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101.
102.
Dr. Matthieu Autillo Md. Ashraful Islam Julie Héron Laetitia Guérin Dr. Eleonor Acher Dr. Christelle Tamain Dr. Marie-Claire Illy Dr. Philippe Moisy Dr. Eric Colineau Dr. Jean-Christophe Griveau Dr. Claude Berthon Dr. Hélène Bolvin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(24):7138-7153
Actinide +VI complexes ( = , and ) with dipicolinic acid derivatives were synthesized and characterized by powder XRD, SQUID magnetometry and NMR spectroscopy. In addition, and complexes were described by first principles CAS based and two-component spin-restricted DFT methods. The analysis of the 1H paramagnetic NMR chemical shifts for all protons of the ligands according to the X-rays structures shows that the Fermi contact contribution is negligible in agreement with spin density determined by unrestricted DFT. The magnetic susceptibility tensor is determined by combining SQUID, pNMR shifts and Evans’ method. The SO-RASPT2 results fit well the experimental magnetic susceptibility and pNMR chemical shifts. The role of the counterions in the solid phase is pointed out; their presence impacts the magnetic properties of the complex. The temperature dependence of the pNMR chemical shifts has a strong contribution, contrarily to Bleaney's theory for lanthanide complexes. The fitting of the temperature dependence of the pNMR chemical shifts and SQUID magnetic susceptibility by a two-Kramers-doublet model for the complex and a non-Kramers-doublet model for the complex allows for the experimental evaluation of energy gaps and magnetic moments of the paramagnetic center. 相似文献
103.
《Mendeleev Communications》2021,31(5):612-614
The high-level ab initio calculations on several derivatives of bicyclo[3.3.1]nonane, 1-aza- and 1,5-diazabicyclo[3.3.1]-nonanes show the ‘double chair’ (CC) conformer as optimal for all of them, dominating over the ‘boat–chair’ (BC) form. Conformational effects of several substitution types involving positions 1, 5 and 9 are quantified, and their values are found rather transferable. 相似文献
104.
Inside Back Cover: A Terminal,Fluxional η4‐Benzene Complex with a Thermally Accessible Triplet State is the Primary Photoproduct in the Intercyclobutadiene Haptotropism of (CpCo)phenylenes (Chem. Eur. J. 12/2015) 下载免费PDF全文
105.
Formation and dissociation of protonated cytosine–cytosine base pairs in i-motifs by ab initio quantum chemical calculations 下载免费PDF全文
Formation and dissociation mechanisms of C-C+ base pairs in acidic and alkaline environments are investigated, employing ab initio quantum chemical calculations. Our calculations suggest that, in an acidic environment, a cytosine monomer is first protonated and then dimerized with an unprotonated cytosine monomer to form a C-C+ base pair; in an alkaline environment, a protonated cytosine dimer is first unprotonated and then dissociated into two cytosine monomers. In addition, the force for detaching a C-C+ base pair was found to be inversely proportional to the distance between the two cytosine monomers. These results provide a microscopic mechanism to qualitatively explain the experimentally observed reversible formation and dissociation of i-motifs. 相似文献
106.
Dr. Chunlin Chen Prof. Zhongchang Wang Dr. Mitsuhiro Saito Dr. Tetsuya Tohei Prof. Yoshiro Takano Prof. Yuichi Ikuhara 《Angewandte Chemie (International ed. in English)》2014,53(6):1543-1547
Atomic‐resolution imaging of beam‐sensitive biominerals is extremely challenging, owing to their fairly complex structures and the damage caused by electron irradiation. Herein, we overcome these difficulties by performing aberration‐corrected electron microscopy with low‐dose imaging techniques, and report the successful direct atomic‐resolution imaging of every individual atomic column in the complex fluorapatite structure of shark tooth enameloid, which can be of paramount importance for teeth in general. We demonstrate that every individual atomic column in shark tooth enameloid can be spatially resolved, and has a complex fluorapatite structure. Furthermore, ab initio calculations show that fluorine atoms can be covalently bound to the surrounding calcium atoms, which improves understanding of their caries‐reducing effects in shark teeth. 相似文献
107.
Włodzimierz Makulski Adam Tulewicz Andrzej Leś 《Magnetic resonance in chemistry : MRC》2014,52(3):106-110
In a recent 17O NMR spectra of liquid sulfur trioxide, several unexpected peaks appeared with the temperature‐dependent integrated peak ratio. In order to interpret NMR spectra and assign peaks to possible molecular structures, the theoretical quantum mechanical density functional theory and Møller–Plesset second‐order perturbation theory calculations were performed. It is suggested that in the liquid sulfur trioxide, apart from monomeric SO3, a significant amount of (SO3)3 cyclic trimers should appear. No theoretical data support hypothesis on (SO3)2 dimers formation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
108.
《Journal of Coordination Chemistry》2012,65(11):2021-2027
Results of quantum-chemical calculations of MCl4–C6H5COCl (M=Si, Ge, Sn) systems of 1?:?1 composition using RHF/3-21?G* and MP2/3-21?G* levels as well as those of 1?:?2 composition using the RHF/3-21?G* level have been represented. MCl4?←?C6H5COCl complexes of 1?:?1 composition are energetically more advantageous. They are formed in solid state provided that the M···O distance in individual systems is considerably less than the sum of van der Waals radii of M and O and their total energies are appreciably less than the sum of total energies of components. These conditions are realized only for M=Sn. In systems of 1?:?2 compositions, calculated M···O distances are practically equal to the sum of covalent radii of M and O. Nonetheless, complexes with such composition are not formed in solid state. Total energy of the system which is lower than the sum of its components’ energies is not an indispensable condition for complex formation. The 35Cl nuclear quadrupole resonance (NQR) frequencies and asymmetry parameters of the electric field gradient at the 35Cl nuclei have been evaluated using the results of ab initio calculations. 相似文献
109.
110.