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961.
962.
An investigation has been carried out on the influence of the velocity of voltage change, of the radius of the capillary and of the size of the electrodes on the decrease of the peak current caused by back-diffusion in anodic amalgam voltammetry. 相似文献
963.
964.
The cellulose solvent Pd-en, an aqueous solution of [(en)Pd(II)(OH)(2)] (en=ethylenediamine), reacts with the monosaccharides D-arabinose (D-Ara), D-ribose (D-Rib), rac-mannose (rac-Man), and D-galactose (D-Gal) under formation of dimetalated aldose complexes, if the molar ratio of Pd and sugar is 2:1 or larger. In the Pd(2) complexes, the aldoses are tetra-deprotonated and act as bisdiolato ligands. Two crystalline pentose complexes were isolated: [(en)(2)Pd(2)(beta-D-Arap1,2,3,4 H(-4))].5 H(2)O (1) and [(en)(2)Pd(2)(beta-D-Ribp1,2,3,4 H(-4))].6.5 H(2)O (2), along with two hexose complexes. With rac-Man, the major solution species is crystallized as the 9.4-hydrate [(en)(2)Pd(2)(beta-rac-Manp1,2,3,4 H(-4))].9.4 H(2)O (3). From the respective D-Gal solutions, [(en)(2)Pd(2)(beta-D-Galf1,3,5,6 H(-4))].5 H(2)O.C(2)H(5)OH (4), with the sugar tetraanion in its furanose form, is crystallized though it is not the major species, rather the second most abundant in purely aqueous solutions. The Galf species is enriched in the mother liquors to the extent of 25 % of total sugar content. Substitution of the en ligand by two molecules of ammonia, methylamine, or isopropylamine, respectively, results in the formation of different solution species. With the bulkiest ligand, isopropylamine, monometalation of the aldoses in the 1,2-position is exclusively observed. 相似文献
965.
Büttner K Bernhardt J Scharf C Schmid R Mäder U Eymann C Antelmann H Völker A Völker U Hecker M 《Electrophoresis》2001,22(14):2908-2935
Proteomics relying on two-dimensional (2-D) gel electrophoresis of proteins followed by spot identification with mass spectrometry is an excellent experimental tool for physiological studies opening a new perspective for understanding overall cell physiology. This is the intriguing outcome of a method introduced by Klose and O'Farrell independently 25 years ago. Physiological proteomics requires a 2-D reference map on which most of the main proteins were identified. In this paper, we present such a reference map with more than 300 entries for Bacillus subtilis proteins with an isoelectric point (pI) between 4 and 7. The most abundant proteins of exponentially growing cells were compiled and shown to perform mainly housekeeping functions in glycolysis, tricarboxylic acid cycle (TCC), amino acid biosynthesis and translation as well as protein quality control. Furthermore, putative post-translational modifications were shown at a large scale, with 47 proteins in total forming more than one spot. In a few selected cases evidence for phosphorylation of these proteins is presented. The proteome analysis in the standard pI range was complemented by either stretching the most crowded regions in a narrow pH gradient 4.5-5.5, or by adding other fractions of the total B. subtilis proteome such as alkaline proteins as well as extracellular proteins. A big challenge for future studies is to provide an experimental protocol covering the fraction of intrinsic membrane proteins that almost totally escaped detection by the experimental procedure used in this study. 相似文献
966.
967.
Pedro A. Fernandes Elsa S. Henriques Vineet Pande Maria. J. Ramos Ana R. R. Maia André A. S. Almeida Bruno F. B. Silva Carla M. S. Ribeiro César F. B. Ribeiro David S. M. Ribeiro Diana A. P. Fonseca Eva M. S. Cunha Filipe R. N. C. Maia Joana A. A. Pereira João P. G. Pacheco Joaquim A. A. D. Ferreira Liliana R. C. Matos Manuel A. B. P. Pinto Maria C. S. Borges Paulo J. C. R. Magalhães Pedro F. R. D. Teixeira Pedro N. B. C. Veloso Ricarte J. F. Ferreira Sandro S. Gomes Tiago F. Barros Tiago S. J. T. Selão Virgínia M. M. C. Fernandes 《Theoretical chemistry accounts》2005,113(4):197-204
We present a series of new inhibitors of the association between nuclear factor kappa B (NF-B) and the corresponding B site in DNA. They were designed using the lead compound 15-deoxy-12,14 -prostaglandin J2 (PGJ2), which is a natural product with demonstrated inhibitory efficiency for this system. First, the binding mode of PGJ2 to NF-B was unraveled by GOLD docking calculation. Subsequently, substitutions were made to PGJ2 to optimize its association with NF-B. Care was taken not to strongly increase the reactivity of the new compounds, and to keep the overall shape, size and hydrophilicity of the lead compound, which should render them a similar bioavailability. Molecular mechanics calculations were performed to decide on the suitability of the substitutions, and to evaluate the energies of association with NF-B. Density functional theory calculations were performed also to study the overall reactivity of the substituted drugs towards NF-B. Important general conclusions were obtained, concerning the improvement of these natural inhibitors; namely, a set of rational methodologies were deduced to improve the association between the PGJ2 derivatives and NF-B, and their efficiency demonstrated by generating a set of substituted complexes, some of them with a very much increased affinity for NF-B, opening new doors to enlarge the therapeutic capabilities of this class of drugs. 相似文献
968.
Josef Edinger Heinz Falk Walter Jungwirth Norbert Müller Ulrich Zrunek 《Monatshefte für Chemie / Chemical Monthly》1984,115(8-9):1081-1099
From an investigation of the ICD of bilatrienes-abc and 2,3-dihydrobilatrienes-abc induced by mixtures of CCl4 with (+)-cis-Pinane, (–)-lactic and (+)-tartaric acid esters it is concluded that specific interactions between chromophore and the chiral reagents afford a partial resolution of the labile racemate of helices. Attaching chiral residues covalently to the chromophore induces very low resolution of the same kind in case of apolar ligands like a cholesteryl-residue. However, with polar ligands as in the case ofBoc-lysyl derivatives enantiomeric excesses up to 90% are achieved depending on the solvent used.
Herrn Prof. Dr.Karl Schlögl zu seinem 60. Geburtstag gewidmet. 相似文献
969.
970.
Klaus Müllen Siglinde Bender Eleni Kotzamani Hans Schmickler Bruno Frei Hans R. Wolf 《Tetrahedron letters》1981,22(36):3513-3516
The conformational mobility of a series of conjugated dienones is investigated by low-temperature NMR- and IR-spectroscopy and interpreted in terms of substituent effects. 相似文献