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排序方式: 共有484条查询结果,搜索用时 15 毫秒
1.
Xu Yifan Zhang Hehe Ding Tangjing Tian Ruiqi Sun Dongmei Wang Ming-Sheng Zhou Xiaosi 《中国科学:化学(英文版)》2022,65(9):1807-1816
Science China Chemistry - Due to their enormous potential for large-scale energy storage, rechargeable potassium-ion batteries have been widely researched and developed. However, the drastic volume... 相似文献
2.
The collisional dynamics of two symmetric droplets with equal intraspecies scattering lengths and particle number density for each component is studied by solving the corresponding extended Gross−Pitaevskii equation in two dimensions by including a logarithmic correction term in the usual contact interaction. We find the merging droplet after collision experiences a quadrupole oscillation in its shape and the oscillation period is found to be independent of the incidental momentum for small droplets. With increasing collision momentum the colliding droplets may separate into two, or even more, and finally into small pieces of droplets. For these dynamical phases we manage to present boundaries determined by the remnant particle number in the central area and the damped oscillation of the quadrupole mode. A stability peak for the existence of droplets emerges at the critical particle numberNc ≃ 48 for the quasi-Gaussian and flat-top shapes of the droplets. 相似文献
3.
Yihan Zhang Cui Bo Yanhao Fan Rui An Long Chen Yifan Zhang Yiqun Jia Xinhong Wang 《Biomedical chromatography : BMC》2019,33(3)
A quick and effective workflow based on ultra‐performance liquid chromatography coupled with electron spray ionization and LTQ‐Orbitrap mass spectrometry (UPLC‐LTQ‐Orbitrap MS) was established for compositional analysis and screening of the characteristic compounds of three species of Atractylodes rhizome for quality evaluation. This technique was employed to determine the seven main components in Atractylodes rhizome samples. Ultimately, 78 constituents were identified; of these, seven characteristic compounds were selected for species discrimination, comprising atractylodin (63), atractylenolide I (43), atractylenolide II (49), atractylenolide III (53), atractylon (69), methyl‐atractylenolide II (54) and (4E,6E,12E)‐tetradecadecatriene‐8,10‐diyne‐1,3‐diacetate (59). The seven main compounds, including six characteristic compounds, were simultaneously determined in 29 batches of Atractylodes rhizome samples. Thus, the method validation showed acceptable results. Quantitative analysis showed significantly different contents of the seven main components among the three species of Atractylodes rhizome, which indicates possible distinctions in the pharmacological effects. This established method can simultaneously provide qualitative and quantitative results for compositional characterization of Atractylodes rhizomes and for quality control. 相似文献
4.
古镇作为集自然景观与人文景观一体的景区,具有丰富的声音类型。本研究以大研古镇为例,通过实地调研探究不同声音偏好的游客对古镇声景观的主观评价差异。基于游客的声音偏好,将游客分为偏爱自然声和偏爱人工声两大类。通过因子分析提取游客声景观主观评价的5个主因子:大小、音质、效价、偏好和唤醒。进一步分析发现,这5个因子具有一定的层级性,其中从大小到唤醒代表声景观评价从声音的物理属性向声音的联想评价逐级提升。其中在低层级评价(大小、音质)中,偏好自然声的游客和偏好人工声的游客无显著差异,低层级评价具有稳定性;而在高层级评价(效价、偏好和唤醒)中,偏好人工声的游客更关注古镇声景观的淳朴性和遗产性。因此,游客对声景观的主观评价可视为一种指标,判断景区声景所处的评价阶段,从而为景区声景观改善提供更有针对性的建议。 相似文献
5.
Hong Chengming Wang Xiaojun Pan Zhigang Zhang Yifan 《Journal of Thermal Analysis and Calorimetry》2015,120(1):427-438
Journal of Thermal Analysis and Calorimetry - The saturated aliphatic binary carboxylic acid, including succinic acid, adipic acid and sebacic acid, were used to improve the curing process of... 相似文献
6.
LC‐MS/MS analysis of Gegen Qinlian Decoction and its pharmacokinetics after oral administration to rats 下载免费PDF全文
Yifan Zhang Jin Yuan Yizhu Zhang Ye Chen Jiaoxian Cao Rui An Xinhong Wang 《Biomedical chromatography : BMC》2015,29(4):485-495
A liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method was developed and validated for the simultaneous determination of 12 constituents of Gegen Qinlian Decoction (GQD), namely puerarin, daidzein, baicalin, wogonoside, wogonin, liquiritin, liquiritigenin, berberine, jatrorrhizine, palmatine, coptisine and glycyrrhetic acid, in rat plasma. The plasma samples were spiked with the internal standard (IS) carbamazepine acidified with HCl and extracted by liquid–liquid extraction with ethyl acetate. Chromatographic separation was achieved on a Shiseido Capcell PAK C18 column utilizing a gradient elution profile and a mobile phase consisting of (A) 0.1% formic acid in water and (B) acetonitrile. Detection was performed in the multiple reaction monitoring mode using electrospray ionization in the positive ion mode at a flow rate of 0.3 mL/min and a run time of 8 min. All of the calibration curves gave good linearity (r > 0.9930) over the concentration range from 0.6–360 to 16.2–9720 ng/mL for all components. The intra‐ and inter‐day precisions were <15.0% in terms of the relative standard deviation, and the accuracies were within ±13.7% in terms of the relative error. The method was successfully applied to investigate the pharmacokinetics of the major active compounds of Gegen Qinlian Decoction after its oral administration to rats. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
Novel highly sensitive chiral organic field-effect transistors(COFET)were developed by directly assembling imidazolium3,5-dimethylphenylcabamoylated-β-cyclodextrin(lm^+-Ph-β-CD)and 3,5-dimethylphenylcarbamoylated-β-CD(Ph-β-CD)respectively onto the semiconductor layer as sensing units.The Im+-Ph-β-CD/COFET afforded better enantioselectivity and a lowest detection concentration of10^-18 L/mol as well as the potentiality in quantitative analysis of commercial medicines. 相似文献
8.
Pengjin Qin Li-An Wang Prof. Joseph M. O'Connor Prof. Kim K. Baldridge Yifan Li Burak Tufekci Jiyue Chen Prof. Arnold L. Rheingold 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18114-18121
Triene 6π electrocyclization, wherein a conjugated triene undergoes a concerted stereospecific cycloisomerization to a cyclohexadiene, is a reaction of great historical and practical significance. In order to circumvent limitations imposed by the normally harsh reaction conditions, chemists have long sought to develop catalytic variants based upon the activating power of metal–alkene coordination. Herein, we demonstrate the first successful implementation of such a strategy by utilizing [(C5H5)Ru(NCMe)3]PF6 as a precatalyst for the disrotatory 6π electrocyclization of highly substituted trienes that are resistant to thermal cyclization. Mechanistic and computational studies implicate hexahapto transition-metal coordination as responsible for lowering the energetic barrier to ring closure. This work establishes a foundation for the development of new catalysts for stereoselective electrocyclizations. 相似文献
9.
Dr. Yifan Gu Prof. Jia-Jia Zheng Prof. Ken-ichi Otake Prof. Kunihisa Sugimoto Prof. Nobuhiko Hosono Prof. Shigeyoshi Sakaki Prof. Fengting Li Prof. Susumu Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15647-15651
To achieve unique molecular-recognition patterns, a rational control of the flexibility of porous coordination polymers (PCPs) is highly sought, but it remains elusive. From a thermodynamic perspective, the competitive relationship between the structural deformation energy (Edef) of soft PCPs and the guest interaction is key for selective a guest-triggered structural-transformation behavior. Therefore, it is vital to investigate and control Edef to regulate this competition for flexibility control. Driven by these theoretical insights, we demonstrate an Edef-modulation strategy via encoding inter-framework hydrogen bonds into a soft PCP with an interpenetrated structure. As a proof of this concept, the enhanced Edef of PCP enables a selective gate-opening behavior toward CHCl3 over CH2Cl2 by changing the adsorption-energy landscape of the compounds. This study provides a new direction for the design of functional soft porous materials. 相似文献
10.
Dr. Ziyu Wang Dr. Ya Zhang Dr. Cheng Chen Dr. Ruixue Zhu Dr. Jiaming Jiang Prof. Tsu-Chien Weng Prof. Quanjiang Ji Prof. Yifan Huang Prof. Chong Fang Prof. Weimin Liu 《Angewandte Chemie (International ed. in English)》2023,62(5):e202212209
Large Stokes shift (LSS) red fluorescent proteins (RFPs) are highly desirable for bioimaging advances. The RFP mKeima, with coexisting cis- and trans-isomers, holds significance as an archetypal system for LSS emission due to excited-state proton transfer (ESPT), yet the mechanisms remain elusive. We implemented femtosecond stimulated Raman spectroscopy (FSRS) and various time-resolved electronic spectroscopies, aided by quantum calculations, to dissect the cis- and trans-mKeima photocycle from ESPT, isomerization, to ground-state proton transfer in solution. This work manifests the power of FSRS with global analysis to resolve Raman fingerprints of intermediate states. Importantly, the deprotonated trans-isomer governs LSS emission at 620 nm, while the deprotonated cis-isomer's 520 nm emission is weak due to an ultrafast cis-to-trans isomerization. Complementary spectroscopic techniques as a table-top toolset are thus essential to study photochemistry in physiological environments. 相似文献