使稳定

1Niche construction can lead to stable coexistence of diverse genotypes in spatially structured population, which supports a stable polymorphism even without heterozygote superiority.(2)With habitat deterioration, niche construction accelerates the formation of steady polymorphism and hence impedes the harmful influences of environment on the population, which might embody a life-history strategy of organism under the unfavorable environment.(3)Niche construction results in the coexistence with alternative polymorphism through genotype-environment feedback and limited gene flow.(4)The niche-constructing organism is an active force to alter its environment and hence the direction of natural selection in order to better survival.(5)Spatial dynamics and distribution pattern of metapopulation are profoundly influenced by time-lagged niche construction.(6)Metapopulation size can reach a fixed level in the recency effect and equal weighting of time lag but is statistical stability in primacy effect, which implies the primacy effect is most remarkable.(7)The increment in the relative weightingof each generation\' niche construction and the length of time lag are significant factors for system destabilization.(8)Moderate capacity of positive niche construction benefits the metapopulation persistence.(9)The narrowing of niche breadth can decrease the metapopulation size and thereby increase the extinction risk.(10)The coupled function of time lag and niche construction make the system oscillation and generate the spiral wave, spiral-broken and circular wave in heterogeneous habitat.The spatial distributions of metapopulation and resource content are complementary due to a phase lag of their both frequencies.(12)Metapopulation persistence with niche construction depends not only on the balance between colonization and extinction, but also on the balance between the ability of niche construction and natural dissipation of habitat.(13)Metapopula-tion can survive under certain condition when the percent of suitable patches in habitat is lower than the ration of extinction to colonization.(14)Two thresholds exist in the process of transition of habitat quality dynamics from unsuitable to suitable, which include the intensity of niche construction and the initial condition of system.(15)Metapopulation size is positive correlated with the ability of positive niche construction, which means that organism or population who has strongly positive influences on their environment plays an important role to maintain the available habitat.

通过上述几个方面的研究，主要得出以下15条结论：(1)生态位构建可使空间结构种群，甚至是在没有杂合子优势的条件下，形成多种可能的稳定基因型分布模式；(2)随着环境的破坏与恶化，种群的生态位构建作用加速其较早形成稳定多态以阻碍环境对种群的不利影响，解释了有机体在不利环境下的一种生活史对策；(3)生态位构建作用通过基因型—环境反馈机制及有限的基因交流导致基因型多态的稳定共存；(4)有机体的生态位构建作用是一种积极的动力改变环境进而改变其自然选择的方向；(5)生态位构建的时滞作用对集合种群动态和空间分布产生深刻影响；(6)集合种群大小在时滞的崭新效应和等权重效应下达到一固定值，而在首位效应下达到统计稳定，表明首位效应的影响最显著；(7)首位效应下生态位构建相对权重的增量和时滞的长度是影响系统不稳定性动态的关键因素；(8)适中的生态位构建强度有利于集合种群的续存；(9)生态位宽度变窄会减少集合种群的数量从而增加其灭绝风险；(10)时滞和生态位构建的双重作用使系统产生周期振荡，并在异质性环境中产生稳定的螺旋波，破碎的螺旋波和环形波三种分布模式；(11)集合种群与资源含量的空间分布因为相滞而互补；(12)具有生态位构建的集合种群续存不仅取决于侵占率与灭绝率之间的平衡，而且依赖于生态位构建能力同其生境的自然消耗速率之间的妥协；(13)当生境中适合侵占的斑块比例小于其侵占率与灭绝率之比时，生态位构建作用促使集合种群在一定条件下续存：(14)生境斑块的状态从不适合到适合转变过程中存在生态位构建强度和系统初始条件这两个阈值；(15)集合种群的大小同正生态位构建能力正相关，意味着对环境具有较强正作用的有机体对维持有效生境起积极作用。

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。

Our numerical results show that the end-results of the image set of the discontinuous border of the mapping function forms a stochastic web.

类耗散性可能使稳定的混沌轨道转变为"混沌类瞬态"，并最终被椭圆岛（可称为"规则类吸引子"）捕获。

Compared with under non-tillage, water infiltration increases under intertillage, especially under the storm events, stable infiltration rate has one fold increase and coefficient of recharge from precipitation increases of more than 50%.

中耕显著增加了水分入渗，特别在高强度降雨下，中耕使稳定入渗率增加1倍以上，入渗补给系数增大50%以上。

Revive revivify 再给予……活力使复苏 While the California company reported a healthy 10%gain in third-quarter profits,most of its toy lines are mature,and for them to grow, must be constantly revitalized, they particularly in the US.

这家加州公司在第三季的获利仍稳定增长 10%，但它大部分的玩具都已经达到市场成熟阶段，若要再增长，势必得不断赋予它们新生命力，特别是在美国市场。

Specifically, itcontains 8 chapters.In chapter 1, the formation, structures, properties and the futureprospect of liposome were thoroughly reviewed;In chapter 2, the stibility and permeability of phopholipid -eleostericacid liposome were studied together with the effect of polymerizationof eleostearic acid. This membrane system was very sensitive to 〓,the effect of 〓 was clarified to increase the aggregation/fusion ofliposomes and made the permeability of mixed liposomes much higher;In chapter 3, two polymerizable conjugated diyne bolaamphiphiles were synthesized. They could form very stable mixed liposome, andthe diyne could be polymerized by UV light in bilayer liposomes, as aresult, the stability of mixed liposome against solvent or surfactantafter polymerization were enhanced. In chapter 4, two kinds of amphiphilic amino acids were synthesized andstable liposomes were formed therefrom After the condensationpolymerization of amino acid in bilayer liposomes, stable polypeptide liposomes were obtained, which had lower phase transition temperatureand higher permeability.In chapter 5, four kinds of glycolipids were synthesized and theiraggregation behavior in water was comparied. When incorporated intophospholipid bilayer membranes, they could increase the phase transitiontemperatures and inhibit the aggregation and fusion of mixedliposomesat lower temperature.In chapter 6 and 7, three kinds of steroidal bolaamphiphiles withdifferent chain lengths were synthesized. Incorporation of steroidalmoiety to the center of lipid bilayer membrane obviously increased themobility of lipid membrane and shifted Tc to lower temperature side incomparasion with cholesterol. The bolaamphiphile which was shorter thanthe hosted lipid bilayer membrane thickness influenced the lipid packingmore obviously.

全文共分8章：第一章对脂质体的形成、结构、性质及展望进行了较为详细的文献综述；第二章研究了磷脂-桐酸脂质体的稳定性，通透能力及桐酸的聚合对这些性质的影响；磷脂-桐酸混合脂质体为一类对〓灵敏的脂质体，〓的作用首先是使脂质体集聚然后使脂质体融合，并加速内包荧光物的释放；第三章通过合成两种可聚合共轭双炔双极性双亲分子DDCA，DDOL，研究了共双炔分子在双分子层脂质体膜上的聚合及对脂质体性质的影响，聚合可以提高脂质体相对于溶剂及表面活性剂的稳定性；第四章合成了两类氨基酸为极性基团的双亲分子，它们均可以在超声下形成稳定的脂质体结构；氨基酸基团可以在脂质体上进行缩聚反应，若聚合后脂质体表面仍有足够的亲水能力，则可得到稳定的多肽型脂质体；聚合后脂质体的相变温度降低，通透能力增加；第五章合成了四种亲水基团为单糖基的双亲分子GL-l，GL-2，GL-3， GL-4，研究了它们在水中的分散情况、集合体形态与分子结构的关系；在DMPC双分子层膜中加入糖脂分子可以使脂质体的相变温度提高，阻止脂质体在低温放置时的集聚与融合；第六章-第七章合成了三种不同碳链长度的双极性含胆甾环双亲分子 CL-1，CL-2，CL-3；它们可以象胆固醇一样与磷脂混合形成稳定脂质体，胆甾环基团位于脂质体双分子层膜的中间；与胆固醇的作用相反，它们可以增加磷脂双分子层膜的流动性，降低混合脂质体的相变温度；三种分子的作用与其碳链长度和磷脂双分子层膜的厚度有关，比膜厚度短的分子影响最大。

Biomass at stationary phase increased by 39％under the high CO〓 level (2800μL L〓 CO〓), and by 9％under the mixotrophic condition.

碳限制时，添加醋酸钠（2 mmol L〓）和提高CO〓浓度均促进海生椭球藻的生长，使稳定期生物量分别增加9％和39％。

Elevated CO〓 to 700μL L〓 enhanced the growth of Nitzschia palea by 4-20％at the beginning of exponential phase, and that of Chaetoceros muelleri by 11-31％in the late exponential phase.

谷皮菱形藻和牟氏角毛藻，在CO〓浓度倍增（700μL L〓 CO〓）条件下，前者的生长从对数期开始受到促进，而后者的促进出现在对数末期；CO〓浓度倍增使稳定期的最大生物量，谷皮菱形藻增加4-20％，牟氏角毛藻增加11-31％。

The results show that for a supersonic shear layer without reaction, a disturbance can make the shear layer become unstable, this results in one vortex or more than one vortex. The combination and seperation of vortex can intensify the mixing. But it is not easy for supersonic reacting shear layer with exotherm to become unstable with disturbance, and the effect duration is very long.

结果表明，对完全气体的超声速剪切层流动，一定的激励方式能使原先较为稳定的剪切层流动变得不稳定，产生单涡或多涡结构，发生多涡间的合并，使混合加剧；但对于存在放热现象的反应超声速剪切层流动，外加激励方式不易使流动从稳定变为不稳定，而且外加扰动的作用特征时间也较长，实际应用前景不乐观。

It is reason that more Ca~(2+) can destroy the balance of electrostatic and hydration shell in the milk system hardly.Homogenization is key to the pinenut milk process attributed to emulsifies enhanced the particles interaction and stability.

它使稳定剂和松仁乳的分散相充分混合，相互作用，降低了颗拉的直径，稳定剂在颗粒表面形成稳定的保护膜和水化层阻止了分散相的聚合。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。