排序方式: 共有32条查询结果,搜索用时 31 毫秒
1.
本文证明君子兰花粉在RNA和蛋白质合成完全被抑制的条件下仍可达到95%右左的萌发率,并长出有限长度的花粉管。RNA酶和蛋白酶均可影响直至完全阻止花粉的萌发和/或花粉管的伸长。统计表明:成熟花粉内已有的蛋白质可维持花粉管约70μm的伸长,预存mRNA转译的蛋白质可维持花粉管约530μm的伸长。散粉后合成的RNA和蛋白质对花粉管后继伸长的速度和晚期生长(>2400μm)都是必需的。环己亚胺3h或放线菌素D,10h以上的处理会引起花粉管畸形,畸变率与抑制剂浓度及处理时间相关。适量的抑制剂在培养的头5h内可阻碍生殖细胞通过分裂中期,10h以后加抑制剂,不再影响精细胞的形成。 相似文献
2.
卡尔曼 波—分光光度法用于复方雷锁辛涂剂中苯酚与间苯二酚的测定 总被引:19,自引:1,他引:19
本文研究了卡尔曼滤波-分光光度法及其在多组分混合物同时光度测定中的应用。测定复方雷琐辛涂剂中苯酚与间苯二酚,平均回收率分别为100.86%与98.76%。 相似文献
3.
Measuring the fermion Yukawa coupling constants is important for understanding the origin of the fermion masses and their relationship with spontaneously electroweak symmetry breaking.In contrast,some new physics(NP)models change the Lorentz structure of the Yukawa interactions between standard model(SM)fermions and the SM-like Higgs boson,even in their decoupling limit.Thus,the precise measurement of the fermion Yukawa interactions is a powerful tool of NP searching in the decoupling limit.In this work,we show the possibility of investigating the Lorentz structure of the bottom-quark Yukawa interaction with the 125 GeV SM-like Higgs boson for future e^+e^- colliders. 相似文献
4.
5.
6.
Exploring fundamental laws of classical mechanics via predicting the orbits of planets based on neural networks
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jian Zhang 《中国物理 B》2022,31(9):94502-094502
Neural networks have provided powerful approaches to solve various scientific problems. Many of them are even difficult for human experts who are good at accessing the physical laws from experimental data. We investigate whether neural networks can assist us in exploring the fundamental laws of classical mechanics from data of planetary motion. Firstly, we predict the orbits of planets in the geocentric system using the gate recurrent unit, one of the common neural networks. We find that the precision of the prediction is obviously improved when the information of the Sun is included in the training set. This result implies that the Sun is particularly important in the geocentric system without any prior knowledge, which inspires us to gain Copernicus' heliocentric theory. Secondly, we turn to the heliocentric system and make successfully mutual predictions between the position and velocity of planets. We hold that the successful prediction is due to the existence of enough conserved quantities (such as conservations of mechanical energy and angular momentum) in the system. Our research provides a new way to explore the existence of conserved quantities in mechanics system based on neural networks. 相似文献
7.
8.
基于非局部近场动力学(PD)理论,在常规微弹脆性(PMB)本构模型基础上,引入能够反映物质点间作用强度随物质点间距变化规律的核函数修正项,以提高PD方法的定量计算精度;并通过附加物质点转动自由度建立以双参数描述的PD微极模型,突破了常规单参数PMB本构模型的泊松比限制等缺陷。通过引入动态松弛算法和粒子系统失衡力准则等系列数值算法,构建了能够自然模拟准脆性裂纹扩展全过程的PD算法体系。经典悬臂梁挠度曲线计算结果表明,本文模型和算法的定量计算误差小于3.5%,对含切口三点弯梁的裂纹扩展过程模拟结果与试验结果吻合。通过改变加载位置和初始裂纹位置,对三点弯梁的破坏模式和承载能力进行了分析。结果表明,裂纹始终由初始裂纹位置向加载位置扩展,且初始裂纹位置和加载位置越靠近三点弯梁中部时,结构的承载能力越低。 相似文献
9.
10.
微机处理吸光度数据矩阵(Ⅰ)——求秩法估计光度分析体系中的吸光物种数 总被引:1,自引:0,他引:1
微机处理吸光度数据矩阵,用求秩法估计Fe-CAS二元体系、添加表面活性剂的Fe-CAS-CTMAB三元体系及Be-CAS-PVPBS体系中的吸光物种数。在给定实验条件下,Fe-CAS体系申存在4种吸光配合物,而Fe-CAS-CTMAB体系中只有2种配合物。配合物种数减少,是加入表面活性剂后体系的表观摩尔吸光系数增加的原因之一。 相似文献