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991.
992.
Glutathione tripeptide (γ-glutamyl-cysteinyl-glycine) is a flexible molecule and its conformational energy landscape is strongly influenced by forming intramolecular hydrogen bond, its charge and the environment. This study employs DFT-B3LYP method with the 6-31+G (d,p) basis set to carry out conformational analysis of neutral, zwitterionic, cationic, and anionic forms of glutathione. In analyzing the structural characteristics of these structures, intramolecular hydrogen bonds were identified and characterized in details by topological parameters such as electron density ρ(r) and Laplacian of electron density $ \nabla^{2} $ ρ(r) from Bader’s atom in molecules theory. Charge transfer energies based on natural bond orbital analysis are also considered to interpret these intramolecular hydrogen bonds. Our results show that these hydrogen bonds are partially electrostatic and partially covalent in nature, in which the covalent contribution increases as the stabilization energy of hydrogen bond increases. Furthermore, the back bone and side chain (Ramachandran map) orientations of various ionic forms of glutathione have been studied and conformation of each constitution of glutathione tripeptide (i.e., Glu, Cys, and Gly moieties) was determined. In most species side chain conformation were found to be hindered gauche–gauche orientation by intramolecular hydrogen bonds. 相似文献
993.
994.
995.
Hasani M Rezaei A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,65(5):1093-1097
The charge-transfer complex formation of iodine with antipyrine has been studied spectrophotometrically in chloroform, dichloromethane (DCM) and 1,2-dichloroethane (DCE) solutions at 25 degrees C. The results indicate the formation of 1:1 charge-transfer complexes. The observed time dependence of the charge-transfer band and subsequent formation of I(3)(-) in solution were related to the slow transformation of the initially formed 1:1 antipyrine:I(2) outer complex to an inner electron donor-acceptor (EDA) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion. The values of the equilibrium constant, K, are calculated for each complex and the influence of the solvent properties on the formation of EDA complexes and the rates of subsequent reaction is evaluated. 相似文献
996.
Sima Sedighi Mohammad T. Baei Masoud Javan Joshua Charles Ince Alireza Soltani Mohammad Hassan Jokar Samaneh Tavassoli 《Surface and interface analysis : SIA》2020,52(11):725-734
This study provides details of the electronic and optical structures and binding energies of sarin (SF) and chlorosarin (SC) with Al–N and Al–P surfaces of Al12N12 and Al12P12 nanoclusters in the gas phase. The adsorption mechanism of SF and SC on these nanoclusters containing the Al3+ central cation was studied. Optimized geometries and thermodynamic parameters of SF and SC adsorption complexes were calculated. SF and SC are chemisorbed on these nanoclusters because of the formation of PO···Al bonds. The chemical bond is formed between an oxygen atom of SF and SC and an aluminum atom of fullerene-likes (chemisorption). However, the binding energies of the complexes with the Al12N12 nanocluster are larger than these values for the Al12P12 nanocluster. The interaction enthalpy and Gibbs free energy of all studied systems were found to be negative. We can conclude that SF and SC will be adsorbed preferably on Al12N12 nanocluster. 相似文献
997.
Farzaneh Sefidabi Alireza Abbasi Saeideh-Sadat Mortazavi Majid Masteri-Farahani 《应用有机金属化学》2020,34(10):e5890
A self-assembled new 2D cadmium network, [Cd (BDC-OH)(DMF)2·DMF]n (Cd-BDC-OH), was synthesized based on 2-hydroxyterephthalic acid (BDC-OH) ligand and utilized as a heterogeneous catalyst for Knoevenagel condensation. The structure was fully elucidated by single-crystal X-ray diffraction, Hirshfeld surface analysis, powder X-ray diffraction, field emission-scanning electron microscopy, Fourier transform-infrared spectroscopy and thermogravimetric analysis. The fabricated coordination polymer exhibited high catalytic activity under ambient conditions, and was used without significant drop in product yield in further cycles. 相似文献
998.
Maryam Mohammadi-Khanaposhtani Hoda Yahyavi Somaye Imanparast Fereshte Nazemi Harandi Mohammad Ali Faramarzi Alireza Foroumadi Bagher Larijani Mahmood Biglar Mohammad Mahdavi 《中国化学会会志》2020,67(5):856-863
Benzoylquinazolinone derivatives 3a–n were synthesized via a simple one-step reaction, and evaluated for in vitro α-glucosidase inhibitory activity. Compounds 3d , 3f–g , 3i , and 3m–n showed more inhibitory activity than standard drug acarbose (IC50 = 750.0 ± 1.5 μM), and among them, compound 3d displayed the highest α-glucosidase inhibitory activity (IC50 = 261.6 ± 0.1 μM). The kinetic analysis of the compound 3d revealed that this compound inhibited α-glucosidase in a competitive manner (Ki = 255 μM). The docking studies were applied to predict binding modes of the synthesized compounds in active site of α-glucosidase. 相似文献
999.
The reaction mechanism of the Pd-catalyzed benzyl/allyl coupling of benzyl chloride with allyltributylstannan, resulting in the dearomatization of the benzyl group, was studied using density functional theory calculations at the B3LYP level. The calculations indicate that the intermediate (eta(3)-benzyl)(eta(1)-allyl)Pd(PH(3)) is responsible for the formation of the kinetically favored dearomatic product. Reductive elimination of the dearomatic product from the intermediate occurs by coupling the C-3 terminus of the eta(1)-allyl ligand and the para-carbon of the eta(3)-benzyl ligand in (eta(3)-benzyl)(eta(1)-allyl)Pd(PH(3)). For comparison, various C-C coupling reaction pathways have also been examined. 相似文献
1000.
Abdolahi Nafiseh Javan Masoud Bezi Katin Konstantin P. Soltani Alireza Shojaee Shamim Kaveh Sara 《Structural chemistry》2020,31(5):1959-1967
Structural Chemistry - Herein, we evaluated the adsorption of thiazole over the surface of BC2N nanotube using PBE and M06-2X functionals and 6-311G** standard basis set. We considered one and two... 相似文献