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141.
L. G. M. Th. Tuinstra A. H. Roos B. Griepink D. E. Wells 《Journal of separation science》1985,8(8):475-480
The Community Bureau of Reference has organized a collaborative interlaboratory project to improve the analytical protocol for some specific chlorobiphenyls (CBs) within the European Community (EC). A series of test procedures were prescribed to optimize the gas chromatographic conditions for splitless and on-column injection, which substantially improved the quality of data. Important parameters included the initial column and injector temperatures and the choice of the polarity of the stationary phase. In a study with cleaned eel-fat extracts, coefficients of variation for reproducibility CV(R) ranging from 11 to 24% at the 0.04–0.3 mg/kg level per CB congener were obtained. No significant difference could be found between splitless- and on-column injection. 相似文献
142.
Duane C. Hrncir Laura M. Barden Mark R. Wells Peter C. Stark 《Journal of inclusion phenomena and macrocyclic chemistry》1988,6(3):233-236
Tetrabutylammonium salts of the mixed haloindates, [Bu4N][InCl3X], X=Cl, Br, I, interact with aromatic solvents forming liquid inclusion compounds. The aromatic/cation ratio (A/C), a measure of the amount of guest aromatic, has been determined for a variety of simple aromatics. The values range from 2.6 to 0.4, substantially lower than the A/A of similar [Bu4N][Al2R6X] liquid clathrates. The ability of these liquid clathrates to function as catalysis media has been explored. The solubility of (Ph3P)2Rh(CO)Cl and (Ph3P)3RhCl in the various clathrates was determined. It was found that significant leaching of the catalyst into the bulk aromatic solvent occurred, ranging from 13 to 94%. A related liquid clathrate, [Li·12-crown-4][InCl4]·(C6H5CH3)2, had <1% of the dissolved catalyst leached. 相似文献
143.
G. T. Jones B. W. Kennedy S. W. O'Neale K. Böckmann W. Gebel C. Geich-Gimbel B. Nellen A. M. Cooper-Sarkar A. Grant H. Klein D. R. O. Morrison P. Schmid H. Wachsmuth J. S. Chima M. M. Mobayyen M. Talebzadeh O. Villalobos-Baillie M. Aderholz L. Deck N. Schmitz K. L. Wernhard W. Wittek G. Corrigan G. Myatt D. Radojicic B. Saitta J. Wells S. Towers P. Shotton 《Zeitschrift fur Physik C Particles and Fields》1985,27(1):43-52
144.
145.
C.R. Pollock F.R. Petersen D.A. Jennings J.S. Wells A.G. Maki 《Journal of Molecular Spectroscopy》1984,107(1):62-71
The absolute frequencies of 39 lines in the 0002-0000, 2001-0000, and 1201-0000 bands of N2O in the range 4300–4800 cm?1 have been measured by heterodyne frequency techniques. The lines were each measured in Doppler-limited absorption, with a color-center laser as a tunable probe of the N2O and two stabilized CO2 lasers as reference frequencies. New rovibrational constants have been fitted to these measurements. Tables of calculated transition frequencies are given, with estimated absolute uncertainties as small as 10?4 cm?1. The pressure shifts of four lines have been measured, and the values fall within the range of 0 to ?2 MHz/kPa (0 to ?0.2 MHz/Torr). 相似文献
146.
M. Mürtz M. Schaefer T. George J. S. Wells W. Urban 《Applied physics. B, Lasers and optics》1995,60(1):31-37
We present an optically stabilized lead-salt diode-laser system which is the nucleus of a very-high-resolution instrument for sub-Doppler molecular spectroscopy in the mid-infrared. By application of external optical feedback, we have narrowed the diode-laser linewidth by two orders of magnitude, yielding a spectral width of less than 200 kHz. The diode- laser frequency is stabilized and controlled via the external reflector by variable-frequency offset-locking the diode-laser to a CO laser frequency. This substantial improvement in the spectral properties enabled us to perform a Lamb-dip experiment on a carbonyl sulfide (OCS) absorption line near 1985 cm–1. We were able to detect a saturated dispersion signal at low pressure (5 Pa) with a signal-to-noise ratio of several thousand. The present paper describes the unique features of the optically stabilized tunable diode-laser system and its use as a spectroscopic tool for sub-Doppler applications. 相似文献
147.
Gehan M. A. El-Subruiti Cecil F. Wells Ibrahim M. Sidahmed 《Journal of solution chemistry》1991,20(4):403-415
The solubility of salts [Co(3Rpy)4Cl2]2]ReCl6] has been determined in water + methanol mixtures. By comparing these with the solubilities of the salt Cs2ReCl6 and using calculated activity coefficients for the ions in the water+methanol mixtures, values for {G
t
o
(Co(3Rpy)4Cl
2
+
)–G
t
o
(Cs+)} can be determined where G
t
o
is the standard Gibbs free energy of transfer from water to an aqueous mixture. G
t
o
(Cs+) from the solvent sorting scale and from the TPTB scale are then used to calculate G
t
o
(Co(3Rpy)4Cl
2
+
). These two sets of values for G
t
o
(Co(3Rpy)4Cl
2
+
) on the differing scales are then inserted into a free energy cycle applied to the bond extension Co(3Rpy)4Cl
2
+
(initial state)Co(3Rpy)4Cl2++Cl– (transition state) for the solvolysis in water and in water + methanol mixtures to produce values for G
t
o
(Co(3Rpy)4Cl2+) using both scales. Data for the solubilites of [Copy4Cl2]2[ReCl6] and [Co(4Rpy)4Cl2]2[ReCl6] have been re-calculated to compare free energies of transfer for these complex cations with those specified above. 相似文献
148.
149.
150.