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排序方式: 共有1172条查询结果,搜索用时 15 毫秒
31.
Huimin Geng Pengfei Zhang Long Liu Yangtao Shangguan Xiang Cheng Hanru Liu Yunpeng Zhao Jingcheng Hao Weiwei Li Jiwei Cui 《Materials Today Chemistry》2022
Surgical procedures are susceptible to the cause of infections, which could induce delayed wound healing, oxidative stress and tissue ischemia. Multifunctional wound dressings (e.g., hydrogels) without the induction of antibiotics is promising for the elimination of surgical site infections and the associated complications. Herein, we report a reductionism approach for the fabrication of bioactive hydrogels to recapitulate antibacterial functions as well as antioxidant, pro-angiogenic and hemostatic properties in surgical infection treatments. The hydrogels composed of naturally derived Cirsium setosum extracts (CE, a traditional medicinal herb) and carboxymethyl chitosan (CS) show their capacity for surgical anti-infections on three different models (i.e., infectious random skin flap model, infectious skin defect model and infectious femur fracture model). Due to the innate bioactivities of CE and CS, CECS hydrogels can also reduce the bleeding loss (85% reduction) on a hemorrhaging liver model and improve the vascularization for skin flap regeneration. Overall, bioactive CECS hydrogels integrated with the ease and scalability of assembly process and biological activities without the addition of antibiotics is promising to act as multifunctional wound dressings for surgical anti-infections. 相似文献
32.
In this review article, we describe turbulence control in excitable systems by using a local periodic pacing method. The controllability conditions of turbulence suppression and the mechanisms underlying these conditions are analyzed. The local pacing method is applied to control Winfree turbulence (WT) and defect turbulence (DT) induced by spiral-wave breakup. It is shown that WT can always be suppressed by local pacing if the pacing amplitude and frequency are properly chosen. On the other hand, the pacing method can achieve suppression of DT induced by instabilities associated with the motions of spiral tips while failing to suppress DT induced by the instabilities of wave propagation far from tips. In the latter case, an auxiliary method of applying gradient field is suggested to improve the control effects. The implication of this local pacing method to realistic cardiac defibrillation is addressed. 相似文献
33.
二维过渡金属硫属化合物(TMDs)因具有可调带隙、 谷电子学性质和高催化活性等优点, 在电子学、 光电子学和能源相关领域受到广泛关注. 为了实现以上应用, 实现大面积、 厚度均匀TMDs薄膜的批量制备至关重要. 化学气相沉积法(CVD)是制备大面积均匀、 高质量二维材料普遍使用的方法. 本文从前驱体的供给和衬底的设计两个角度, 总结了目前合成大面积TMDs薄膜的CVD方法, 并讨论了高质量TMDs的生长机制和参数优化方法; 介绍了高质量TMDs在电子学、 光电子学和电/光催化等方面的应用; 讨论了目前合成大面积均匀、 高质量TMDs所面临的挑战, 并对该领域的发展方向进行了展望. 相似文献
34.
Yongyue Wang Zhirong Cui Jun Chi Pengfei Tang Meihui Zhang Jixin Li Yongyi Li Hao Zhang Jun Luo Lingyi Kong 《中国化学》2021,39(1):129-136
Sarcaglarols A—D ( 1 — 4 ), two pairs of lindenane?monoterpene heterodimers fused by a 1,2‐dioxane moiety, were discovered and isolated from the leaves of Sarcandra glabra guided by MS/MS molecular networking‐based strategy. Their planar structures, absolute configurations of basic skeleton and flexible polyhydric side chain were established by analysis of HRESIMS, NMR spectroscopic data, ECD spectrum, and the X‐ray diffraction study of isopropylidene derivatives. An intermolecular [2+2+2] cycloaddition may play a key role in the biosynthesis pathway of the 1,2‐dioxane moiety fused lindenane?monoterpene heterodimer skeleton, which can be recognized as the biogenetic precursors of our previous reported lindenane?normonoterpene conjugates. In addition, compounds 1 , 3 and 4 exhibited moderate inhibitory effects of lipid accumulation in free fatty acid‐exposed L02 cells. 相似文献
35.
Chen Huang Lihong Han Liyuan Wu Rui Su Jun Chen Pengfei Lu 《The European Physical Journal B - Condensed Matter and Complex Systems》2015,88(6):147
The electronic structure and optical properties of boron-doped, sulfur-doped, andboron-sulfur-codoped graphene systems have been studied by using first-principlescalculations. Energy band structure and density of states are presented to describe theelectronic properties. The doping can open the band gap and change the optical propertiesof graphene. For all optical properties of doped graphene systems, parallel(E ∥) polarization and perpendicular(E ⊥) polarization are presented. Theoptical properties under two kinds of polarizations are reflected in the range of peakheight and the change of some extraordinary features. 相似文献
36.
Synergistic Effects of Lewis Bases and Substituents on the Electronic Structure and Reactivity of Boryl Radicals 下载免费PDF全文
Dr. Dongmei Lu Dr. Chao Wu Dr. Pengfei Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1630-1637
Boryl radicals have the potential for the development of new molecular entities and for application in new radical reactions. However, the effects of the substituents and coordinating Lewis bases on the reactivity of boryl radicals are not fully understood. By using first‐principles methods, we investigated the spin‐density distribution and reactivity of a series of boryl radicals with various substituents and Lewis bases. The substituents, along with the Lewis bases, only affect the radical reactivity when an unpaired electron is in the boron pz orbital, that is, for three‐coordinate radicals. We found evidence of synergistic effects between the substituents and the Lewis bases that can substantially broaden the tunability of the reactivity of the boryl radicals. Among Lewis bases, pyridine and imidazol‐2‐ylidene show a similar capacity for stabilization by delocalizing the spin density. Electron‐donating substituents, such as nitrogen, more efficiently stabilize boryl radicals than oxygen and carbon atoms. The reactivity of a boryl radical is always boron based, irrespective of the spin density on boron. 相似文献
37.
Rationally Investigating the Influence of T1 Location on Electroluminescence Performance of Aryl Amine Modified Phosphine Oxide Materials 下载免费PDF全文
Chunmiao Han Liping Zhu Jing Li Fangchao Zhao Dr. Hui Xu Prof. Dongge Ma Prof. Pengfei Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16350-16359
The correspondence between triplet location effect and host‐localized triplet–triplet annihilation and triplet–polaron quenching effects was performed on the basis of a series of naphthyldiphenylamine (DPNA)‐modified phosphine oxide hosts. The number and ratio of DPNA and diphenylphosphine oxide was adjusted to afford symmetrical and unsymmetrical molecular structures and different electronic environments. As designed, the first triplet (T1) states were successfully localized on the specific DPNA chromophores. Owing to the meso‐ and multi‐insulating linkages, identical optical properties and comparable electrical performance was observed, including the same first singlet (S1) and T1 energy levels to support the similar singlet and triplet energy transfer and the close frontier molecular orbital energy levels. This established the basis of rational investigation on T1 location effect without interference from other optoelectronic factors. 相似文献
38.
Xianwen Fang Bingqin Yang Zhao Cheng Pengfei Zhang Meipan Yang 《Research on Chemical Intermediates》2014,40(4):1715-1725
A series of novel 3-[N, N-bis(2-hydroxyethyl)-amino]-chalcone derivatives 3a–3j were synthesized by the aldol condensation of [N, N-bis(2-hydroethyl)-3-amino]-acetophenone 2 with aromatic aldehydes. Their structures were further confirmed by ESI-HRMS, 1H NMR, IR and elemental analysis. X-ray analysis reveals crystal 3b is a monoclinic system with P21/n space group. The antimicrobial activities of the newly synthesized chalcones in vitro were evaluated and the results indicated that most compounds presented moderate to good antimicrobial activities, especially the antifungal capability. Compounds 3a, 3d, 3f and 3g revealed obvious potency against Candida albicans with MIC values of 32 μg/mL, which were better compared with others. 相似文献
39.
以王水、氟化钾、Fe3+溶液为溶剂,对化探样品进行水浴加热分解1.5 h,经泡沫塑料吸附后,于90℃以上硫脲溶液中解吸20 min,然后采用石墨炉原子吸收光谱仪测定其中的金含量。对仪器分析条件进行了优化。金的质量分数在0.1~100.0 ng/g范围内与吸光度呈良好的线性,线性相关系数r2=0.999 3,检出限为0.100 ng/g。该方法对金标准物质测定结果的相对标准偏差为5.96%~9.25%(n=12),对国家一级标准物质进行分析,测定结果与标准值相符合。该方法满足1∶50 000化探样品中痕量金的分析要求。 相似文献
40.
Pengfei Xu Dr. Liang Gao Prof. Dr. Chunhua Cai Prof. Dr. Jiaping Lin Dr. Liquan Wang Prof. Dr. Xiaohui Tian 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(34):14387-14391
Toroids and helices are fundamental geometrical structures in nature. Polymers can self-assemble into various nanostructures, including both toroids and helices; however, nanostructures combining toroidal and helical morphologies (that is, helical toroids) are rarely observed. A binary system is reported containing polypeptide homopolymer and its block copolymer, which can hierarchically self-assemble into uniform helical nanotoroids in solution. The formation of the helical toroids is a successive two-step process. First, the homopolymers aggregate into fibrils and convolve into toroids, thereby resembling the toroidal condensation of deoxyribonucleic acid (DNA) chains. Second, the block copolymers self-assemble on the homopolymer toroids and result in helical surface patterns. Additionally, the chirality of the surface helical patterns can be varied by the chirality of the polypeptide block copolymers. 相似文献