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排序方式: 共有192条查询结果,搜索用时 15 毫秒
1.
浅析二阶齐次线性变系数微分方程的一个可积类型 总被引:1,自引:0,他引:1
姬志飞 《应用数学与计算数学学报》2006,20(1):125-128
本文讨论了二阶齐次线性变系数微分方程的特殊形式,给出了这种微分方程的一个可积类型. 相似文献
2.
In this paper, we prove the global well-posedness of the 3-D magnetohydrodynamics(MHD) equations with partial diffusion in the periodic domain when the initial velocity is small and the initial magnetic field is close to a background magnetic field satisfying the Diophantine condition. 相似文献
3.
Wei Wang Pingwen Zhang Zhifei Zhang 《Archive for Rational Mechanics and Analysis》2013,210(3):837-855
We prove the local well-posedness of the Ericksen–Leslie system, and the global well-posedness for small initial data under a physical constraint condition on the Leslie coefficients, which ensures that the energy of the system is dissipated. Instead of the Ginzburg–Landau approximation, we construct an approximate system with the dissipated energy based on a new formulation of the system. 相似文献
4.
Li Chenglang Dou Qiang Bai Zhifei Lu Quliang 《Journal of Thermal Analysis and Calorimetry》2015,122(1):407-417
Journal of Thermal Analysis and Calorimetry - The effect of cadmium phenylmalonate (PMA-Cd) as a novel nucleating agent on the crystallization behaviors and spherulitic morphology of poly(lactic... 相似文献
5.
Dr. Xiaolong Liang Xiaoda Li Lijia Jing Peng Xue Lingdong Jiang Prof. Qiushi Ren Prof. Dr. Zhifei Dai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(47):16113-16121
This paper reports the facile design and synthesis of a series of lipidic organoalkoxysilanes with different numbers of triethoxysilane headgroups and hydrophobic alkyl chains linked by glycerol and pentaerythritol for the construction of cerasomes with regulated surface siloxane density and controlled release behavior. It was found that the number of triethoxysilane headgroups affected the properties of the cerasomes for encapsulation efficiency, drug loading capacity, and release behavior. For both water‐soluble doxorubicin (DOX) and water‐insoluble paclitaxel (PTX), the release rate from the cerasomes decreased as the number of triethoxysilane headgroups increased. The slower release rate from the cerasomes was attributed to the higher density of the siloxane network on the surface of the cerasomes, which blocks the drug release channels. In contrast to the release results with DOX, the introduction of one more hydrophobic alkyl chain into the cerasome‐forming lipid resulted in a slower release rate of PTX from the cerasomes due to the formation of a more compact cerasome bilayer. An MTT viability assay showed that all of these drug‐loaded cerasomes inhibited proliferation of the HepG2 cancer cell line. The fine tuning of the chemical structure of the cerasome‐forming lipids would foster a new strategy to precisely regulate the release rate of drugs from cerasomes. 相似文献
6.
o‐Fluorination of Aromatic Azides Yields Improved Azido‐Based Fluorescent Probes for Hydrogen Sulfide: Synthesis,Spectra, and Bioimaging 下载免费PDF全文
Chao Wei Runyu Wang Dr. Lv Wei Longhuai Cheng Zhifei Li Prof. Dr. Zhen Xi Prof. Dr. Long Yi 《化学:亚洲杂志》2014,9(12):3586-3592
Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple biological functions. To visualize the endogenous in situ production of H2S in real time, new coumarin‐ and boron‐dipyrromethene‐based fluorescent turn‐on probes were developed for fast sensing of H2S in aqueous buffer and in living cells. Introduction of a fluoro group in the ortho position of the aromatic azide can lead to a greater than twofold increase in the rate of reaction with H2S. On the basis of o‐fluorinated aromatic azides, fluorescent probes with high sensitivity and selectivity toward H2S over other biologically relevant species were designed and synthesized. The probes can be used to in situ to visualize exogenous H2S and D ‐cysteine‐dependent endogenously produced H2S in living cells, which makes them promising tools for potential applications in H2S biology. 相似文献
7.
新型药物辅料2-羟丙基-β-环糊精的色谱分离纯化 总被引:1,自引:2,他引:1
利用薄层色谱方法对碱浓度为1.5%、β-环糊精∶环氧丙烷(摩尔比)=1∶21的条件下生成的2-羟丙基-β-环糊精进行了定性分析,并通过对展开剂的选择和优化,得到了3种能有效分离不同取代度2-羟丙基-β-环糊精的展开剂体系,分别为正丙醇-水-浓氨水(6∶3∶1,V/V),异丙醇-水-浓氨水(6∶4∶0.5,V/V)和乙醇-水-浓氨水(6∶3∶0.8,V/V)。通过以乙醇体系为洗脱剂的硅胶柱色谱对其进行分离纯化,得到了两种不同取代的2-羟丙基-β-环糊精。经过ESI-MS谱图分析,确定分离后产品分别为单取代和双取代2-羟丙基-β-环糊精。 相似文献
8.
Qionglei Chen Changxing Miao Zhifei Zhang 《Archive for Rational Mechanics and Analysis》2010,195(2):561-578
In this paper, we prove the local well-posedness for the ideal MHD equations in the Triebel–Lizorkin spaces and obtain a blow-up
criterion of smooth solutions. Specifically, we fill a gap in a step of the proof of the local well-posedness part for the
incompressible Euler equation in Chae (Comm Pure Appl Math 55:654–678 2002). 相似文献
9.
Novel formulations of vitamins and insulin by nanoengineering of polyelectrolyte multilayers around microcrystals 总被引:4,自引:0,他引:4
Dai Z Heilig A Zastrow H Donath E Möhwald H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(24):6369-6374
Microcapsules loaded with vitamin K3 (VK3), biotin, or insulin were prepared by using a novel coating technology based on the layer-by-layer (LbL) deposition of oppositely charged polyelectrolytes onto microcrystal templates. This produced multilayered, polymeric shells of varying thickness around the crystalline cores. Dissolution of the core material (VK3 with ethanol, biotin with basic solution, and insulin with acidic solution), resulted in its release through the shells. Microelectrophoresis was employed to monitor the microcrystal coating process; confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) were used to verify multilayer coating and the formation of hollow polymer shells following removal of the microcrystal templates. The release rates of both VK3 and insulin decreased as the wall thickness (the number of polyelectrolyte layers deposited onto the microcrystal cores), increased. The release time could be varied by a factor of more than ten, depending on the number of polyelectrolyte layers applied. Following the addition of 70 mass % ethanol, the solubility of VK3 increased by as much as 170-fold, resulting in an increased rate of VK3 release. By selecting appropriate polymer materials for the shells, and by controlling the number of polyelectrolyte layers applied, shells of various thickness, stiffness, aqueous solubility, dispersibility, biocompatibility, and permeability can be constructed. 相似文献
10.
On the interior regularity criteria and the number of singular points to the Navier-Stokes equations
We establish some interior regularity criteria for suitable weak solutions of the 3-D Navier-Stokes equations which allow the vertical part of the velocity to be large under the local scaling invariant norm. As an application, we improve Ladyzhenskaya-Prodi-Serrin’s criterion and Escauriza-Seregin-?verák’s criterion. We also show that if a weak solution u satisfies $\left\| {u( \cdot ,t)} \right\|_{L^p } \leqslant C( - t)^{(3 - p)/2p} $ for some 3 < p < ∞, then the number of singular points is finite. 相似文献