angle and the velocity ratio are 30 mm,45 °and 2, respectively. The best combustion result can be achieved. 相似文献
998.
With establishing the fundamental equation of prestressed circular membrane under Fppl von Kármán membrane theory, Hencky transform is extended and the general solution of axisymmetrical deformation of prestressed circular membrane under uniformly distributed loads is obtained. The central deflection, the radial and circumferential stresses of the membrane are given in the form of power series. And it is found that the solution approaches to the results from Hencky theory when the prestressing is far less than the loads; and the solution approaches to the results based on linear theory when the prestressing is far greater than the loads. 相似文献
999.
An adaptive algorithm for image de noising is proposed based on the multi scale and multi orientation features. The coefficients in different scales and different directions are obtained by image decomposition using the nonsubsampled contourlet transform. Then thresholds functions are adaptively set with these coefficients. The texture of the image information is introduced by using the mean of decomposition scale and the energy of regional. The greater the energy, the more information of the texture while the same decomposition scales, the smaller the threshold is set. On the contrary, the greater the threshold is set. After the de noising and then reconstruction of these coefficients, image de noising is implemented. Compare to the wavelet transform threshold and contourlet transform threshold, the nonsubsampled contourlet transform pick up the image detail better and improve the quality of the image. 相似文献
1000.
Based on the landslide control scheme optimized by considering technical index and other factors,a landslide comprehensive control thought of “treating scheme optimization combined monitoring information feedback” is put forward.The multi level hierarchical comprehensive evaluation index on landslide control scheme is set up on the basis of analyzing many engineering examples,and formula of weight,fuzzy complementary judgment matrix and the consistency check method of judgment matrix of fuzzy analytical hierarchy process are given,the solution of multi objective decision problems based on improved fuzzy analytical hierarchy process is developed,too.Validity and reliability of this method is proved through the scheme selection for Xiangjiapo landslide control.It provides an effective method for construction decision makers. 相似文献