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461.
462.
-Benzylidene--2,4,6-tri--butylphenylphosphine containing phosphorus in low coordination state was irradiated to give the corresponding -isomer: both isomers were isolated and characterized and the reactions with chromium(O) carbonyls were described. 相似文献
463.
A high-resolution infrared spectrum of methane-d2 has been measured in the C-D stretching band region (2025–2435 cm?1). Rotational structures of the ν2 and ν8 bands have been assigned by use of the ASSIGN-diagram method, and the c-type Coriolis interaction between ν2 and ν8 has been analyzed. The band origins, ν2 = 2203.22 ± 0.01 cm?1 and ν8 = 2234.70 ± 0.01 cm?1, the rotational constants and the centrifugal distortion constants for the two bands, and the Coriolis coupling constant, , have been determined. 相似文献
464.
Masashi Uematsu Hisato Hiraishi Tsutomu Fukuyama Tamotsu Kondow Kozo Kuchitsu 《Chemical physics》1982,64(3):381-387
When benzene, acetylene and ethylene were allowed to collide with Ne Rydberg atoms (17?n?40), significant Ne+ ions were observed. Their cross sections were estimated, with reference to the ionization by H2O, to be as large as 10?14–10?15 cm2. However, no Ne+ signals were observed when ethane, methane and N2 were used as targets. Theoretical estimates of the cross sections for ionization by interaction of the quadrupole moment and polarizability of the first three molecules are several orders of magnitude smaller than the experimental cross sections given above. A similarity of this phenomenon to the scattering of a thermal electron by benzene etc., observed by Christophorou et al., is suggested. 相似文献
465.
Kaoru Yamanouchi Hajime Watanabe Seiichiro Koda Soji Tsuchiya Kozo Kuchitsu 《Chemical physics letters》1984,107(3):290-294
Laser-induced fluorescence spectra of Ne- and Ar -aniline complexes were observed with a resolution of 0.04 cm?1. By a simulation analysis of the rotational structures, the distances between the rare-gas atom and the aromatic ring of aniline were found to be 3.35 ± 0.04 and 3.50 ± 0.04 A in the X?1A1 state of the Ne and Ar complexes, respectively, and about 0.05 A shorter when aniline was excited to the Ã1B2 state. 相似文献
466.
467.
The negative ion mass spectra of dicarboxylic acids show [M]?˙ and prominent [M – H]?ions. These ions can therefore be used to determine the molecular weight of dicarboxylic acids which do not give positive molecular ions. The [C2H3]? ion is a base peak in the spectra of maleic and fumaric acids. Isomeric phthalic acids are readily differentiated. 相似文献
468.
Takehiko Yamato Koji Fujita Naoki Shinoda Kozo Noda Yoshiaki Nagano Takashi Arimura Masashi Tashiro 《Research on Chemical Intermediates》1996,22(9):871-897
The hydrolysis of 8-bromomethyl[2.2]metacyclophanes 3 to the corresponding 8-hydroxymethyl derivatives 4 was carried out in 83% aqueous dioxane solution at 25°C. Substituent effect through space on the rate of the hydrolysis of bromomethyl groups attached on the opposite aromatic ring was first found in this investigation. Interestingly, the introduction of the substituents at the internal position 16 tends to enhance the hydrolysis reaction rate 10–100 times. It was found also that the stabilization by both the direct through-space cation-π-interaction and the interaction through the intra-annular 8,16-position are possible in the [2.2]metacyclophane 8-benzyl cations. The good correlation with log(K/KH) and σp + was observed for the hydrolysis of internally unsubstituted 5-bromomethyl[2.2]MCPs 7, in which the direct through-space cation-π-interactions are not possible. TiCl4 and Nafion-H, a perfluorinated resinsulfonic acid, catalysed Friedel-Crafts benzylation of benzene and substituted benzenes with 8-bromomethyl- and 8-hydroxymethyl[2.2]metacyclophanes to afford 8-benzyl[2.2]metacyclophanes is described. A high substrate and positional selectivity were observed in the present benzylation reaction quite different from those obtained from the benzyl bromide and benzyl alcohol. The benzyl cation intermediate stabilized by the through-space electronic interaction among the opposite benzene ring was first demonstrated in the benzylation of [2.2]metacyclophane systems. The mild and selective transannular reaction attributable to the highly strained character of [2.2]metacyclophane skeleton and the increased stabilization of the 5-benzyl cation intermediate arising from the electronic interactions among the opposite benzene ring through the intra-annular 8,16-positions was also observed. 相似文献
469.
Nagao M Umeyama H Mukai K Yamashita Y Yoshinobu J Akagi K Tsuneyuki S 《Journal of the American Chemical Society》2004,126(32):9922-9923
We report the direct observation of a precursor state for the cycloaddition reaction (the di-sigma bond formation) of ethylene on Si(100)c(4 x 2) using high-resolution electron energy loss spectroscopy at low temperature, and the meta-stable precursor state is identified as a weakly bonded pi-complex type. The activation energy from the pi-complex precursor to the di-sigma bonded species is experimentally estimated to be 0.2 eV. First-principles calculations support the pi-complex precursor mediated cycloaddition reaction of ethylene on Si(100)c(4 x 2). 相似文献
470.
Eleven kinds of aluminas were prepared from various starting materials by different methods. An alumina prepared from sodium aluminate by precipitation with carbon dioxide was found to exhibit an extraordinarily high catalytic activity for aldol condensation of acetone at 0 °C.
. , , 0°C.相似文献