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排序方式: 共有46条查询结果,搜索用时 15 毫秒
1.
Zhu Yaochen 《数学年刊B辑(英文版)》1991,12(4):400-406
The transcendental degree of certain numbers concerned with the exponential funotion over a field of finite transcendence type is considered. 相似文献
2.
Yaochen Zheng Zhirong Xin Yan Sheng Wanzhong Ren 《Journal of Polymer Science.Polymer Physics》2014,52(15):1037-1045
The architecture effects on phases and surface enrichment behaviors of epoxy nanocomposites containing fluorinated block copolymers are investigated by the incorporation of two novel copolymers composed of poly (2, 2, 2‐trifluoroethyl methacrylate) (PTFEMA) and poly (ε‐caprolactone) (PCL), PCL‐b‐PTFEMA and PTFEMA‐b‐PCL‐b‐PTFEMA, with identical molecular weight and composition. These fluorinated copolymers in epoxy display distinguished self‐assembled structures, as evidenced by dynamic laser scattering and scanning electron microscopy measurements. Static contact angle detection suggests that the nanocomposites display an obvious improvement in surface water repellency and a reduction in surface free energy. The enhancement in surface hydrophobicity is attributed to the enrichment of PTFEMA blocks at the nanocomposite surface and to the formation of the specific surface morphology, as confirmed by atomic force microscopy. The different architectures of the two block copolymers give rise to differences in phase‐structures, and the ultimate surface performances of composites. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1037–1045 相似文献
3.
Yaochen Zheng Jian Liu Yan Guo Qian Zhang Xuan Gao Zhengguo Gao Tao He Qingfu Ban 《Journal of polymer science. Part A, Polymer chemistry》2020,58(12):1664-1674
Cationic compounds often serve as antibacterial materials for a wide range of applications. However, the relationship of topology−antibacterial activity has been rarely revealed. Herein, three cationic polythioethers (CPTEs) with hyperbranched topologies are well designed and facilely synthesized via an all-click chemistry strategy (including thiol-ene and epoxy-amine additions). These as-prepared CPTEs were found to exhibited outstanding antibacterial activity against Escherichia coli and Staphylococcus aureus with minimum inhibitory concentrations against E. coli of 7.3, 14.6, and 14.6 μg ml−1, and against S. aureus of 14.6, 29.2, and 29.2 μg ml−1, respectively. The antibacterial activity is coincident with their degree of branching (DB, their DB values of 0.81, 0.48, and 0.27), which is mainly attributed to the inherent three-dimensional structure. The present strategy reveals the relationship of polymer topology and antibacterial activity, providing a novel possibility for designing and/or synthesis of high-efficiency antibacterial agents. 相似文献
4.
Jian Yang Tingting Feng Junming Hou Xinran Li Boyu Chen Cheng Chen Zhi Chen Yaochen Song Mengqiang Wu 《Journal of Energy Chemistry》2022,(2):583-591
Lithium metal is the ultimate anode material for next-generation high-energy batteries.Yet,the practical application of lithium metal anodes is limited by the formation of Li dendrites and large volume changes.Herein,an effective multi-dimensional hybrid flexible film(MD-HFF)composed of iodine ion(0 dimension),CNTs(1 dimension)and graphene(2 dimensions)is designed for regulating Li deposition and mitigating volume changes.The multi-dimensional components serve separate roles:(1)iodine ion enhances the conductivity of the electrode and provides lithiophilic sites,(2)CNTs strengthen interlaminar conductance and mechanical strength,acting as a spring in the layered structure to alleviate volume changes during Li plating and stripping and(3)graphene provides mechanical flexibility and electrical conductivity.The resulting MD-HFF material supports stable Li plating/stripping and high Coulombic efficiency(99%)over 230 cycles at 1 mA cm-2 with a deposition capacity of 1 mAh cm-2.Theoretical calculations indicate that LiI contributes to the lateral growth of Li on the MD-HFF surface,thereby inhibiting the formation of Li dendrites.When paired with a typical NCM811 cathode,the assembled MD-HFF‖NCM811 cell exhibit improved capability and stable cycling performance.This research serves to guide material design in achieving Li anode materials that do not suffer from dendrite formation and volume changes. 相似文献
5.
Zhu Yaochen 《中国科学A辑(英文版)》2001,44(6)
The algebraic independence of values of certain Fourier series with algebraic coefficients and their derivatives at algebraic points is proved. 相似文献
6.
金属板材冲压成型过程的有限单元法模拟 总被引:8,自引:0,他引:8
用有限单元法模拟了金属板材的冲压成型过程。在模拟过程中,应用了同时考虑了薄膜力和弯矩的板壳大变形理论,考虑了板材在塑性阶段各向异性的强化性质,考虑了模具和工件的接触和摩擦条件,分析了金属板在冲压过程中的屈曲现象,建立了增量形式的变分原理。弹塑性薄壳单元被引入,它的位移模式在变分的意义上满足单元边界上一阶导数连续的条件,并有足够的秩来适应单元的有限拉伸、转动和弯曲,计算中采用了罚函数方法,即在模具和工件的接触面上,模具的表面被假设为文克尔地基,采用了修正的库伦摩擦定律,迭代法被用来决定模具与工件的接触条件和金属板的塑性行为。本文最后提供了一个算例。 相似文献
7.
8.
Yaochen Zhu 《数学学报(英文版)》1995,11(4):422-434
In the present paper a general formula for exact calculation of the discrepancy of an arbitrary finite point set of dimensiond2 is explicitly given only in terms of the components of the points. 相似文献
9.
Criteria of algebraic independence of complex numbers over a field of finite transcendence type (II)
Zhu Yaochen 《数学学报(英文版)》1990,6(1):24-34
In the present paper we establish a criterion of algebraic independence of complex numbers
1, ...,
n
over a field
of finite transcendence type using a sequence of nonzero polynomials in several variables with integral coefficients, which satisfy simultaneously certain upper and lower estimates in different orders of magnitude at the point (
1, ...,
q
,
1, ...,
n
), where {
1, ...,
q
} is a transcendence basis of
over .The Project Supported by the National Natural Science Foundation of China 相似文献
10.
Zhu Yaochen 《数学学报(英文版)》1989,5(4):329-336
In the present paper a form of generalization of Gelfond's lemma on dense sequences of polynomials is proposed. For a set of complex numbers
1, ...,
s
we define the coefficientsgk(
1, ...,
s
) (0ks) and give the relations between them and the transcendental degrees or the transcendence types of the field © (
1, ...,
s
) or its subfields.This work was completed at the Dept. of Math., Univ. of Southern Mississippi, USA in 1987. 相似文献