代用

The reaction of calcium L-threonate with hydrogen bromide in acetic acid readily yields (2S, 3S)-2, 4 -dibromo-3 -hydroxy butanoic acid which was further converted into methyl (2s, 3S)-2,4-dibromo-3-hydroxybutanoate by treatment of methanol.

在化合物12上引入氨基甲酰基可用二氯磷异氰酸酯、氯乙酰异氰酸酯或氯磺酰异氰酸酯，随之引入的二氯磷酰基、氯乙酰基或氯磺酰基可分别用碳酸氢钠、N-甲基二硫代氨基甲钠或亚硫酸钠脱去。

Methods POB, COB and MSC were isolated and cultured respectively in vitro from the periosteum, calvarium and bone marrow of 5-month embryos aborting spontaneously. The 6th-generation osteoblasts were studied comparatively. The morphological features of POB, COB and MSC were observed under microscope and transmission electron microscope.

从人5个月龄胚胎骨膜、颅骨和骨髓组织中分离培养出骨膜成骨细胞（periosteal osteoblast， POB）、颅骨成骨细胞（cranial osteoblast， COB）和骨髓基质干细胞（marrow stromal cell， MSC），用第6代细胞进行比较研究。

There can be several iterations within a section, you can specify an additional constraint to get a subset of the Cartesian product (constraint=), and you can repeat each one several times with different seeds.

一个代码段中会有几个迭代，你可以指定额外的限制条件来得到一个笛卡尔乘积的子集(constraint=)，你可以用不同的种子重复每一个工作几次。

In part one,"I" means Cenozoic painters who have individual thought.

本文第一部分用"我"代指以个体意识出发的新生代油画家。

In this paper,the effect of cerium ion on cAMP and cGMP of primary hepatocyte and organs in rat was studied.

研究了Ce3＋对原代肝细胞内cAMP和cGMP的影响，并测定了用Ce3＋长期喂养的大白鼠脏器肝、肾、脾、肾上腺中cAMP和cGMP的含量。

This paper presents a method of synthesizi ng non-equiripple low-pass filter based on iteration analysis,in which the rat ional fraction formed of Chebyshev polynomial is used as the filter characterist ic function.

提出一种用切比雪夫多项式构成有理分式作为滤波器的特征函数，并利用迭代分析进行非等波纹低通滤波器综合的方法。

I filled out the room with a late-eighteenth-century Chippendale sofa, the oldest piece of furniture in the White House collection, and an antique table bought by Mary Todd Lincoln, on which we put the silver commemorative cup from the 1898 treaty.

我在这个房间里摆放了一件18世纪晚期的奇彭代尔式沙发和一张玛丽。托德。林肯购买的古董桌子。那张沙发是白宫里收藏的最古老的家具；桌子我用来摆放纪念1898年条约的银杯。

Processing study of sodium copper chlorophyll production from water lettuce leaves ;2. This paper studied the technological process of the preparation of sodium cobalt Chlorophyllin from water lettuce leaves .

本文报道了以水浮莲叶为原料制取钴叶绿酸钠的方法及其最佳的工艺条件为：用95％乙醇在70℃提取1h，5％NaOH皂化60min，20％CoCl_2溶液钴代，2％NaOH溶液成盐。

The optimization algorithms are commonly used to approach the minima of the roundness objective functions through iteration when a microcomputer is applied to assess roundness errors by minimum zone, minimum circumscribed circle, and maximum inscribed circle methods.

引言在用计算机求最小区域、最小外接圆和最大内切圆评定法求圆度误差时，广泛采用最优化算法，通过迭代去逼近目标函数的极小值。

Firstly establishing mechanical model of casing structure , and then processing casing forces analysis using space finite-element method and superposition method(put structure stress and outer force stress together), it computes the stress of casing in three dimensions, and gets the internal force and transmutation. The structure of casing-coadjutor is computed overlaply and the question of contact is solved. In the aspect of design, it provides the mixed integer-discrete variable optimization method of casing cross section size and coadjutor layout.

本文就上述两个问题的最优化设计展开研究，首先建立了套管结构的力学模型，进行套管的受力分析，用了空间有限元法和叠加法(结构应力和外载应力相叠加)，对套管进行三维计算，确定结构的内力和变形，对套管—扶正器结构进行整体的叠代计算，解决接触问题；在设计方面，提出了解决套管截面尺寸参数和扶正器布局的混合整数—离散变量优化方法。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐