全文获取类型
收费全文 | 114篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
化学 | 118篇 |
晶体学 | 1篇 |
数学 | 1篇 |
物理学 | 8篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 3篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 6篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2000年 | 11篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 1篇 |
排序方式: 共有128条查询结果,搜索用时 15 毫秒
51.
Dr. Tiancheng Pu Jiaqi Ding Fanxing Zhang Dr. Ke Wang Ning Cao Prof. Emiel J. M. Hensen Prof. Pengfei Xie 《Angewandte Chemie (International ed. in English)》2023,62(40):e202305964
The pursuit of high metal utilization in heterogeneous catalysis has triggered the burgeoning interest of various atomically dispersed catalysts. Our aim in this review is to assess key recent findings in the synthesis, characterization, structure-property relationship and computational studies of dual-atom catalysts (DACs), which cover the full spectrum of applications in thermocatalysis, electrocatalysis and photocatalysis. In particular, combination of qualitative and quantitative characterization with cooperation with DFT insights, synergies and superiorities of DACs compare to counterparts, high-throughput catalyst exploration and screening with machine-learning algorithms are highlighted. Undoubtably, it would be wise to expect more fascinating developments in the field of DACs as tunable catalysts. 相似文献
52.
Selective Coke Combustion by Oxygen Pulsing During Mo/ZSM‐5‐Catalyzed Methane Dehydroaromatization
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Nikolay Kosinov Ferdy J. A. G. Coumans Evgeny Uslamin Prof. Freek Kapteijn Prof. Emiel J. M. Hensen 《Angewandte Chemie (International ed. in English)》2016,55(48):15086-15090
Non‐oxidative methane dehydroaromatization is a promising reaction to directly convert natural gas into aromatic hydrocarbons and hydrogen. Commercialization of this technology is hampered by rapid catalyst deactivation because of coking. A novel approach is presented involving selective oxidation of coke during methane dehydroaromatization at 700 °C. Periodic pulsing of oxygen into the methane feed results in substantially higher cumulative product yield with synthesis gas; a H2/CO ratio close to two is the main side‐product of coke combustion. Using 13C isotope labeling of methane it is demonstrated that oxygen predominantly reacts with molybdenum carbide species. The resulting molybdenum oxides catalyze coke oxidation. Less than one‐fifth of the available oxygen reacts with gaseous methane. Combined with periodic regeneration at 550 °C, this strategy is a significant step forward, towards a process for converting methane into liquid hydrocarbons. 相似文献
53.
负载型纳米金催化剂由于其独特的化学性质在一系列氧化反应中受到广泛关注.其中,一氧化碳氧化不仅在实际应用领域(如汽车尾气处理)发挥重要作用,而且作为一种理想的模型反应用以深入研究和理解催化剂的构效关系.为了获得高效的纳米金催化剂,我们需要把金负载到载体上,载体不仅为金的分散提供必要的表面,而且还会和金产生相互作用,这种金属-载体相互作用对金的氧化态,金颗粒大小及其热稳定性均有重要影响.金属氧化物是负载金最常用的载体.为了提高纳米金催化剂的性能,需要调变金属氧化物的性质.常用的策略是调控金属氧化物的组成、晶相以及晶粒大小.此外,对金属氧化物的形貌进行精细调控也是一种重要的方法,因为具有不同形貌的氧化物可能会暴露出不同的晶面,而且可能具有不同的缺陷位点.α-Fe2O3是一种热稳定性强而且对环境友好的载体,可是有关其形貌对负载金催化剂在一氧化碳氧化反应中性能影响的研究尚不充分.因此,本文采用水热法合成了具有纳米球和纳米棒两种形貌的氧化铁,并采用沉积-沉淀的方法将金纳米颗粒负载于其表面.高分辨透射电镜照片显示,和氧化铁纳米球(α-Fe2O3(S))相比,氧化铁纳米棒(α-Fe2O3(R))的表面更为粗糙,具有更多的缺陷位点.Au和α-Fe2O3(R)之间有更强的金属载体相互作用,导致纳米棒氧化铁上的金纳米颗粒更小而且多呈半球形.相比之下,纳米球氧化铁上的金纳米颗粒较大,多呈球形,且分布不均匀.反应结果表明,Au/α-Fe2O3(R)具有更高的一氧化碳氧化活性.对反应后的催化剂进行表征发现,Au/α-Fe2O3(R)上金颗粒烧结程度较低,平均粒径从1.5增至2.4 nm,而Au/α-Fe2O3(S)上金颗粒烧结较为严重,平均粒径从2.0 nm增加到4.0 nm.氢气程序升温还原结果表明,Au/α-Fe2O3(R)具有更强的还原性,这也促进了其催化活性的提高. 相似文献
54.
55.
Crystal Structure of N,N′-Bis(trimethylsilyl)-imidazoliumiodide [(Me3Si)2(C3H3N2)]+I? Me3SiI forms with N-Trimethylsiylimidazole (NTMSI) a 1:1 compound which is stable at room temperature. Single crystals can be isolated from a solution of chloroform. The X-ray crystal structure investigation proves an ionic structure. 相似文献
56.
Synthesis and Crystal Structure Determination of Hexachloro-μ-dichloro-bis[N-(trimethylsilyl)imidazol]dititanium Chloroform (1/2) Hexachloro-μ-dichloro-bis[N-(trimethylsilyl)-imidazol]dititanium chloroform (1/2) 1 has been prepared by the reaction of titanium tetrachloride with N-trimethylsilylimidazole (NTMSI) in chloroform solution as orange crystals. The structure consists of two distorted TiCl5N octahedrons, which are connected by two chlorine atoms via common edges to a centrosymmetric dimer [Ti2Cl8(NTMSI)2] · 2 CHCl3. The N-trimethylsilylimidazole ligands each are located at one axial position of each octahedron, whereas the equatorial positions are occupied by the chloro ligands. The results presented are discussed assuming a gradual formation of an 1 : 1 and 1 : 2 adduct. 相似文献
57.
Using a statistical shell-model, the equilibrium internuclear distances and total molecular energies have been computed for Li 2 + , Li2, Na 2 + and Na2. The results are in good agreement with experimental data. 相似文献
58.
Crystal- and Molecular Structures of Chlorotrispyridinium-bis-(tetrachloroaluminate(III)) and a New Modification of Pyridinium Chloride The compounds PyHCl and ((PyH)3Cl)(AlCl4)2 are formed by hydrolysis during the synthesis of adducts in the system AlCl3/pyridine. The second room temperature modification of PyHCl crystallizes in the space group P21/c with the lattice constants a = 847.9(3), b = 1770.2(3), c = 801.9(3) pm, β = 95.23(3)°, Z = 8. The atomic parameters were refined from 4471 measured intensities to R(F) = 6,9%. The N? Cl distances are 306.8(7) and 311.0(8) pm. The unit cell of ((PyH)3Cl)(AlCl4)2 is orthorhombic (space group Pbca) and has the lattice constants a = 1306.3(4), b = 1589.4(4), c = 2708.6(7) pm, Z = 8. The crystal structure was refined from 7226 measured intensities to R(F) = 6.7%. The cation shows three pyridinium ions to have NH…?Cl hydrogen bonds to a central positioned chloride ion with N? Cl distances of 301.4(7), 305(1) and 306(1) pm. 相似文献
59.
Ionic Structures of 4- and 5-coordinated Silicon. Novel Ionic Crystal Structures of 4- and 5-coordinated Silicon: [Me3Si(NMI)]+ Cl?, [Me2HSi(NMI)2]+ Cl?, [Me2Si(NMI)3]2+ 2 Cl?. NMI Me3SiCl forms with N-Methylimidazole (NMI) a crystalline 1:1-compound which is stable at room temperature. The X-ray single crystal investigation proves the ionic structure [Me3Si(NMI)]+Cl? 1 which is the result of the cleavage of the Si? Cl bond and the addition of an NMI-ring. The reaction of Me2HSiCl with NMI (in the molar ratio of 1:2), under cleavage of the Si? Cl bond and co-ordination of two NMI rings, yields the compound [Me2HSi(NMI)2]+Cl? 2 . The analogous reaction of Me2SiCl2 with NMI (molar ratio 2:1) leads to a compound which consists of Me2SiCl2 and NMI in the molar ratio of 1:2. During the sublimation single crystals of the compound [Me2Si(NMI)3]2+ 2 Cl?. NMI 3 are formed. 相似文献
60.
Navneet K. Gupta Dr. Anastasia Pashigreva Dr. Evgeny A. Pidko Prof. Emiel J. M. Hensen Prof. Leslaw Mleczko Dr. Stefan Roggan Dr. Erika E. Ember Prof. Johannes A. Lercher 《Angewandte Chemie (International ed. in English)》2016,55(5):1728-1732
Active sites in carbon‐catalyzed phosgene synthesis from gaseous CO and Cl2 have been identified using C60 fullerene as a model catalyst. The carbon atoms distorted from sp2 coordination in non‐planar carbon units are concluded to generate active Cl2. Experiments and density functional theory calculations indicate the formation of a surface‐bound [C60???Cl2] chlorine species with radical character as key intermediate during phosgene formation. It reacts rapidly with physisorbed CO in a two‐step Eley–Rideal‐type mechanism. 相似文献