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41.
Confined Ultrathin Pd‐Ce Nanowires with Outstanding Moisture and SO2 Tolerance in Methane Combustion 下载免费PDF全文
Dr. Honggen Peng Cheng Rao Prof. Ning Zhang Xiang Wang Wenming Liu Wenting Mao Lu Han Prof. Pengfei Zhang Prof. Sheng Dai 《Angewandte Chemie (International ed. in English)》2018,57(29):8953-8957
An efficient strategy (enhanced metal oxide interaction and core–shell confinement to inhibit the sintering of noble metal) is presented confined ultrathin Pd‐CeOx nanowire (2.4 nm) catalysts for methane combustion, which enable CH4 total oxidation at a low temperature of 350 °C, much lower than that of a commercial Pd/Al2O3 catalyst (425 °C). Importantly, unexpected stability was observed even under harsh conditions (800 °C, water vapor, and SO2), owing to the confinement and shielding effect of the porous silica shell together with the promotion of CeO2. Pd‐CeOx solid solution nanowires (Pd‐Ce NW) as cores and porous silica as shells (Pd‐CeNW@SiO2) were rationally prepared by a facile and direct self‐assembly strategy for the first time. This strategy is expected to inspire more active and stable catalysts for use under severe conditions (vehicle emissions control, reforming, and water–gas shift reaction). 相似文献
42.
利用电场作用通过交流和直流等离子体在低温、常压和低功率下催化反应将甲烷直接转化为碳二烃(乙烷、乙烯、乙炔)。考察了在对称电场作用下催化剂的催化性能。实验结果表明,在交流电场作用下,碳二烃选择性差别不大;甲烷转化率的大小顺序为: MnO_2/Al2O3>Ni/Al2O3>MoO_3/Al2O3>Al2O3>Ni/Al2O3>MoO_3/Al2O3>Ni/NaY>Pd/ZSM-5>Ni/H4Mg2Si3O4>Ni/ZSM-5>Co/ZSM-5>无催化剂:在直流电场作用下,碳二烃选择性差别也不大(除Ni/NaY外),甲烷转化率的大小顺序为: Ni/A12O3>Ni/H4Mg2Si3O4>Ni/ZSM-5>Co/ZSM-5>MnO2/A12O3>MoO3/A12O3>Ni/NaY>无催化剂>Pd/ZSM-5。 相似文献
43.
镍基催化剂上积碳是甲烷干气重整反应急需解决的关键问题。实验采用TPSR、TPD、XPS和脉冲反应等方法系统研究了镍基催化剂表面积碳的形态和特点。热力学研究表明,在573 K到1273 K的温度范围内,催化剂的表面积碳是不可避免的。TPSR、XPS和TPD研究表明,甲烷在催化剂表面裂解将形成至少三种碳物种:Cα、Cβ和Cγ。这三种碳物种具有不同的表面迁移能力、热稳定性和反应活性。其中,Cα物种在甲烷干气重整反应中是一种非常活泼和重要的中间体;Cγ物种则可能是表面积碳的前驱物:部分脱氢的Cβ物种能够与H2或CO2反应生成CH4或CO。 相似文献
44.
Florian Blasberg 《Journal of organometallic chemistry》2011,696(23):3593-3600
The synthesis, structural characterization, and coordination behavior of ditopic ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands (ortho-(OH)2C6H3-4-CHpz2, ortho-(OH)2C6H3-4-CH(3-Phpz)2, and ortho-(OH)2C6H3-4-CH(3-tBupz)2) with pyrazole, 3-phenylpyrazole, and 3-tert-butylpyrazole as donors are described. The reaction of a soluble PdCl2-source with ortho-(OH)2C6H3-4-CHpz2 in acetonitrile yielded the related square-planar N,N-coordinated Pd(II) dichloride complex, whereas treatment of ortho-(OH)2C6H3-4-CH(3-Phpz)2 or ortho-(OH)2C6H3-4-CH(3-tBupz)2 with PdCl2 in acetonitrile resulted in degradation of these ligands. The Pd(II) complexes trans-(3-PhpzH)2PdCl2 and trans-(3-tBupzH)2PdCl2 were isolated and fully characterized including X-ray diffraction analyses. 相似文献
45.
本文探讨了CO,CH_4和NH_3在LaNiO_3,La_2NiO_4和LaSrNiO_4三个催化剂上的氧化行为,并得出结论:对于CO氧化,关键步骤在于CO在催化剂表面上的络合活化。Ni ̄(3+)含量越高,越利于CO的络合活化。对于氨氧化,催化反应遵循氧化-还原机理。Ni ̄(3+)是主要的活性离子,晶格氧是主要活性氧种。对于CH_4氧化,催化机理较复杂,只是发现A_2BO_4型氧化物(La_2NiO_4,LaSrNiO_4)比ABO_3型氧化物(LaNiO_3)较利于CH_4的氧化。 相似文献
46.
Dr. Moritz Balkenhohl Prof. Dr. Paul Knochel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3688-3697
For the preparation of zinc organometallics bearing highly sensitive functional groups such as ketones, aldehydes or nitro groups, especially mild halogen–zinc exchange reagents have proven to be of great potential. In this Minireview, the latest research in the area of the halogen–zinc exchange reaction is reported, with a special focus lying on novel dialkylzinc reagents complexed with lithium alkoxides. Additionally, the preparation and application of organofluorine zinc reagents and transition-metal-catalyzed halogen–zinc exchange reactions are reviewed. 相似文献
47.
48.
求取二氧化碳在饱和液态甲烷中的溶解度,对于在较高温度下实现液化天然气至关重要。文中在理想溶液基础上,采用正规溶液关系式和改进的Scatchard-H ildebrand关系式进行二氧化碳的溶解度计算,并且在临界点附近采用经验公式对其进行修正。将上述计算结果与Davis实验数据进行比较后表明,改进的正规溶液理论计算方法在低于140K温区时可推荐用于此项溶解度计算,经验公式可用于接近临界温度区域的溶解度计算。 相似文献
49.
Gengliang ChenResearch Institute of Natural Gas Technology Southwest Oil Gas Field Company Petro- China 《天然气化学杂志》2002,(Z2)
One of the main goals for developing the C1 chemical industry is the direct conversion of methane and carbon dioxide to useful products. To realize this goal, researches on new catalytic systems are being globally focused. The exploration has been evolved from traditional heterogeneous catalysis into homogeneous catalysis. Coordinate complexes, biochemical and bionics, and photo- and electrochemical catalysis have been extensively studied in recent years. Tests in laboratories have verified for the direct conversion of CH4 to CH3OH that single-pass converstion of CH4 can reach over 70% in both Hg(II) salt and Pt(II) complex systems. The main problem of these systems is the obstacles involving reaction kinetics, so they must be solved before moving to pilot tests. Other catalytic systems discussed in the present article include explorations in the early stage. Among them, features of photo and enzymatic catalyst systems, such as mild reaction conditions, better selectivity and environmentally friendliness 相似文献
50.
A metal-support interaction between Pd and various kinds of zeolite and metal oxide supports was studied, which were active in the catalytic combustion and selective reduction of NO. The acid-base properties of supports affected the oxidation state, structure and catalytic activity of Pd. The acid sites of zeolite played the role to anchor the dispersed PdO as evidenced by the dynamic structural change of Pd. It was found that the metal-support interaction is an important factor, affecting the oxidation state, structure and catalytic performance of Pd. 相似文献