稳定的

Since the roots of the characteristic equation of the digital control system must stay inside the unit circle =1 in the z-plane for the overall system to be asymptotically stable,we see that the second-order digital control system can be unstable for large values of T.

由于基层的特征方程的数字控制系统必须留在单位内循环= 1中的Z -飞机的整体系统是渐近稳定的，我们看到，二阶数字控制系统可为大型值不稳定普通应用评委的稳定性试验的特征方程的均衡器。

To obtain a complete picture about shock formation in non-viscous flow, in the succeeding chapter we investigate the isothermal shocks in adiabatic flows. We find that in this case the shock solution still exists, but the structure and the properties of the solution are greatly different from above even qualitatively. In some region of the parameter space there only exists unstable shock solution and in some region of the parameter space there may exist two stable shock solutions.

为得到完整的无粘流体中激波形成的图象，在接下来的第四章，我们研究绝热流体中等温作为激波条件时的情况，发现此时激波解仍存在，但解的结构和性质甚至在定性上都与前两章有了显著的不同：某些参数空间只存在非稳定的激波解，某些参数空间则会同时出现两个稳定的激波解。

The long-term food security means a reasonable deployment and the sustainable usage of agriculture resource, as well as stable and unstinted food supply capability. Further more, it concerns about the middle and long term forecast of China\s food supply and demand, agriculture competence and farmer\s income within WTO frame, and the protection on agriculture environment.

短期粮食安全指保证粮食的短期供需平衡和粮食价格的稳定，主要考虑短期粮食安全的指标评价、粮食储备和短期粮食国际贸易等问题；长期粮食安全指农业资源的合理配置和可持续利用，保证国家有稳定的、充裕的粮食供给能力，主要考虑我国粮食供需的中长期预测、WTO 框架下农业的竞争力与农民收入以及农业生态环境保护问题。

It is also revealed that in the vicinity of heavy rain, the diagnostic fields such as vorticity and divergence at low levels was coordinated to that at high levels of atmosphere, contributing to the sustaining strong updraft, one of the favorable conditions for occurrence and persistence of the rain.

通过对这次过程中的物理量场的特征分析和能量场的分析发现，在暴雨区附近，涡度、散度等物理量场的高低空配置，有利于维持较强的垂直速度，对暴雨的产生和维持有利：低空急流的存在为暴雨提供了充沛的水汽条件；暴雨区维持的一个高能、饱和、潜在不稳定的环境为暴雨的产生提供了不稳定的能量条件。

The Earth possibly is one by occupies the major part material stably the counter-flow inner layer as well as occupies the few parts the counter-flow outer layer to be composed, the former is constitutes the Earth quite stable movement, the attraction, the magnetic field and so on the macroscopic phenomenon foundation; The latter constitutes the Earth most to be rich in the change the beautiful semblance, such as: Land, islands, volcano, earthquake, plate movement and so on nature environment with each kind of great phenomenon, eliminate this this also are decide the Earth for the perfectly round spheroid basic reason, because the internal heat circular reactions is from starts, the huge energy finally becomes the Earth good fortune a beautiful rich life the star.

地球可能是一个由较稳定占绝大部分物质的对流内层以及占较少部分的对流外层组成，前者是构成地球比较稳定的运动、引力、磁场等宏观现象的基础；后者则构成地球最富于变化的美丽外表，诸如：陆地、岛屿、火山、地震、板块运动等等自然界环境与各种伟大的现象，除此这也是决定地球为浑圆球体的根本原因，因为内热循环反应是从一点开始的，巨大的能量最终把地球造化成一颗美丽的富有生命的星球。

The sand dunes analyses data have shown they mainly consist of well sorted, symmetry skewness and find sands, and the kurtosis peak is narrow or very narrow. There are abundant impacts of mechanic process on the surface of quartz grains. The traces of eolian process often superpose on the traces stamped by river and beach processes. The dish--shaped concavities and mechanic pits are the most common surface textures, but the barchan concavities and curved grain edges are indicated the marks by eolian environment. The heavy minerals assemblages of coastal dunes are dominated by relatively high specific gravity which have stable chemical properity suggesting the mordern high dynamic environments of coast area. The depositional structures of coastal dunes are typified by corss--bed sets composed of steep foreset laminates and gentle windward dipping sets. It also contains some shell fragments and strong worn foraminiferal tests that are impossibly found in inland desert. On the other hand, the sandy deposits of the continental shelf of East China Sea are with wide range of grains, and the depositional pattens are quite complicated.

海岸沙丘是晚全新世以来相对稳定的海平面背景下的海岸带风成堆积，其沉积特征是以细沙为主，分选好，搬运方式以跃移占绝对优势，偏度上近对称，峰态窄到很窄；石英颗粒表面机械作用形态丰富，风成作用形态叠加于河流和海滩过程形态之上，碟形坑和撞击麻点是最为常见的表面形态，而新月形坑和曲脊是其指示性的特征标志；沙丘沙重矿物以化学性质稳定、比重较大的种类为主，反映了海岸带目前的高能动力环境；海岸沙丘沙的沉积构造以高角度前积层和低角度顶积层组成的交错层理为典型特征，同时还含有少量内陆沙漠所没有的少量贝壳碎屑和强烈磨损的有孔虫壳体。

There are two main factors govern the diverse structures of complexes 15 and 16:(1) reaction time and temperature, that is to say, complex 15 is kinetically stable complex, while complex 16 is thermally stable one.

它们结构的不同主要有两个方面的影响因素：一、反应的时间和温度的影响，即晶体15是动力学稳定的产物，晶体16是热力学稳定的产物；二、溶液pH值的影响，即晶体15在pH值较大(≈6)的情况下析出，而晶体16在pH值较小(≈4)的条件下析出。

Synchronous fluorescence showed that the addition of POM could enhance the fluorescence intensity of CV, which was explained in terms of the hindrance of the formation of the nonfluorescent twisted intramolecular charge transfer states of CV by the assembled POM-CV system, and the surfactant CTAB could enhance the luminescence by coordinated assembly.

具有同样Keggin结构的4种稀土杂多阴离子与结晶紫的作用总体一致，稀土元素不同体系的光活性会表现出一定的差异。实验证实，阳离子表面活性剂CTAB的存在会进一步增强体系的发光活性。三者协同作用，形成了更稳定的杂多阴离子－CV-CTAB三元超分子体系，而β-CD的存在对稀土杂多酸盐与结晶紫的超分子体系稳定不利。

The dissertation modifies the model of Holdridge's indexes of lifezone according to the features of the ecological climate of Xinjiang. The influence of the variation of vegetation caused by the climate variation of Xinjiang in recent decades is also analyzed. In recent 40 years, the type of life zone hasn't changed, the area and number of patch changed only. The diversity changed but not too much..That is, diversity of life zone changed in little range, the whole entiroment is still be a rather stable state, whill be goo for desertation expand contrandictorily.

根据新疆生态气候特征和生物地理规律对Holdridge生命地带分类模型进行修正，分析新疆近几十年来气候变化所引起的植被变化对于新疆土地荒漠化的影响。40多年来，新疆生命地带的类型数量并没有产生变化，只是各类型的面积和斑块数的变化，多样性有所波动，但是波动不大，也就是说生命地带多样性的震荡幅度不大，整个生态环境处于一种相对稳定的状态，这种稳定的生态环境状态有利于荒漠化的逆向发展； 7。

The highest occupied molecular orbit and the lowest unoccupied molecular orbit are calculated, and the energy gap of the two orbits determines the activity of the reagents, and yet, in an alkaline solutions for flotation, the HOMOs of the corresponding ions decide the rigidity of the reagents and therefore determine the reaction activity with different rigidity metal cations in minerals, which vary flotation performance to different minerals, and the experimental results were verified.

药剂与矿物作用的能量计算结果表明：苯氧乙酸类抑制剂与方解石和一水硬铝石作用后的能量变化均为负值，能量变化有利，可以形成稳定的吸附；而与黄铁矿作用后的能量变化为正，能量的变化是不利的，故不能形成稳定的吸附，表现出较弱的抑制作用。

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％。