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991.
Uncertainty relations based on information theory for both discrete and continuous distribution functions are briefly reviewed. We extend these results to account for (differential) Rényi entropy and its related entropy power. This allows us to find a new class of information-theoretic uncertainty relations (ITURs). The potency of such uncertainty relations in quantum mechanics is illustrated with a simple two-energy-level model where they outperform both the usual Robertson–Schrödinger uncertainty relation and Shannon entropy based uncertainty relation. In the continuous case the ensuing entropy power uncertainty relations are discussed in the context of heavy tailed wave functions and Schrödinger cat states. Again, improvement over both the Robertson–Schrödinger uncertainty principle and Shannon ITUR is demonstrated in these cases. Further salient issues such as the proof of a generalized entropy power inequality and a geometric picture of information-theoretic uncertainty relations are also discussed. 相似文献
992.
Second‐order rate constants were gathered for solution Diels–Alder reactions of substituted and unsubstituted acenes, with the intention of ascertaining ideal diene–dienophile combinations. Particular focus was placed on the larger ring systems namely tetracene, pentacene, and rubrene. The rate constants between the acenes ranged roughly six orders of magnitude, from the slowest reacting diene, rubrene, to the fastest diene, pentacene. The utilized dienophiles covered a large range of reactivity from 2,3‐dichloromaleic anhydride to tetracyanoethylene. To aid in the interpretation of acene reactivity, constants were compared to the extensive body of Diels–Alder literature with well‐studied dienes such as anthracene and trans‐1‐methoxy‐1,3‐butadiene serving as points of reference. Complex reaction kinetics for the addition of MeTAD and rubrene was found: initial fast consumption generated an intermediate, followed by dramatically slower product formation. The kinetic data creates a foundation for the analysis of prior and future reactions between organic semiconductor acene materials with volatized dienophiles, a surface functionalization technique for enhancing these electronic materials. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
993.
Zuolun Zhang Robert M. Edkins J?rn Nitsch Katharina Fucke Andreas Steffen Lauren E. Longobardi Douglas W. Stephan Christoph Lambert Todd B. Marder 《Chemical science》2015,6(1):308-321
Three compounds with phenyl (1), 4-tert-butylphenyl (2) and 4-N,N-diphenylaminophenyl (3) groups attached to bis(fluoromesityl)boryl ((FMes)2B) through B–C bonds have been prepared. The restricted rotation about the B–C bonds of boron-bonded aryl rings in solution has been studied by variable-temperature 19F NMR spectroscopy, and through-space F–F coupling has been observed for 3 at low temperature. Steric congestion inhibits binding of 1 by Lewis bases DABCO and tBu3P and the activation of H2 in their presence. Photophysical and electrochemical studies have been carried out on 2, 3, and an analogue of 3 containing a bis(mesityl)boryl ((Mes)2B) group, namely 4. Both 2 and 3 show bright emission in nonpolar solvents and in the solid-state, very strong electron-accepting ability as measured by cyclic voltammetry, and good air-stability. In addition, 2 displayed unusually long-lived emission (τ = 2.47 s) in 2-MeTHF at 77 K. The much stronger acceptor strength of (FMes)2B than (Mes)2B leads to significantly red-shifted emission in solution and the solid state, stronger emission solvatochromism, and significantly lower reduction potentials. Theoretical calculations confirm that 2 and 3 tend to form highly twisted excited states with good conjugation between one FMes group and the boron atom, which correlate well with their blue-shifted solid-state emissions and low k
r values in solution. 相似文献
994.
Z. Vivian Feng Ian L. Gunsolus Tian A. Qiu Katie R. Hurley Lyle H. Nyberg Hilena Frew Kyle P. Johnson Ariane M. Vartanian Lisa M. Jacob Samuel E. Lohse Marco D. Torelli Robert J. Hamers Catherine J. Murphy Christy L. Haynes 《Chemical science》2015,6(9):5186-5196
Although nanomaterials facilitate significant technological advancement in our society, their potential impacts on the environment are yet to be fully understood. In this study, two environmentally relevant bacteria, Shewanella oneidensis and Bacillus subtilis, have been used as model organisms to elucidate the molecular interactions between these bacterial classes and Au nanoparticles (AuNPs) with well-controlled and well-characterized surface chemistries: anionic 3-mercaptopropionic acid (MPA), cationic 3-mercaptopropylamine (MPNH2), and the cationic polyelectrolyte poly(allylamine hydrochloride) (PAH). The data demonstrate that cationic, especially polyelectrolyte-wrapped AuNPs, were more toxic to both the Gram-negative and Gram-positive bacteria. The levels of toxicity observed were closely related to the percentage of cells with AuNPs associated with the cell surface as measured in situ using flow cytometry. The NP concentration-dependent binding profiles were drastically different for the two bacteria strains, suggesting the critical role of bacterial cell surface chemistry in determining nanoparticle association, and thereby, biological impact. 相似文献
995.
Marc C. Jacob Jérôme Boudet Damiano Casalino Marc Michard 《Theoretical and Computational Fluid Dynamics》2005,19(3):171-196
A low Mach number rod-airfoil experiment is shown to be a good benchmark for numerical and theoretical broadband noise modeling. The benchmarking approach is applied to a sound computation from a 2D unsteady-Reynolds-averaged Navier–Stokes (U-RANS) flow field, where 3D effects are partially compensated for by a spanwise statistical model and by a 3D large eddy simulation. The experiment was conducted in the large anechoic wind tunnel of the Ecole Centrale de Lyon. Measurements taken included particle image velocity (PIV) around the airfoil, single hot wire, wall pressure coherence, and far field pressure. These measurements highlight the strong 3D effects responsible for spectral broadening around the rod vortex shedding frequency in the subcritical regime, and the dominance of the noise generated around the airfoil leading edge. The benchmarking approach is illustrated by two examples:
In both cases, the ability of computational fluid dynamics to model the source mechanisms and of the CAA approach to predict the far field are assessed separately. PACS 43.28Ra; 47.27Sd; 47.27Eq; 47.85Gj 相似文献
| the validation of a stochastical noise generation model applied to a 2D U-RANS computation; |
| the assessment of a 3D LES computation using a new subgrid scale (SGS) model coupled to an advanced-time Ffowcs–Williams and Hawkings sound computation. |
996.
997.
998.
We developed a potentiometric aflatoxin M1-immunosensor which utilizes 3-(4-hydroxyphenyl)propionic acid (p-HPPA) as electron donating compound for horseradish peroxidase (HRP; EC 1.11.1.7). The assay system consists of a polypyrrole-surface-working electrode coated with a polyclonal anti-M1 antibody (pAb-AFM1), a Ag/AgCl reference electrode and a HRP-aflatoxin B1 conjugate (HRP-AFB1 conjugate).To optimize the potentiometric measuring system p-HPPA as well as related compounds serving as electron donating compounds were compared. Also the influence of different buffer systems, varying pH and substrate concentrations on signal intensity was investigated. Our results suggest that reaction conditions that favor the formation of Pummerer's type ketones lead to an increase in signal intensity rather than formation of fluorescent dye. Comparison with commercial ready-to-use HRP electron donating compounds such as 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), o-phenylenediamine (OPD) or 3,3′,5,5′-tetramethylbenzidine (TMB) showed that only 34%, 77% and 49% of the signal intensity of p-HPPA were reached, respectively.The optimized assay had a detection limit of 40 pg mL−1 and allowed detection of 500 pg mL−1 (FDA action limit) aflatoxin M1 (AFM1) in pasteurized milk and UHT-milk containing 0.3-3.8% fat within 10 min without any sample treatment. The working range was between 250 and 2000 pg mL−1 AFM1. 相似文献
999.
The standard molar Gibbs free energy of formation of Co2TiO4, CoTiO3, and CoTi2O5 as a function of temperature over an extended range (900 to 1675) K was measured using solid-state electrochemical cells incorporating yttria-stabilized zirconia as the electrolyte, with CoO as reference electrode and appropriate working electrodes. For the formation of the three compounds from their component oxides CoO with rock-salt and TiO2 with rutile structure, the Gibbs free energy changes are given by:Accurate values for enthalpy and entropy of formation were derived. The compounds Co2TiO4 with spinel structure and CoTi2O5 with pseudo-brookite structure were found to be entropy stabilized. The relatively high entropy of these compounds arises from the mixing of cations on specific crystallographic sites. The stoichiometry of CoTiO3 was confirmed by inert gas fusion analysis for oxygen. Because of partial oxidation of cobalt in air, the composition corresponding to the compound Co2TiO4 falls inside a two-phase field containing the spinel solid solution Co2TiO4–Co3O4 and CoTiO3. The spinel solid solution becomes progressively enriched in Co3O4 with decreasing temperature. 相似文献
1000.
Different RP-HPLC columns (phenyl, conventional ODS, cross-linked C(18) and special end-capped C(8) and C(18) phases) were used to investigate the separation of four basic ionizable isomers. Using ACN/20mM NH(4)OAc aq., a separation was observed exclusively on RP columns with higher silanol activity at unusual high ACN concentration, indicating cation-exchange as main retention mechanism. Using MeOH/20mM NH(4)OAc aq., another separation at low MeOH concentrations was observed on both, RP columns with higher as well as RP columns with lower silanol activity, which is mainly based on hydrophobic interactions. The isomers were also separated on a bare silica column at higher MeOH content using NH(4)OAc. Since cation-exchange governs this retention, the elution order was different compared to the RP phases. A strong retention on the silica column was observed in ACN, which could be attributed to partition processes as additional retention mechanism. 相似文献