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31.
32.
In the reaction of C5H5 Co(C3F7)(CO)I with the Schiff base NN′, derived from S-(-)-?-phenylethylamine and pyridine carbaldehyde-2, the salt [C5H5Co(C3F7)NN′]+ I? (Ia,b) is formed, which can be transformed to [C5H5 Co(C3F7)NN′]+ PF6? (IIa,b). The sodium salt Na+ [NN″]? of the Schiff base, derived from S-(-)-α-phenylethylamine and pyrrol carbaldehyde-2, in the reaction with C5H5 C0(C3F7)(CO)I yields the neutral complex C5H5 Co(C3F7)NN″ (IIIa,b). The diastereoisomeric pairs IIa,b and IIIa,b are separated by fractional crystallisation and chromatography respectively into the optically pure components which differ in their 1H NMR spectra. The IR, UV, CD, mass spectra and optical rotations of the new compounds IIa, IIb, IIIa and IIIb are compared. 相似文献
33.
Ohne ZusammenfassungHerrn Prof. Dr.A. Franke in aufrichtiger Verehrung zum 80. Geburtstag gewidmet. 相似文献
34.
Henri Brunner Christian Zettler Manfred Zabel 《Monatshefte für Chemie / Chemical Monthly》2003,134(9):1253-1269
Summary. The synthesis of new chiral tridentate ligands is reported which coordinate transition metals in a meridional way. The ligands contain a pyridine ring, an oxazoline ring, and a strongly coordinating diphenylphosphanyl group. The methionine-derived ligand forms a copper complex, which has been studied by X-ray crystallography. The new ligands were tested in models of enantioselective catalyses, such as hydrogenation of ketopantolactone, hydrosilylation of acetophenone, and transfer hydrogenation of acetophenone.X-ray structure analysesReceived March 4, 2003; accepted March 4, 2003
Published online August 18, 2003 相似文献
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2-iodobenzonitrile, its derivatives, and various heterocyclic analogues undergo palladium(0)-catalyzed annulation onto diarylacetylenes or bicyclic alkenes to afford 2,3-diarylindenones and polycyclic aromatic ketones in very good to excellent yields. This reaction represents one of the first examples of the addition of an organopalladium moiety to the carbon-nitrogen triple bond of a nitrile. The reaction is compatible with a number of functional groups. A reaction mechanism, as well as a model accounting for the electronic effects of substituents on the aromatic ring of the nitrile, is proposed. 相似文献
37.
Brunner H Cattey H Meier W Mugnier Y Stückl AC Wachter J Wanninger R Zabel M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(16):3796-3802
The reaction of the cluster salts [Cp(2*) Nb(CO)(2)](n)[Co(11)Te(7)(CO)(10)] (Cp*=C(5)Me(5); n=1, 2) with excess PMe(2)Ph gave the neutral, dark brown clusters [Co(11)Te(7)(CO)(6)(PMe(2)Ph)(4)] (5) and [Co(11)Te(7)(CO)(5)(PMe(2)Ph)(5)] (6) with 147 metal valence electrons. The new compounds were characterized by IR spectroscopy, elemental analyses, and mass spectrometry. The molecular structure of 6 was determined by X-ray crystallography. Like its precursor anion, it consists of a pentagonal-prismatic [Co(11)Te(7)] core, but with a ligand sphere composed of five CO and five PMe(2)Ph ligands. Detailed electrochemical studies of both reactions reveal that a stepwise substitution of CO ligands in the initial cluster anions takes place leading to intermediate [Co(11)Te(7)(CO)(10-m)(PMe(2)Ph)(m)](n-) ions (m=1-5; n=1, 2). Each of these intermediates is distinguished by at least one oxidation and two reduction waves, giving rise to a total of 21 redox couples and 27 electroactive species. The electron sponge character of the new compounds is particularly pronounced in 5, which exhibits charges n between +1 and -4 corresponding to metal valence electron counts of between 146 and 151. 相似文献
38.
Fonseca GS Umpierre AP Fichtner PF Teixeira SR Dupont J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(14):3263-3269
Stable transition-metal nanoparticles of the type [M(0)](n) are easily accessible through the reduction of Ir(I) or Rh(III) compounds dissolved in "dry" 1-n-butyl-3-methylimidazolium hexafluorophosphate ionic liquid by molecular hydrogen. The formation of these [M(0)](n) nanoparticles is straightforward; they are prepared in dry ionic liquid whereas the presence of the water causes the partial decomposition of ionic liquid with the formation of phosphates, HF and transition-metal fluorides. Transmission electron microscopy (TEM) observations and X-ray diffraction analysis (XRD) show the formation of [Ir(0)](n) and [Rh(0)](n) nanoparticles with 2.0-2.5 nm in diameter. The isolated [M(0)](n) nanoparticles can be redispersed in the ionic liquid, in acetone or used in solventless conditions for the liquid-liquid biphasic, homogeneous or heterogeneous hydrogenation of arenes under mild reaction conditions (75 degrees C and 4 atm). The recovered iridium nanoparticles can be reused several times without any significant loss in catalytic activity. Unprecedented total turnover numbers (TTO) of 3509 in 32 h, for arene hydrogenation by nanoparticles catalysts, have been achieved in the reduction of benzene by the [Ir(0)](n) in solventless conditions. Contrarily, the recovered Rh(0) nanoparticles show significant agglomeration into large particles with a loss of catalytic activity. The hydrogenation of arenes containing functional groups, such as anisole, by the [Ir(0)](n) nanoparticles occurs with concomitant hydrogenolysis of the C-O bond, suggesting that these nanoparticles behave as "heterogeneous catalysts" rather than "homogeneous catalysts". 相似文献
39.
(±)-Muscone (5) has been synthesized from methyl 13-(chloroformyl)tridecanoate (6) in nine steps in an overall yield of 24%. The key steps involve an efficient transformation of the readily accessible 14-hydroxy-15-methyl-15-hexadecenoic acid (9) into the tetradecanolide 1 and a subsequent Ireland-Claisen rearrangement of its triethylsilyl enolate 2 to a 8:1-mixture of the stereoisomeric 15-membered carbocycles 4 and 10 (Scheme 4). 相似文献
40.
Enhanced fluorescence from arrays of nanoholes in a gold film 总被引:1,自引:0,他引:1
Brolo AG Kwok SC Moffitt MG Gordon R Riordon J Kavanagh KL 《Journal of the American Chemical Society》2005,127(42):14936-14941
Arrays of sub-wavelength holes (nanoholes) in gold films were used as a substrate for enhanced fluorescence spectroscopy. Seven arrays of nanoholes with distinct periodicities (distances between the holes) were fabricated. The arrays were then spin-coated with polystyrene films containing different concentrations of the fluorescent dye oxazine 720. The dye was excited via resonant extraordinary transmission of the laser source through the nanoholes. Enhanced fluorescence was observed when the geometric characteristics of the arrays allowed for an enhancement in the transmitted excitation. This enhancement occurred via surface plasmon excitation by the laser and a consequential increase in the local electromagnetic field in a sub-wavelength region at the metal-film interface. It was demonstrated that the sensitivity of the fluorescence measurement (change in signal vs change in dye concentration in the polymer film) is significantly larger at the surface plasmon resonance conditions than that obtained from equivalent films on glass substrates. Enhancement factors for the fluorescence emission were calculated for each array, with a maximum enhancement of close to 2 orders of magnitude as compared to the emission of films on glass. The results presented here indicate that arrays of nanoholes are interesting substrates for the development of fluorescence sensors based on surface plasmon resonance, as they provide a platform that allows both spatial confinement and enhancement of excitation light. Moreover, the collinear characteristics of the present optical setup, due to the resonant extraordinary transmission through the nanohole arrays, are more conducive to miniaturization and chip integration than more traditional experimental geometries. 相似文献