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排序方式: 共有481条查询结果,搜索用时 15 毫秒
41.
A method is proposed for obtaining the spectrum for noise that causes the phase decoherence of a qubit directly from experimentally available data. The method is based on a simple relationship between the spectrum and the coherence time of the qubit in the presence of a π pulse sequence. The relationship is found to hold for every system of a qubit interacting with the classical-noise, bosonic, and spin baths. 相似文献
42.
Seiji Yamaguchi Eriko Hamade Hajime Yokoyama Yoshiro Hirai Shunsaku Shiotani 《Journal of heterocyclic chemistry》2002,39(2):335-339
Birch reduction of four furopyridines 1a‐d effected the characteristic cleavage of the furan ring, giving ethnylpyridinols 2a‐d , vinylpyridinols 3b,d , and ethylpyridinols 4a‐d , and the reduction of the furan ring, giving dihydrofuropyridine 5c,d. 相似文献
43.
44.
Andreas Richter Ken-ichi Matsuda Tatsushi Akazaki Tadashi Saku Hiroyuki Tamura Yoshiro Hirayama Hideaki Takayanagi 《Physica E: Low-dimensional Systems and Nanostructures》2005,25(4):472-478
We present studies on the electric transport in a lateral GaAs/AlGaAs quantum dot defined by a patterned single connected metallic front-gate. This gate design allows to easily couple a large number of quantum dots and therefore holds high potential in the design of new materials with tailor-made band structures based on quantum dot superlattices of controlled shape. Clear Coulomb diamond structures and well pronounced tunneling peaks observed in experiment indicate that single-electron control has been achieved. However, the dependence on electron density in the heterostructure embedding the dot, which is controlled by an additional back-gate, reveals that transport characteristics are strongly influenced supposedly by potential fluctuations in the dot and lead regions. 相似文献
45.
Yoshiro Masuyama Kazuki YoshikawaNoriyuki Suzuki Kenji HaraAtsushi Fukuoka 《Tetrahedron letters》2011,52(51):6916-6918
Copper(II)-exchanged hydroxyapatite, prepared by ion-exchanging of Ca(II) in calcium hydroxyapatite [Ca10(PO4)6(OH)2] with Cu(NO3)2 at 70 °C in water, functions as a reusable heterogeneous catalyst with neither reducing agents nor bases for azide-alkyne [3+2] cycloaddition at 50 °C in water under air. 相似文献
46.
A remarkable effect of ionic liquids in transition-metal-free aerobic oxidation of benzylic alcohols
Yoshiro OdaKoji Hirano Tetsuya SatohSusumu Kuwabata Masahiro Miura 《Tetrahedron letters》2011,52(41):5392-5394
The transition-metal-free aerobic oxidation of benzylic alcohols is uniquely accelerated by a 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6)/PhCF3 biphasic system and Cs2CO3 to afford the corresponding ketones in good yields. The reaction system is also applicable to an oxidative cross-esterification of primary benzyl alcohols with a higher aliphatic alcohol. 相似文献
47.
The rotational time correlation function (RTCF) of solute benzene molecules in the ionic liquid (1-butyl-3-methylimidazolium chloride) has been studied using classical molecular dynamics simulation. The effect of solvent charge on the functional form of RTCF was investigated by comparing four force fields for the solvent where the total charge on the anion and the cation was set to ±1e, ±0.7e, ±0.5e, and 0, respectively. For all three charged solvent models, the RTCF exhibits a long-time tail where the relaxation rate exhibits a significant slowdown. This feature is strengthened by higher solvent charges as well as lower temperatures, indicating the influence of the strong Coulombic fields arising from the solvent charges. The long-time tail is caused by the extraordinarily slow solvent structural relaxation of ionic liquids compared to the time scale of their local vibrational and librational dynamics. 相似文献
48.
Room temperature ionic liquids (IL) have been used in numerous applications in chemistry. Addition of water alters many of their properties making it possible to custom design solvents for specific applications. Along with experiments, computational studies using various approaches have provided key insights into the structure and dynamics of IL systems, as well as aggregate formation and phase behavior of the IL/water mixtures. These systems provide computational challenges since ILs and IL/water mixtures are viscous liquids with intrinsically slow processes and structural organization over surprisingly large length scales, which push the limits of applicability of the available techniques. Recent developments in the studies of IL/water mixtures using computational methodologies are reviewed and the future prospects for the field are briefly discussed. 相似文献
49.
Imura Y Tanuma H Sugimoto H Ito R Hojo S Endo H Morita C Kawai T 《Chemical communications (Cambridge, England)》2011,47(22):6380-6382
Straight ultrathin Au nanowires (NWs) with diameters less than 2 nm were synthesized using the lamellar structure of C18AA in an organogel and its selective adsorption for specific gold surfaces. In addition, the potential to form a bilayer structure with interdigitated hydrocarbon chains enabled the production of water-dispersible Au NWs without morphological change. 相似文献
50.
Kosumi D Kusumoto T Fujii R Sugisaki M Iinuma Y Oka N Takaesu Y Taira T Iha M Frank HA Hashimoto H 《Physical chemistry chemical physics : PCCP》2011,13(22):10762-10770
Carotenoids containing a carbonyl group in conjugation with their polyene backbone are naturally-occurring pigments in marine organisms and are essential to the photosynthetic light-harvesting function in aquatic algae. These carotenoids exhibit spectral characteristics attributed to an intramolecular charge transfer (ICT) state that arise in polar solvents due to the presence of the carbonyl group. Here, we report the spectroscopic properties of the carbonyl carotenoid fucoxanthin in polar (methanol) and nonpolar (cyclohexane) solvents studied by steady-state absorption and femtosecond pump-probe measurements. Transient absorption associated with the optically forbidden S(1) (2(1)A) state and/or the ICT state were observed following one-photon excitation to the optically allowed S(2) (1(1)B) state in methanol. The transient absorption measurements carried out in methanol showed that the ratio of the ICT-to-S(1) state formation increased with decreasing excitation energy. We also showed that the ICT character was clearly visible in the steady-state absorption in methanol based on a Franck-Condon analysis. The results suggest that two spectroscopic forms of fucoxanthin, blue and red, exist in the polar environment. 相似文献