体

Meiotic pachytene bivalents were obtained from porcine testes using prolonged hypotonic treatment combined with high chloroform Carnory's fixative solution. Mitotic metaphase chromosomes were prepared from blood cell culture. Comparative studies on division index and length of pachytene bivalents and mitosis metaphase chromosomes showed that those of the former are 5 times higher and 3.42(1.87～5.98) times longer than the latter, respectively. Chromomere maps of bivalents are more abundant than mitotic metaphase G-bands, while they are correspondent with mitotic early-metaphase G-bands. The result was found by using the chromosome 12 as a sample.

以性成熟公猪睾丸和外周血为材料，采用长低渗、高氯仿卡诺固定液固定和外周血细胞培养制备减数分裂粗线期二价体和有丝分裂中期染色体，通过对二价体和有丝分裂中期染色体分裂指数和长度的比较研究，发现二价体的分裂指数和长度分别是有丝分裂中期染色体的5倍和3.42倍(1.87～5.98)；同时以12号染色体为例，比较了二价体上的染色粒结构带与有丝分裂中期染色体G-带，表明染色粒结构带比中期染色体G-带带纹丰富，而与早中期G-带带纹吻合。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastocysts followed by fusion of cytoplasm and nucleus and cleavage in vitro. During the fusion of cytoplasm, the DNA methylation levels of the fused embryos are as high as these of two-cell diploid embryos in vivo Then the embryos are rapidly demethylated when the nucleus begin to fuse, resulting in the lowest DNA methylation levels when the nucleus are fused completely. After that, the DNA methylation levels of the fused embryos are gradually increased until the morula stage. However, whereas an asymmetric distribution of DNA methylation is established in vivo-derived blastocysts with a higher methylation level in the inner cell mass than that in the trophectoderm, we can not detect the asymmetric distribution in most in vitro-derived tetraploid blastocysts.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在桑葚胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastocysts followed by fusion of cyto-plasm and nucleus and cleavage in vitro. During the fusion of cytoplasm, the DNA methylation levels of the fused embryos are as high as these of two-cell diploid embryos in vivo Then the embryos are rapidly demethylated when the nucleus begin to fuse, resulting in the lowest DNA methylation levels when the nucleus are fused completely. After that, the DNA methy-lation levels of the fused embryos are gradually increased until the morula stage. However, whereas an asymmetric distribu-tion of DNA methylation is established in vivo-derived blastocysts with a higher methylation level in the inner cell mass than that in the trophectoderm, we can not detect the asymmetric distribution in most in vitro-derived tetraploid blastocysts.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在桑葚胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastcysts fellowed by fusion of cytoplasm and nucleus and cleavage in vitro.After fusion of cytoplasm, the DNA methylation levels of the fused embryos was very high as well as two-cell diploid embryos in vivo.Then the embryos was rapiddly demethylated when the nucleus begin to fuse, resulting the lowest DNA methylation levels when the nucleus fused completely.After that, the DNA methylation levels of fused embryos were gradually increased until the blastocysts stage.However, whereas an asymmetric distribution of DNA methylation was established in an vivo-derived blastocysts with a higher methylation level in the inner cell mass than in the trophectoderm, in most vitro-derived tetraploid blastocysts, we can not detect the asymmetric distribution.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在囊胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

There are four kinds of fracture ways of 7075/SiC composite under high-temperature compression, which are the evulsions of SiC from the matrix due to forming cavity near the interface and intensive phase , ductile fracture of the matrix due to the nucleation of cavity near the interface , the fracture near SiC particulate coacervate and brittle fracture of the SiC particulate.

喷射沉积7075/SiC复合材料高温压缩时的断裂方式主要有四种，即空洞在增强相与基体界面处形成而出现增强相从基体中拔出的现象、空洞在基体中形核长大而引起基体的延性断裂、颗粒团聚处的断裂和颗粒的脆性断裂。

Nit mutants could be selected from chlorate-resistant sectors on Czapek but not on minimal medium . A total of 328 stable nit mutants were selected from 3504 sectors on Czapek and used for the further study. Of these nit mutants, 58. 8% were classed as nit1, 26. 8% as nit3, 13. 8% as NitM, 0.6% as nitD unable to from each isolate were complementally paired in all possible combination.

全部3504抗氯酸盐突变体在Czapek中共鉴定出328个稳定的nit突变体，其中nit1占58.8％，nit3占26.8％，NitM占13.8％，nitD占0.6％。37个菌株中，21个（73％）获得了nit突变体，16个（26％）还没有，仅5个菌株获得了NitM突变体。

0Mg/L 6-benzylaminopurine was the optimal concentration of shoots quantity inducing which frequency of inducing shoots and number of shoots per explant were 100% and 11.1 respectively. 0.5mg/L 6-benzylaminopurine was the optimal concentration of shoots length inducing which average length of shoots was 12.0mm. Explant size had significantly effects on direct shoots quantity and length induction. When complete cotyledon used as explant, frequency of inducing shoots, number of shoots per explant and average length of shoots could approach to 100%, 6.7 and 17.1mm respectively. 2.0mg/L silver nitrate could significantly increase shoot quantity induction, both frequency of inducing shoots and number of shoots per explant could be as high as 97.2% and 4.2 respectively. But silver nitrate also could restrain shoots elongation.

结果表明：不同黄瓜品种直接不定芽数量诱导存在显著差异，但长度诱导无显著差异；6-苄氨基嘌呤对直接不定芽数量和长度的诱导作用显著，其中4.0mg/L为数量诱导适宜浓度，其出芽率和每外植体出芽数达到最高，分别为100.0%和11.1，0.5mg/L为长度诱导适宜浓度，其平均芽长12.0mm；外植体的大小对直接不定芽数量和长度均具显著影响，随着子叶的增大诱导直接不定芽的数量和长度增加，其中单片完整子叶为最适宜大小，其出芽率、每外植体出芽数和平均芽长分别达到100%、6.7和17.1mm；硝酸银也对直接不定芽数量诱导影响显著，其中2.0mg/L为适宜浓度，出芽率和每外植体出芽数分别达到97.2%和4.2，但对芽长有抑制作用。

Many-body analysis was also carried out to obtain relaxation energy and many-body interaction energy (two, three, and four-body), and the most stable conformer has the basis set superposition error corrected interaction energy of －102.61 kJ/mol.

多体相互作用分析表明，最稳定的氢键结构经基组重叠误差校正后总相互作用能为-102.61 kJ/mol，驰豫能，两体与三体相互作用能对总相互作用能的贡献较大，四体相互作用能对总相互作用能有很小的贡献。

The total inter-action energy of the most stable conformer has the basis set superposition error corrected total interaction energy 99.53 kJ/mol, and many-body analysis shows that two-and three-body energies have significant contribution to the total interaction energy whereas the relaxation energies and four-body energies are small.

对8个稳定氢键结构进行多体相互作用分析表明，最稳定的氢键结构经基组重叠误差校正后总相互作用能为－99.53kJ/mol，两体与三体相互作用能对总相互作用能的贡献较大，驰豫能与四体相互作用能对总相互作用能有很小的贡献。

Since the multiple scattering should be considered, the scattering problem of many-cylinders is more complicated than single cylinder. By using scattering matrix method to solve the scattering problem of many-cylinders, first we have to express the incident fieldand scattered field by special function（for example, Bessel function and Hankel function）under cylindrical coordinate, then use the addition theorem of special function to get a linear system of equations to relate the incident field coefficients and scattered field coefficients. The incident and scattered field coefficients for every cylinder can be solved from the linear equations by matching electromagnetic boundary condition pointwisely.

单颗圆柱散射体的散射场解析解很早就被解出，而多个圆柱阵列的散射场问题因为涉及到入射光在圆柱与圆柱间的多重散射，故散射行为较单颗圆柱的散射复杂，因此圆柱阵列的多重散射问题需要利用加法定理来处理；散射矩阵法的主要精神即是先用圆柱座标下的特殊函数对平面波和圆柱散射体的内外域电磁场做无穷级数展开，再藉由特殊函数的加法定理将所有圆柱散射体的展开中心移到同一个展开中心，最后可以得到一组连结整个散射系统的入射电磁场系数及散射电磁场系数的线性方程组，将该组线性方程配合电磁场在散射体边界的连续条件，便可分别求出圆柱阵列中各个圆柱体的内部电磁场与外部散射场，再利用线性叠加原理即可求得整个圆柱系统的全域电磁场分布。

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。