全文获取类型
收费全文 | 2302篇 |
免费 | 413篇 |
国内免费 | 346篇 |
专业分类
化学 | 1779篇 |
晶体学 | 24篇 |
力学 | 12篇 |
综合类 | 7篇 |
数学 | 38篇 |
物理学 | 1201篇 |
出版年
2024年 | 6篇 |
2023年 | 33篇 |
2022年 | 30篇 |
2021年 | 47篇 |
2020年 | 106篇 |
2019年 | 83篇 |
2018年 | 59篇 |
2017年 | 61篇 |
2016年 | 94篇 |
2015年 | 88篇 |
2014年 | 92篇 |
2013年 | 178篇 |
2012年 | 139篇 |
2011年 | 127篇 |
2010年 | 98篇 |
2009年 | 144篇 |
2008年 | 143篇 |
2007年 | 214篇 |
2006年 | 130篇 |
2005年 | 79篇 |
2004年 | 94篇 |
2003年 | 147篇 |
2002年 | 112篇 |
2001年 | 157篇 |
2000年 | 101篇 |
1999年 | 73篇 |
1998年 | 71篇 |
1997年 | 71篇 |
1996年 | 50篇 |
1995年 | 49篇 |
1994年 | 41篇 |
1993年 | 28篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有3061条查询结果,搜索用时 31 毫秒
1.
2.
Li Li Liu Shi Xiaohu Yu Shaojun Qing Zhixian Gao Qiquan Luo Gang Feng Rongbin Zhang 《中国化学快报》2019,30(6):1147-1152
The adsorption energies for single Ni atom on CuAl2O4(100) and (110) surfaces are 5.30 and 4.08 eV, respectively. The growth and aggregation of Ni can be effectively inhibited on the perfect CuAl2O4(100) surface. The adsorption of Ni on the spinel surface is accompanied by charge transfer. The interaction of Ni with CuAl2O4 surface is stronger than with the γ-Al2O3(110) surface. 相似文献
3.
G. L. Gutsev K. V. Bozhenko L. G. Gutsev A. N. Utenyshev S. M. Aldoshin 《Journal of computational chemistry》2019,40(3):562-571
The geometrical structures and properties of the M8O12, M8O12H8, and M8O12H12 clusters are explored using density functional theory with the generalized gradient approximation for all 3d-metals M from Sc to Zn. It is found that the geometries and total spin magnetic moments of the clusters depended strongly on the 3d-atom type and the hydrogenation extent. More than the half of all of the 30 clusters had singlet lowest total energy states, which could be described as either nonmagnetic or antiferromagnetic. Hydrogenation increases the total spin magnetic moments of the M8O12H12 clusters when MMn Ni, which become larger by four Bohr magneton than those of the corresponding unary clusters M8. Hydrogenation substantially affects such properties as polarizability, forbidden band gaps, and dipole moments. Collective superexchange where the local total spin magnetic moments of two atom squads are coupled antiparallel was observed in antiferromagnetic singlet states of Fe8O12H8 and Co8O12H8, whereas the lowest total energy states of their neighbors Mn8O12H8 and Ni8O12H8 are ferrimagnetic and ferromagnetic, respectively. Hydrogenation leads to a decrease in the average binding energy per atom when moving across the 3d-metal atom series. © 2018 Wiley Periodicals, Inc. 相似文献
4.
Caixia Dong Limin Han Jucai Yang Lin Cheng 《International journal of quantum chemistry》2019,119(18):e25978
The systematic structures search for neutral and Zintl anionic Ti-doped silicon clusters TiSin0/−/2− (n = 6-16) have been carried out using the ABCluster global search technique combined with a double-hybrid density functional method. Based on the predicted energies, adiabatic electron affinities, vertical detachment energies and the consistency between simulated and experimental photoelectron spectroscopy, the true global minimum structures are confirmed. The results show that structural growth pattern of neutral TiSin clusters is from linked structures (n = 10-12) to encapsulated configurations (n = 13-16). In contrast, the evolution pattern of Zintl anionic TiSin−/2− clusters begins with the pentagonal bipyramid structure (n = 6). As the Si atoms increase, these Si atoms attach to the surface adjacent to Ti atom, and gradually surround Ti atom. Eventually, the encapsulated structure is formed when n = 12. Moreover, two extra electrons not only perfect the structure of TiSi12 but also improve its chemical and thermodynamic stability. 相似文献
5.
Configurations, stabilities and adsorption mechanisms of ground-state MonN and MonN2 (n?=?1–8) clusters are calculated by using the density functional method within the PBE level. Evidently, N atoms tend to approach more Mo atoms. Doping with two N impurity prefers to occupy symmetrical position of the host Mon (n?=?1–8) cluster except for Mo2N2 clusters. Mo4N, Mo6N, Mo2N2, Mo4N2 and Mo6N2 clusters have higher structural stabilities than their neighbors by the second derivative of total binding energy. Mo2N, Mo4N and Mo7N, Mo2N2, Mo5N2 and Mo7N2 clusters have higher kinetic reactivity than their neighbors by the HOMO–LUMO gaps. The adsorption capacity of a N atom to Mo4 cluster is stronger than the other Mo–N clusters. 相似文献
6.
7.
Andreas Herburger Dr. Milan Ončák Dr. Chi-Kit Siu Ephrem G. Demissie Jakob Heller Dr. Wai Kit Tang Prof. Dr. Martin K. Beyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(43):10165-10171
Understanding the intrinsic properties of the hydrated carbon dioxide radical anions CO2.−(H2O)n is relevant for electrochemical carbon dioxide functionalization. CO2.−(H2O)n (n=2–61) is investigated by using infrared action spectroscopy in the 1150–2220 cm−1 region in an ICR (ion cyclotron resonance) cell cooled to T=80 K. The spectra show an absorption band around 1280 cm−1, which is assigned to the symmetric C−O stretching vibration νs. It blueshifts with increasing cluster size, reaching the bulk value, within the experimental linewidth, for n=20. The antisymmetric C−O vibration νas is strongly coupled with the water bending mode ν2, causing a broad feature at approximately 1650 cm−1. For larger clusters, an additional broad and weak band appears above 1900 cm−1 similar to bulk water, which is assigned to a combination band of water bending and libration modes. Quantum chemical calculations provide insight into the interaction of CO2.− with the hydrogen-bonding network. 相似文献
8.
9.
Inside Back Cover: Stepwise Assembly of MII7 Clusters Revealed by Mass Spectrometry,EXAFS, and Crystallography (Chem. Eur. J. 51/2016) 下载免费PDF全文
10.
Niklas Rinn Dr. Jens P. Eußner Willy Kaschuba Dr. Xiulan Xie Prof. Dr. Stefanie Dehnen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):3094-3104
Reactions of R1SnCl3 (R1=CMe2CH2C(O)Me) with (SiMe3)2Se yield a series of organo‐functionalized tin selenide clusters, [(SnR1)2SeCl4] ( 1 ), [(SnR1)2Se2Cl2] ( 2 ), [(SnR1)3Se4Cl] ( 3 ), and [(SnR1)4Se6] ( 4 ), depending on the solvent and ratio of the reactants used. NMR experiments clearly suggest a stepwise formation of 1 through 4 by subsequent condensation steps with the concomitant release of Me3SiCl. Furthermore, addition of hydrazines to the keto‐functionalized clusters leads to the formation of hydrazone derivatives, [(Sn2(μ‐R3)(μ‐Se)Cl4] ( 5 , R3=[CMe2CH2CMe(NH)]2), [(SnR2)3Se4Cl] ( 6 , R2=CMe2CH2C(NNH2)Me), [(SnR4)3Se4][SnCl3] ( 7 , R4=CMe2CH2C(NNHPh)Me), [(SnR2)4Se6] ( 8 ), and [(SnR4)4Se6] ( 9 ). Upon treatment of 4 with [Cu(PPh3)3Cl] and excess (SiMe3)2Se, the cluster fragments to form [(R1Sn)2Se2(CuPPh3)2Se2] ( 10 ), the first discrete Sn/Se/Cu cluster compound reported in the literature. The derivatization reactions indicate fundamental differences between organotin sulfide and organotin selenide chemistry. 相似文献