查询词典 tetrad

The abnormality of tetrad callose wall degradation and tapetum development was associated with the abortion of microspore.

导致小孢子败育的原因与四分体胼胝质壁不适时解体和绒毡层细胞发育异常、延迟解体有关。

The presence of REE tetrad effects in apatites and whole rocks of S-type granites has been reported by Sha and Chappell (1999) and Zhao et al.(1999), respectively. The REE tetrad effect in minerals, such as apatite, spessartite, beryl, alkali feldspar and spodumene, from all zones of Altay No. 3 pegmatite has been found remarkable, and the fractionations among isovalent incompatible elements in these minerals are also significant. This paper puts forward that the REE tetrad effect is one of the basic features of peraluminous melts and the origin of REE tetrad effect might be probably related to some processes prior to the formation of pegmatite magma. The immiscibile liquid separation between silicate melt and hydrosaline melt may be responsible for it.

由于阿尔泰3号伟晶岩脉各带磷灰石以及与其共生的石榴石、绿柱石、碱性长石、锂辉石矿物均存在明显的稀土"四重效应"以及相同电价、相似离子半径的不相容元素间存在显著的分异，并结合最近赵振华等(1999)和Sha and Chappell(1999)报道S型花岗岩全岩和单矿物(磷灰石、独居石、长石、黄玉等)均存在稀土"四重效应"这一现象，本文研究提出，稀土"四重效应"是富挥发分过铝质岩浆体系的一个基本特征，其机制既不可能由含稀土的副矿物早期结晶引起残余熔体相中REE含量变化的结果，也不能定性地归因于流体相与熔体相相互作用过程中稀土元素在流体/熔体之间分异的结果，而很可能与伟晶岩岩浆形成之前某些过程密切相关，S型花岗岩岩浆在液相线以上存在硅酸盐熔体与高盐熔体的不混溶液相分离有可能是过铝质岩浆体系产生稀土"四重效应"的主要原因。

See also chiasma; independent assortment; tetrad.

参见 chiasma； independent assortment； tetrad 。

Due to effect of temperature, the differentiation of clinandrium began when bud were about 1.6-2 mm, after then all buds differentiated clinandriums, and one anther could differentiate to 1 ~ 4 clinandriums in which there were microspores which in stage from tetrad to mature pollen grains.

由于温度的影响，1.6～2mm大小的花蕾开始出现花粉囊的分化，以后各大小的蕾都分化了个数不等的花粉囊，一个花药可分化出1～4个花粉囊，可见到自四分体到成熟花粉粒的各阶段小孢子。

In diplotene the pairs of chromatids begin to separate from the tetrad formed by the association of homologous chromosomes. Chiasmata can often be seen at this stage.

双线期时，配对的染色单体开始从四分体中分离，此时常可见染色体交叉。

Barley seeds were irradiated with five different doses of 60 Co-γ ray.There were many kinds of chromosome aberration in pollen mother cells,such as bridge,laggards in anaphase I and anaphase II,asymmetrical division in anaphase I and asynchronous division in anaphase II,ring quadrivalent in metaphase I,three pole division and micro-nuclei in telophase I,micro-nuclei in tetrad and some micro-nucleus separates from the tetrad to form polyad.

大麦种子经5种不同剂量γ射线辐照后， M1植株的花粉母细胞出现多种染色体畸变类型，例如后Ⅰ、后Ⅱ中出现桥、落后，后Ⅰ中出现不对称分裂，后Ⅱ中出现不同步分裂，中期Ⅰ出现环状四价体，末期Ⅰ中有三极分裂和微核，四分体中出现微核且有的微核独立于四分体，从而形成多分体。

The other cells of the tetrad undergo degeneration. The mature embryo sac consists of an egg apparatus, a central cell, and 3 antipodal cells. The embryo sac is a monosporic Polygonum type. The zygote develops into a mature embryo going through proembryo, globular, heart, and torpedo stages.

胚囊发育类型为单孢子蓼型胚囊； 2胚的发育经过原胚、球形胚、心形胚和鱼雷胚等阶段发育为成熟胚；胚柄在球形胚时期最发达，但胚柄短小，只由3个扁平细胞组成，之后逐渐退化。

Results showed that the PMC meiosis of autotetraploid was similar to the diploid except some particularities. In metaphase Ⅰ, multivalent, quadrivalent, trivalent, bivalent and univalent were observed and some of the chromosomes were found not to rank on the metaphase plate and so did in metaphase Ⅱ cells. In anaphase Ⅰ and anaphase Ⅱ cells, there were lagging chromosomes, chromosome bridge and fragment. During anaphase Ⅱ and telophase Ⅱ, chromosome segregation was not synchronous or equal. At tetrad stage, dyad, triad, tetrad with micronucleus and polyad appeared.

结果表明，同源四倍体花粉母细胞减数分裂过程与二倍体相比，中期Ⅰ染色体构型复杂，有多价体、四价体、三价体、二价体和单价体；中期Ⅰ及中期Ⅱ有部分染色体没有排列在赤道板上；后期Ⅰ及后期Ⅱ出现落后染色体、染色体桥及断片；后期Ⅱ和末期Ⅱ有染色体不同步分离及不等分裂的现象；四分体时期还出现二分体、三分体、含微核的异常四分体及多分体。

In 2006, we completed a US$50 million private placement of shares to Tetrad, Intel and New Horizon.

于2006年，公司完成私人配售50，000，000美元之股份予 Tetrad，Intel及New Horizon。

The observation showed that sterile plants and fertile plants in the pollen mother cell stage is not very different, when microspore mother cells of male sterile plants enter meiosis period, it could form normal tetrad cell , tetrad cell is normal in early development stage, In the uninucleate microspore stage , tapetal cells were vacuolization, the microspores were extruded to the middle by tapetal cells.

本研究利用石蜡切片法，结合光学显微镜技术对樱桃萝卜核质互作雄性不育系的不育株和对应保持系可育株的花药发育过程进行细胞形态学观察，观察结果表明：不育株与可育株在花粉母细胞时期差别不大，不育株的花药小孢子母细胞进入减数分裂期后，可以正常的形成四分体，四分体前期发育正常，而在单核小孢子期绒毡层细胞出现液泡化，绒毡层细胞向中间挤压小孢子。

For a big chunk of credit-card losses; the number of filings (and thus charge-off rates) would be rising again, whether

年美国个人破产法的一个改动使得破产登记急速下降，而后引起了信用卡大规模的亏损。

Eph. 4:23 And that you be renewed in the spirit of your mind

弗四23 而在你们心思的灵里得以更新