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411.
In this article, our aim is to consider inflation, dark energy and dark matter in the framework of a real scalar field. To
this end, we use the quintessence approach. We have tried a real scalar field with a specific self-interaction potential in
a spacially flat universe. Numerical results indicate that this potential can drive the expansion of the universe in three
distinct phases. The first phase behaves as an inflationary expansion. For this stage, setting the scalar field’s initial
value to ϕ
0≥1.94 leads to N 3 68\mathcal{N}\geq 68 favored by observation. After the inflationary phase, the scalar field starts an oscillatory behavior which averages to a
=0\bar{w}=0 fluid. This stage can be taken as a cold dark matter (p≈0) epoch expected from works on the structure formation issue. Observations and cosmological models indicate that t
inf
≈10−35 s and the matter dominated lasts for t
m
≈1017 s, hence
(\fractmtinf)obs ? 1052(\frac{t_{m}}{t_{inf}})_{obs}\approx10^{52}. We have shown that the present model can satisfy such a constraint. Finally, the scalar field leaves the oscillatory behavior
and once again enters a second inflationary stage which can be identified with the recent accelerated expansion of the universe.
We have also compared our model with the ΛCDM model and have found a very good agreement between the equation of state parameter of both of models during the DM and DE
era. 相似文献
412.
Reversible hybridization reaction plays a key role in fundamental biological processes, in many laboratory techniques, and also in DNA based sensing devices. Comprehensive investigation of this process is, therefore, essential for the development of more sophisticated applications. Kinetics and thermodynamics of the hybridization reaction, as a second order process, are systematically investigated with the aid of the soft and hard chemometric methods. Labeling two complementary 21 mer DNA single strands with FAM and Texas red fluorophores, enabled recording of the florescence excitation−emission matrices during the experiments which led to three-way data sets. The presence of fluorescence resonance energy transfer in excitation and emission modes and the closure in concentration mode, made the three-way data arrays rank deficient. To acquire primary chemical information, restricted Tucker3 as a soft method was employed. Herein a model-based method, hard restricted trilinear decomposition, is introduced for in depth analysis of rank deficient three-way data sets. By employing proposed hard method, the nonlinear model parameters as well as the correct profiles could be estimated. In addition, a simple constraint is presented to extract chemically reasonable output profiles regarding the core elements of restricted Tucker3 model. 相似文献
413.
414.
Masoud Bezi Javan Samaneh Ebrahimi 《Applied Physics A: Materials Science & Processing》2014,114(2):529-536
We studied the structural, electronic, and magnetic properties of C59Ir, C58Ir2, and C69Ir heterofullerenes by employing density functional theory and the generalized gradient approximation. There are six distinct isomers of C58Ir2 with high probability to form stable structures. The most stable structure of the C69Ir heterofullerene was investigated by comparing the iridium binding energies at the different atomic sites on the D5h C70 cage. There is a strong hybridization between the atomic orbitals of the iridium and those of the carbon atoms, leading to the spin quenching of the iridium atoms in the most stable C58Ir2 heterofullerene. 相似文献
415.
416.
Somayyeh Piri Farideh Piri Bahare Rajabi Sahar Ebrahimi Abbasali Zamani Mohammad Reza Yaftian 《中国化学会会志》2015,62(11):1045-1052
Aluminum oxide/polyaniline nanocomposite is prepared by a new and one‐pot method including in situ electrooxidation of aluminum and electropolymerization of aniline. The product has been characterized by elemental analysis, FT‐IR spectroscopy, X‐ray diffraction (XRD), Field Emission Scanning Electron Micrographs (FESEM), and Transmission Electron Micrographs (TEM) techniques. ICP‐OES was used for determination of aluminum in the prepared nanocomposite. A porous structure of the prepared composite has been shown by FESEM images. TEM of the product confirms the presence of exfoliated aluminum oxide nanofibers. The adsorption potentials of the prepared nanocomposite towards Cu2+, Pb2+, Zn2+, Cd2+, Ni2+ and Co2+ ions were evaluated in batch adsorption experiments. The results show that the adsorption efficiency is controlled by aqueous phase pH. The experimental data was well interpreted by considering the Langmuir model. The kinetics of the adsorption processes can be well interpreted by pseudo‐second‐order equation. 相似文献
417.