全文获取类型
收费全文 | 217篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 147篇 |
力学 | 1篇 |
数学 | 23篇 |
物理学 | 49篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 15篇 |
2011年 | 8篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 13篇 |
2007年 | 25篇 |
2006年 | 10篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1930年 | 2篇 |
排序方式: 共有220条查询结果,搜索用时 15 毫秒
1.
Sinkov Sergey I. Hall Gabriel B. Lumetta Gregg J. 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(2):773-784
Journal of Radioanalytical and Nuclear Chemistry - The activity and osmotic coefficients of fission product systems CsOH?+?CsCl, CsOH?+?CsBr and CsOH?+?CsI are... 相似文献
2.
Roberta Ragni Enrico Orselli Gregg S. Kottas Omar Hassan Omar Francesco Babudri Adriana Pedone Francesco Naso Gianluca M. Farinola Prof. Dr. Luisa De Cola Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(1):136-148
The synthesis and photophysical and electrochemical characterisation of new heteroleptic iridium complexes with electron‐withdrawing sulfonyl groups and fluorine atoms bound to phenylpyridine ligands are reported. The emission energy of these materials strongly depends on the position of the sulfonyl groups and on the number of fluorine substituents. A 90 nm wide tuning range of photoluminescence from the blue‐green (λem=468 nm) of iridium(III)bis[2‐(4′‐benzylsulfonyl)phenylpyridinato‐N,C2′][3‐(pentafluorophenyl)‐pyridin‐2‐yl‐1,2,4‐triazolate] to the orange (λem=558 nm) of iridium(III)bis[2‐(3′‐benzylsulfonyl)phenylpyridinato‐N,C2′](2,4‐decanedionate) has been achieved. Emission quantum yields ranging from 47 to 71 % have also been found for degassed solutions of the complexes, and a surprisingly high value of 16 % was recorded for iridium(III)bis[2‐(5′‐benzylsulfonyl‐3′,6′‐difluoro)phenylpyridinato‐N,C2′](2,4‐decanedionate) in air‐equilibrated dichloromethane. A unusual stereochemistry of the benzylsulfonyl‐substituted dimer and heteroleptic complexes has been detected by 1H NMR spectroscopy, and is characterised by the mutual cis disposition of the pyridyl nitrogen atoms of the phenylpyridine ligands, which differs from the most common trans arrangement reported in the literature. 相似文献
3.
Qin Zhao Matthew W. Soyk Gregg M. Schieffer Katrin Fuhrer Marc M. Gonin R. S. Houk Ethan R. Badman 《Journal of the American Society for Mass Spectrometry》2009,20(8):1549-1561
This instrument combines the capabilities of ion/ion reactions with ion mobility (IM) and time-of-flight (TOF) measurements for conformation studies and top-down analysis of large biomolecules. Ubiquitin ions from either of two electrospray ionization (ESI) sources are stored in a three dimensional (3D) ion trap (IT) and reacted with negative ions from atmospheric sampling glow discharge ionization (ASGDI). The proton transfer reaction products are then separated by IM and analyzed via a TOF mass analyzer. In this way, ubiquitin +7 ions are converted to lower charge states down to +1; the ions in lower charge states tend to be in compact conformations with cross sections down to ~880 Å2. The duration and magnitude of the ion ejection pulse on the IT exit and the entrance voltage on the IM drift tube can affect the measured distribution of conformers for ubiquitin +7 and +6. Alternatively, protein ions are fragmented by collision-induced dissociation (CID) in the IT, followed by ion/ion reactions to reduce the charge states of the CID product ions, thus simplifying assignment of charge states and fragments using the mobility-resolved tandem mass spectrum. Instrument characteristics and the use of a new ion trap controller and software modifications to control the entire instrument are described. 相似文献
4.
Gregg Jaeger 《Foundations of Physics》2010,40(9-10):1396-1409
Two physical approaches—as distinct, under the classification of Mittelstaedt, from formal approaches—to the problem of individuation of quantum objects are considered, one formulated in spatiotemporal terms and one in quantum mechanical terms. The spatiotemporal approach itself has two forms: one attributed to Einstein and based on the ontology of space-time points, and the other proposed by Howard and based on intersections of world lines. The quantum mechanical approach is also provided here in two forms, one based on interference and another based on a new Quantum Principle of Individuation (QPI). It is argued that the space-time approach to individuation fails and that the quantum approach offers several advantages over it, including consistency with Leibniz’s Principle of Identity of Indiscernibles. 相似文献
5.
6.
Mark D. Ogden Serguei I. Sinkov Mikael Nilson Gregg J. Lumetta Robert D. Hancock Kenneth L. Nash 《Journal of solution chemistry》2013,42(1):211-225
The complexant 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) is a planar tetradentate ligand that is more preorganized for metal complexation than its unconstrained analogue ethylendiiminodiacetic acid (EDDA). Furthermore, the backbone nitrogen atoms of PDA are aromatic, hence are softer than the aliphatic amines of EDDA. It has been hypothesized that PDA will selectively bond to trivalent actinides over lanthanides. In this report, the results of spectrophotometric studies of the complexation of Nd(III) and Am(III) by PDA are reported. Because the complexes are moderately stable, it was necessary to conduct these titrations using competitive equilibrium methods, competitive cation complexing between PDA and diethylenetriaminepentaacetic acid, and competition between ligand protonation and complex formation. Stability constants and ligand protonation constants were determined at 0.1 mol·L?1 ionic strength and at 0.5 mol·L?1 ionic strength nitrate media at 21 ± 1 °C. The stability constants are lower than those predicted from first principles and speciation calculations indicate that Am3+ selectivity over Nd3+ is less than that exhibited by 1,10-phenanthroline. 相似文献
7.
Karenowska AD Gregg JF Tiberkevich VS Slavin AN Chumak AV Serga AA Hillebrands B 《Physical review letters》2012,108(1):015505
We describe a general mechanism of controllable energy exchange between waves propagating in a dynamic artificial crystal. We show that if a spatial periodicity is temporarily imposed on the transmission properties of a wave-carrying medium while a wave is inside, this wave is coupled to a secondary counterpropagating wave and energy oscillates between the two. The oscillation frequency is determined by the width of the spectral band gap created by the periodicity and the frequency difference between the coupled waves. The effect is demonstrated with spin waves in a dynamic magnonic crystal. 相似文献
8.
9.
Gregg Jaeger 《Foundations of Physics》2014,44(7):709-724
A view of the constitution of quantum objects as reducible, in the sense of being decomposable to elementary particles, is outlined. On this view, parts of composite quantum systems are considered to be identified according to a recently introduced, specifically quantum notion of individuation (Jaeger, Found Phys 40:1396 2010). These parts can typically also be considered particles according to Wigner’s symmetry-based notion. Particles are considered elementary when they satisfy a condition of elementarity, newly introduced here, that improves on that provided by Newton and Wigner. In any given instance, the compound character of a physical object can be verified in principle by decomposition, ultimately to a set of such elementary parts, through appropriate precise quantum measurements during experimentation consistently with this principle of individuation. 相似文献
10.
S.S. Roy C. Morros R.M. Bowman J.M. Gregg 《Applied Physics A: Materials Science & Processing》2005,81(4):881-885
Strongly oriented thin films of lead zinc niobate (PZN)–lead zirconium titanate (PZT) with (La,Sr)CoO3 lower electrodes were grown on MgO {001} substrates by pulsed laser deposition. The films were perovskite-dominated with strong in-plane and out-of-plane orientations. Room-temperature functional characterisation indicated that the films were ferroelectric, with dielectric constant ∼550 and loss tangent ∼0.08 at 1 kHz. The crystallographic strain, as a function of applied dc field, was monitored by in situ X-ray diffraction. The maximum electric-field-induced crystallographic strain (∼0.22%) was comparable to that observed in bulk, but at significantly greater field (∼150 kV cm-1). The effective d33 value obtained from the crystallographic strain data was around 150 pm V-1, which is high for ferroelectric thin films 400 nm in thickness. The local polarisation-switching properties of the films were investigated using a piezo-response atomic force microscope. Domain maps for a 5×5 μm2 region of material were recorded as a function of dc bias, and confirmed the ferroelectric switching behaviour. PACS 81.05.Je; 81.40.Vw; 68.37.Lp 相似文献