对称

In this paper, an iterative algorithm is proposed to find the generalized centrosymmetric solution pair of matrix equation AXA~T+BYB~T=C. The solvability of the matrix equation can be determined automatically in the iterative process. When the matrix equation is consistent, the solution pair can be obtained within finite steps in the absence of round-off errors.

该论文运用迭代方法研究了矩阵方程的一般中心对称解解，特别地，当矩阵方程是相容的时，经过有限步就能求出该方程的一般中心对称解解，然后以此为主要依据进一步研究了矩阵方程的最优近似解，最后举例验证了该论文的主要结论。

We also studied the enantioselective conjugate addition of chalcone in the presents of chiral Ni2 aminoalcohol complexes.

我们还研究了手性氨基醇配体/镍盐催化的a，β-不饱和酮的不对称迈克尔加成反应，以及酰腙的不对称烯丙基化反应。

Chiral auxiliary controlled asymmetric reaction is one of the main methods in asymmetric synthesis.

手性助剂控制的不对称反应是不对称合成的主要方法之一。

Summarizing the results above, we further obtained: Hα blue asymmetry observed usually in the early stage of flares may be caused by chromospheric condensation in transition region; the Hα red asymmetry appeared later may be resulted from the downward movement of upper chromosphere; and still later CaIIK asymmetry may be explained to have 10-20 km/s downward velocity in middle or lower part of chromosphere, This explanation is self-consistent among the observations of Hα and CaIIK line during the flare.

综合所有计算的不对称特征，我们进一步得到：耀斑早期的短时间兰不对称性可由过渡区里的色球凝聚引起，随后的红不对称性是色球上部物质向下运动的结果，而后来出现的CaⅡK不对称特征则表明色球中下部具有10-20km/s的向下运动速度。

On the basis of analyzing the decentralization and centralization strategy of the buyer and supplier under symmetric information , this paper discusses the inventory coordination strategy using coalitional game with transferable payoff.

在分析信息对称情况下制造商和供应商库存分散控制策略和集中控制策略的基础上，运用转移支付联盟博弈讨论了制造商和供应商库存协调策略，然后分三种情况探讨了不对称信息下供应商和制造商库存协调、协调的有效性以及达到双赢所要遵循的原则。

The systems include application sub-system and cretification authority, application sub-system apply symmetric and asymmetric cryptosystem and public-key certificate which was authoticated by CA and can certify the valid user-identity to set up secure communication channel, exchange session key and provide message integrity, confidetiality, authentication and nondeniability.

系统包括证书中心和应用子系统，证书中心签发证书用来证明用户的合法身份，应用子系统应用证书和对称、非对称密码体制，识别用户合法身份，建立了安全通信通道和交换会话密钥，实现了通信数据的完整性、保密性、真实性、不可否认性。

The structure consists ofpolyborate groups 〓 and four crystallographically independent Y positions, ofwhich two positions are on inversion center and the other two are on general positions.

中的硼酸根离子为三个四面体构成的〓基团，结构中存在有四种不同的Y原子格位，其中两种Y格位具有中心对称，另外两种Y格位没有对称中心。

Crystal structural analysis reveals that, because water molecules bond to Cu atoms, the dhbd ligand can only adopt a hydroxyl oxygen atom to bridge two reversed U-shaped subunits into a novel centrosymmetric dual-U-shaped tetranuclear Cu structure. Each U-shaped frame consists of two crystallographically distinct Cu atoms, two dpphen ligands and one coordinated water molecule.

晶体结构分析表明，由于水的配位阻断， 2，3-二羟基丁二酸根仅通过单羟基氧桥联两个U形双核亚单元形成具有一个对称中心的双U形四核结构，其中U型亚单元包含晶体学上不对称的2个Cu原子、1个2，3-二羟基丁二酸根、2个4，7-二苯基-1，10-邻菲咯啉和1个配位H2O分子。

For certain reactions, they function as chemoenzymes and produce both good chemical and optical yields. Over the last decade a wide range of C〓-symmetric chiral bisoxazoline ligands have been synthesized from readily available diacid derivatives and amino alcohols.

但是，手性双噁唑啉催化的某些不对称反应的机理以及影响双噁唑啉分子催化性能的结构要素目前仍不是很清楚，诱导某些反应的不对称选择性仍有待于进一步提高，因此需设计和合成新的双噁唑啉类配体。

What's more, we expanded the reaction to aliphatic ketones and aldehydes undersimilar conditions and found that these reactions led to dialkyl diselenides underatmospheric pressure in the absence of base in from moderate to good yields.

在相同条件下，把底物扩展到杂环醛，也得到了一类相应的新的对称的杂环二硒醚，同时，把底物扩展到脂肪醛和脂肪酮，在类似条件下，也合成了一系列对称的烷基二硒醚，产率从中等到良好。

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％。