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861.
Graham Smith Urs D. Wermuth 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(8):o428-o430
For the hydrated proton‐transfer compound 6‐chloro‐9‐[(4‐diethylammonio‐2‐methylbutyl)amino]‐2‐methoxyacridinium 3‐carboxylato‐4‐hydroxybenzenesulfonate dihydrate, C23H32ClN3O2+·C7H4O6S2−·2H2O, (I), the conformational features, specifically those of the extended side chain at the 9‐position of the acridine parent, have been compared with those of quinacrinium dichloride dihydrate (the drug atabrine or mepacrine). Racemic compound (I) has a three‐dimensional hydrogen‐bonded framework structure similar to atabrine but also involves the water molecules and both the carboxylate and sulfonate groups of the anion in structure extension. The comparable conformational features found in this uncommon derivative of quinacrine indicate that (I) has potential as a possible pharmaceutical substitute for atabrine. 相似文献
862.
Graham Smith Urs D. Wermuth Jonathan M. White 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(9):o532-o536
The crystal structures of the 1:1 proton‐transfer compounds of 4,5‐dichlorophthalic acid with the three isomeric monoaminobenzoic acids, namely the hydrate 2‐carboxyanilinium 2‐carboxy‐4,5‐dichlorobenzoate dihydrate, C7H8NO2+·C8H3Cl2O4−·2H2O, (I), and the anhydrous salts 3‐carboxyanilinium 2‐carboxy‐4,5‐dichlorobenzoate, C7H8NO2+·C8H3Cl2O4−, (II), and 4‐carboxyanilinium 2‐carboxy‐4,5‐dichlorobenzoate, C7H8NO2+·C8H3Cl2O4−, (III), have been determined at 130 K. Compound (I) has a two‐dimensional hydrogen‐bonded sheet structure, while (II) and (III) are three‐dimensional. All three compounds feature sheet substructures formed through anilinium N+—H...Ocarboxyl and anion carboxylic acid O—H...Ocarboxyl interactions and, in the case of (I), additionally linked through the donor and acceptor associations of the solvent water molecules. However, (II) and (III) have additional lateral extensions of these substructures though cyclic R22(8) associations involving the carboxylic acid groups of the cations. Also, (II) and (III) have cation–anion π–π aromatic ring interactions. This work provides further examples illustrating the regular formation of network substructures in the 1:1 proton‐transfer salts of 4,5‐dichlorophthalic acid with the bifunctional aromatic amines. 相似文献
863.
The P/GC—MS and TG/DTA analysis, in an inert atmosphere, of bis(diethyldithiocarbamato)diphenyl tin (IV) indicates that the thermal decomposition proceeds in two consecutive stages. Loss of the dithiocarbamate ligands and the phenyl groups occurs within the temperature range of 210–380°C leaving tin (II) sulphide as residue. The stability of the phenyl radical as a reactive intermediate, together with the unidentate bonding of the dithiocarbamate ligand, dramatically influence the major mode of thermal decomposition. 相似文献
864.
The substrate and field dependencies of surface SPINOE enhancements using optical pumping and magic angle spinning NMR were monitored. Relaxation rates and enhancements were examined to gain an understanding of the parameters that determine the SPINOE enhancement. (13)C-labeled deuterated methanol was adsorbed on three different substrates (SnO(2), TiO(2), Ti/SiO(2)) with heats of adsorption for xenon ranging from 14.2 to 22.6 kJ/mol. The different heats of adsorption led to a range of xenon coverages and xenon relaxation rates. Using a simple model along with experimental values for the xenon surface polarization and cross- and self-relaxation rates, the (13)C signal enhancement could be predicted and compared with experimental enhancement values. Magnetic field dependence studies were also made by monitoring the (13)C enhancements via SPINOE from hyperpolarized xenon at fields of 0.075, 4.7, and 9.4 T. The pertinent parameters necessary to achieve maximum SPINOE enhancement are discussed. 相似文献
865.
866.
A series of five gold(I) halide complexes with the two isomeric methoxy-substituted triarylphosphines, tris(2-methoxyphenyl)phosphine [P(oanis)3], [AuP(oanis)3X] [for X = Cl, (1); X = Br, (2) and X = I, (3)] and tris(4-methoxyphenyl)phosphine [P(panis)3], [AuP(panis)3X] [for X = Br (4) and X = I (5)] have been synthesized and characterized by single crystal X-ray diffraction and solution 31P{1H} NMR spectroscopy. The structure determinations confirm the expected presence of linear two-coordination about the gold centres in all five complexes with bond distance and angle data typical of this type of compound [Au–P, 2.239(2)–2.259(3) Å; Au–Cl, 2.294(2) Å; Au–Br, 2.385(2)–2.402(2) Å; Au–I, 2.546(1)–2.554(1) Å; P–Au–X; 175.3(1)–180°]. All analogues except the iodo complex 5 crystallize with one complex molecule in the crystallographic asymmetric unit. The bromo and iodo complexes 2 and 3 constitute a trigonal isomorphous set while the bromo complex 4 is also isomorphous with the previously determined chloro complex [AuP(panis)3Cl]. The 2-methoxy analogues are stabilized by significant methoxy-O?Au interactions. 相似文献
867.
Copper‐Catalyzed Cross‐Coupling of Boronic Esters with Aryl Iodides and Application to the Carboboration of Alkynes and Allenes 下载免费PDF全文
Yiqing Zhou Wei You Kevin B. Smith Prof. M. Kevin Brown 《Angewandte Chemie (International ed. in English)》2014,53(13):3475-3479
Copper‐catalyzed Suzuki–Miyaura‐type cross‐coupling and carboboration processes are reported. The cross‐couplings function well with a variety of substituted aryl iodides and aryl boronic esters and allows for orthogonal reactivity compared to palladium‐catalyzed processes. The carboboration method includes both alkynes and allenes and provides access to highly substituted and stereodefined vinyl boronic esters. The alkyne carboboration method is highlighted in the simple one‐pot synthesis of Tamoxifen. 相似文献
868.
D. H. Davies D. C. Phillips J. D. B. Smith 《Journal of polymer science. Part A, Polymer chemistry》1977,15(11):2673-2684
The zinc chloride-catalyzed polymerization of 2-vinylnaphthalene (VN) with both photoinitiation and electronitiation methods was examined. Good yields were obtained with both methods, the electroinitiated process being somewhat faster. The mechanism for polymerization initiation was investigated through a detailed comparison of the kinetics. Both initiation methods show a similar response to increasing input energy and to change in salt to monomer mole ratio. Both methods indicate formation of a ZnCl2–(2-VN)2 complex as intermediate with the formation of the species being rate-determining. These results, together with other similar investigations, are then used to deduce a mechanism that involves the formation of an electronically excited donor–acceptor complex. It is argued that in certain salt-stabilized, electron-delocalized, aromatic systems, such excitation is possible in electroinitiation. 相似文献
869.
Lewis acid promoted anomeric substitution reactions of a stereoselectively prepared hexahydro-2H,5H-pyrano[2,3-b]pyran-2-one derivative was studied as a model for diarylheptanoid synthesis. Aromatic nucleophiles consistently provided the expected thermodynamic C-aryl pyranoside product. 相似文献
870.