全文获取类型
收费全文 | 841篇 |
免费 | 41篇 |
国内免费 | 3篇 |
专业分类
化学 | 627篇 |
晶体学 | 3篇 |
力学 | 16篇 |
数学 | 106篇 |
物理学 | 133篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 6篇 |
2016年 | 34篇 |
2015年 | 25篇 |
2014年 | 33篇 |
2013年 | 38篇 |
2012年 | 50篇 |
2011年 | 72篇 |
2010年 | 38篇 |
2009年 | 36篇 |
2008年 | 62篇 |
2007年 | 51篇 |
2006年 | 59篇 |
2005年 | 50篇 |
2004年 | 42篇 |
2003年 | 22篇 |
2002年 | 30篇 |
2001年 | 18篇 |
2000年 | 14篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1970年 | 4篇 |
1963年 | 2篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有885条查询结果,搜索用时 15 毫秒
1.
Yersak Thomas A. Hao Fang Kang Chansoon Salvador James R. Zhang Qinglin Malabet Hernando Jesus Gonzalez Cai Mei 《Journal of Solid State Electrochemistry》2022,26(3):709-718
Journal of Solid State Electrochemistry - In this study, hot pressing was evaluated as a method of cell fabrication to increase the energy density of next-generation all-solid-state batteries with... 相似文献
2.
Electrically Switchable Magnetic Molecules: Inducing a Magnetic Coupling by Means of an External Electric Field in a Mixed‐Valence Polyoxovanadate Cluster 下载免费PDF全文
Dr. Salvador Cardona‐Serra Dr. Juan M. Clemente‐Juan Prof. Eugenio Coronado Dr. Alejandro Gaita‐Ariño Dr. Nicolas Suaud Dr. Ondrej Svoboda Dr. Roland Bastardis Prof. Nathalie Guihéry Dr. Juan J. Palacios 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):763-769
Herein we evaluate the influence of an electric field on the coupling of two delocalized electrons in the mixed‐valence polyoxometalate (POM) [GeV14O40]8? (in short V14) by using both a t‐J model Hamiltonian and DFT calculations. In absence of an electric field the compound is paramagnetic, because the two electrons are localized on different parts of the POM. When an electric field is applied, an abrupt change of the magnetic coupling between the two delocalized electrons can be induced. Indeed, the field forces the two electrons to localize on nearest‐neighbors metal centers, leading to a very strong antiferromagnetic coupling. Both theoretical approaches have led to similar results, emphasizing that the sharp spin transition induced by the electric field in the V14 system is a robust phenomenon, intramolecular in nature, and barely influenced by small changes on the external structure. 相似文献
3.
4.
Dr. Jan H. Blank Dr. Salvador Moncho Allen M. Lunsford Prof. Edward N. Brothers Prof. Marcetta Y. Darensbourg Prof. Ashfaq A. Bengali 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12752-12760
The mechanism and energetics of CO, 1‐hexene, and 1‐hexyne substitution from the complexes (SBenz)2[Fe2(CO)6] (SBenz=SCH2Ph) ( 1 ‐CO), (SBenz)2[Fe2(CO)5(η2‐1‐hexene)] ( 1 ‐(η2‐1‐hexene)), and (SBenz)2[Fe2(CO)5(η2‐1‐hexyne)] ( 1 ‐(η2‐1‐hexyne)) were studied by using time‐resolved infrared spectroscopy. Exchange of both CO and 1‐hexyne by P(OEt)3 and pyridine, respectively, proceeds by a bimolecular mechanism. As similar activation enthalpies are obtained for both reactions, the rate‐determining step in both cases is assumed to be the rotation of the Fe(CO)2L (L=CO or 1‐hexyne) unit to accommodate the incoming ligand. The kinetic profile for the displacement of 1‐hexene is quite different than that for the alkyne and, in this case, both reaction channels, that is, dissociative (SN1) and associative (SN2), were found to be competitive. Because DFT calculations predict similar binding enthalpies of alkene and alkyne to the iron center, the results indicate that the bimolecular pathway in the case of the alkyne is lower in free energy than that of the alkene. In complexes of this type, subtle changes in the departing ligand characteristics and the nature of the mercapto bridge can influence the exchange mechanism, such that more than one reaction pathway is available for ligand substitution. The difference between this and the analogous study of (μ‐pdt)[Fe(CO)3]2 (pdt=S(CH2)3S) underscores the unique characteristics of a three‐atom S?S linker in the active site of diiron hydrogenases. 相似文献
5.
Simulating periodic trends in the structure and catalytic activity of coinage metal nanoribbons 下载免费PDF全文
John J. Determan Salvador Moncho Edward N. Brothers Benjamin G. Janesko 《International journal of quantum chemistry》2015,115(24):1718-1725
We present a systematic density functional theory (DFT) study of the structure and catalytic activity of group 10 (Ni, Pd, Pt) and group 11 (Cu, Ag, Au) coinage metal nanoribbons. These infinite, periodic, quasi‐one‐dimensional structures are conceptually important as intermediates between small metal clusters and close‐packed metal surfaces, and have been shown experimentally to be practical catalysts. We find that nanoribbons have significantly higher predicted H2 dissociation activity than close‐packed metal surfaces consistent with their lower coordination numbers. Computed periodic trends are reasonable, with late transition states and low barriers for H2 dissociation over late group 10 nanoribbons, suggesting their promise as practical catalysts. These trends are consistent with the isolated nanoribbons' computed molecular electrostatic potentials. Calculations also predict nearly linear Brønsted–Evans–Polanyi relationships between the nanoribbons' H2 dissociation energies and dissociation barriers. We also test new meta‐generalized gradient approximation (GGA) and hybrid DFT approximations for H2 dissociation over these nanoribbons. These new functionals increase the (generally underestimated) dissociation barriers predicted by standard GGAs, motivating their continued application in surface chemistry. © 2015 Wiley Periodicals, Inc. 相似文献
6.
Simultaneous Titration of Ternary Mixtures of Pb(II), Cd(II) and Cu(II) with Potentiometric Electronic Tongue Detection 下载免费PDF全文
An automatic titration method is reported to resolve ternary mixtures of transition metals (Pb2+, Cd2+ and Cu2+) employing electronic tongue detection and a reduced number of pre‐defined additions of EDTA titrant. Sensors used were PVC membrane selective electrodes with generic response to heavy‐metals, plus an artificial neural network response model. Detection limits obtained were ca. 1 mg L?1 for the three target ions and reproducibilities 3.0 % for Pb2+, 4.1 % for Cd2+ and 5.2 % for Cu2+. The system was applied to contaminated soil samples and high accuracy was obtained for the determination of Pb2+. In the determination Cd2+ and Cu2+, sample matrix showed a significant effect. 相似文献
7.
Textile/Metal–Organic‐Framework Composites as Self‐Detoxifying Filters for Chemical‐Warfare Agents 下载免费PDF全文
Elena López‐Maya Dr. Carmen Montoro Dr. L. Marleny Rodríguez‐Albelo Dr. Salvador D. Aznar Cervantes Dr. A. Abel Lozano‐Pérez Prof. José Luis Cenís Dr. Elisa Barea Prof. Jorge A. R. Navarro 《Angewandte Chemie (International ed. in English)》2015,54(23):6790-6794
The current technology of air‐filtration materials for protection against highly toxic chemicals, that is, chemical‐warfare agents, is mainly based on the broad and effective adsorptive properties of hydrophobic activated carbons. However, adsorption does not prevent these materials from behaving as secondary emitters once they are contaminated. Thus, the development of efficient self‐cleaning filters is of high interest. Herein, we report how we can take advantage of the improved phosphotriesterase catalytic activity of lithium alkoxide doped zirconium(IV) metal–organic framework (MOF) materials to develop advanced self‐detoxifying adsorbents of chemical‐warfare agents containing hydrolysable P? F, P? O, and C? Cl bonds. Moreover, we also show that it is possible to integrate these materials onto textiles, thereby combining air‐permeation properties of the textiles with the self‐detoxifying properties of the MOF material. 相似文献
8.
Inside Cover: Textile/Metal–Organic‐Framework Composites as Self‐Detoxifying Filters for Chemical‐Warfare Agents (Angew. Chem. Int. Ed. 23/2015) 下载免费PDF全文
9.
10.
Exploring the Effect of Ligand Structural Isomerism in Langmuir–Blodgett Films of Chiral Luminescent EuIII Self‐Assemblies 下载免费PDF全文
Agostino Galanti Dr. Oxana Kotova Dr. Salvador Blasco Chloe J. Johnson Dr. Robert D. Peacock Shaun Mills Prof. John J. Boland Prof. Martin Albrecht Prof. Thorfinnur Gunnlaugsson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9709-9723
Here we have investigated the influence of the antenna group position on both the formation of chiral amphiphilic EuIII‐based self‐assemblies in CH3CN solution and, on the ability to form monolayers on the surface of quartz substrates using the Langmuir–Blodgett technique, by changing from the 1‐naphthyl ( 2(R) , 2(S) ) to the 2‐naphthyl ( 1(R) , 1(S) ) position. The evaluation of binding constants of the self‐ assemblies in CH3CN solution was achieved using conventional techniques such as UV/Visible and luminescence spectroscopies along with more specific circular dichroism (CD) spectroscopy. The binding constants obtained for EuL , EuL2 and EuL3 species in the case of 2‐naphthyl derivatives were comparable to those obtained for 1‐naphthyl derivatives. The analysis of the changes in the CD spectra of 1(R) and 1(S) upon addition of EuIII not only allowed us to evaluate the values of the binding constants but the resulting recalculated spectra may also be used as fingerprints for assignment of the chiral self‐assembly species formed in solution. The obtained monolayers were predominantly formed from EuL3 (≈85 %) with the minor species present in ≈15 % EuL2 . 相似文献