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101.
Rather E Gatlin JT Nixon PG Tsukamoto T Kravtsov V Johnson DW 《Journal of the American Chemical Society》2005,127(10):3242-3243
We report the single-crystal structure of an inorganic gallium cluster [Ga13(mu3-OH)6(mu2-OH)18(H2O)24](NO3)15.6H2O prepared using a simple organic reaction to drive the formation of the crystalline inorganic cluster. 相似文献
102.
Paul D. Robinson Kevin R. Smith Lori A. Vermeulen 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o632-o634
The structure of the title compound, C14H16N2O6S2·2C6H6O2, consists of 2,2′‐(4,4′‐bipyridinium‐1,1′‐diyl)di(ethanesulfonate) molecules (with crystallographically imposed twofold symmetry) that are hydrogen bonded to each other, as well as to hydroquinone molecules, in a complex three‐dimensional motif. The orange color of the crystals is indicative of the donor–acceptor interaction between the electron‐rich hydroquinone π‐donor and the electron‐deficient bipyridinium π‐acceptor. The dihedral angle between the bipyridyl planes is 38.31 (11)°. The distance from the centroid of one of the hydroquinone molecules to the center of the bipyridinium group is 3.653 (3) Å, which is within the range typically observed for molecular complexes exhibiting charge‐transfer characteristics. 相似文献
103.
The oxidation of [RuIII(hedta)(H2O)]=(1) to its RuIV monomeric complex at a glassy carbon electrode is abserved to promote oxidation of alcohols bearing an a-hydrogen (i-PrOH benzyl alcohol,sec-phenethyl alcohol). Tertiary substitution blocks the oxidation (t-BuOH). The oxidation of the alcohols is detected by an enhancement in the current of the RuIV/III waves at potentials above 0.96V, caused by scavenging (reduction) of RuIV by the alcohols. Binuclear complexes which possess RuIV bridged by oxo to either a second RuIV or to RuIII in species of composition [LRuORuL]n−, L=hedta3−, fail to oxidize the alcohols. The terminal oxo moiety attached to RuIV is postulated to facilitate the oxidation of primary and secondary alcohols in a manner analogous to Meyer's [RuO(trpy)(bpy)]2+ catalyst. The dissociation of the (III,IV) binuclear complex into its monomers provides a pathway which increases catalytic
activity at the expense of the inactive (III, IV) binuclear complex's concentration.
TMC 2531 相似文献
104.
Hossein Eshtiagh-Hosseini Harold W. Kroto John F. Nixon Osamu Ohashi 《Journal of organometallic chemistry》1979,181(2):C1-C3
The previously postulated phosphaalkene intermediate CF3 P=CF2 in the alkaline hydrolyses of (CF3)2 PH has been trapped and characterised by its 19F and 31P NMR spectra. 相似文献
105.
Syntheses of Co2Rh2(CO)8(PF3)4 and Co2Rh2(CO)10(PF3)2 are described and their structures are discussed. Evidence is presented for an intermolecular ligand exchange between several tetranuclear cluster complexes. 19F and 31P NMR and mass spectroscopic data are presented and discussed. The complexes Rh4(CO)4(PF3)8 and Co2Ir2(CO)8(PF3)4 have been identified by their mass spectra. 相似文献
106.
Knippenberg S Nixon KL Brunger MJ Maddern T Campbell L Trout N Wang F Newell WR Deleuze MS Francois JP Winkler DA 《The Journal of chemical physics》2004,121(21):10525-10541
We report on the results of an exhaustive study of the valence electronic structure of norbornane (C(7)H(12)), up to binding energies of 29 eV. Experimental electron momentum spectroscopy and theoretical Green's function and density functional theory approaches were all utilized in this investigation. A stringent comparison between the electron momentum spectroscopy and theoretical orbital momentum distributions found that, among all the tested models, the combination of the Becke-Perdew functional and a polarized valence basis set of triple-zeta quality provides the best representation of the electron momentum distributions for all of the 20 valence orbitals of norbornane. This experimentally validated quantum chemistry model was then used to extract some chemically important properties of norbornane. When these calculated properties are compared to corresponding results from other independent measurements, generally good agreement is found. Green's function calculations with the aid of the third-order algebraic diagrammatic construction scheme indicate that the orbital picture of ionization breaks down at binding energies larger than 22.5 eV. Despite this complication, they enable insights within 0.2 eV accuracy into the available ultraviolet photoemission and newly presented (e,2e) ionization spectra, except for the band associated with the 1a(2) (-1) one-hole state, which is probably subject to rather significant vibronic coupling effects, and a band at approximately 25 eV characterized by a momentum distribution of "s-type" symmetry, which Green's function calculations fail to reproduce. We note the vicinity of the vertical double ionization threshold at approximately 26 eV. 相似文献
107.
Lee K. Robertst Donathan G. Beasley Douglas B. Learn Lori D. Giddens John Beard Joseph W. StanfieW 《Photochemistry and photobiology》1996,63(6):874-884
Acute exposure to UV radiation causes immunosuppression of contact hypersensitivity (CH) responses. Past studies conducted with unfiltered sunlamps emitting nonsolar spectrum UV power (wavelengths below 295 nm) or using excessive UV doses have suggested sunscreens may not prevent UV-induced immunosuppression in mice. This study was thus designed to evaluate critically the effects of different UV energy spectra on the immune protection capacity of sunscreen lotions. Minimum immune suppression doses (MISD), i.e. the lowest UV dose to cause~50% suppression of the CH response to dinitrofluorobenzene in C3H mice, were established for three artificial UV sources. The MISD for each UV source was 0.25 kJ/m2 for unfiltered FS20 sunlamps (FS), 0.90 kJ/m2 for Kodacel-filtered FS20 sunlamps (KFS), which do not emit UV power at wavelengths <290 nm, and 1.35 kJ/m2 for a 1000 W filtered xenon arc lamp solar simulator. Using MISD as baseline, sunscreens with labeled sun protection factors (SPF) of 4, 8, 15 and 30 were tested with each UV source to establish their relative immune protection factors. The immune protection factor of each sunscreen exceeded its labeled SPF in tests conducted with the solar simulator, which has a UV power spectrum (295–400 nm) similar to that of sunlight. Conversely, sunscreen immune protection factors were significantly less than the labeled SPF in tests conducted with FS and KFS. Comparison of the immunosuppression effectiveness spectra showed that relatively small amounts of nonsolar spectrum UV energy, i.e. UVC (200–290 nm) and/or shorter wavelength UVB (between 290 and 295 nm), produced by FS and KFS contributes significantly to the induction of immunosuppression. For example, 36.3% and 3.5% of the total immunosuppressive UV energy from FS and KFS, respectively, lies below 295 nm. Sunscreen absorption spectra showed that transmission of immunosuppressive UV energy below 295 nm for FS was at least eight-fold higher than that for KFS. Compared to the solar simulator UV spectrum the transmission of nonsolar immunosuppressive UV energy through sunscreens was >15-fold higher for FS and ≥1.5-fold higher for KFS. These data demonstrate that relevant evaluations of sunscreen immune protection can only be obtained when tests are conducted with UV sources that produce UV power spectra similar to that of sunlight and UV doses are employed that are based on established MISD. 相似文献
108.
Kalovidouris SA Gama CI Lee LW Hsieh-Wilson LC 《Journal of the American Chemical Society》2005,127(5):1340-1341
We report a fucose alpha(1-2) galactose-mediated pathway for the modulation of neuronal growth and morphology. Our studies provide strong evidence for the presence of Fucalpha(1-2)Gal glycoproteins and lectin receptors in hippocampal neurons. Additionally, we show that manipulation of Fucalpha(1-2)Gal-associated proteins using small-molecule and lectin probes induces dramatic changes in neuronal morphology. These findings may provide a novel pathway to stimulate neuronal growth and regeneration. 相似文献
109.
Michael De Rosa Nicola Stepani Todd Cole Jaclyn Fried Lisa Huang-Pang Lori Peacock Michael Pro 《Tetrahedron letters》2005,46(34):5715-5717
The 2-nitrobenzenesulfonamide cleavage using a solid-phase thiophenolate reagent gives simple 2-(alkylamino)-pyrroles without the presence of the competing nucleophilic substitution product. 相似文献
110.
A detailed rotational analysis of the microwave spectrum between 26.5 and 40 GHz of phosphaethene, CH2=PH, has been carried out. This molecule is the simplest member of a new class of unstable molecules—the phosphaalkenes. The species can be produced by pyrolysis of (CH3)2PH, CH3PH2 and also somewhat more efficiently from Si(CH3)3CH2PH2. Full first-order centrifugal distortion analyses have been carried out for both 12CH231PH and 12CH231PD yielding: A0 = 138 503.20(21), B0 = 16 418.105(26), and C0 = 14 649.084(28) MHz for 12CH231PH. The 101-000 μA lines have also been detected for 13CH2PH, cis-CDHPH and trans-CHDPH. These data have enabled an accurate structure determination to be carried out which indicates: r(HcC) = 1.09 ± 0.015 Å, (HcCP) = 124.4 ± 0.8°; r(HtC) = 1.09 ± 0.015 Å, (HtCP) = 118.4 ± 1.2°; r(CP) = 1.673 ± 0.002 Å, (HCH) = 117.2 ± 1.2°; r(PH) = 1.420 ± 0.006 Å, (CPH) = 97.4 ± 0.4°. The dipole moment components have been determined as μA = 0.731 (2), μB = 0.470 (3), μ = 0.869 (3) D for CH2PH; μA = 0.710 (2), μB = 0.509 (10), μ = 0.874 (7) D for CH2PD. 相似文献