全文获取类型
收费全文 | 416篇 |
免费 | 20篇 |
专业分类
化学 | 362篇 |
力学 | 1篇 |
数学 | 27篇 |
物理学 | 46篇 |
出版年
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 23篇 |
2012年 | 22篇 |
2011年 | 44篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 19篇 |
2007年 | 17篇 |
2006年 | 30篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1994年 | 2篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 4篇 |
1959年 | 1篇 |
1958年 | 2篇 |
1955年 | 1篇 |
1933年 | 2篇 |
1927年 | 3篇 |
排序方式: 共有436条查询结果,搜索用时 31 毫秒
21.
Redox‐Induced Spin‐State Switching and Mixed Valency in Quinonoid‐Bridged Dicobalt Complexes
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
David Schweinfurth Yvonne Rechkemmer Stephan Hohloch Naina Deibel Irina Peremykin Jan Fiedler Raphael Marx Dr. Petr Neugebauer Prof. Dr. Joris van Slageren Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3475-3486
The complexes [{(tmpa)CoII}2(μ‐L1)2?]2+ ( 12+ ) and [{(tmpa)CoII}2(μ‐L2)2?]2+ ( 22+ ), with tmpa=tris(2‐pyridylmethyl)amine, H2L1=2,5‐di‐[2‐(methoxy)‐anilino]‐1,4‐benzoquinone, and H2L2=2,5‐di‐[2‐(trifluoromethyl)‐anilino]‐1,4‐benzoquinone, were synthesized and characterized. Structural analysis of 22+ revealed a distorted octahedral coordination around the cobalt centers, and cobalt–ligand bond lengths that match with high‐spin CoII centers. Superconducting quantum interference device (SQUID) magnetometric studies on 12+ and 22+ are consistent with the presence of two weakly exchange‐coupled high‐spin cobalt(II) ions, for which the nature of the coupling appears to depend on the substituents on the bridging ligand, being antiferromagnetic for 12+ and ferromagnetic for 22+ . Both complexes exhibit several one‐electron redox steps, and these were investigated with cyclic voltammetry and UV/Vis/near‐IR spectroelectrochemistry. For 12+ , it was possible to chemically isolate the pure forms of both the one‐electron oxidized mixed‐valent 13+ and the two‐electron oxidized isovalent 14+ forms, and characterize them structurally as well as magnetically. This series thus provided an opportunity to investigate the effect of reversible electron transfers on the total spin‐state of the molecule. In contrast to 22+ , for 14+ the metal–ligand distances and the distances within the quinonoid ligand point to the existence of two low‐spin CoIII centers, thus showing the innocence of the quintessential non‐innocent ligands L. Magnetic data corroborate these observations by showing the decrease of the magnetic moment by roughly half (neglecting spin exchange effects) on oxidizing the molecules with one electron, and the disappearance of a paramagnetic response upon two‐electron oxidation, which confirms the change in spin state associated with the electron‐transfer steps. 相似文献
22.
23.
Carlotta Borgarelli Yvonne E. Klingl Dr. Abril Escamilla-Ayala Prof. Dr. Sebastian Munck Prof. Dr. Ludo Van Den Bosch Prof. Dr. Wim M. De Borggraeve Dr. Ermal Ismalaj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(34):8605-8641
Despite the fact that transmembrane proteins represent the main therapeutic targets for decades, complete and in-depth knowledge about their biochemical and pharmacological profiling is not fully available. In this regard, target-tailored small-molecule fluorescent ligands are a viable approach to fill in the missing pieces of the puzzle. Such tools, coupled with the ability of high-precision optical techniques to image with an unprecedented resolution at a single-molecule level, helped unraveling many of the conundrums related to plasma proteins’ life-cycle and druggability. Herein, we review the recent progress made during the last two decades in fluorescent ligand design and potential applications in fluorescence microscopy of voltage-gated ion channels, ligand-gated ion channels and G-coupled protein receptors. 相似文献
24.
25.
This paper describes the approach to bubble related phenomena using a novel 'acoustoelectrochemical' technique designed to investigate the physical and chemical effects of the acoustically induced motion of the bubble wall. In particular it describes the behaviour of a suspended gas bubble irradiated with sound of an appropriate frequency and pressure to induce bubble wall oscillation. The first electrochemical measurement of the growth of a bubble through rectified diffusion is demonstrated. The technique employed relies on the sensitivity of a scanning electrochemical microscope (SECM) deployed close to the gas/liquid interface of a bubble. The growth rate of the bubble (<0.1 microms(-1)) is reported. It will be also demonstrated that gas exchange across the phase boundary at the bubble wall, can be successfully probed when the bubble is stationary. 相似文献
26.
Kapetanaki SM Ramsey M Gindt YM Schelvis JP 《Journal of the American Chemical Society》2004,126(20):6214-6215
Transient absorption spectroscopy is used to demonstrate that the electric dipole moment of the substrate cyclobutane thymine dimer affects the charge recombination reaction between fully reduced flavin adenine dinucleotide (FADH-) and the neutral radical tryptophan 306 (Trp306*) in Escherichia coli DNA photolyase. At pH 7.4, the charge recombination is slowed by a factor of 1.75 in the presence of substrate, but not at pH 5.4. Photolyase does bind substrate at pH 5.4, and it seems that this pH effect originates from the conversion of FADH- to FADH2 at lower pH. The free-energy changes calculated from the electric field parameters and from the change in electron transfer rate are in good agreement and support the idea that the substrate electric dipole is responsible for the observed change in electron transfer rate. It is expected that the substrate electric field will also modify the physiologically important from excited 1FADH- to the substrate in the DNA repair reaction. 相似文献
27.
Nadia Tagnaouti Sven Loebrich Frank Heisler Yvonne Pechmann Susanne Fehr Adèle De Arcangelis Elisabeth Georges-Labouesse Josephine C Adams Matthias Kneussel 《BMC neuroscience》2007,8(1):28
Background
The kelch repeat protein muskelin mediates cytoskeletal responses to the extracellular matrix protein thrombospondin 1, (TSP1), that is known to promote synaptogenesis in the central nervous system (CNS). Muskelin displays intracellular localization and affects cytoskeletal organization in adherent cells. Muskelin is expressed in adult brain and has been reported to bind the Cdk5 activator p39, which also facilitates the formation of functional synapses. Since little is known about muskelin in neuronal tissues, we here analysed the tissue distribution of muskelin in rodent brain and analysed its subcellular localization using cultured neurons from multiple life stages. 相似文献28.
A new multi‐variable‐measurement approach for characterizing and correlating the nanoscale and microscale morphology of crystal‐amorphous polymer blends with melt‐phase behavior is described. A vertical small‐angle light scattering (SALS) instrument optimized for examining the scattering and light transmitted from structures ranging from 0.5 to 50 μm, thereby spanning the size range characteristic of the initial‐to‐late stages of thermal‐phase transitions (e.g., melt‐phase separation and crystallization) in crystal‐amorphous polymer blends, was constructed. The SALS instrument was interfaced with differential scanning calorimetry (DSC), and simultaneous SALS/DSC/transmission measurements were performed. We show that the measurement of transmitted light and SALS under HV (cross‐polarized) optical alignments during melting can be used to reliably measure the thermodynamic (e.g., crystal melting and melt‐phase separation temperatures) and structural variables (e.g., crystalline fraction within the superstructures and volume fraction of superstructures) necessary for describing the multiphase behavior of crystal‐amorphous blends in one combined measurement. We also evaluate the orientation correlations of crystalline volume elements within the superstructures. Our results indicate that simultaneous measurement of transmitted light can provide a reliable estimate of the total scattering from density and orientation fluctuations and the melt‐phase separation temperature of polymer blends. For solution‐cast poly(?‐caprolactone)/poly(D,L‐lactic acid) blends, our multivariable measurements during melting provide the parameters necessary to generate a crystal–liquid and liquid–liquid phase diagram and characterize the solid‐state morphology. This opens up the challenge to explore use of our vertical SALS instrument as a rapid and convenient method for developing structure–property relationships for crystal‐amorphous polymer blends. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2714–2727, 2002 相似文献
29.
Martin Sahlberg Premysl Beran Thomas Kollin Nielsen Yngve Cerenius Krisztina Kads Marko P.J. Punkkinen Levente Vitos Olle Eriksson Torben R. Jensen Yvonne Andersson 《Journal of solid state chemistry》2009,182(11):3113-3117
A novel aluminium rich alloy for hydrogen storage has been discovered, ScAl0.8Mg0.2, which has very promising properties regarding hydrogen storage capacity, kinetics and stability towards air oxidation in comparison to hydrogen absorption in state-of-the-art intermetallic compounds. The absorption of hydrogen was found to be very fast, even without adding any catalyst, and reversible. The discovered alloy crystallizes in a CsCl-type structure, but decomposes to ScH2 and Al(Mg) during hydrogen absorption. Detailed analysis of the hydrogen absorption in ScAl0.8Mg0.2 has been performed using in situ synchrotron radiation powder X-ray diffraction, neutron powder diffraction and quantum mechanical calculations. The results from theory and experiments are in good agreement with each other. 相似文献