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51.
Dy3+-doped SrB4O7 phosphors were synthesized by solid-state reaction. The luminescence properties of white-light SrB4O7:Dy3+ under vacuum ultraviolet (VUV) excitation were firstly investigated. According to strong absorption around 147 nm in excitation spectra, energy can easily be transferred to the energy levels of Dy3+ from host absorption, and hence luminescence of SrB4O7:Dy3+ under VUV excitation was effective, and it has the potential of being applied to a white lamp-house for mercury-free lamp. 相似文献
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Peng‐Fei Gou Wei‐Pu Zhu Ning Xu Zhi‐Quan Shen 《Journal of polymer science. Part A, Polymer chemistry》2009,47(24):6962-6976
Well‐defined drug‐conjugated amphiphilic A2B2 miktoarm star copolymers [(PCL)2‐(PEG)2‐D] were prepared by the combination of controlled ring‐opening polymerization (CROP) and “click” reaction strategy. First, bromide functionalized poly(ε‐caprolactone) (PCL‐Br) with double hydroxyl end groups was synthesized by the CROP of ε‐caprolactone using 2,2‐bis(bromomethyl)propane‐1,3‐diol as a difunctional initiator in the presence of Sn(Oct)2 at 110 °C. Next, the bromide groups of PCL‐Br were quantitatively converted to azide form by NaN3 to give PCL‐N3. Subsequently, the end hydroxyl groups of PCL‐N3 were capped with ibuprofen as a model drug at room temperature. Finally, copper(I)‐catalyzed cycloaddition reaction between ibuprofen‐conjugated PCL‐N3 and slightly excess alkyne‐terminated poly(ethylene glycol) (A‐PEG) led to ibuprofen‐conjugated A2B2 miktoarm star copolymer [(PCL)2‐(PEG)2‐D]. The excess A‐PEG was removed by dialysis. 1H NMR, FTIR and SEC analyzes confirmed the expected miktoarm star architecture. These amphiphilic miktoarm star copolymers could self‐assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). In addition, the drug‐loading capacity of these drug‐conjugated miktoarm star copolymers as well as their nondrug‐conjugated analogs were also investigated in detail. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009 相似文献
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Xingxing Gou Xiaohua Pu Zongxiao Li 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(11):2110-2116
In this paper, we selected quercetin and aromatic amino acids (tryptophan, tyrosine, phenylalanine) as the research objects to investigate the change rules in the reaction process. The thermodynamic functions (Ka, ΔG, and ΔS) of the interactions between quercetin and aromatic amino acids (tryptophan, tyrosine, phenylalanine) were measured by isothermal titration calorimetry. The values of binding constant (Ka) reached maximum at 25°C; the entropies and Gibbs free energies were both negative at different temperatures. The kinetic parameters of quercetin and amino acids in the interaction process was determined by microcalorimetry. The results inferred that the driving force of the reaction was hydrogen bond or van der Waals force. 相似文献
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Based on the analysis of the near-field evanescent wave in total internal reflection, the flip-chip light-emitting diode (LED) structure was proposed by placing a plasmonic Ag grating and a perforated sapphire grating in the substrate. The finite difference time domain (FDTD) method has been applied to study the spectral properties of the hybrid structure and the enhancement factor of light extraction efficiency of the LED model. From the computation examples, the effects of structure parameters on the extraction enhancement have been investigated. The results indicate that the plasmonic grating can enhance the near-field evanescent wave and couple it to propagation wave in the specific wavelength bands, which leads to the photons emitting out of the LED chip with high extraction efficiency. Due to the combined gratings used, the enhancement factor of the light extraction efficiency can reach approximately 4 times at a relatively longer wavelength. 相似文献
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Asymmetric 1,4‐conjugation addition of dialkylzinc (diethylzinc and dimethylzinc) to cyclic enones, chalcone and nitroalkenes was achieved by a 25 mol% (R)‐6,6′‐Br2‐BINOL( 1f ), 25 mol% CuSPh and 100 mol% dicyclohexylmethylamin(Cy2NMe) catalyst system. The Cu(I) catalyst system enables the cyclic enone, chalcone and nitroalkene generality with high enantioselectivity (up to 84% ee) and isolated yield (up to 94%) under mild reaction conditions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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