全文获取类型
收费全文 | 335篇 |
免费 | 15篇 |
专业分类
化学 | 245篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 8篇 |
物理学 | 93篇 |
出版年
2023年 | 3篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 33篇 |
2011年 | 19篇 |
2010年 | 16篇 |
2009年 | 6篇 |
2008年 | 21篇 |
2007年 | 12篇 |
2006年 | 7篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 15篇 |
1999年 | 12篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1977年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1966年 | 2篇 |
1936年 | 2篇 |
1928年 | 1篇 |
1927年 | 2篇 |
1906年 | 1篇 |
排序方式: 共有350条查询结果,搜索用时 31 毫秒
1.
2.
Kraus RM Lagoudakis PG Müller J Rogach AL Lupton JM Feldmann J Talapin DV Weller H 《The journal of physical chemistry. B》2005,109(39):18214-18217
We study the interplay between Auger effects and ionization processes in the limit of strong electronic confinement in core/shell CdSe/ZnS semiconductor nanocrystal quantum dots. Spectrally resolved fluorescence decay measurements reveal a monotonic increase of the photoluminescence decay rate on excitation density. Our results suggest that Auger recombination accelerates ionization processes that lead to the occupation of dark, nonemissive nanocrystal states. A model is proposed in the quantized Auger regime describing these experimental observations and providing an estimate of the Auger assisted ionization rates. 相似文献
3.
4.
5.
It has been shown, that in vitro incubation of Laminaria digitata extract (containing mainly As-sugar 1 (glycerol-arsenoribose) and As-sugar 3 (sulfonate-arsenoribose)) with liver cytosol, produced the same two arsenicals, as when L. digitata extract was treated with H(2)S. By parallel use of HPLC-ICP-MS and HPLC-ES-MS the compounds displayed mainly m/z 345 and m/z 409. A pure As-sugar 1 standard was obtained, and a standard of arsinothioyl-sugar 1 (m/z 345) was produced, by purging a solution of As-sugar 1 with gaseous H(2)S. The identity of arsinothioyl-sugar 1 was characterised by ES-MS, 1D and 2D NMR. Arsinothioyl-sugar 1 showed the same chromatographic behaviour and MS characteristics as one of the two arsenic-containing compounds (m/z 345) produced by incubation of L. digitata extracts with liver cytosol, and as the product of the incubation of As-sugar 1 with liver cytosol (HPLC-ICP-MS, HPLC-ES-MS). Assuming that As-sugar 3 reacts in a similar way to As-sugar 1 with H(2)S, it is most likely that the second unknown (m/z 409) is arsinothioyl-sugar 3. The degradation of As-sugar 1 in acidic solution (100 mM HCl) was followed by (1)H-NMR, and the relative slow degradation (t(1/2)= 17 h) suggests that arsenosugars are taken up from the stomach in their original chemical form, hence the study of arsenosugar incubation in tissue is highly relevant. The arsinothioyls are a new group of organoarsenicals, which have only recently been identified in nature. Here, arsinothioyl sugars are detected for the first time. The in vitro formation of arsinothioyl-sugars in liver cytosol suggests that arsinothioyls may be of large biochemical and toxicological importance. 相似文献
6.
7.
M. Guillot F. Tchéou A. Marchand P. Feldmann 《Zeitschrift für Physik B Condensed Matter》1984,56(1):29-39
Using neutron diffraction data, the thermal evolution of the magnetic structure of Ho3Fe5O12 has been studied. Below the compensation temperature (T
comp=137 K), the umbrella structure parameters which fit the spontaneous ferrite magnetizations have been determined. AboveT
comp, the compound behaves as a Néel type ferrimagnet. Particular attentions have been given to the magnetic form factors of both iron sublattice on one hand and on the other hand to a rhombohedral distorsion fromI a3d toR
below 30 K and in first approximation toR
c forT>30 K. 相似文献
8.
9.
H. Blume R. Färber N. Feldmann K. Heinloth D. Kramarczyk F. Kuckelkorn H. J. Michels J. Päsler J. P. Dowd 《Zeitschrift fur Physik C Particles and Fields》1983,16(4):283-289
The electroproduction of π0-mesons on protons has been measured with electrons of 1.7 and 2.1 GeV energy in the region of the nucleon resonances at \(W = \sqrt {(q + p)^2 } = 1,400 - 2,000MeV\) at rather low values of |q 2|=|(e?e′)2|=0.01–0.1 GeV2 but at high values of the nucleon recoil |t|=|(p?p′)2|≈0.6–2.2 GeV2 corresponding to \(\Theta _\pi ^{cm} \approx 145^ \circ - 180^ \circ\) . Up toW≈1,650 MeV the cross section for π0-production with virtual photons of |q 2|≈0.03 GeV2 is only slightly smaller than that with real photons. ForW?1,700 MeV the cross section at |q 2|≈0.03 GeV2 is on average a factor of 2 smaller than that atq 2=0 but only slightly higher than that at |q 2|≈0.3–1 GeV2. 相似文献
10.
Fabian Gyger André Sackmann Michael Hübner Pascal Bockstaller Dagmar Gerthsen Henning Lichtenberg Jan‐Dierk Grunwaldt Nicolae Barsan Udo Weimar Claus Feldmann 《Particle & Particle Systems Characterization》2014,31(5):591-596
Pd@SnO2 and SnO2@Pd core@shell nanocomposites are prepared via a microemulsion approach. Both nanocomposites exhibit high‐surface, porous matrices of SnO2 shells (>150 m2 g?1) with very small SnO2 crystallites (<10 nm) and palladium (Pd) nanoparticles (<10 nm) that are uniformly distributed in the porous SnO2 matrix. Although similar by first sight, Pd@SnO2 and SnO2@Pd are significantly different in view of their structure with Pd inside or outside the SnO2 shell and in view of their sensor performance. As SMOX‐based sensors (SMOX: semiconducting metal oxide), both nanocomposites show a very good sensor performance for the detection of CO and H2. Especially, the Pd@SnO2 core@shell nanocomposite is unique and shows a fast response time (τ90 < 30 s) and a very good response at low temperature (<250 °C), especially under humid‐air conditions. Extraordinarily high sensor signals are observed when exposing the Pd@SnO2 nanocomposite to CO in humid air. Under these conditions, even commercial sensors (Figaro TGS 2442, Applied Sensor MLC, E2V MICS 5521) are outperformed. 相似文献