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221.
4-O-(2,6-diamino-2,3,4,6-tetradeoxy-3-C-methyl-β-L-arabino and lyxo-hexopyranosyl) and 4-O-(2-amino2,3,4,6-tetradeoxy-5-c-methyl-L-threo-hexopyranosyl-6-O-(3-amino-3-decxy-α-D-glucopyranosyl)-2-deoxystreptamine (, and ) were synthesized from a kanamycin B derivative () by regiospecific methylation and stereospecific hydrogenation followed by removal of masking groups, converting a D-sugar moiety (4-O-glycoside portion) into L-sugar. The usual conformation of and were determined as boat and skew by 250 MHz PMR spectra respectively. 相似文献
222.
Sun BY Sato Y Suenaga K Okazaki T Kishi N Sugai T Bandow S Iijima S Shinohara H 《Journal of the American Chemical Society》2005,127(51):17972-17973
Exohedral C60-based metallofullerenes, CsC60, have been synthesized and successfully encapsulated into single-wall carbon nanotubes (SWNTs) in high yield by reducing C60 molecules into anions. High-resolution transmission electron microscopy (HRTEM) images and in situ electron energy loss spectroscopy (EELS) indicate that Cs atoms and C60 molecules align within SWNTs as CsC60 exohedral metallofullerenes, and that the formal charge state of encaged CsC60 is expressed as Cs+1C60-1. The present peapods with the exohedral metallofullerenes provide a new insight and the possibility to fine-tune the electronic and transport properties of carbon nanotubes. 相似文献
223.
Single-step conversion of methanol into acetic acid (methyl acetate) has been found possible by use of Ru(II)-Sn(II) hetero-bimetallic catalysts. By analyzing the homogeneous solution reactions, reaction paths are elucidated. Applications of lacunary heteropolyanions as model oxide ligands and of Y-type zeolite as a unique support for the gas-phase reaction are presented. 相似文献
224.
Jong‐Ha Choi Takayoshi Suzuki Sumio Kaizaki 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):m539-m541
In the title compound, [CrBr2(C5H14N2)2]2Br2·HClO4·6H2O, there are two independent CrIII complex cations which are conformational isomers of each other. The Cr atoms lie respectively on a center of symmetry and on a mirror plane and have octahedral environments, coordinated by the N atoms of two 2,2‐dimethylpropane‐1,3‐diamine ligands and by two Br atoms in trans positions. The Cr—N and Cr—Br bond lengths are in the ranges 2.078 (3)–2.089 (3) and 2.4495 (9)–2.5017 (9) Å, respectively. The crystal structure consists of two CrIII complex cations, two Br? anions, a (ClO4)? anion and an [H13O6]+ hydrogen‐bonded cluster cation. 相似文献
225.
Kaizaki Sumio Kita Przemyslaw Wis´niewska Joanna Sakagami Narumi 《Transition Metal Chemistry》1997,22(3):229-233
The kinetics of anation of [Cr(S-pdtra)(H2O)] and [Cr(edtrp)(H2O)] complexes (S-pdtra=S-propane-1,2-diamine-N,N,N -triacetate, edtrp=ethylenediamine-N, N,N-tripropionate) by thiocyanates and aquation of the [Cr(NCS)(S-pdtra)]– and [Cr(NCS)(edtrp)]– ions have been studied in aqueous HClO4 solutions. The rate laws and the activation parameters have been determined and discussed. The observed decrease in reactivity for the edtrp complexes corresponds with a changeover of the reaction mechanism from Ia to Id for reactions of the CrIII-S-pdtra and CrIII-edtrp species, respectively. 相似文献
226.
Fumio Hamazu Sumio Akashi Tatsuya Koizumi Toshikazu Takata Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1991,29(13):1845-1851
Benzyl o-, m-, and p-substituted phenyl methyl sulfonium salts ( 2b – 2g ) were synthesized and their activities as cationic initiators were evaluated in the bulk polymerization of phenyl glycidyl ether (PGE). Especially, their activities were estimated with respect to the effect of substituents on the aryl groups. In the polymerizations of PGE with a series of benzyl p-substituted phenyl methyl sulfonium salts, the order of their activities was found to be 2c (CH3OCOO) > 2b (CH3COO) > 2d (CH3O) ~ 2a (HO). In particular, 2c was the most active initiator of all, capable of initiating the polymerization of PGE even at room temperature. In the polymerizations with 2a, 2e (m-Cl), 2f (o-CH3), and 2g (m-CH3), the activity of 2e was the highest of all while those of 2a, 2f , and 2g were almost the same. These results strongly suggested that the electron-withdrawing group placed on the aryl group undoubtedly enhanced the activity of the sulfonium salts as the cationic initiators. 相似文献
227.
Jun-ichiro Inoue Sumio Ishihara Wataru Koshibae Sadamichi Maekawa 《Czechoslovak Journal of Physics》1996,46(4):1861-1862
An effective Hamiltonian of perovskite type LaMnO3 is derived by taking into account the degeneracy ofe g orbitals, Hund coupling and strong Coulomb interactions betweend-electrons in Mn ions. Spin and orbital excitations are calculated by using the effective Hamiltonian. 相似文献
228.
229.
Okazaki T Okubo S Nakanishi T Joung SK Saito T Otani M Okada S Bandow S Iijima S 《Journal of the American Chemical Society》2008,130(12):4122-4128
We report optical band gap modifications of single-walled carbon nanotubes upon C60 insertions by using photoluminescence and the corresponding excitation spectroscopy. The shifts in optical transition energies strongly depend on the tube diameter (dt) and the "2n + m" family type, which can be explained by the local strain and the hybridization between the nanotube states and the C60 molecular orbitals. The present results provide possible design rules for nanotube-based heterostructures having a specific type of electronic functionality. 相似文献
230.