全文获取类型
收费全文 | 1278篇 |
免费 | 30篇 |
国内免费 | 2篇 |
专业分类
化学 | 1056篇 |
晶体学 | 22篇 |
力学 | 4篇 |
数学 | 108篇 |
物理学 | 120篇 |
出版年
2023年 | 14篇 |
2022年 | 77篇 |
2021年 | 55篇 |
2020年 | 31篇 |
2019年 | 33篇 |
2018年 | 22篇 |
2017年 | 23篇 |
2016年 | 48篇 |
2015年 | 41篇 |
2014年 | 45篇 |
2013年 | 116篇 |
2012年 | 86篇 |
2011年 | 77篇 |
2010年 | 51篇 |
2009年 | 59篇 |
2008年 | 53篇 |
2007年 | 65篇 |
2006年 | 62篇 |
2005年 | 47篇 |
2004年 | 51篇 |
2003年 | 36篇 |
2002年 | 26篇 |
2001年 | 18篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 16篇 |
1994年 | 7篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1974年 | 3篇 |
1962年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有1310条查询结果,搜索用时 15 毫秒
91.
(S)-trans-4-Phenylbut-3-en-2-ol has been obtained in excellent yields and with high enantiomeric excess in the reduction of trans-4-phenylbut-3-en-2-one using the comminuted roots of carrot (Daucus carota L.), celeriac (Apium graveolens L. var. rapaceum), and beetroot (Beta vulgaris L. subsp. Vulgaris) in isooctane. This is the first Letter of this bioreduction with plant tissue in an organic solvent. 相似文献
92.
Micha Sowa Katarzyna
lepokura Ewa Matczak‐Jon 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(7):o262-o265
Cocrystallization of baicalein with nicotinamide yields a 1:1 cocrystal [systematic name: pyridine‐3‐carboxamide–5,6,7‐trihydroxy‐2‐phenyl‐4H‐chromen‐4‐one (1/1)], C6H6N2O·C15H10O5. The asymmetric unit contains one baicalein and one nicotinamide molecule, both in neutral forms. Molecules in the cocrystal form column motifs stabilized by an array of intermolecular hydrogen bonds. 相似文献
93.
Marek Wichtowski Andrzej Ziółkowski Ewa Weinert-Rączka 《Central European Journal of Physics》2008,6(3):546-554
In our work we propose a novel method of analysis of photorefractive transport equations. The method based on a perturbative
approach can be used in the case of two wave mixing and four wave mixing geometry, i.e. for the samples illuminated by interference
patterns. Presented approach can be employed for a broad range of material and experimental parameters, particularly for arbitrary
depth of light modulation pattern. The approximate analytical solution is compared with results of numerical calculations
and a good agreement practically in every case was found.
Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Šwinoujście, Poland 相似文献
94.
Rudolf Haag Daniel Kastler Ewa B. Trych-Pohlmeyer 《Communications in Mathematical Physics》1974,38(3):173-193
For an infinite dynamical quantum system idealized as aC*-algebra acted upon by time-translations automorphisms in an asymptotically abelian way, we propose to characterize equilibrium states by the three properties of stationarity, stability for local perturbations of the dynamics, and relative purity. We show that a state with these properties either gives rise to a one-sided energy spectrum or is a KMS- (i.e. essentially a limit Gibbs-) state. 相似文献
95.
96.
The kinetics of 1-naphthyl phosphate and phenyl phosphate hydrolysis, catalyzed by human prostatic acid phosphatase (PAP) entrapped in AOT-isooctane-water reverse micelles, has been studied over surfactant hydration degree (w0) range 5 to 35. Continuous spectrophotometric acid phosphatase assays, previously prepared, were employed. PAP was catalytically active over the whole w0 studied range. In order to determine steady-state reaction constants the experimental data were fitted to Hill rate equation. Positive cooperativity in substrate binding was observed, as it was earlier found in aqueous solutions. The extent of cooperativity (expressed as the value of the Hill cooperation coefficient h) increased from 1 to 4, when the micellar water-pool size was growing, at fixed enzyme concentration. In the plots of catalytic activity (kcat) versus w0, the maxima have been found at w0=10 (pH 5.6) and 23 (pH 3.8). It is suggested that catalytically active monomeric and dimeric PAP forms are entrapped in reverse micelles of w0=10 and 23, respectively. 相似文献
97.
Pacholska E Espinosa E Guilard R 《Dalton transactions (Cambridge, England : 2003)》2004,(20):3181-3183
A meso-aryl-substituted face-to-face biscorrole was synthesised in a two-step reaction and the corresponding homo- and heterobimetallic complexes were obtained and fully characterised. 相似文献
98.
99.
Pacholska E Latos-Grazyński L Ciunik Z 《Angewandte Chemie (International ed. in English)》2001,40(23):4466-4469
100.
Rebecca A.H. Butler Paul Helminger Ewa Bialkowska-Jaworska 《Journal of Molecular Spectroscopy》2007,244(2):113-116
The pure rotational spectrum of chlorine nitrate in its v6 = 1 excited vibrational state has been studied. A total of 2901 lines, with Ka extending to 33 in the 35Cl isotopologue and 30 in the 37Cl isotopologue, respectively, have been recorded and assigned. This analysis, along with our recently reported study of the ν5/ν6ν9 dyad and the improved energy levels of ν9 reported in this paper, should make possible accurate simulation of the corresponding ν6 band and its complex hot band structure near 435 cm−1. 相似文献