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61.
Manson JL Baldwin AG Scott BL Bendix J Del Sesto RE Goddard PA Kohama Y Tran HE Ghannadzadeh S Singleton J Lancaster T Möller JS Blundell SJ Pratt FL Zapf VS Kang J Lee C Whangbo MH Baines C 《Inorganic chemistry》2012,51(14):7520-7528
[Ni(HF(2))(3-Clpy)(4)]BF(4) (py = pyridine) is a simple one-dimensional (1D) coordination polymer composed of compressed NiN(4)F(2) octahedra that form chains with bridging HF(2)(-) ligands. In spite of significant distortion of the HF(2)(-) bridge, a quasi-1D antiferromagnetic (AFM) behavior was observed with J(FHF) = 4.86 K. 相似文献
62.
A necessary and sufficient condition is given for a sum of squares operator to be globally hypoelliptic on an N-dimensional torus. This condition is expressed in terms of Diophantine approximation properties of the coefficients. The proof of the Theorem is based on L2-estimates and microlocalization. 相似文献
63.
Duncan A. J. Harding Eric G. Hope Gregory A. Solan John Fawcett 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):m321-m322
The reaction between carbonyl fluoride and [Ir(COD)(PPh3)2]BF4 (COD is cycloocta‐1,5‐diene) in dichloromethane solution affords the novel title iridium salt, [IrCl2(C18H15P)2(CO)2]BF4. The cation lies across a twofold rotation axis in the space group P21212 and its structure confirms the presence in a cis relationship of two metal‐bound chlorides, while the phosphine ligands occupy a trans pair of sites. The anion also lies across a twofold rotation axis, and the F atoms are disordered over two sets of sites. 相似文献
64.
65.
14N- and 1H-Coupling constants, determined by ESR, ENDOR, and general-TRIPLE-resonance spectroscopy, are reported for the radical cations of tetrazinodi(heteroarenes) 1–8 . The results comply with the expectation that donor properties of these compounds are mainly due to the electron-rich dihydrotetrazine ring. 相似文献
66.
67.
68.
The ESR.-spectra of the radical anion of syn-1, 6; 8, 13-bis-oxido-[14]annulene have been recorded. The hyperfine structure of the electrolytically generated anion (solvent: N, N-dimethylformamide; gegenion: Et4N⊕) is that of an unassociated species; on the other hand, evidence of strong ion-pairing can be derived from the spectra of chemically prepared anions (solvent: 1,2-dimethoxyethane; gegenion: K⊕ or Na⊕). The distribution of the n-spin population confirms the conclusion previously drawn for the radical anion of 1,6-oxido-[70]annulene that the overall effect of the oxygen bridging is electron repelling. 相似文献
69.
Peter Fürderer Fabian Gerson Hiroaki Ohya-Nishiguchi Ingrid Bhm Henning Hopf 《Helvetica chimica acta》1979,62(8):2569-2576
The radical anions of the following substituted [2.2]paracyclophanes have been characterized by ESR. and ENDOR. spectroscopy: 4, 16-dicyano- ( o - 2 ), 4, 12-dicyano- ( p - 2 ), 4,5,12,13-tetracyano- ( 3 ) and 4,5,12,13-tetrakis (alkoxycarbonyl)- [2.2]paracyclophanes ( 4-R , where R = Me, Et, iPr or tBu is the ester alkyl group); 4,5-bis(methoxycarbonyl)[2.2]paracyclophane-12, 13-dicarboxylic anhydride ( 5 ); [2.2]paracyclophane-4,5:12, 13-tetracarboxylic bisanhydride ( 6 ) and bisimides ( 7-R , where R = H, D, Me or Ph is the substituent at the imide N-atom). Comparison of the hyperfine data for these radical anions with those for analogously substituted derivatives of benzene indicates that the most prominent coupling constants are approximately halved on passing from the latter to the former. Lowering of the symmetry, as a consequence of ion pairing, has been observed for the radical anions 4- i Pr \documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} and 4- t Bu \documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} associated with the counterion K ⊕ in 1,2-dimethoxyethane at 183 K, but not for 4-Me \documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} and 4-Et \documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} under the same conditions. This result suggests that the migration of K ⊕ between the preferred sited in two equivalent ion pairs is slowed down by the steric hindrance arising from the bulky iPr and tBu ester groups. 相似文献
70.
Christoph Elschenbroich Fabian Gerson Virgil Boekelheide 《Helvetica chimica acta》1975,58(5):1245-1253
The radical anion of trans-10b, 10c-dihydropyrene (V), which is formed upon reduction of the isomeric [2.2]metacyclophane-1,9-diene (III) with solvated electrons, has been identified by its ESR.-spectrum. The large coupling constant (19.1 Gauss), due to the two equivalent β-protons in the alkyl bridge, gives evidence of an important hyperfine interaction between the σ-MO's of the C(sp3)-H bonds and the singly occupied π-MO of the fourteen-membered perimeter. This finding supports the assumption that the unexpected energy sequence of the lowest antibonding perimeter MO's in the dihydropyrene V and its 10b, 10c-dimethyl derivative (VI) is determined by hyperconjugation rather than by the inductive effect of the alkyl bridge. When the solution of V○ in 1,2-dimethyoxyethane (DME) is brought in contact with an alkali metal mirror, an immediate conversion of VΦ into the radical anion of pyrene (IV) occurs. The anion IVΦ also results from reduction of [2.2.2](1,3,5)cyclophane-1,9,17-triene (VIII) with potassium in DME, whereas the radical anions of 4,5,9,10-tetrahydropyrene (II) and its 2,7-dimethyl-derivative (IX) are obtained by corresponding reactions of [2.2]metacyclophane (I) and [2.2.2](1,3,5)cyclophane (VII), respectively. 相似文献