查询词典 natural selection

Since 2000, the project I had/have been responsible for include:Health Effects of Fine/Ultrafine particles in ambient air of Beijing founded by Natural Science Foundation China and also cooperated with GSF, Germany; Energy Selection and Health Benefits in Beijing and China funded by IES program of USEPA, Study of Environmental Cost Model in China funded by USEPA, Risk Assessment for health Effects of Biological Indoor Air Pollutants and outdoor air pollution funded by China Ministry of Science and Technology; Health Effects of Fine Particles from the Dust Storms in China funded by NSFC and also cooperated with NIER, South Korea, etc.?

目前有在读的博士生2人、硕士生6人，MPH5人。主要研究方向为室内外空气污染对人群健康影响的定量评价及方法、环境污染健康风险评价及方法学。目前主持承担的科研项目有：国家自然科学基金重点项目"大气细颗粒和超细颗粒的环境行为。界面过程和健康效应"，国家"十一五"科技支撑计划项目"建筑室内生物污染控制与改善关键技术研究"和"环境污染的健康风险评估与管理技术研究"，欧盟课题"健康与环境网络建设"、韩国环科院合作项目《亚洲沙尘污染对儿童健康影响的比较风险研究》等

BACKGROUND: The selection and development of materials for reconstructing ureteric defect is a hotspot in tissue engineering research, while, human amnion may be a potential ideal natural material.

背景：输尿管等尿路重建材料的选择和开发是目前组织工程学研究的热点，人羊膜是一潜在的理想天然材料。

The highest enzyme producer alkalophilic Bacillus sp SHY8-1 among the inductive strains was mutagenized several times, by adding enzyme production repression aegents into screen medium, combined with natural seperation and pressure selection, finally a CMCase-hyperproductive mutant SHY8-1-25 (partitally resistant to catabolite) was obtained, with the yield of CMCase raised to 13-16u/ml, maximally reached 18-20u/ml, while its parent strain 0.654u/ml.

对诱导型产酶菌-嗜碱芽孢杆菌SHY8-1进行了多次诱变改良，采用添加产酶阻遏剂的平板作为筛子，结合反复的自然分离、压力选择，最终成功地获得了高产变异株SHY8-1-25(已部分解除分解代谢阻遏)，产酶量由0.654u/ml提高到13-16u/ml，最高达到18-20u/ml，讨论了诱变机理策略，考察了碳、氮源等对产酶的影响，对培养基和摇瓶培养条件进行了优化。

The effect of tribology factors on bearing vibration is studied experimentally. AR model and WPT are used to processing the normal arid abnormal signals. The results are as follows:1. The vibration of ball bearings is caused by the tribology action of contact pairs of ball and ring races and has the essential of tribo-dynamics. Any factors affecting the tribology characteristics of contact pairs will affect vibration and noise of bearings consequently.2. Vibration characteristics of bearing keep almostly unchanged with the increasing of axial load expecting the increasing of nature frequencies. When radial load increasing with axial load unchanged, nature frequencies keep unchanged but some new vibration peaks appears in the spectrum.3. Vibration amplitudes are damped and nature frequency are enhanced with sufficient lubrication. Vibration and noise of bearings increase obviously and roar can happen and the contact surfaces scratch slightly under insufficient and unclean lubrication state. Bearing will be disabled in a few minutes without any lubrication.4. Bearing vibration is unstable under low speed. With the speed increasing, the vibration become stable and natural frequencies increase slightly but the amplitudes increase apparently.5. Bearing vibration can be excited only by some harmonics ofwaviness without lubrication and by all harmonics with lubrication based on the theoretical analysis.6. The nature frequencies of ball bearings decrease with the increasing sizes. When international clearance increasing, nature frequencies decrease in radial and increase in axial and angular and the amplitudes increase in radial and decrease in axial and angular. When the number of balls increasing, nature frequencies increase and amplitudes decrease. When the pitch diameter increasing, axial nature frequency increase and others nearly keep no change. When outer race groove curvature radius increasing, nature frequencies increase in radial and decrease in axial and angular and amplitudes keep no change in radial and increase in axial and angular. When inner race groove curvature radius increasing, nature frequencies decrease and amplitudes increase.7. The distortion in amplitude and frequency components of bearing vibration signals picked up by the present probe measurement method is founded and right conclusions cannot be achieved by the signals. When accelerometer is rigidly screwed with steel stud onto a flat outer surface of a ball bearing, vibration signal can be got without distortion and the reliability of research on bearing vibration is assured.8. AR model is suitable for large samples of bearing vibration signals, square root of length of samples can be used as the upper limitation of order determination and the FPE order selection criterion is effective. Many advantages of AR spectrum are founded over the classical based on FFT.9. Time-Frequency analysis is necessary for abnormal noise of ball bearings. WPT overcomes the principle shortcomings of STFT and proved to be a best tool to process the abnormal signals.

理论分析和试验研究表明： 1球轴承振动是钢球—滚道接触副中的各种摩擦学作用引起的，具有摩擦动力学的本质，任何对接触副的摩擦学特性有影响的因素都将对球轴承的振动和噪声特性产生影响； 2中心轴向载荷作用下，载荷增大使球轴承的固有振动频率升高，载荷越大同样的载荷增幅引起的频率升幅减小，足够大的中心轴向载荷作用下载荷的变化对球轴承振动的频率特性不会产生明显的影响； 3轴向和径向联合载荷作用下，径向载荷不大时球轴承振动的固有频率基本不变，但是可能引起变刚度激励的非线性振动，出现新的频峰，过大的径向载荷将使部分钢球脱离接触，使球轴承的振动和噪声呈现不稳定状态； 4润滑对球轴承的振动和噪声特性有重要的影响，良好的润滑对振动有明显的抑制作用，润滑不充分时，振动和噪声的水平会有明显增高，一定条件下还会激发接触副中的谐振，发出啸声，造成接触表面的伤害，无润滑干接触时，短时的运转就会损伤接触副表面，使振动和噪声迅速增大，并随时可能引发严重的磨损和卡滞失效；接触副润滑良好时，油膜的"刚化效应"使球轴承振动的固有频率有所提高，润滑剂中含有弥散性污浊时，振动的幅度总体升高，但弥散性污浊不会改变球轴承振动的频率特性；浙江大学博士学位论文：球轴承振动的研究 5低速时，球轴承振动的基本特征呈现不稳定状态，随着转速的提高，球轴承振动的频率特性趋于稳定，固有频率频峰升高； 6理论分析表明，干接触时钢球和滚道表面波纹度的某些谐波分量能激励球轴承的振动，振动的幅值与谐波幅值成正比，实际球轴承中钢球的分布不可能完全均匀，波纹度的激励作用会随时发生；润滑接触的分析表明，波纹度的任意谐波分量均能激励球轴承的振动； 7球轴承的几何和结构参数分析表明，球轴承尺寸越大，径向、轴向和角振动的固有频率越低；钢球中心圆直径增大，球轴承的径向和轴向振动的固有频率基本不变，角振动的固有频率有所上升，振动的幅频特性基本不变；径向游隙加大使球轴承的径向振动固有频率降低，轴向和角振动的固有频率有所升高，径向振动幅频特性的幅值升高，而轴向和角向降低；钢球的数量增多使球轴承振动的固有频率上升，幅频特性的幅值下降，径向振动的幅值下降最为明显；外圈沟曲率半径系数增大使球轴承径向振动的固有频率升高，轴向和角振动的固有频率降低，径向幅频特性基本不变，轴向和角向幅频特性幅值升高；内圈沟曲率半径系数增大使径向、轴向和角振动固有频率均下降，振动幅频特性的幅值均有升高； 8试验对比表明，传感器采用探针式安装时，由于探针接触副接触特性的影响，钡(量得到的球轴承振动信号有失真，采用专门设计和制作的试验球轴承，以固定式安装加速度计，首次测量得到了球轴承振动的真实信号，通过对振动信号的分析，验证了球轴承振动的理论模型； 9)基于时间序列分析的AR模型适用于大样本球轴承振动信号的分析，以样本长度的均方根值作定阶上界，FPE做判阶准则，给出的AR谱光滑，频率分辨率高，是球轴承振动分析的简便而可靠的手段； 10以时频域分析的小波包变换分析球轴承异音信号能够比较好地定位和聚焦异音发生的时间，时间间隔，频率范围，同样是球轴承振动分析的可靠的手段，可用作球轴承故障诊断技术。

Raw material for coconut oil derivatives, natural formulations, its better quality, and its unique patented triple washing system (also used three kinds of selection of different types of high-performance surface-active agent, other brands of only 1-2 kinds of ), detergency strong, and easily over the water, even if a small amount of residue that would not harm the human body.

原料为椰子油衍生物，天然配方材料，其质量更好，其独特的专利三重清洗系统（也可用于3的高性能表面选择不同类型的各种活性剂，只有1-2种其它品牌），去污力强，很容易在水，即使残留物，将不会损害人体少量。

On the base of the principal factors selected from natural, social and economical conditions in Shenyang, 230 varieties virescence plants are analyzed and ranked, the paper picks out diaphysis trees, basic trees, ongoing expansion trees, adequately retained trees and selective trees from them, and the selection and adjustment program of basic trees and diaphysis trees.

在此基础上，采用园林专家咨询评价的方法，结合前人的研究成果及园林工作的实践总结，从生态适应性、观赏性、生态效能等方面全面系统的建立了沈阳市绿化植物的评价应用的综合指标体系，并根据沈阳市的自然条件和实际情况确定了主要的指标因子对沈阳市常见的230种绿化植物进行了综合评判和分级，筛选出最适宜的骨干树种和适宜的基本树种及宜继续推广的、可适当保留的或应淘汰的种类，提出了沈阳市绿化基调树种和骨干树种选择和调整的方案。

"Chinese children's growth must read" to the initial reading ability and the knowledge base have yet to build up young children to read objects, including the children are most curious, most interested in understanding the mysteries of the universe, animal the world, historical records, children's fables and other types of encyclopedic knowledge, natural science, humanities, are the main areas covered, in the full and comprehensive knowledge of structure, to new ideas, new materials, new results for the selection of the standard , and strive to provide the best spiritual nourishment to our children, our future society is designed to open a new owner of the window fan to see the world, build a vessel about to sail the knowledge of marine vessels.

"中国儿童成长必读书"以初步具备阅读能力而知识基础尚未搭建起来的幼童为阅读对象，内容包括孩子们最感好奇、最有兴趣了解的宇宙奥秘、动物世界、历史记载、童话寓言等百科全书式的各类知识领域，自然科学、人文科学的主要领域均有涉及，在完整、全面的知识结构内，以新观点、新材料、新成果为选择标准，力求提供最好的精神营养给我们的孩子们，旨在为我们未来社会的新主人打开一扇扇看世界的窗子，打造一艘艘即将扬帆远航知识海洋的船只。

Based on the simulation of natural death process of 5% B-cell in biology clone selection, this paper proposes 8 kinds of updating algorithms according to intergeneration differential, theory of chaos, principle of mutation respectively, and selects the updated particles in terms of simulated annealing method.

因此模拟生物克隆选择中5%的B细胞自然消亡过程，在粒子群优化算法进化过程中分别基于代间差分、混沌理论、变异原理等方法设计了8种粒子更新算法，并按照模拟退火方法进行更新后粒子的选择。

Lyell and Hooker agreed that a joint paper should be presented at the Linnean Society, and on 1 July 1858, the papers entitled On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection, by Wallace and Darwin respectively, were read out but drew little reaction.

莱尔和胡克赞成在林奈学会上提交一份联合论文；1858年7月1日，一个题名为"论物种形成品种的趋势，以及通过自然方式选择的品种和物种的无限延续"的报告，由华莱士和达尔文分别宣读，但没有引起人们的注意。

Boat ship wood furniture that material obtained from a unique material, material selection of superior Mesua ferrea, oil Blastophagus wood, teak, elm, and a hundred years experience of the natural temper by wind, rain, mine, electric, beach, waves, sun centuries baptism , set the world on the Aura and the essence of the sun, at first glance rot residual state, but does not cover defective jade, it is increasingly clear texture, earned, the structure of natural pristine, angular run full health, the atmosphere thick texture and color out of the ordinary people, all in all Art is a gift given by nature, highly dynamic and personalized expression.

船说船木家具索取素材材质独特，材质选用上乘的铁力木、油梢木、柚木、榆木，又经历大自然百年锤炼雕凿和风、雨、雷、电、沙滩、海浪、阳光的百年洗礼，集天地日月之灵气及精华，乍看残腐不堪、但瑕不掩玉、愈发显得纹理清晰、酣畅、结构自然质朴、棱角饱满健润、质感色泽厚重大气与众不凡，所有的所有都是大自然赋予的艺术恩赐，极富活力和个性表现力。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。