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91.
Concepción P Corma A Silvestre-Albero J Franco V Chane-Ching JY 《Journal of the American Chemical Society》2004,126(17):5523-5532
Pt on mesostructured CeO(2) nanoparticles embedded within ultrathin layers of highly structured SiO(2) binder shows highest activity reported with 80% selectivity for the chemoselective hydrogenation of crotonaldehyde. Characterization by transmission electron microscopy (TEM), CO adsorption, and X-ray photoelectron spectroscopy (XPS) show the presence of small Pt metal particles, preferentially located on CeO(2) (70%) together with the formation of Pt-CeO(2-x) sites at the interface between Pt and CeO(2) (4 nm) nanoparticles. These sites are able to polarize the carbonyl group and facilitate the selective hydrogenation of this with respect to the double bond. 相似文献
92.
Andrs Zelcer Zulema D. Chaia Fabio D. Cukiernik Oscar E. Piro Eduardo E. Castellano 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):m144-m146
The title compound, catena‐poly[[tetrakis(μ‐decanoato‐κ2O:O′)diruthenium(II,III)(Ru—Ru)]‐μ‐octanesulfonato‐κ2O:O′], [Ru2(C10H19O2)4(C8H17O3S)], is an octanesulfonate derivative of the mixed‐valence complex diruthenium tetradecanoate. The equatorial carboxylate ligands are bidentate, bridging two Ru atoms to form a dinuclear structure. Each of the two independent dinuclear metal complexes in the asymmetric unit is located at an inversion centre. The octanesulfonate anion bridges the two dinuclear units through axial coordination. The alkyl chains of the carboxylate and sulfonate ligands are arranged in a parallel manner. The global structure can be seen as infinite chains of polar moieties separated by a double layer of non‐polar alkyl groups, without interdigitation of the alkyl chains. 相似文献
93.
Fontana José D. Almeida Eduardo R. A. Baron Madalena Guimaraes Manoel F. Deschamps Francisco C. Schwartsmann Gllberto Cervi Armando C. Zanette Flávio Vilegas Janete LanÇas Fernando M. 《Applied biochemistry and biotechnology》1994,(1):295-313
The acetogenins are strongly bioactive natural compounds present in the bark, roots, leaves, and seeds of manyAnnonaceae plants. They are modified fatty acids and their cytotoxicities have been determined for different biological models including
the in vitro growth inhibition of several human cancer cell lines.
Very low acetogenin yield (< 0.1 g%) has been found previously in native phytobiomass, and we have now investigated the nonpredatory
exploitation of the seeds as acetogenin sources characterizing the seed triacylglycerols (dominant fraction; > 90% of the
whole lipid extracts) as potential valuable by-products. 相似文献
94.
Eduardo Corts Corts Rafael Sosa Mendoza Maximiliano Santibez Gutirrez Olivia Garca‐Mellado De Corts 《Journal of heterocyclic chemistry》2004,41(2):273-276
The preparation and spectral properties often novel methyl 5‐[(o‐, m‐, and p‐substituted)‐phenylthio]‐2‐benzimidazolecarbamates with possible pharmacological activity as antihelmintics is described; by condensation and cyclization between 5‐methylthioures sulfate chloroformic acid methyl ester and 3,4‐diaminophenyl‐substituted‐phenylthio ether dissolved in ethanol. The structures of all final products were corroborated by ir; 1H‐nmr, 13C‐nmr and ms. 相似文献
95.
96.
Martín M Torres O Oñate E Sola E Oro LA 《Journal of the American Chemical Society》2005,127(51):18074-18084
In the presence of ligands such as acetonitrile, ethylene, or propylene, the Ir(I) complex [Ir(1,2,5,6-eta-C8H12)(NCMe)(PMe3)]BF4 (1) transforms into the Ir(III) derivatives [Ir(1-kappa-4,5,6-eta-C8H12)(NCMe)(L)(PMe3)]BF4 (L = NCMe, 2; eta2-C2H4, 3; eta2-C3H6, 4), respectively, through a sequence of C-H oxidative addition and insertion elementary steps. The rate of this transformation depends on the nature of L and, in the case of NCMe, the pseudo-first-order rate constants display a dependence upon ligand concentration suggesting the formation of five-coordinate reaction intermediates. A similar reaction between 1 and vinyl acetate affords the Ir(III) complex [Ir(1-kappa-4,5,6-eta-C8H12){kappa-O-eta2-OC(Me)OC2H3}(PMe3)]BF4 (7) via the isolable five-coordinate Ir(I) compound [Ir(1,2,5,6-eta-C8H12){kappa-O-eta2-OC(Me)OC2H3}(PMe3)]BF4 (6). DFT (B3LYP) calculations in model complexes show that reactions initiated by acetonitrile or ethylene five-coordinate adducts involve C-H oxidative addition transition states of lower energy than that found in the absence of these ligands. Key species in these ligand-assisted transformations are the distorted (nonsquare-planar) intermediates preceding the intramolecular C-H oxidative addition step, which are generated after release of one cyclooctadiene double bond from the five-coordinate species. The feasibility of this mechanism is also investigated for complexes [IrCl(L)(PiPr3)2] (L = eta2-C2H4, 27; eta2-C3H6, 28). In the presence of NCMe, these complexes afford the C-H activation products [IrClH(CH=CHR)(NCMe)(PiPr3)2] (R = H, 29; Me, 30) via the common cyclometalated intermediate [IrClH{kappa-P,C-P(iPr)2CH(CH3)CH2}(NCMe)(PiPr3)] (31). The most effective C-H oxidative addition mechanism seems to involve three-coordinate intermediates generated by photochemical release of the alkene ligand. However, in the absence of light, the reaction rates display dependences upon NCMe concentration again indicating the intermediacy of five-coordinate acetonitrile adducts. 相似文献
97.
Eduardo Corts Cortas Miryan Adaya Baos Olivia García‐Mellado De Corts 《Journal of heterocyclic chemistry》2004,41(2):277-280
A new synthesis to obtain eleven novel derivatives of 11‐[(o‐ m‐ and p‐substituted)‐phenyl]‐8‐chloro‐3,3‐dimethyl‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐ones with possible pharmacological activity in the central nervous system in two efficient steps has been developed. The final products were obtained by condensation and cyclization between 3‐[4‐chloro‐1,2‐phenylenediamine]‐5,5‐dimethyl‐2‐cyclohexenone with (o‐ m‐ and p‐substituted)benzaldehyde. The structure of all products was corroborated by ir, 1H‐nmr, 13C‐nmr and high resolution in ms. 相似文献
98.
Eduardo Corts Corts Isidro Ebromares Martínez Olivia García Mellado 《Journal of heterocyclic chemistry》2002,39(6):1189-1193
A series of twelve new 7‐chloro‐5‐[(o‐ and p‐R1)phenyl]‐1‐R2‐3H‐[1,4] benzo‐diazepin‐2‐ones, which have possible pharmacological properties were synthesized. The synthesis of all the final compounds was carried out by four steps. The structure of all final products was corroborated by ir, 1H nmr, 13C nmr and ms, and have been obtained in 35‐94% yield. 相似文献
99.
100.