多变化的

This paper bases on the technique of virtual prototype and utilizes software platform of UG, ADAMS and ANSYS to establish three-dimensional digitized virtual prototype of double link jib system of portal crane and systematically do its analysis of dynamics emulation of multi-body system.

本文基于虚拟样机技术，利用UG、ADAMS、ANSYS软件平台，建立了门座起重机四连杆组合臂架系统的三维数字化虚拟样机，并对其进行了较为系统的多体系统动力学仿真分析，实现了计算机对组合臂架系统在各种工况下随载荷变化的运行状态及随时间变化过程的仿真，得到的相关仿真分析数据对于门座起重机组合臂架系统动态设计提供了有效的手段。

This paper chose Carbendazim, Daconil, Imidacloprid and Methomyl as experiment objects, determined their influence to soil respiration of field, shed and school using obturate direct absorb method; discussed not only the variety of soil respiration under different pesticide's sorts, concentration and soil conditions but also the relationship between soil respiration and the variety of bacteria number in soil; confirmed the toxicity grade and dangerous index; provided an scientific basis for environment safety evaluation of pesticide's using.

因此，本论文选取多菌灵、百菌清、吡虫啉、万灵为受试农药，用密闭直接吸收法测定了农药对三种土壤（农田土、大棚土和校园土）呼吸作用的影响；讨论了农药种类、浓度、土壤条件的改变引起的土壤呼吸作用强度的变化及土壤呼吸量与土壤中细菌数量变化的关系；确定了农药的毒性等级和危害系数，为农药使用的环境安全性评价提供科学依据。

Methods A retrospective evaluation was done for all the newborns who were born in the provincial women and children's health care hospital from 1995 to 2004-The morbidity, mortality and fatality rate were calculated for each observed year and different seasons. The influence of gender, body weight, gestational age as well as polyembryony and mode of delivery on the asphyxia was analyzed.

对近10年郑州大学第三附属医院分娩的所有活产新生儿的病历资料进行回顾性分析，计算窒息的发生率、死亡率、病死率，观察上述指标的逐年变化趋势及季节变化的情况，并探讨性别、双／多胎、出生体质量、胎龄分娩方式对这些指标的影响。

Finally, the best values of the diameter of prefabricate hole and extrusion speed is determined through optimize simulation results,In the end, forming experiments study of cold extrusion is processed, experiments results shows that internal thread of C195 knuckle axis can be formed by cold extrusion method, and the extrusion torque is varied when diameter of prefabricate hole and extrusion speed is a series of different value.

最后对挂钩轴内螺纹的加工进行了一系列的实验研究，经过多次实验的失败反复，最终挤压加工出了符合要求的内螺纹；实验结果表明该零件内螺纹时可以采用冷挤压成形方法加工的，并且验证了成形过程中挤压扭矩是随着工件底孔直径和挤压速度的变化而变化的。

As an often used physical model with good theoretical and practical values, StreeterPhelps model has been widely used to study water quality. However, in some special water areas the utilitization of StreeterPhelps model has some limitation as confirming reaeration coefficient often comes from tests in rivers with fast water flow speed with no consideration of wave effects. Furthermore, in practical research in Three Gorges Reservoir, the changing rule of COD appears abnormally. In some water areas far from pollution source, the value of COD changes with time, but does not follow the exponential attenuation rule. This phenomenon can not be explained by former modified StreeterPhelps model.

StreeterPhelps模型是目前进行河流水质研究常用的物理模型，具有良好的理论和实用价值，然而在某些特定水域，该模型的应用受到限制，主要原因是复氧系数的取定多在水流速度较大情况下得到的，而未考虑水面波动对复氧系数的影响，另外，在实际研究过程中发现三峡库区COD变化的规律出现异常：在离排污口相当远的水域，COD随时间变化趋势并不是指数衰减，而是在某个常值附近微小摆动，以往很多修正过的StreeterPhelps模型都无法解释这个现象。

However, in some special water areas the utilitization of StreeterPhelps model has some limitation as confirming reaeration coefficient often comes from tests in rivers with fast water flow speed with no consideration of wave effects. Furthermore, in practical research in Three Gorges Reservoir, the changing rule of COD appears abnormally. In some water areas far from pollution source, the value of COD changes with time, but does not follow the exponential attenuation rule. This phenomenon can not be explained by former modified StreeterPhelps model.

StreeterPhelps模型是目前进行河流水质研究常用的物理模型，具有良好的理论和实用价值，然而在某些特定水域，该模型的应用受到限制，主要原因是复氧系数的取定多在水流速度较大情况下得到的，而未考虑水面波动对复氧系数的影响，另外，在实际研究过程中发现三峡库区COD变化的规律出现异常：在离排污口相当远的水域，COD随时间变化趋势并不是指数衰减，而是在某个常值附近微小摆动，以往很多修正过的StreeterPhelps模型都无法解释这个现象。

Multicarrier modulation in data transmission is discussed in the fourth chapter. The performance of MCM and single tone modulation over twisted pairs is compared. Discrete multitone modulation is used in ADSL system. A new variable constellation TCM method is proposed, It can adapt to the subchannel capacity automatically. The simulation results prove that this method is quite effective.

第四章讨论了多载波调制技术在数据传输中的应用，针对市话信道的具体传输环境，比较了单载波调制与多载波调制的性能；针对ADSL传输的目标，采用离散多频音DMT技术，独立提出一种新的星座图变化的格状码方案VCTCM，能动态地适应不同子信道的传输能力，给出的计算机仿真结果表明该方案有较好的效果。

Daxing as the case study has been studied in this dissertation, with the help of geostatistics and GIS, on the basis of data of the second general soil quality investigation in 1982 and the corresponding data of indoors soil analyzed, the spatio-temporal law of organic total-N, hydrolyzable nitrogen, available-P and available-K below the surface of soil (0-20cm) within 20 years in Daxing has been studied, as the same time, the change of soil quality has been evaluation applying to the method of soil quality compressive index, the main results are as follows

本文以北京市大兴区为研究样区，以相同样点的1982年第二次土壤普查土壤肥力数据和2000年的新采土样分析数据为基础，运用GIS与地统计学结合的方法，研究了20年来北京市大兴区300多点位的表层土壤的(0-20cm)有机质、全氮、碱解氮、速效磷、速效钾等肥力要素的时空变化规律，应用土壤质量综合指数法定量评价了表层土壤质量的变化，研究主要结论如下

Results showed that contents of IAA and ABA in peduncle, bourse and the tissues around abscission zone among several cultivars were very different, but their trend of change was similar, IAA content decreased and ABA content increased toward harvest time for all the cultivars. Ethylene evolution in fruit of the cultivars with higher preharvest drop was evidently higher than the cultivars with less preharvest drop. Cellulase activity in the tissues around abscission zone of the cultixars with higher prehanest drop rapidly increased toward harvest time.

结果表明：不同品种果柄、果台和离层部位组织中IAA和ABA含量变化有差异，但它们变化的总趋势相似，都是随着果实成熟IAA含量下降，而ABA含量上升；不同品种的成熟果实中乙烯发生量有很大差异，以落果多的品种显著大于落果少的品种；采前落果重的品种离层部位组织中细胞壁分解酶的活性在果实成熟期急剧增加。

The species structure and importance value dynamics of annual plants in herbage synusia during a growth period have been observed, and the ecological mechanisms of these changes have been analyzed also.

通过跟踪观测一年生植物层片在一个生长周期内种类组成及其重要值的变化，并分析变化的生态学机理，得出如下结论：①在固沙区草本层片内，小画眉草的多度、盖度和重要值在群落中所占比例较大，是群落优势种；②在充足的降雨后，一年生植物都突发性萌发，但随着降雨的减少，层片内的一年生植物种群都呈衰退之势，其中小画眉草和虎尾草种群急剧减少，狗尾草、雾冰藜和虫实种群减少幅度不大。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。