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31.
Abstract The IR spectra of the linkage isomers [Pd(bipy)(SCN)2] and [Pd(bipy)(NCS)2] have been determined in the C≡N stretching region (2200–2000 cm?1) and below 500 cm?1. The band shifts resulting from deuteration of the 2,2′-bipyridine (bipy) ring and 15NCS-labelling are shown to provide a ready means for distinguishing between the internal ligand modes, the μPd-N(bipy) and μPd-SCN/μPd-NCS vibrations. The assignment technique has been further extended to the complexes [Pt(bipy)(SCN)2] and [Pd(phen)(SCN)2] (phen = 1,10-phenanthroline). Finally, a comparison between the IR spectra of [Pd(bipy)(NCO)2], [Pd(bipy)(NCS)2] and [Pd(bipy)(SCN)2] reveals that the frequencies μM-NCO, μM-NCS and μM-SCN decrease in the sequence NCO > NCS > SCN. 相似文献
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Tanmoy Dutta Yong Li Aaron L. Thornton Da‐Ming Zhu Zhonghua Peng 《Journal of polymer science. Part A, Polymer chemistry》2013,51(18):3818-3828
Donor‐acceptor conjugated polymers containing a new imide‐functionalized naphthodithiophene (INDT) as the acceptor unit and a 2,2'‐bithiophene with varied substituents as the donor unit have been synthesized. The bandgaps of these polymers depend strongly on the dihedral angle of the 2,2'‐bithiophene unit. The 3,3'‐dialkoxy substitution (polymers PDOR / PBOR ) leads to near planar bithiophene conformation due to the well‐known S–O short contact, while the 3,3'‐dialkyl substitution (polymer PDR ) results in significant twisting due to the steric effect. Consequently PDOR / PBOR shows the lowest bandgap of 1.82/1.85 eV while PDR has a bandgap of 2.38 eV. Bulk‐heterojunction solar cells of the polymer/fullerene blends have been fabricated. Preliminary results show that PBOR gives the best device performance with power conversion efficiencies as high as 2.45% in air without any thermal annealing treatment, indicating the promising potential of INDT‐containing conjugated polymers for efficient solar cells. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3818–3828 相似文献
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The (111)B surface of GaAs has been investigated using scanning tunneling microscopy (STM) and a number of different reconstructions have been found at different surface stoichiometries. In accordance with electron diffraction studies, we find the series (2 × 2), (1 × 1)LT, (
) and (1 × 1)HT with increasing annealing temperature, corresponding to decreasing surface As concentration. The (1 × 1)LT is of particular interest, since it only occurs in a narrow temperature window between the two more established reconstructions, the (2 × 2) and the (
). We find the (1 × 1)LT to take the form of a mixture of the local structures of both the (2 × 2) and (
) phases, rather than having a distinct structure. This is behaviour consistent with a kinetically limited system, dominated by the supply of As adatoms to the surface, and may be an example of a continuous phase transition. Above the (1 × 1)LT transition, atomic resolution images of the (
) surface reveal only a three-fold symmetry of the hexagonal structural units, brought about by inequivalent surface bonding due to the 23.4° rotation of the surface unit cell relative to the substrate. This is responsible for the disorder found in the (
) reconstruction, since the structure may form in one of two domains. At lower surface As concentration, the (1 × 1)HT surface adopts a structure combining small domains of a
19.1° structure and random disorder. There is no apparent similarity between the (1 × 1)LT and (1 × 1)HT structures, which may be due to our measurements being conducted at room temperature and without an As flux to control the surface As concentration. 相似文献
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Ohne Zusammenfassung 相似文献
38.
G. S. Jamieson R. Wrenshall Ericson V. Lenher W. G. Crawford J. W. Mellor B. Neumann R. K. Murphy Kaiser A. J. Rossi E. Knecht P. W. Shimer E. B. Shimer F. A. Gooch H. D. Newton W. M. Thornton Jr. F. Bourion K. Schröder J. Bellucci L. Grassi C. R. Mc Cabe und A. R. Scott 《Fresenius' Journal of Analytical Chemistry》1915,54(12):606-617
Ohne Zusammenfassung 相似文献
39.
G. H. Bailey Thornton Lamb Harry F. Keller Edgar F. Smith A. Joly und E. Leidié 《Fresenius' Journal of Analytical Chemistry》1893,32(1):636-645
Ohne Zusammenfassung 相似文献
40.
Turowski M Yamakawa N Meller J Kimata K Ikegami T Hosoya K Tanaka N Thornton ER 《Journal of the American Chemical Society》2003,125(45):13836-13849
Hydrogen/deuterium isotope effects on hydrophobic binding were examined by means of reversed-phase chromatographic separation of protiated and deuterated isotopologue pairs for a set of 10 nonpolar and low-polarity compounds with 10 stationary phases having alkyl and aryl groups bonded to the silica surface. It was found that protiated compounds bind to nonpolar moieties attached to silica more strongly than deuterated ones, demonstrating that the CH/CD bonds of the solutes are weakened or have less restricted motions when bound in the stationary phase compared with the aqueous solvent (mobile phase). The interactions responsible for binding have been further characterized by studies of the effects of changes in mobile phase composition, temperature dependence of binding, and QSRR (quantitative structure-chromatographic retention relationship) analysis, demonstrating the importance of enthalpic effects in binding and differentiation between the isotopologues. To explain our results showing the active role of the hydrophobic (stationary) phase we propose a plausible model that includes specific contributions from aromatic edge-to-face attractive interactions and attractive interactions of aliphatic groups with the pi clouds of aromatic groups present as the solute or in the stationary phase. 相似文献