全文获取类型
收费全文 | 9811篇 |
免费 | 992篇 |
国内免费 | 592篇 |
专业分类
化学 | 6593篇 |
晶体学 | 145篇 |
力学 | 849篇 |
综合类 | 28篇 |
数学 | 652篇 |
物理学 | 3128篇 |
出版年
2024年 | 18篇 |
2023年 | 68篇 |
2022年 | 217篇 |
2021年 | 219篇 |
2020年 | 384篇 |
2019年 | 258篇 |
2018年 | 215篇 |
2017年 | 280篇 |
2016年 | 412篇 |
2015年 | 380篇 |
2014年 | 401篇 |
2013年 | 687篇 |
2012年 | 646篇 |
2011年 | 593篇 |
2010年 | 499篇 |
2009年 | 681篇 |
2008年 | 687篇 |
2007年 | 707篇 |
2006年 | 594篇 |
2005年 | 476篇 |
2004年 | 476篇 |
2003年 | 403篇 |
2002年 | 337篇 |
2001年 | 255篇 |
2000年 | 221篇 |
1999年 | 244篇 |
1998年 | 211篇 |
1997年 | 135篇 |
1996年 | 104篇 |
1995年 | 116篇 |
1994年 | 66篇 |
1993年 | 66篇 |
1992年 | 57篇 |
1991年 | 47篇 |
1990年 | 31篇 |
1989年 | 31篇 |
1988年 | 23篇 |
1987年 | 20篇 |
1986年 | 24篇 |
1985年 | 14篇 |
1984年 | 26篇 |
1983年 | 4篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
Joseph D. Martin 《Annalen der Physik》2019,531(10)
Mildred Dresselhaus is known for her influential research on the physics of carbon. Her wide‐ranging influence as a physics teacher, although well‐known to her students, has been less thoroughly examined. Exploring how Dresselhaus grew into her role teaching solid state physics at MIT reveals much about how that subfield evolved. 相似文献
143.
Jing Zhao Prof. Jingjun Liu Chun Jin Nan Wang Prof. Feng Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(55):12606-12614
The construction of nano-scale hybrid materials with a smart interfacial structure, established by using rare earth oxides and carbon as building blocks, is essential for the development of economical and efficient catalysts for oxygen reduction reactions (ORRs). In this work, hexagonal La2O3 nanocrystals on a nitrogen-doped porous carbon (NPC) derived from crop radish, served as building bricks, are prepared by chemical precipitation and then calcination at elevated temperatures. The obtained La2O3/NPC hybrid exhibits a very high ORR activity with a half-wave potential of 0.90 V, exceeding that of commercial Pt/C (0.83 V). Both DFT theoretical and experimental results have verified that the significantly enhanced catalytic performance is ascribed to the formation of the C−O−La covalent bonds between carbon and La2O3. Through the covalent bonds, electrons can transfer from the carbon to La2O3 and occupy the unfilled eg orbital of the La2O3 phase. This results in the accelerated adsorption of active oxygen and the facilitated desorption of the surface hydroxides (OHad−), thereby promoting the ORR over the catalyst. 相似文献
144.
Beryllates show an interesting and diverse structural chemistry, resembling that of well-investigated silicates. The coexistence of tetrahedral and trigonal coordination of Be by O atoms in oxoberyllates allows for an even broader variety of structural motives and implies a plurality of possible atomic ratios Be:O in ternary or higher compounds. We have now synthesized the novel strontium oxoberyllate Sr3Be2O5 via a high-temperature high-pressure reaction and have structurally characterized the ternary oxide by single-crystal and powder X-ray diffraction analysis. Sr3Be2O5, a low condensed oxoberyllate, contains unprecedented [Be2O5]6– double triangles and Sr atoms in both double-capped trigonal-prismatic and octahedral coordination. These motifs show striking resemblance to α-SrBeO2 and SrO, combining their structural properties. Lattice energy (MAPLE) calculations corroborate found parallels to the known phases SrO and α-SrBeO2. 相似文献
145.
Dr. Wan-Shan Li Dr. Ren-Jie Yan Yi Yu Prof. Zhi Shi Dr. Attila Mándi Dr. Li Shen Prof. Tibor Kurtán Prof. Jun Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):13128-13136
Marine dinoflagellates produce remarkable organic molecules, particularly those with polyoxygenated long-carbon-chain backbones, namely super-carbon-chain compounds (SCCCs), characterized by the presence of numerous stereogenic carbon centers on acyclic polyol carbon chains. Even today, it is a challenge to determine the absolute configurations of these compounds. In this work, the planar structures and absolute configurations of two highly flexible SCCCs, featuring either a C69- or C71-linear carbon backbone, gibbosols A and B, respectively, each containing thirty-seven stereogenic carbon centers, were unambiguously established by a combined chemical, spectroscopic, and computational approach. The discovery of gibbosols A and B with two hydrophilic acyclic polyol chains represents an unprecedented class of SCCCs. A reasonable convergent strategy for the biosynthesis of these SCCCs was proposed. 相似文献
146.
Sebastian Spicher Prof. Stefan Grimme 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15795-15803
Modern chemistry seems to be unlimited in molecular size and elemental composition. Metal-organic frameworks or biological macromolecules involve complex architectures and a large variety of elements. Yet, a general and broadly applicable theoretical method to describe the structures and interactions of molecules beyond the 1000-atom size regime semi-quantitatively is not self-evident. For this purpose, a generic force field named GFN-FF is presented, which is completely newly developed to enable fast structure optimizations and molecular-dynamics simulations for basically any chemical structure consisting of elements up to radon. The freely available computer program requires only starting coordinates and elemental composition as input from which, fully automatically, all potential-energy terms are constructed. GFN-FF outperforms other force fields in terms of generality and accuracy, approaching the performance of much more elaborate quantum-mechanical methods in many cases. 相似文献
147.
Dr. Francesc Viñes Prof. Dr. Andreas Görling 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11478-11491
Cu@Pt nanoparticles (NPs) are experimentally regarded as improved catalysts for NOx storage/reduction, with higher activities and selectivities compared with pure Pt or Cu NPs, and with inverse Pt@Cu NPs. Here, a density functional theory-based study on such NP models with different sizes and shapes reveals that the observed enhanced stability of Cu@Pt compared with Pt@Cu NPs is due to energetic reasons. On both types of core@shell NPs, charge is transferred from Cu to Pt, strengthening the NP cohesion energy in Pt@Cu NPs, and spreading charge along the surface in Cu@Pt NPs. The negative surface Pt atoms in the latter diminish the NO bonding owing to an energetic rise of the Pt bands, as detected by the appliance of the d-band model, although other factors, such as atomic low coordination or the presence of an immediate subsurface Pt atom do as well. A charge density difference analysis discloses a donation/back-donation mechanism in the NO adsorption. 相似文献
148.
149.
Guanjia Zhu Prof. Wan Jiang Prof. Jianping Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1488-1496
The successful commercialization of promising silicon-based anode materials has been hampered by their poor cycling stability caused by the huge volume change. Integration of the carbon matrix with silicon-based (C/Si-based) anode materials has been demonstrated to be a powerful solution to achieve satisfactory electrochemical performance. This minireview aims to outline recent developments on C/Si-based composites, with the emphasis on the importance of carbon distribution at multiple scales. In addition, the forms of the carbon framework (carbon sources and doping of heteroatoms) have been summarized. Particularly, a novel C/Si-based hybrid with carbon distributed at the atomic scale has been highlighted. 相似文献
150.
Dr. Yong-Zhi Li Gang-Ding Wang Hong-Yun Yang Prof. Lei Hou Prof. Yao-Yu Wang Prof. Zhonghua Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(69):16402-16407
To develop efficient adsorbent materials for storage and separation of C2H2, an unprecedented supercage MOF, [Me2NH2]⋅[Zn3(ALP)(TDC)2.5]⋅3.5DMF⋅2 H2O ( 1 ) was constructed through medicinal molecule allopurinol (ALP) and S-containing 2,5-thiophenedicarboxylic acid (H2TDC). 1 contains a novel linear trinuclear cluster that is composed by ALP and carboxylates and forms a final uncommon 5-connected yfy topological framework. The framework possesses three types of interlinked cages decorated by rich functional sites, and reveals not only high adsorption capacity for C2H2 but also excellent selective separation for C2H2/CO2 and C2H2/CH4 at 298 K. Dynamic breakthrough experiments on C2H2/CO2 (1:1) mixture and C2H2/CH4 (1:1) mixture also demonstrated the potential of the material to separate C2H2 from CO2 or CH4 mixtures. Molecular simulations were also studied to identify the different CO2- and C2H2- binding sites in 1 , such as carboxylate groups, S atoms and carbonyl groups. 相似文献