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991.
Menggenbateer Giovanni Ferrara Tienan Jin Yoshinori Yamamoto 《Tetrahedron letters》2010,51(35):4627-1712
AuBr3-catalyzed regiospecific intermolecular hydrothiolation of aromatic allenes and aromatic thiols afforded the corresponding dithioacetals in good yields at 0 °C in 5 min. 相似文献
992.
Farid Jahouh Rina Saksena Donatella Aiello Anna Napoli Giovanni Sindona Pavol Kováč Joseph H. Banoub 《Journal of mass spectrometry : JMS》2010,45(10):1148-1159
We present the MALDI‐TOF/TOF‐MS analyses of various hapten–bovine serum albumin (BSA) neoglycoconjugates obtained by squaric acid chemistry coupling of the spacer‐equipped, terminal monosaccharide of the O‐specific polysaccharide of Vibrio cholerae O1, serotype Ogawa, to BSA. These analyses allowed not only to calculate the molecular masses of the hapten–BSA neoglycoconjugates with different hapten–BSA ratios (4.3, 6.6 and 13.2) but, more importantly, also to localize the covalent linkages (conjugation sites) between the hapten and the carrier protein. Determination of the site of glycation was based on comparison of the MALDI‐TOF/TOF‐MS analysis of the peptides resulting from the digestion of BSA with similar data resulting from the digestion of BSA glycoconjugates, followed by sequencing by MALDI‐TOF/TOF‐MS/MS of the glycated peptides. The product‐ion scans of the protonated molecules were carried out with a MALDI‐TOF/TOF‐MS/MS tandem mass spectrometer equipped with a high‐collision energy cell. The high‐energy collision‐induced dissociation (CID) spectra afforded product ions formed by fragmentation of the carbohydrate hapten and amino acid sequences conjugated with fragments of the carbohydrate hapten. We were able to identify three conjugation sites on lysine residues (Lys235, Lys437 and Lys455). It was shown that these lysine residues are very reactive and bind lysine specific reagents. We presume that these Lys residues belong to those that are considered to be sterically more accessible on the surface of the tridimensional structure. The identification of the y‐series product ions was very useful for the sequencing of various peptides. The series of a‐ and b‐product ions confirmed the sequence of the conjugated peptides. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
993.
Alessia Aprea Valentina Colombo Simona Galli Norberto Masciocchi Angelo Maspero Giovanni Palmisano 《Solid State Sciences》2010,12(5):795-802
Thiazolo[5,4-d]thiazole-2,5-dicarboxylic acid, C6H2N2O4S2, was isolated as a polycrystalline material, and its crystal structure was determined by ab-initio X-ray powder diffraction (XRPD) methods. This species, upon deprotonation, was subsequently used in preparing the new coordination polymers Ag2(C6N2O4S2), Mn(C6N2O4S2)(H2O)2, Co(C6N2O4S2)(H2O)2, Cu(C6N2O4S2)(H2O) and Zn(C6N2O4S2)(H2O)2, fully characterized by analytical, thermal and XRPD structural methods – including in situ thermodiffractometry and simultaneous TGA and DSC. In the first-row transition metal derivatives, the [C6N2O4S2]2? anion systematically prefers the N,O-chelating, vs. the expected O,O′-bridging, coordination mode, not allowing the formation of porous 3D frameworks. Indeed, these species are dense 1D coordination polymers. At variance, the silver derivative possesses a complex, dense 3D framework, due to the presence of μ6-[C6N2O4S2]2? ligands showing two μ2-bridging carboxylates and two monohapto N-donor sites. When dehydration is viable, materials of En(C6N2O4S2) formulation are irreversibly recovered (n = 1 for E = Mn, Co, Zn, Cu; n = 2, for E = H). 相似文献
994.
995.
Calucci L Cloke FG Englert U Hitchcock PB Pampaloni G Pinzino C Puccini F Volpe M 《Dalton transactions (Cambridge, England : 2003)》2006,(35):4228-4234
M(eta(6)-arene)(2) species (M = Cr, arene = 1,3,5-Me(3)C(6)H(3); M = Mo, arene = 1,3,5-Me(3)C(6)H(3), 1,3,5-(i)Pr(3)C(6)H(3)), have been prepared by a modified Fischer-Hafner synthesis or by metal vapour techniques. The reaction of Cr(eta(6)-1,3,5-Me(3)C(6)H(3))(2) with the fulvene derivatives pentacarbomethoxycyclopentadiene (pcmcpH), 1-benzoyl-6-hydroxy-6-phenylfulvene (dbcpH), or 1-benzoyl-3-nitro-6-hydroxy-6-phenylfulvene (dbncpH) proceeds with evolution of dihydrogen and formation of the ionic derivatives [Cr(eta(6)-1,3,5-Me(3)C(6)H(3))(2)][E], where E = pcmcp, dbcp, or dbncp. Mo(eta(6)-arene)(2) derivatives (arene = toluene, 1,3,5-Me(3)C(6)H(3), 1,3,5-(i)Pr(3)C(6)H(3)) are oxidized to [Mo(eta(6)-arene)(2)](+) by pcmcpH. The crystal and molecular structures of [M(eta(6)-1,3,5-R(3)C(6)H(3))(2)][pcmcp] (M = Cr, R = Me; M = Mo, R = Me, (i)Pr) have been solved by X-ray single crystal diffraction. 相似文献
996.
The interaction of small gold clusters (Au(n), n = 1-4, 20) and a gold monolayer with the MgO (100) surface surrounding a neutral oxygen vacancy (F(s) center) is investigated using density-functional (DF) calculations. It is found that the presence of the defect modifies the interaction of gold not only with the vacancy itself, but also with the oxygen and magnesium atoms around it by increasing both the adhesion energy and the equilibrium bond distances. This is at variance with the interaction of metal atoms with the regular MgO (100) surface or the F(s) defect itself, in which an increase of the adhesion energy is associated with a shortening of the metal-surface distance. The resulting double frustration and cylindrical invariance of the metal-surface interaction cause small gold clusters growing around an F(s) nucleation center to be highly fluxional in terms both of rotational freedom and of multiple competing structural motifs. Fragmentation energies of the gold clusters are also discussed, finding that the lowest-energy pathway corresponds to the detachment of a dimer. 相似文献
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