全文获取类型
收费全文 | 426篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 226篇 |
晶体学 | 1篇 |
力学 | 13篇 |
数学 | 54篇 |
物理学 | 138篇 |
出版年
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 14篇 |
2012年 | 21篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 10篇 |
2008年 | 29篇 |
2007年 | 15篇 |
2006年 | 22篇 |
2005年 | 32篇 |
2004年 | 24篇 |
2003年 | 20篇 |
2002年 | 18篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1969年 | 1篇 |
1939年 | 2篇 |
1932年 | 1篇 |
1917年 | 1篇 |
排序方式: 共有432条查询结果,搜索用时 625 毫秒
31.
Dr. Ludovic Fournier Dr. Isabelle Aujard Dr. Thomas Le Saux Sylvie Maurin Sandra Beaupierre Prof. Dr. Jean‐Bernard Baudin Prof. Dr. Ludovic Jullien 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17494-17507
The small and synthetically easily accessible coumarinylmethyl backbone has been modified to generate a family of photolabile protecting groups with redshifted absorption. We relied on introducing electron‐donating groups in the 7 position and electron‐withdrawing groups in the 2‐, and 2‐ and 3 positions. In particular, we showed that the diethylamino‐thiocoumarylmethyl and the diethylamino‐coumarylidenemalononitrilemethyl are relevant for uncaging with cyan light. They both exhibit a significant action cross section for uncaging in the 470–500 nm wavelength range and a low light absorption between 350 and 400 nm. These attractive features are favorable to perform chromatic orthogonal photoactivation with UV and blue‐cyan light sources, respectively. 相似文献
32.
A. Tamion C. Raufast E. Bonet V. Dupuis T. Fournier T. Crozes E. Bernstein W. Wernsdorfer 《Journal of magnetism and magnetic materials》2010,322(9-12):1315-1318
Technological improvements require the understanding of dynamical magnetization reversal processes at the nanosecond time scales. In this paper, we present the first magnetization reversal measurements performed on a single cobalt cluster (counting only a thousand of spins), using the micro-superconducting quantum interference device (SQUID) technique by applying a constant magnetic field combined with a radio-frequency (RF) field pulse. First of all, we present the different technical steps necessary to detect the magnetic reversals at low temperature (T=35 mK) of a well-defined nanoparticle prepared by low energy clusters beam deposition (LECBD). We previously showed that the three-dimensional (3D)-switching Stoner-Wohlfarth astroid represents the magnetic anisotropy of the nanoparticle. Then, an improved device coupled with a gold stripe line, allow us to reverse such macrospin, using a RF pulse. A qualitative understanding of the magnetization reversal by non-linear resonance has been obtained with the Landau-Lifschitz-Gilbert (LLG) equation. 相似文献
33.
Gas-phase behaviour of negative ions produced from thiazidic diuretics under electrospray conditions
Garcia P Popot MA Fournier F Bonnaire Y Tabet JC 《Journal of mass spectrometry : JMS》2002,37(9):940-953
A systematic mass spectrometric study of 10 thiazidic diuretics and related compounds was undertaken by mass spectrometry (MS) with electrospray ionization in the negative ion mode. Collisional dissociation 'in-source' (CID-MS) and in a low-pressure collision cell (CID-MS/MS) were compared in both excitation regions. Spectra obtained by CID-MS and by CID-MS/MS were matched. Using the two methods, loss of HCl and consecutive dissociations from 2HCl losses were exhibited from compounds such as methyclothiazide and trichlormethiazide but not from other thiazidic diuretics that contain chlorine substituents in the aromatic moiety. However, deprotonated dichlorphenamide gave rise to loss of HCl by CID-MS and CID-MS/MS. For other diuretics such as hydroflumethiazide and hydrochlorothiazide, the loss of HCN and [HCN + SO(2)] was relevant. Reaction mechanisms were checked by means of deuterium-hydrogen exchange, which showed that deprotonation took place regioselectively on the heterocyclic moiety. The cleavage pathways require molecular isomerization forming ion-dipole complexes prior to decompositions, allowing long-distance proton transfer for neutral elimination. Identifications of the most specific fragmentations presented in this paper were applied to the screening and unambiguous identification of diuretics for horse doping control. 相似文献
34.
The high propensity of organosilanes towards polycondensation and reaction with nucleophilic moieties has facilitated the formation of new organic-inorganic hybrids based on the lacunary divacant heteropolyanion [gamma-SiW10O36]8-. Depending on the experimental conditions two different types of derivatives were obtained with the general formula [gamma-SiW10O36(RSi)2O]4- (1) (>90% yield) and [gamma-SiW10O36(RSiO)4]4- (2) (>85% yield) (R = H (1a, 2a), vinyl (1b), -C3H6OC(O)C-(Me)=CH2 (1c, 2c), phenyl (1d, 2d)). The structures of the hybrid anions have been inferred from spectroscopic data, in particular from multinuclear (29Si and 183W) NMR solution studies and from MALDI-TOF mass spectrometry. Both species correspond to the grafting of an oxo-bridged siloxane unit onto the surface of the lacunary polyoxoanion. 相似文献
35.
Raman Spectra of the Rare Earth Orthovanadate The laser-Raman spectra of the tetragonal rare earth orthovanadates of the type LnVO4 (Ln = Pr to Lu) as well as those of ScVO4 and YVO4 has been recorded and interpreted with the aid of both, the site symmetry and the factor group analysis, using also IR data reported previously. The influence of the cations on the internal vibrations of the anion are discussed in detail. 相似文献
36.
J.-C Fournier 《Journal of Combinatorial Theory, Series B》1980,29(3):321-327
In this note we characterize isomorphism between two hypergraphs by means of equicardinality of certain edge intersections and the exclusion of certain pairs of subhypergraphs. Our result is slightly stronger than Theorem 3 of C. Berge and R. Rado (J. Combinatorial Theory Ser. B13 (1972), 226–241) in particular in that isolated vertices are admitted. As a corollary we obtain a result due to J.-L. Paillet. 相似文献
37.
38.
39.
[reaction: see text] Syntheses of two novel omuralide derivatives are described. 相似文献
40.
It is shown that, when a Monte Carlo algorithm is used for estimation of any physical quantity A, a simple and fast additional procedure can be implemented that simultaneously estimates the sensitivity of A to any problem parameter. The proposed approach is general and systematic in the sense that: (i) it includes domain-deformation sensitivities, i.e., cases where a change in the parameter modifies the domain over which the sampled random variables are defined and (ii) a simple generic procedure is presented to address all remaining free choices in terms of variance minimization. 相似文献