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991.
Novel composite polymer electrolytes based on poly(ether-urethane) network polymer and fumed silicas
X. J. Wang H. P. Zhang J. J. Kang Y. P. Wu S. B. Fang 《Journal of Solid State Electrochemistry》2007,11(1):21-26
Novel composite solid polymer electrolytes (CSPEs) and composite gel polymer electrolytes (CGPEs) have been prepared. CSPE
consists of poly(ether-urethane) network polymer (PUN), fumed silicas and LiClO4. The ionic conductivity of CSPEs can be enhanced nearly 20 times in comparison with the plain system without the addition
of fumed silicas and can be above 1×10−5 S/cm at room temperature. The effects of both kinds of fumed silicas, viz. uSiO2 with hydrophilic groups at the surface and mSiO2 with hydrophobic groups at the surface on ionic conductivity were investigated. CGPE comprising of the CSPE and LiClO4–PC solution with good mechanical strength exhibits ionic conductivity in the order of 10−3 S/cm at room temperature and above 3×10−4 S/cm at low temperature −40 °C. 相似文献
992.
Investigation of the root extract of Antidesma pentandrum var. barbatum led to the isolation of seven new compounds, antidesmol ( 1 ), antidesmanins E ( 2 ) and F ( 3 ), antidesnone ( 4 ), antidesnol ( 5 ), barbatumols A ( 6 ) and B ( 7 ), together with 14 known compounds including sodium aristolochate‐I ( 10 ) and aristolochic acid‐I methyl ester ( 11 ). 相似文献
993.
994.
In this paper, we present a detailed mechanism for the complete decomposition of NH3 to NHx(a) (x = 0-2). Our calculations show that the initial decomposition of NH3 to NH2(a) and H(a) is facile, with a transition-state energy 7.4 kcal mol-1 below the vacuum level. Further decomposition to N(a) or recombination-desorption to NH3(g) is hindered by a large barrier of approximately 46 kcal mol-1. There are two plausible NH2 decomposition pathways: 1) NH2(a) insertion into the surface Si-Si dimer bond, and 2) NH2(a) insertion into the Si-Si backbond. We find that pathway (1) leads to the formation of a surface Si = N unit, similar to a terminal Si = Nt pair in silicon nitride, Si3N4, while pathway (2) leads to the formation of a near-planar, subsurface Si3N unit, in analogy to a central nitrogen atom (Nc) bounded to three silicon atoms in the Si3N4 environment. Based on these results, a plausible microscopic mechanism for the nitridation of the Si(100)-(2 x 1) surface by NH3 is proposed. 相似文献
995.
Since alkynes have higher symmetry than olefins, it is not easy to infer the mechanism of a triplet carbene’s addition to
an alkyne by traditional product analysis studies. Specifically, no stereochemical information which might offer insight into
the carbene’s spin state can be extracted from the cyclopropene products. In 1971, Hendrick, Baron, and Jones showed that
diphenylcarbene reacts with terminal alkynes in solution to produce indenes via a “self-trapping” vinylcarbene. They also examined the diphenylcarbene reaction with disubstituted alkynes and found at most
trace amounts of the “self-trapping” indene product.
In this work, we report the direct observation by organic matrix EPR of the vinylcarbenes generated from triplet fluorenylidene
and terminal alkynes. Our efforts to confirm the identities of these intermediates by independent synthesis, intermolecular
trapping, and an intramolecular “self-trapping” method-halogen-migration-are also recounted. These findings are among the
few instances in which fluorenylidene undergoes carbon-carbon bond formation rather than atom abstraction reactions in a low-temperature
matrix, and in which the biradical adduct of a triplet carbene and a π-bonded substrate can be directly observed. 相似文献
996.
Yu JI Kim KH Bae IH Lee DY Kim DL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2640-2642
Photoreflectance measurements were performed to investigate the optical properties in the electron beam irradiation semi-insulating GaAs(e-beam irradiation GaAs) and semi-insulating GaAs(SI-GaAs). A considerable increase of the PR amplitudes has been registered after the e-beam irradiation in comparison with the GaAs. It is that result of a higher electron scattering on the lattice defects created by the e-beam. 相似文献
997.
Lee L Wang JX Adzić RR Robinson IK Gewirth AA 《Journal of the American Chemical Society》2001,123(36):8838-8843
X-ray reflectivity, cyclic voltammetry, and scanning tunneling microscopy (STM) are used to examine the structure of alpha-SiW12O4(4-) or silicotungstic acid (STA) adsorbed on Ag(100) in acid solution. The voltammetry shows that STA passivates the Ag surface relative to electron transfer to a solution redox species. STM images reveal the formation of a series of lattice structures, one of which can be associated with a commensurate ( radical13x radical13)R33.69 degrees structural model. X-ray reflectivity measurements show uniquely that STA orients with its four-fold axis perpendicular to the Ag(100) surface and that the center of the STA molecule is 4.90 A above the top layer of the Ag substrate. Analysis of bond lengths leads to a footprint of STA on Ag(100), in which the four terminal O atoms are located near the hollow sites and have a Ag-O bond length of 2.06 A. This bond length is consistent with a strong covalent interaction between STA and the Ag surface. 相似文献
998.
Young-Joo Eo Duk-Jun Kim Byeong-Soo Bae Ki-Chang Song Tae-Young Lee Seung-Won Song 《Journal of Sol-Gel Science and Technology》1998,13(1-3):409-413
Tetraethylorthosilicate (TEOS)/vinyltriethoxysilane (VTES) hybrid materials were prepared and the hydrolysis and condensation reactions during processing were investigated by means of 29Si NMR solution spectroscopy. The variation of drying characteristics of the coating films was examined with respect to the tetraethylorthosilicate (TEOS)/vinyltriethoxysilane (VTES) ratio, as well as drying temperature, by FT-IR spectroscopy. It is shown that the TO mode of Si–O–Si stretching absorption was enhanced with increasing tetraethylorthosilicate (TEOS) content and drying temperature. Also, the wettability of the coating films on polymer films was independent of the solution composition but enhanced by the precoating of poly(4-hydroxystrene) (PHS) as a wetting agent. The adhesion between the coating and the films was also enhanced when the vinyltriethoxysilane (VTES) content in the coating solution was increased. 相似文献
999.
Difference in Conversions Between Dimethyl Sulfide and Methanethiol in a Cold Plasma Environment 总被引:1,自引:0,他引:1
Cheng-Hsien Tsai Wen-Jhy Lee Chuh-Yung Chen Perng-Jy Tsai Guor-Cheng Fang Minliang Shih 《Plasma Chemistry and Plasma Processing》2003,23(1):141-157
This study compared the conversion of two malodorous substances, dimethyl sulfide (CH3SCH3, DMS) and methanethiol (CH3SH) in a cold plasma reactor. The DMS and CH3SH were successfully destroyed at room temperature. DMS decomposed less than CH3SH at the same conditions. In oxygen-free condition, CS2 and hydrocarbons were the major products, while SO2 and COx were main compounds in oxygen-rich environments. The DMS/Ar plasma yielded more hydrocarbons and less CS2 than that of CH3SH/Ar plasma. In the CH3SH/O2/Ar plasma, rapid formation of SO and CO resulted in the yields much more amounts of SO2 and CO2 than those in the DMS/O2/Ar plasma; and remained only a trace of total hydrocarbons, CH2O, CH3OH, CS2, and OCS. The major differences between the reaction mechanisms of DMS and CH3SH were also proposed and discussed. 相似文献
1000.
Seo K Kim C Choi YS Park KA Lee YH Kim B 《Journal of the American Chemical Society》2003,125(46):13946-13947
CO2 molecule chemisorbs selectively on the zigzag tube edge without an activation barrier, whereas it physisorbs on the armchair edge of nanotubes. In addition, carbon nanotubes can be etched by an adsorbed oxygen atom of CO2 molecule. From our results, we suggest a selective etching mechanism for tuning the chirality of the mass-produced carbon nanotubes. 相似文献