全文获取类型
收费全文 | 244篇 |
免费 | 9篇 |
专业分类
化学 | 193篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 22篇 |
物理学 | 34篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 9篇 |
2013年 | 8篇 |
2012年 | 13篇 |
2011年 | 16篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 8篇 |
2007年 | 18篇 |
2006年 | 23篇 |
2005年 | 12篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有253条查询结果,搜索用时 15 毫秒
81.
Ralph Z. Lange Kevin Synnatschke Haoyuan Qi Niklas Huber Gregor Hofer Baokun Liang Christian Huck Annemarie Pucci Ute Kaiser Claudia Backes A. Dieter Schlüter 《Angewandte Chemie (International ed. in English)》2020,59(14):5683-5695
2D polymer sheets with six positively charged pyrylium groups at each pore edge in a stacked single crystal can be transformed into a 2D polymer with six pyridines per pore by exposure to gaseous ammonia. This reaction furnishes still a crystalline material with tunable protonation degree at regular nano‐sized pores promising as separation membrane. The exfoliation is compared for both 2D polymers with the latter being superior. Its liquid phase exfoliation yields nanosheet dispersions, which can be size‐selected using centrifugation cascades. Monolayer contents of ≈30 % are achieved with ≈130 nm sized sheets in mg quantities, corresponding to tens of trillions of monolayers. Quantification of nanosheet sizes, layer number and mass shows that this exfoliation is comparable to graphite. Thus, we expect that recent advances in exfoliation of graphite or inorganic crystals (e.g. scale‐up, printing etc.) can be directly applied to this 2D polymer as well as to covalent organic frameworks. 相似文献
82.
Dilshad Hussain Muhammad Najam-ul-Haq Fahmida Jabeen Muhammad N. Ashiq Muhammad Athar Matthias Rainer Christian W. Huck Guenther K. Bonn 《Analytica chimica acta》2013
Diamond is known for its high affinity and biocompatibility towards biomolecules and is used exclusively in separation sciences and life science research. In present study, diamond nanopowder is derivatized as Immobilized Metal Ion Affinity Chromatographic (IMAC) material for the phosphopeptides enrichment and as Reversed Phase (C-18) media for the desalting of complex mixtures and human serum profiling through MALDI-TOF-MS. Functionalized diamond nanopowder is characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Diamond-IMAC is applied to the standard protein (β-casein), spiked human serum, egg yolk and non-fat milk for the phosphopeptides enrichment. Results show the selectivity of synthesized IMAC-diamond immobilized with Fe3+ and La3+ ions. To comprehend the elaborated use, diamond-IMAC is also applied to the serum samples from gall bladder carcinoma for the potential biomarkers. Database search is carried out by the Mascot program (www.matrixscience.com) for the assignment of phosphorylation sites. Diamond nanopowder is thus a separation media with multifunctional use and can be applied to cancer protein profiling for the diagnosis and biomarker identification. 相似文献
83.
In the frame of an unscreened point charge model we calculated all possible electric field gradients for first neighbor atom
arrangements in disordered binary fcc alloys. With these values and a distribution of isomer shifts we fit experimental spectra
of nearly disordered alloys. 相似文献
84.
Horst Huck 《Journal of Solid State Electrochemistry》2002,6(8):534-539
Two types of non-integer electron-exchange numbers from uniform and reversible surface-redox reactions without side reactions
have been distinguished. The first being the apparent number, n
app, of the apparent faradaic charge corresponding to cyclovoltammetric peak areas above the interpolated baseline, and the second
the thermodynamically defined surface-redox valency, n', of Nernstian slopes of cyclovoltammetric peak potentials depending on different solution pH. An analytical expression has
been derived for n
app based on a simplified capacitive equivalent circuit and for n' using the potential-dependent free adsorption energies of the reactants involved. It should be pointed out that the different
experimental values of n
app and n' refer to the same integer number of electrons per molecule oxidized or reduced.
Electronic Publication 相似文献
85.
86.
Dai X Zhou F Khan N Huck WT Kaminski CF 《Langmuir : the ACS journal of surfaces and colloids》2008,24(22):13182-13185
We apply confocal fluorescence microscopy for real time studies of reversible conformational changes of poly(methacryloyloxyethyl phosphate) (PMEP) brushes chemically grafted onto gold substrates. Oregon green 488 fluorophores chemically attached onto the PMEP polymers were used as reporters for probing the conformational changes. Use of a specially designed liquid flow microchamber allowed dynamic imaging of the brushes under varying environmental conditions. The fluorescence intensities exhibited fully reversible brightness changes on alternation of the solution in the chamber between water and KCl. This reversible quenching behavior is consistent with a conformational change between an extended and a collapsed brush configuration. The fluorescence quenching behavior of the brushes was found to be dependent on ion concentration as well as polymer grafting density and was caused by nonradiative energy transfer to the polymer scaffold and the gold substrate. 相似文献
87.
88.
The design of novel stationary phases is a permanent demanding challenge in chromatographic separation science to enable analysis with enhanced selectivity, specificity and speed. Therefore, the characterisation of chemical and physical properties is next to calculation of chromatographic parameters essential. Conventionally, chemical parameters including surface coverage are determined by burning combustion or frontal analysis, physical parameters including particle size, pore size, pore volume and surface area are determined by SEM, mercury intrusion porosimetry (MIP) and Brunauer-Emmett-Teller (BET). All these methods are time consuming, invasive and require besides special equipment some special trained laboratory staff. Therefore, we introduced near-infrared spectroscopy (NIRS) as a noninvasive, easy-to-handle technology with wavenumber ranging from 4000 to 10,000 cm(-1) enabling analysis within only a few seconds at higher precision than the conventional methods. Investigated materials comprise porous and nonporous silica gel, carbon-based nanomaterials (fullerenes), polymer beads and monoliths. Different carriers themselves and their kind of derivatisations (RP, normal-phase, ion-exchanger, IMAC (immobilised metal affinity chromatography), affinity) can be determined by applying principal component analysis (PCA) of recorded spectra. Partial least square regression (PLSR) enables the determination of particle size, pore size, pore volume, porosity, total porosity and surface area with one single measurement. For the optimised design of well-defined polymer beads and monoliths, real-time in situ monitoring to control, e. g. particle and pore sizes as well as monomer content during the polymerisation process, can be extremely helpful. In this article, the advantages of this fast, noninvasive high-throughput NIRS methods are summarised, discussed in detail and different applications of the individual characterised materials are shown. 相似文献
89.
90.
This paper describes a fabrication strategy based on polymer brushes (20-150 nm thick) and soft lithographic techniques, for creating hydrophobic, cross-linked, laterally patterned polymer films. The hydrophobicity of the resulting micrometer-scale "quasi-2D" objects is shown to allow the polymer to act as an etch resist. By adjusting the etching time, we demonstrate that underetching of the gold from underneath the edges of the laterally patterned films can be used to create free-standing polymer-gold hybrid structures. These structures retain their structural integrity when lifted wholly or partially from the substrate and can hence be imaged in suspension. Characterization of the quasi-2D objects was carried out using atomic force microscopy (AFM), ellipsometry, optical microscopy, and Fourier transform infrared spectroscopy (FTIR). A continuous film, containing embedded polymer-gold objects, can be lifted, folded, and re-deposited onto a substrate without damaging the conductivity of the embedded metallic objects. 相似文献