难得的

Due to the restriction of computational complication and precision,WRM boundary collocation method can only be used to simulate temperature fields of single-particle model,as for the case of some more complicated particle geometry shape it is very hard to obtain sufficient approximation solutions.Thus,BEM is adopted to analyze the thermal conduction problem of composites with particle of arbitrary geometry.

由于受计算复杂程度和计算精度的限制，采用加权残值法只能分析单夹杂问题，且对于更复杂的夹杂形状很难得到良好的近似解，因此接下来采用边界元方法分析了具有任意形状夹杂复合材料的温度场问题。

However, measurement noises from different sensors are generally correlated with covariance matrix which is difficult to be determined accurately.

但各传感器测量噪声会出现相关的情况，而且很难得到相关测量噪声的方差矩阵的精确值，测量系统往往是不确定的。

The conventional matrix decomposition methods have been used to find the least-squares solutions of the abovementioned inconsistent matrix equations over given matrix set in many references, and the general expressions of these solutions were obtained. But it is difficult to determine the solution of Problem I by utilizing these expressions due to the fact that the orthogonal invariance of Frobenius norm does no hold for the general nonsingular matrices.

对于求上述不相容矩阵方程在给定矩阵集合上的最小二乘解，很多文献中利用传统的矩阵分解方法得到了其通解表达式，但是利用该表达式很难得到问题Ⅰ的解，这是因为一般的非奇异矩阵并不满足Frobenius范数的正交不变性。

Junius Brutus had never been placed in such a position as this, and seeing no way of getting out of this dilemma, by acting after his favourite model, Mr. Talboys was fain to be natural for once in his life, and to confess that he had suffered much uneasiness and pain of mind about his only son, since his conversation with Robert Audley; and that he would be heartily glad to take his poor boy to his arms, whenever he should return to England.

布鲁特斯从来没碰到过这样的处境；鉴于仿效他喜爱的模范人物也无法摆脱这一困境，托尔博伊斯先生不得已而生平难得合乎天性、顺乎人情一番：他承认自从他同罗伯特·奥德利谈话以来，他心里为他的独生子感到十分不安和痛苦，不论可怜的儿子什么时候回到英国来，他都要热烈地把他抱在怀里。

An excessive emotion was required to wring from him, once or twice a year, that lugubrious laugh of the convict, which is like the echo of the laugh of a demon

必得有一种外来的刺激才能使他发出一种象是魔鬼笑声的回音的苦笑，那也是一年难得一两次的事。

He laughed not at all. An excessive emotion was required to wring from him, once or twice a year, that lugubrious laugh of the convict, which is like the echo of the laugh of a demon.

他从不笑。必得有一种外来的刺激才能使他发出一种象是魔鬼笑声的回音的苦笑，那也是一年难得一两次的事。

ABSTRACT It is very difficult to get exact mathematical models of industrial processes, models used in design procedure of control systems are commonly mathematical models through approximation.

在实际工程应用中通常很难得到被控对象的精确数学模型，在控制系统设计过程中所采用的模型常常是在一定程度上的经过近似化处理的数学模型。

These interactions often result in formation of insoluble and noncrystalline protein assemblies.

一些生物大分子，如膜蛋白，蛋白质复合体，蛋白质纤维等，在生命过程中起着极为重要的作用，但是由于难以得到这些生物分子的单晶以及它们在溶液中的低溶解度，用X-ray和液体NMR很难得到它们的结构。

As we said, Dolly was born and has been cloned by using the cell from a part of the body. It is much harder to use the cell from the body than the ovum.

就像我们所说的那样，多利的出生和克隆用的是身体某一部分的细胞，这比采用卵细胞困难得多。

The space group of form 2 was not determined because it was difficult to get large single crystals. Form 3 crystals were obtained by using ammonium sulfate as precipitant.

当在晶型1的晶体生长条件中加入0.2M MgCl〓时，可得到六棱柱状的晶型2的晶体，由于很难得到大单晶，晶型2晶体的空间群未被确定。

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。