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91.
H. Jory D. Wagner M. Blank S. Chu K. Felch 《International Journal of Infrared and Millimeter Waves》2001,22(10):1395-1407
A microwave system is described which allows testing of the quasi-optical mode converter in a gyrotron, which is completely assembled except for the attachment of the electron gun. Test results are presented for a TE6,2,1 gyrotron, and a similar design for a TE28,7,1 gyrotron is shown. 相似文献
92.
Dr. Jan H. Blank Dr. Salvador Moncho Allen M. Lunsford Prof. Edward N. Brothers Prof. Marcetta Y. Darensbourg Prof. Ashfaq A. Bengali 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12752-12760
The mechanism and energetics of CO, 1‐hexene, and 1‐hexyne substitution from the complexes (SBenz)2[Fe2(CO)6] (SBenz=SCH2Ph) ( 1 ‐CO), (SBenz)2[Fe2(CO)5(η2‐1‐hexene)] ( 1 ‐(η2‐1‐hexene)), and (SBenz)2[Fe2(CO)5(η2‐1‐hexyne)] ( 1 ‐(η2‐1‐hexyne)) were studied by using time‐resolved infrared spectroscopy. Exchange of both CO and 1‐hexyne by P(OEt)3 and pyridine, respectively, proceeds by a bimolecular mechanism. As similar activation enthalpies are obtained for both reactions, the rate‐determining step in both cases is assumed to be the rotation of the Fe(CO)2L (L=CO or 1‐hexyne) unit to accommodate the incoming ligand. The kinetic profile for the displacement of 1‐hexene is quite different than that for the alkyne and, in this case, both reaction channels, that is, dissociative (SN1) and associative (SN2), were found to be competitive. Because DFT calculations predict similar binding enthalpies of alkene and alkyne to the iron center, the results indicate that the bimolecular pathway in the case of the alkyne is lower in free energy than that of the alkene. In complexes of this type, subtle changes in the departing ligand characteristics and the nature of the mercapto bridge can influence the exchange mechanism, such that more than one reaction pathway is available for ligand substitution. The difference between this and the analogous study of (μ‐pdt)[Fe(CO)3]2 (pdt=S(CH2)3S) underscores the unique characteristics of a three‐atom S?S linker in the active site of diiron hydrogenases. 相似文献
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97.
I. B. Blank A. I. Yanovskii Yu. T. Struchkov I. V. Voznyi A. A. Suvorov M. A. Kuznetsov 《Russian Chemical Bulletin》1989,38(5):981-985
1. | It has been established by x-ray structure analysis that 5,5-dimethyl-1-pyrazolinio-Z-phthalimidoimidate exists in the Z,E-configuration. The basic relationships in structure of a new class of 1,3-bipolar compounds, azimines, have been established through a comparative analysis of literature data. |
2. | The similarity in structure between this compound and the sterically unstrained Z,E-2,3-dimethyl-1-phthalimidoazimine is fully consistent with the ease of addition of phthalimidonitrene to Z-azo compounds. |
98.
ter Steege DH Smits M de Lange CA Westwood NP Peel JB Visscher L 《Faraday discussions》2000,(115):259-69; discussion 303-30
A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods. 相似文献
99.
Mirenskaya I. I. Litvinenko V. I. Blank A. B. Belikov V. V. 《Chemistry of Natural Compounds》1970,6(6):781-782
Chemistry of Natural Compounds - 相似文献
100.
J. Sekulic J.E. ten Elshof D.H.A. Blank 《Journal of Sol-Gel Science and Technology》2004,31(1-3):201-204
A procedure for the preparation of microporous titania membranes by the polymeric sol-gel technique is reported. The influence of acid/titanium ratio, water/titanium ratio, method of mixing components and refluxing time on particle size and sol stability was investigated. The thermal evolution, structural characteristics and liquid permeation properties of calcined materials were studied. Highly reproducible amorphous microporous titania layers with pore sizes ≤0.8 nm were obtained on both mesoporous γ-alumina and titania/zirconia coated substrates. The upper limit of thermal stability of the amorphous phase is ~300°C. Higher calcination temperatures led to phase transformation into anatase, which was accompanied by a collapse of the microstructure. The material was found to be chemically stable in a wide pH interval. 相似文献