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61.
Madan G. Barthakur 《Tetrahedron letters》2006,47(28):4925-4927
An efficient one-pot synthesis of substituted 4H-thiopyrans has been accomplished from a three-component reaction of α,β-unsaturated ketones, Lawesson’s reagent and alkynes under microwave irradiation. 相似文献
62.
Four cone calix[4]arene-1,2-crown ethers each with two ionisable side arms containing dansyl groups are synthesised. The crown ether ring on the lower rim is varied from crown-4 to crown-5 with hydrogen or tert-butyl groups on the para position of the upper rim. Di(tetramethylammonium) salts of the di-ionised ligands are utilised for spectrofluorimetric titration experiments in MeCN. The influence of alkali metal, alkaline earth metal and selected transition and heavy metal (Co2+, Fe2+, Hg2+, Mn2+, Pb2+, Zn2+ and Fe3+) cations on the spectroscopic properties of the two dansyl groups linked to the lower rim of the conformationally locked, di-ionised calix[4]arene-1,2-crown ether frameworks is investigated by emission spectrophotometry. All of the metal cations induce red shifts in the emission spectra of the di-ionised ligands. The metal cations produce enhancement or quenching of the fluorescence emissions. Changes in the fluorescence emission as a function of the metal cation identity, the lower rim crown ether ring size and the absence or presence of upper rim tert-butyl groups are investigated. 相似文献
63.
64.
Shahabuddin Memon Ashfaque Ali Bhatti Asif Ali Bhatti Ümmühan Ocak Miraç Ocak 《Journal of the Iranian Chemical Society》2016,13(12):2275-2282
This article reports the selective sensing ability of a newly synthesized calix[4]arene Schiff base (C4TSB) derivative. C4TSB exhibited strong turn-off fluorescence affinity for Hg2+ and Au3+. The selective sensing ability of receptor was investigated in the presence of different co-existing competing ions. The limit of detection for Hg2+ and Au3+ was determined as 1.9 × 10?5 and 1.0 × 10?6 M, respectively. Receptor forms 1:1 stoichiometric complex with both metals and their binding constants were calculated as 7.9 × 103 M?1 for Hg2+ and 5.7 × 103 M?1 for Au3+. Complexes were also characterized through FT-IR spectroscopy. 相似文献
65.
66.
Relationship between topochemical indices and anti-HIV-1 (HTLV-III) inhibitory activity of 1-alkoxy-5-alkyl-6-(arylthio)uracils
has been studied. Superadjacency, an adjacency-cum-distance-based, topochemical index and Wiener’s, a distance-based, topochemical
index were calculated for a set of 36 1-alkoxy-5-alkyl-6-(arylthio)uracils. Resulting data were analyzed and suitable models
were developed after identification of the active ranges. Subsequently, a biological activity was assigned to each of the
compounds using these models and compared with the reported anti-HIV-1 activity. High accuracy of prediction was observed
using these models. Statistical analysis revealed significance of the proposed models as well as a lack of correlation between
the topochemical indices employed for the chosen data set. 相似文献
67.
68.
69.
Hwang IW Park M Ahn TK Yoon ZS Ko DM Kim D Ito F Ishibashi Y Khan SR Nagasawa Y Miyasaka H Ikeda C Takahashi R Ogawa K Satake A Kobuke Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(12):3753-3761
The excitation-energy-hopping (EEH) times within two-dimensional cyclic zinc(II)-porphyrin arrays 5 and 6, which were prepared by intermolecular coordination and ring-closing metathesis reaction of olefins, were deduced by modeling the EEH process based on the anisotropy depolarization as well as the exciton-exciton annihilation dynamics. Assuming the number of energy-hopping sites N = 5 and 6, the two different experimental observables, that is, anisotropy depolarization and exciton-excition annihilation times, consistently give the EEH times of 8.0 +/- 0.5 and 5.3 +/- 0.6 ps through the 1,3-phenylene linkages of 5 and 6, respectively. Accordingly, the self-assembled cyclic porphyrin arrays have proven to be well-defined two-dimensional models for natural light-harvesting complexes. 相似文献
70.
Seema Thakral A. K. Madan 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(3-4):203-209
In the present study, urea, a well-known adductor for linear compounds was successfully utilized for inclusion of glipizide—a
highly substituted cyclic organic compound through a modified technique. Formation of glipizide co-inclusion compounds in
urea was confirmed by FTIR, DSC and XRD. The minimum proportion of rapidly adductible endocyte (RAE) required for adduction
of glipizide in urea was estimated by a modified Zimmerschied calorimetric method. Urea–GLP–RAE inclusion compounds containing
varying proportions of guests were prepared and their thermal behaviour studied by DSC. The co-inclusion compounds were found
to exhibit good content uniformity. Through the formation of co-inclusion compounds of urea, it was possible to achieve steep
improvement in the dissolution efficiency of glipizide, which is a BCS class II drug. 相似文献