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Primary Allylic Amine Synthesis via Pd-Catalyzed Direct Amination of Allylic Alcohols with Ammonium Acetate 通过钯催化烯丙基醇与乙酸铵的直接胺化合成伯氨基烯丙基胺
IF 4.354 2区 化学 Q1 CHEMISTRY, ORGANIC Pub Date : 2024-07-15 DOI: 10.1021/acs.joc.4c00921
Shunsuke Kataoka, Hiroyuki Morimoto, Takashi Ohshima
Pd/DPEphos-catalyzed direct amination of allylic alcohols with readily available ammonium acetate as a nitrogen source provides access to convenient and scalable syntheses of primary allylic amines with high monoallylation selectivity. Mechanistic studies revealed that ammonium acetate functions as a Brønsted acid to activate the hydroxyl groups and inhibit overreaction.
Pd/DPEphos 催化的烯丙基醇直接胺化反应以易于获得的醋酸铵为氮源,从而方便地合成了具有高单烯丙基化选择性的伯胺。机理研究表明,醋酸铵可作为布氏酸激活羟基并抑制过度反应。
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引用次数: 0
Copper Catalyzed Borylation of Alkynes: An Experimental Mechanistic Study. 铜催化的炔烃硼酸化:实验机制研究。
IF 3.5 3区 化学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-07-15 Epub Date: 2024-06-24 DOI: 10.1002/asia.202400286
Philipp M Rutz, Christian Kleeberg

The copper catalyzed hydroboration of alkynes with B2pin2 was studied by in detail studies of individual relevant steps along the catalytic pathway. A number of reaction steps were retraced by in situ NMR spectroscopy as well as central intermediates and side-products were isolated and comprehensively characterized. A copper boryl complex is central to the catalytic process by inserting the terminal alkyne substrate into the B-Cu bond. The selectivity of this step - depending on the NHC auxiliary ligand - determines the α/β selectivity observed in the product. The latter complex is protonated by the auxiliary alcohol reagent resulting in hydroboration product formation and formation of a Cu alkoxido complex. Reaction of the latter with B2pin2 results in the regeneration of the central copper boryl complex. This alcoholysis step depends on the acidity of the alcohol, in particular on the relative acidity of the alcohol vs. the alkyne substrate. A number of side reactions leading to the hydrogenation product of the alkyne substrate and a bis hydroborated product were identified and studied in some detail. It is concluded that the performance of a particular catalytic system depends crucially on the relative acidities of the reagents and generalizations may be difficult.

通过详细研究催化路径上的各个相关步骤,研究了铜催化炔烃与 B2pin2 的氢硼化反应。通过原位核磁共振光谱回溯了多个反应步骤,并分离和全面鉴定了中心中间产物和副产物。铜硼烷基络合物通过将末端炔基底物插入 B-Cu 键而成为催化过程的核心。这一步骤的选择性(取决于 NHC 辅助配体)决定了产物的 α/β 选择性。后一种复合物被辅助醇试剂质子化,形成氢硼化合产物,并形成 Cu 烷氧基复合物。后者与 B2pin2 反应后,中央铜硼烷基复合物再生。这一醇解步骤取决于醇的酸度,特别是醇与炔基底物的相对酸度。对导致炔基底氢化产物和双硼氢化产物的一系列副反应进行了鉴定和详细研究。结论是,特定催化体系的性能主要取决于试剂的相对酸性,很难一概而论。
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引用次数: 0
Phosphine vs DBU-Catalyzed Annulation Reactions of β'-Acetoxy Allenoates with Acyl-Tethered Benzothiazole Bisnucleophiles: (4 + 3) or (4 + 1) vs (3 + 3) Annulation. 膦与 DBU 催化的β'-乙酰氧基烯酸盐与乙酰拴苯并噻唑双亲核物的琥珀化反应:(4 + 3)或(4 + 1)与(3 + 3)琥珀化。
IF 3.3 2区 化学 Q1 CHEMISTRY, ORGANIC Pub Date : 2024-07-15 DOI: 10.1021/acs.joc.4c01085
Sachin Chauhan, K C Kumara Swamy

Dearomative annulation reaction of acyl-tethered benzothiazole bisnucleophiles with β'-acetoxy allenoates by switching the Lewis base is developed. The DBU-catalyzed reaction gives benzothiazole-fused 1,4-dihydropyridine carboxylates by (3 + 3) annulation chemoselectively. By contrast, the PR3-catalyzed reaction gives benzothiazole-fused azepines by (4 + 3) annulation and cyclopentene carboxylates by (4 + 1) annulation; the ratio of the latter two products depends on the solvent. A possible rationale for the difference in the reactivity, based on the 1,4/1,5-addition of the 2-acyl-tethered benzothiazole to the key phosphonium intermediate, is provided.

通过转换路易斯碱,开发了酰基系苯并噻唑双核亲和物与β'-乙酰氧基异戊烯酸酯的窘迫环化反应。DBU 催化的反应通过 (3 + 3) 环化化学选择性地得到苯并噻唑融合的 1,4- 二氢吡啶羧酸盐。相比之下,PR3 催化反应通过 (4 + 3) 环化作用生成苯并噻唑融合氮杂卓,通过 (4 + 1) 环化作用生成环戊烯羧酸盐;后两种产物的比例取决于溶剂。根据 2-酰基系链苯并噻唑与关键膦中间体的 1,4/1,5-加成,提供了反应性不同的可能原因。
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引用次数: 0
Red-to-Blue Triplet-Triplet Annihilation Upconversion for Calcium Sensing. 用于钙传感的红-蓝三重-三重湮灭上转换。
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-15 DOI: 10.1021/acs.jpclett.4c01528
Valeriia D Andreeva, Irene Regeni, Tingxiang Yang, Anna Elmanova, Martin Presselt, Benjamin Dietzek-Ivanšić, Sylvestre Bonnet

Triplet-triplet annihilation upconversion is a bimolecular process converting low-energy photons into high-energy photons. Here, we report a calcium-sensing system working via triplet-triplet annihilation (TTA) upconverted emission. The probe itself was obtained by covalent conjugation of a blue emitter, perylene, with a calcium-chelating moiety, and it was sensitized by the red-light-absorbing photosensitizer palladium(II) tetraphenyltetrabenzoporphyrin (PdTPTBP). Sensing was selective for Ca2+ and occurred in the micromolar domain. In deoxygenated conditions, the TTA upconverted luminescence gradually appeared upon adding an increasing concentration of calcium ions, to reach a maximum upconversion quantum yield of 0.0020.

三重-三重湮灭上转换是一种将低能光子转换为高能光子的双分子过程。在这里,我们报告了一种通过三重-三重湮灭(TTA)上转换发射工作的钙传感系统。探针本身是通过蓝色发射体过江龙与钙螯合基团共价共轭得到的,并通过吸收红光的光敏剂四苯基四苯并卟啉钯(II)(PdTPTBP)敏化。对 Ca2+ 的感应是选择性的,并发生在微摩尔域。在脱氧条件下,当加入的钙离子浓度增加时,TTA 上转换发光逐渐出现,达到 0.0020 的最大上转换量子产率。
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引用次数: 0
Intercalated Water Drives Anomalous Thermal Expansion in the Tetragonal Zircon Structured Bismuth Vanadate BiVO4 Photocatalyst. 锆石四方结构钒酸铋 BiVO4 光催化剂中的夹杂水推动了异常热膨胀。
IF 3.5 3区 化学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-07-15 Epub Date: 2024-06-11 DOI: 10.1002/asia.202400408
Bryce G Mullens, Frederick P Marlton, Maria K Nicholas, Ahmadi J Permana, Helen E A Brand, Helen E Maynard-Casely, Philip A Chater, Brendan J Kennedy

The thermal transformation of the tetragonal-zircon (tz-) to tetragonal-scheelite (ts-)BiVO4 was studied by in situ synchrotron X-ray diffraction, thermogravimetric analysis, and Fourier-transformed infrared spectroscopy. Upon heating, the tetragonal zircon polymorph of BiVO4 (tz-BiVO4) transitioned to the ts-polymorph between 693-773 K. Above 773 K, single phase ts-BiVO4 was observed before transitioning to the monoclinic fergusonite (mf-) polymorph upon cooling. An anomaly in thermal expansion was observed between 400-500 K, associated with the loss of intercalated H2O/NH4 + from the coprecipitation procedure. Heating tz-BiVO4 resulted in contraction of the V-O bond distance and VO4 polyhedra volume, ascribed to rotation of the tetrahedra groups. Attempts to study this by neutron diffraction failed due to the large incoherent scatter from the hydrogenous species. Efforts to remove these species while maintaining the tz-BiVO4 structure were unsuccessful, suggesting they play a role in stabilizing the tz-polymorph. The local structure of both mf-BiVO4 and tz-BiVO4 were investigated by X-ray pair distribution function analysis, revealing local distortions.

通过原位同步辐射 X 射线衍射和 TGA/FTIR 分析,研究了 BiVO4 中锆石向白钨矿的热转变。加热时,BiVO4 的四方锆石多晶体(tz-BiVO4)在 693-773 K 之间转变为四方白钨矿(ts-)多晶体,冷却后又转变为单斜铁素体(mf)多晶体。在 400-500 K 之间观察到热膨胀异常,这与 H2O/NH4+ 的损失有关。由于 VO4 的旋转,加热 tz-BiVO4 导致 V-O 键距离和 VO4 多面体体积收缩。由于含氢物质会产生大量非相干散射,试图用中子衍射法研究这一现象的努力失败了。在保持 tz-BiVO4 结构的同时去除这些物质的努力也没有成功,这表明它们在稳定锆石多晶体方面发挥了作用。通过 X 射线对分布函数分析研究了 mf-BiVO4 和 tz-BiVO4 的局部结构。
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引用次数: 0
Zeolite-Templated Carbons Supported Rh and Ru Electrocatalysts for Highly Active Hydrogen Evolution Reaction. 用于高活性氢气进化反应的沸石模板碳支持 Rh 和 Ru 电催化剂。
IF 3.5 3区 化学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-07-15 Epub Date: 2024-06-11 DOI: 10.1002/asia.202400342
Yuanxin Cao, Xiaoming Yu, Tianfu Wang, Jiahao Li, Nan Li, Anbang Ge, Jie Ying, Tongwen Yu

Here, we report the systematical synthesis of zeolite-templated carbon (ZTC) supported Ru and Rh mono- or bi-metallic electrocatalysts towards hydrogen evolution reaction (HER). The zeolite A or ZSM-5 derived ZTC supports and metal sites were adjusted, and all electrocatalysts outperformed the commercial Pt/C electrocatalyst for HER performance. In particular, the RhRu/(ZTC/ZSM5) sample exhibited superior catalytic performance with the overpotential of 24.8 mV@10 mA ⋅ cm-2, and outstanding stability with 1 mV drop after 20000 cyclic voltammetry circles. This work offers a simple impregnation method for the synthesis of highly performed HER electrocatalysts supported on porous zeolite-templated carbon.

在此,我们报告了系统地合成沸石模板碳(ZTC)支撑的 Ru 和 Rh 单金属或双金属氢进化反应(HER)电催化剂的过程。通过调整沸石 A 或 ZSM5 衍生的 ZTC 支撑物和金属位点,所有电催化剂的氢进化性能均优于商用 Pt/C 电催化剂。其中,RhRu/(ZTC/ZSM5)样品表现出卓越的催化性能,过电位为 24.8 mV@10 mA-cm-2,并且具有出色的稳定性,在 20000 次循环伏安法测试后仅有 1 mV 的下降。这项工作为在多孔碳上合成高性能 HER 电催化剂提供了一种简单的浸渍方法。
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引用次数: 0
Active-Site Oxygen Accessibility and Catalytic Loop Dynamics of Plant Aromatic Amino Acid Decarboxylases from Molecular Simulations. 从分子模拟看植物芳香族氨基酸脱羧酶的活性位点氧可得性和催化环动力学
IF 2.9 3区 生物学 Q3 BIOCHEMISTRY & MOLECULAR BIOLOGY Pub Date : 2024-07-15 DOI: 10.1021/acs.biochem.4c00144
Yitao Gou, Tianjie Li, Yi Wang

Aromatic amino acid decarboxylases (AAADs) are pyridoxal-5'-phosphate (PLP)-dependent enzymes that catalyze the decarboxylation of aromatic amino acid l-amino acids. In plants, apart from canonical AAADs that catalyze the straightforward decarboxylation reaction, other members of the AAAD family function as aromatic acetaldehyde synthases (AASs) and catalyze more complex decarboxylation-dependent oxidative deamination. The interconversion between a canonical AAAD and an AAS can be achieved by a single tyrosine-phenylalanine mutation in the large catalytic loop of the enzymes. In this work, we report implicit ligand sampling (ILS) calculations of the canonical l-tyrosine decarboxylase from Papaver somniferum (PsTyDC) that catalyzes l-tyrosine decarboxylation and its Y350F mutant that instead catalyzes the decarboxylation-dependent oxidative deamination of the same substrate. Through comparative analysis of the resulting three-dimensional (3D) O2 free energy profiles, we evaluate the impact of the key tyrosine/phenylalanine mutation on oxygen accessibility to both the wild type and Y350F mutant of PsTyDC. Additionally, using molecular dynamics (MD) simulations of the l-tryptophan decarboxylase from Catharanthus roseus (CrTDC), we further investigate the dynamics of a large catalytic loop known to be indispensable to all AAADs. Results of our ILS and MD calculations shed new light on how key structural elements and loop conformational dynamics underlie the enzymatic functions of different members of the plant AAAD family.

芳香族氨基酸脱羧酶(AAADs)是一种依赖于吡哆醛-5'-磷酸(PLP)的酶,可催化芳香族氨基酸 l-氨基酸的脱羧反应。在植物中,除了典型的 AAADs 能催化直接的脱羧反应外,AAAD 家族的其他成员也能作为芳香族乙醛合成酶(AASs)发挥作用,催化更复杂的脱羧依赖性氧化脱氨反应。典型 AAAD 与 AAS 之间的相互转换可以通过酶的大催化环中的单个酪氨酸-苯丙氨酸突变来实现。在这项工作中,我们报告了隐式配体取样(ILS)计算的结果,计算的对象是催化 l-酪氨酸脱羧的巴布亚新几内亚(Papaver somniferum)典型 l-酪氨酸脱羧酶(PsTyDC)及其 Y350F 突变体,后者转而催化同一底物的脱羧依赖性氧化脱氨。通过对由此产生的三维(3D)氧气自由能曲线进行比较分析,我们评估了关键的酪氨酸/苯丙氨酸突变对 PsTyDC 野生型和 Y350F 突变体氧气可及性的影响。此外,我们还利用分子动力学(MD)模拟了蔷薇色氨酸脱羧酶(CrTDC),进一步研究了已知对所有 AAADs 都不可或缺的大催化环的动力学。我们的 ILS 和 MD 计算结果揭示了植物 AAAD 家族不同成员的酶功能是如何通过关键结构元素和环路构象动力学来实现的。
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引用次数: 0
Unveiling the Role of Spin Currents on the Giant Rashba Splitting in Single-Layer WSe2 揭示自旋电流对单层 WSe2 中巨型拉什巴分裂的作用
IF 6.475 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-15 DOI: 10.1021/acs.jpclett.4c01607
Alberto Boccuni, Bárbara Maria Teixeira Costa Peluzo, Filippo Bodo, Giacomo Ambrogio, Jefferson Maul, Davide Mitoli, Giovanni Vignale, Stefano Pittalis, Elfi Kraka, Jacques K. Desmarais, Alessandro Erba
The Rashba spin splitting in uniaxial, inversion-asymmetric materials has attracted considerable interest for spintronic applications. The most widely used theoretical framework to model such states is Kohn–Sham density functional theory (DFT) in combination with standard (semi)local exchange–correlation density functional approximations (DFAs). However, in the presence of spin–orbit coupling, DFT misses contributions due to modification of the many-body interaction by spin currents J⃗. Inclusion of the latter effects requires a spin current DFT (SCDFT) formulation, which is seldom considered. We investigate the giant Rashba splitting in single-layer WSe2, and we quantify the effect of including spin currents in DFAs of the SCDFT. Crucially, we show that SCDFT allows fully capturing the giant Rashba band splitting in single-layer WSe2, otherwise previously systematically underestimated by standard (semi)local DFAs within the DFT framework. We find the inclusion of J⃗ on the DFA increases the Rashba splitting by about 20%.
单轴反转不对称材料中的拉什巴自旋分裂在自旋电子应用方面引起了极大的兴趣。最广泛应用的理论框架是结合标准(半)局部交换相关密度泛函近似(DFAs)的 Kohn-Sham 密度泛函理论(DFT)来模拟这种状态。然而,在存在自旋轨道耦合的情况下,DFT 会忽略由于自旋电流 J⃗ 对多体相互作用的修正而产生的贡献。要将后一种效应包括在内,需要使用自旋电流 DFT(SCDFT)公式,而这种公式很少被考虑。我们研究了单层 WSe2 中的巨型 Rashba 分裂,并量化了将自旋电流纳入 SCDFT DFA 的影响。最重要的是,我们发现 SCDFT 可以完全捕捉到单层 WSe2 中的巨型 Rashba 带分裂,而之前在 DFT 框架内的标准(半)局部 DFA 则系统性地低估了这种分裂。我们发现在 DFA 中加入 J⃗ 会使 Rashba 带分裂增加约 20%。
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引用次数: 0
Electronic Polarization Leads to a Drier Dewetted State for Hydrophobic Gating in the Big Potassium Channel. 电子极化导致大钾通道疏水门控的干湿状态
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-15 DOI: 10.1021/acs.jpclett.4c01359
Jiahua Deng, Qiang Cui

In the hydrophobic gating mechanism proposed for some ion channels, ion permeation is not blocked by the physical dimension of the channel pore but by its dewetted state which constitutes the energetic bottleneck. A major source of uncertainty in the mechanism is that the dewetted state was not observed in experiments and only probed in simulations using nonpolarizable force fields, which do not accurately represent the properties of confined water. Here we analyze hydration of the central cavity in the pore-gate domain of the Big Potassium channel using molecular dynamics and grand canonical Monte Carlo simulations with enhanced sampling techniques. Including polarization leads to a much drier dewetted state and a higher barrier for the transition to the wet state, suggesting more effective hydrophobic gating. The simulations also identify two backbone carbonyls at the bottom of the selectivity filter as good candidates for characterizing the dewetted state using infrared spectroscopies.

在针对某些离子通道提出的疏水门控机制中,离子渗透不受通道孔隙物理尺寸的阻碍,而是受其露湿状态的阻碍,而露湿状态构成了能量瓶颈。该机制的一个主要不确定因素是实验中没有观察到露湿状态,只能通过使用非极化力场进行模拟探测,而非极化力场并不能准确代表封闭水的特性。在这里,我们利用分子动力学和大规范蒙特卡洛模拟以及增强采样技术分析了大钾通道孔-栅域中央空腔的水合作用。包括极化在内的水合作用会导致更干燥的脱湿态和更高的湿态转换障碍,这表明疏水门控更为有效。模拟还确定了选择性过滤器底部的两个骨架羰基,它们是利用红外光谱分析露湿状态特征的良好候选物。
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引用次数: 0
(Ca0.5Mn0.5)2MnTeO6 - An Anomalously Stable High-Pressure Double Perovskite. (Ca0.5Mn0.5)2MnTeO6--异常稳定的高压双过氧化物。
IF 3.5 3区 化学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-07-15 Epub Date: 2024-06-11 DOI: 10.1002/asia.202400280
Azizah Almadhi, Kunlang Ji, Sean D Injac, Clemens Ritter, J Paul Attfield

High pressure high temperature treatments of the composition CaMnMnTeO6 are found to yield only an A2BB'O6-type double perovskite (Ca0.5Mn0.5)2MnTeO6, rather than a AA'BB'O6 double double perovskite with A- and B- site cation order as found in analogs CaMnMnReO6 and CaMnMnWO6 with similar cation sizes. Double perovskite (Ca0.5Mn0.5)2MnTeO6 adopts a monoclinic structure in space group P21/n with a framework of highly tilted MnO6 and TeO6 octahedra enclosing disordered Ca2+ and Mn2+ cations. Magnetic measurements show that (Ca0.5Mn0.5)2MnTeO6 is a highly frustrated spin glass with a freezing transition at 5 K, and no long-range spin order is apparent by neutron diffraction at 1.6 K.

对 CaMnMnTeO6 成分进行高压高温处理后,发现只能生成 A2BB'O6 型双过氧化物 (Ca0.5Mn0.5)2MnTeO6,而不是类似阳离子大小的 CaMnMnReO6 和 CaMnMnWO6 中具有 A 位和 B 位阳离子顺序的 AA'BB'O6 型双过氧化物。双过氧化物(Ca0.5Mn0.5)2MnTeO6 采用空间群 P21/n 的单斜结构,由高度倾斜的 MnO6 和 TeO6 八面体组成的框架包围着无序的 Ca2+ 和 Mn2+ 阳离子。磁性测量结果表明,(Ca0.5Mn0.5)2MnTeO6 是一种高度沮散的自旋玻璃,在 5 K 时出现凝固转变,在 1.6 K 时的中子衍射没有明显的长程自旋秩序。
{"title":"(Ca<sub>0.5</sub>Mn<sub>0.5</sub>)<sub>2</sub>MnTeO<sub>6</sub> - An Anomalously Stable High-Pressure Double Perovskite.","authors":"Azizah Almadhi, Kunlang Ji, Sean D Injac, Clemens Ritter, J Paul Attfield","doi":"10.1002/asia.202400280","DOIUrl":"10.1002/asia.202400280","url":null,"abstract":"<p><p>High pressure high temperature treatments of the composition CaMnMnTeO<sub>6</sub> are found to yield only an A<sub>2</sub>BB'O<sub>6</sub>-type double perovskite (Ca<sub>0.5</sub>Mn<sub>0.5</sub>)<sub>2</sub>MnTeO<sub>6</sub>, rather than a AA'BB'O<sub>6</sub> double double perovskite with A- and B- site cation order as found in analogs CaMnMnReO<sub>6</sub> and CaMnMnWO<sub>6</sub> with similar cation sizes. Double perovskite (Ca<sub>0.5</sub>Mn<sub>0.5</sub>)<sub>2</sub>MnTeO<sub>6</sub> adopts a monoclinic structure in space group P2<sub>1</sub>/n with a framework of highly tilted MnO<sub>6</sub> and TeO<sub>6</sub> octahedra enclosing disordered Ca<sup>2+</sup> and Mn<sup>2+</sup> cations. Magnetic measurements show that (Ca<sub>0.5</sub>Mn<sub>0.5</sub>)<sub>2</sub>MnTeO<sub>6</sub> is a highly frustrated spin glass with a freezing transition at 5 K, and no long-range spin order is apparent by neutron diffraction at 1.6 K.</p>","PeriodicalId":145,"journal":{"name":"Chemistry - An Asian Journal","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140896647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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