首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3篇
  免费   0篇
  国内免费   8篇
化学   5篇
物理学   6篇
  2017年   1篇
  2015年   2篇
  2010年   2篇
  2009年   4篇
  2003年   2篇
排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
在空气中直接加热三聚氰胺和氧化石墨烯(GO)的混合物制备了g-C3N4/rGO杂化催化剂.实验结果表明,混合物中的g-C3N4保留了石墨型氮化碳原始的特征结构, g-C3N4和还原的氧化石墨烯(rGO)之间的异质结主要通过π-π作用构筑.当原料中三聚氰胺/GO的质量比是800/1时,所得催化剂对罗丹明B的催化作用最强,其一阶动力学常数是纯g-C3N4的2.6倍.这种强化作用主要是由于rGO促进了光生电子-空穴对的分离.此外, g-C3N4/rGO还表现出显著的pH值敏感特性,催化降解速率随pH的降低而增加.当pH =1.98时,其一阶动力学常数是纯g-C3N4的8.6倍.这是由于酸性条件下质子(H+)消耗掉光生电子,促进了空穴对罗丹明B的氧化作用,其中rGO充当了一个快速的光生电子转移平台.  相似文献   
2.
李宁  姚海波  陈曦  吴式枢 《中国物理 C》2010,34(12):1830-1835
By using the rigorous spectral representation of relativistic random phase approximation, the low-lying excitation of finite nuclei and its longitudinal response function for quasielastic electron scattering are calculated in the σ-ω model of quantum hadrodynamics. It is shown that the reproduction of the correct order of the 1- and 3- excitation states of 16O is due to the contribution of the exchange vertex. There is no significant influence of the retardation effect on the low-lying excitation states. In contrast, the retardation effect plays an important role in the electron scattering process of nuclei. The theoretical longitudinal responses of 12C and 40Ca, including the contributions of the exchange vertex and the retardation effect, are suppressed and reproduce the experimental data better than the results excluding them.  相似文献   
3.
综合2,5-二氨苯基嘧啶(PRM)的刚性结构特征和配位化学特征以及二苯醚二胺(ODA)的柔性结构特征,制备出一系列性能可控的含嘧啶聚酰亚胺.含嘧啶聚酰亚胺的玻璃化转变温度、热稳定性、拉伸强度和模量等,均随聚酰亚胺中PRM比例的升高而增加.但热膨胀系数却随PRM比例的增加而降低,当PRM和ODA的比例为1∶1时,热膨胀系数为17×10-6K-1,与铜箔的热膨胀系数一致,可与铜箔形成尺寸稳定的无胶挠性覆铜板;同时,这一比例的含嘧啶聚酰亚胺与铜箔的粘结强度也达到最高(17.3 N·cm-1).这种含嘧啶聚酰亚胺的性能可以满足无胶挠性印制电路对基底膜材料的尺寸稳定性和粘结性能的要求.  相似文献   
4.
Arguments are provided which show that extension of renormalizability in quantum field theory is possible. By an appropriate choice of effective Lagrangian, a dressed Feynman propagator is obtained. In this scheme, higher order Feynman diagrams become self-convergent and nonrenormalizable interactions become renormalizable. As an example, the vacuum fluctuation effects on ρ meson mass for the vector-tensor coupling model is discussed. It is found that the result can agree with the experimental value when coupling constant is adjusted.  相似文献   
5.
电子反常供需型Diels-Alder反应(inverse electron demabd Diels-Alder reaction,IDA)因其在天然生物碱及类似物合成中的应用,在近20年来已经逐渐引起关注[1].含氮芳杂环体系1,2,4-三嗪由于其特有的缺电子特征,作为双烯体非常适于进行这类反应[2].本文利用IDA反应从3-吡啶基-5,6-二取代-1,2,4-三嗪出发,设计出一条简捷、低成本的合成路线,成功地合成出不对称取代的2,3′-联吡啶和2,4′-联吡啶.这一类化合物已被应用于药物中间体或有机配体.  相似文献   
6.
Arguments are provided which show that extension of renormalizability in quantum field theory is possible. By an appropriate choice of effective Lagrangian, a dressed Feynman propagator is obtained. In this scheme, higher order Feynman diagrams become self-convergent and nonrenormalizable interactions become renormalizable. As an example, the vacuum fluctuation effects on ρ meson mass for the vector-tensor coupling model is discussed. It is found that the result can agree with the experimental value when coupling constant is adjusted.  相似文献   
7.
A topological way to distinguish divergences of the Abelian axial-vector current in quantum field theory is proposed. By using the properties of the Atiyah-Singer index theorem, the nomtrivial Jacobian factor of the integration measure in the path-integral formulation of the theory is connected with the topological properties of the gauge field. The singularity of the fermion current related to the topological character can be correctly examined in a gauge background.  相似文献   
8.
姚海波  吴式枢 《中国物理 C》2009,33(10):842-847
We study the effective masses of p-mesons for different charged states in asymmetric nuclear matter (ANM) using the Quantum Hadrodynamics II model. The closed form analytical results are presented for the effective masses of p-mesons. We have shown that the different charged p-mesons have mass splitting similar to various charged pions. The effect of the Dirac sea is also examined, and it is found that this effect is very important and leads to a reduction of the different charged p-meson masses in ANM.  相似文献   
9.
在原位聚合制备氧化石墨烯/聚酰亚胺复合材料的过程中,加入季铵盐表面活性剂,抑制氧化石墨烯在高温亚胺化时的聚集,同时将氧化石墨烯原位还原,获得高介电常数的石墨烯/聚酰亚胺复合材料.结果表明,采用四丁基溴化铵和四丁基碘化铵作为还原剂,利用原位化学还原方法所制备的石墨烯/聚酰亚胺复合材料的介电常数超过聚酰亚胺薄膜40倍以上,复合材料的热稳定性和机械性能也优于聚酰亚胺薄膜.热重分析结果表明,在复合材料高温亚胺化过程中,季铵盐发生热分解,未残留在复合材料中.  相似文献   
10.
The study of finite nuclei containing antibaryon(s) in addition to nucleons is an interesting topic in nuclear physics. The calculation of the lifetime of an antibaryon embedded in a nucleus was performed in the framework of the standard quantum field theory. It was shown that the annihilation probability of the antibaryon in nuclei is strongly dependent on the effective masses of mesons involved in the annihilation channels. The contribution of the Dirac sea to the annihilation probability makes the lifetime of the antibaryon short. If the Dirac sea effect is neglected, the lifetime of the bound antibaryon tends to be longer with the nuclear density increasing. Particularly, when the nuclear density is larger than a critical value, the antibaryon may exist stably in a nucleus.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号