嗜热拟青霉固体发酵产木聚糖酶的纯化和应用研究

利用一株拟青霉新种嗜热拟青霉J18,以天然农业废弃物小麦秸杆为碳源固体发酵产木聚糖酶,优化发酵条件后,产木聚糖酶水平达到16500U/g干基碳源。粗酶液经硫酸铵沉淀、凝胶过滤层析和离子交换层析3个步骤纯化,得到了电泳级纯酶。研究了该酶对馒头品质的影响,发现在面团中添加木聚糖酶能够明显改善面团的操作性能,提高馒头的比容,改善馒头的组织结构,延缓馒头的老化。     

中国西北地区生态农业现状与建设思路

对中国西北地区农业生态环境的现状进行分析，根据地域分异规律，提出以植被的恢复建设为突破口，通过退耕还林草等措施，实现农业生态环境的改善。     

PARAMETRIC DESINGN OF DC FILTERS

The effect of phase angles of commutating voltages on the performance of dc filters is analgzed for the first time and a heurestic method is presented to choose appropriate parameters for swoothing reactors and dc filters.     

Advancement of High Pulsed Electric Field for Inactivation of Microorganism

Inactivation of microorganisms can be realized by the accurately controlling the pulse electric field the strength and time for microorganism cell membrane. Use of high pulsed electric field for inactivation of microorganisms is one of the more promising nonthermal processing methods. Compare with pasteurization,it possesses the advantage of instant and even distribution throughout a conductive food system,short treatment time and very little heating of the medium in continuous processing. In addition, HPEF can decrease the loss of nutrition as little as possible. The author critically review the results of earlier experiment studies on HPEF,the mechanisms of inactivation by HPEF,and we suggest the future work that is required in this field.     

Machine Vision Aided Testing System for Flatness Based on Equal Inclination Interference Theory

An approach is described on the automated tracking of interference circle fringe to get the flatness accurately based on the Equal Inclination Interference Theory (EIIT). The system,based on the theory of EIIT, can be applied to grasp the changing fringe information, which is white alternating with black through the CCD camera. Following the basic principle of fringes image centro-symmetric, we create some windows, process only the interference fringes information in the windows. According to the position of the processed interference fringe and the position of the last adjacent interference fringe in the windows, the interference fringe variation value N from the starting measured point is received, it implies the changed altitude value from the starting measurement point. This method allows us not only get the fringe information of the half-wavelength integer multiple but also denote those of the half-wavelength decimal multiple. The system is proved to be effective experimentally. It is useful in metrology department for the high-precision flatness standard unit.     

Effect of Dynamic Viscosity on Marangoni Convection in Liquid Bridge With Liquid Encapsulation

The authors establish the physical and mathomatical model of the Marangoni convection in liquid bridge with liquid encapsulation (or two immiscible coaxial liquid columns). A Numerical simulation of the Marangoni convection in liquid bridge with liquid encapsulation is performed by employed vorticity-streamfunction method and the Alternative Direction Implicit scheme in finite difference. The distribution of temperature and flow in two liquid columns is then obtained. The influence law of the dynamic viscosity ratio of the inner liquid to the outer liquid to the Marangoni convection in liquid bridge with liquid encapsulation is obtained.     

板栗叶片性状表型多样性研究

对中国板栗自然分布区8个产地采集的板栗叶片进行取样测定,分别测定叶片3项形态指标,结果表明,各指标在同一群体不同品种间差异显著。板栗叶片形态在群体间和群体内存在广泛差异,其中,叶片长、叶片宽及叶片长宽比等3个性状群体内的差异均达极显著水平,F值分别为7.50、6.36及7.39;群体间,叶片长、叶片宽及叶片长宽比3个性状差异均达极显著水平,其F值分别为19.36、18.32和3.40。根据3个性状的平均,群体间的方差分量占总变异的11.417%,群体内的占39.86%,机误占48.72%。板栗叶片3个性状群体间的表型分化系数平均为13.03%,而群体内的平均表型变异占86.97%,表明群体内变异是板栗叶片表型变异的主要来源。     

影响红掌愈伤组织诱导、增殖和芽分化的因素

以Pink champion等盆栽植株和试管苗为材料，研究了影响红掌愈伤组织诱导、增殖和芽分化的因素。结果表明，不同品种的愈伤组织诱导率和外植体褐变率均存在显著差异，诱导率和褐变率之间呈显著的负相关关系。外植体、外源激素和培养基对愈伤组织的诱导有显著影响，不同品种和外植体的适宜诱导培养基不同。光照对愈伤组织的诱导有显著的抑制作用；高浓度生长素、低浓度细胞分裂素，促进愈伤组织的增殖，高浓度细胞分裂素及低浓度生长素促进愈伤组织芽分化；固体培养比液体培养更有利于愈伤组织的增殖和芽分化。     

秦川牛及其利秦杂种牛IGFBP3基因PCR—SSCP多态性研究

以IGFBP3基因作为侯选基因,对秦川牛及其利秦杂种牛群体共计114头个体IGFBP3位点进行多样性分析。结果发现,秦川牛(Q)及其利秦牛(LQ)群体IGFBP3基因座的等位基因A/B频率分别为:0.6667/0.3333和0.6829/0.3171;从位点间杂合度(He)来看,LQ>QQ;位点间有效等位基因数(Ne):QQ>LQ位点间Shannon信息熵SQQ>LQ位点间多态信息含量PICQQ>LQ     

板栗空棚产生原因及降低板栗空棚率技术措施的研究

板栗空棚严重影响燕山板票的产量.产生原因与土壤中缺硼有关.通过早春施硼肥可使空棚率由85.53%下降到2.43%,产量提高7.7倍.但花期喷硼效果不稳定;人工辅助授粉和增施氮、磷、钾肥料及浇水对降低空棚率均无明显效果.