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101.
Numerical Algorithms - A method for solving least squares problems (A ? Bi)x = b whose coefficient matrices have generalized Kronecker product structure is presented. It is based on the... 相似文献
102.
A contracted basis set of triple zeta (TZ) valence quality for the atoms from K to Kr was constructed from fully-optimized Gaussian basis sets generated in this work. Gaussian polarization functions (d, f, and g symmetries), which were optimized at the second-order Mφller–Plesset level, were added to the TZ set. This extends earlier work on segmented contracted TZ basis set for atoms H-Ar. This set along with the BP86 non-hybrid and B3LYP hybrid functionals were used to calculate geometric parameters, dissociation energy, harmonic vibrational frequency, and electric dipole moment of a sample of molecules and, then, comparison with results obtained with other basis sets and with experimental data reported in the literature is done. CCSD(T) atomic excitation energies and bond lengths, dissociation energies, and harmonic vibrational frequencies of some diatomics were also evaluated. Using density functional theory and gauge-including atomic orbitals, 57Fe and 77Se nuclear magnetic resonance chemical shifts in Fe(C5H5)2, H2Se, (CH3)SeH, CSe2, SeCO, H2CSe, and SeF6 were calculated. Comparison with theoretical and experimental values previously published in the literature was done. It is verified that in general these results give good agreement with experimental and benchmark values. 相似文献
103.
A bead-injection system is proposed for total mercury determination in river-water samples. The procedure is based on the introduction of a defined quantity of a resin suspension in the flow system. The selected beads are packed inside of a flow cell and the formed resin mini-column constitutes the optical path. The sample volume is then selected, and its passage by the mini-column allows retention of the mercury ions on the surfaces of the beads. The introduction of a spectrophotometric reagent in the flow system leads to the formation of a colored Hg-dithizone complex on the surface of the bead, which is spectrophotometricaly monitored. The spent beads are directed to waste, allowing the system to become ready to process another sample. The proposed system handles about 20 measurements per hour, consuming 1000 microl of the sample, 1 mg of Chelex 100 resin and 1.25 microg of Dithizone per determination. When 1000 microl of the sample is injected, a linear analytical curve is obtained (A = 0.0052[Hg] + 0.1028, from 0 up to 30 microg l(-1), R2 = 0.995); the detection limit is estimated to be 0.9 microg l(-1). The results are precise, r.s.d. < 9%; spiked sample recoveries within 91.2 and 109% are found. 相似文献
104.
Jaime Rodríguez André Ferraz Raquel F. P. Nogueira Irene Ferrer Elisa Esposito Nelson Durán 《Applied biochemistry and biotechnology》1997,62(2-3):233-242
The lignin biodegradation process has an important role in the carbon cycle of the biosphere. The study of this natural process
has developed mainly with the use of basidiomycetes in laboratory investigations. This has been a logical approach since most
of the microorganisms involved in lignocellulosic degradation belong to this class of fungi. However, other microorganisms
such as ascomycetes and also some bacteria, are involved in the lignin decaying process. This work focuses on lignin biodegradation
by a microorganism belonging to the ascomycete class,Chrysonilia sitophila. Lignin peroxidase production and characterization, mechanisms of lignin degradation (lignin model compounds and lignin in
wood matrix) and biosynthesis of veratryl alcohol are outstanding. Applications of C.sitophila for effluent treatment, wood biodegradation and single-cell protein production are also discussed. 相似文献
105.
106.
Matthew Herbert Francisco Montilla Raquel Moyano Antonio Pastor Eleuterio Álvarez Agustín Galindo 《Polyhedron》2009,28(18):3929-3934
Commercially available molybdenum(VI) compounds, including molybdenum trioxide, were successfully employed as catalyst precursors in the epoxidation of olefins with urea–hydrogen peroxide adduct (UHP) in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6]. After oxidation, the corresponding epoxides were isolated by extraction with diethyl ether. Additionally the ionic liquid–catalyst mixture was recycled and reused in further catalytic cycles. The catalytic species is assumed to be an oxodiperoxomolybdenum species which forms in situ. A representative complex of this type was thus isolated and characterised. Reaction of excess 4-methylpyridine-1-oxide (4-MepyO) with MoO3 dissolved in aqueous hydrogen peroxide afforded [Mo(O)(O2)2(4-MepyO)2]·H2O (1) as yellow crystals. Compound 1, an active epoxidation catalyst, was subsequently characterised and its structure determined by X-ray crystallography. 相似文献
107.
Raquel S. Amim Marcelo R.L. Oliveira Genivaldo J. Perptuo Jan Janczak Liany D.L. Miranda Mayura M.M. Rubinger 《Polyhedron》2008,27(7):1891-1897
The reaction of 4-iodobenzenesulfonamide or 4-fluorobenzenesulfonamide with CS2 and KOH in dimethylformamide yielded the potassium N-R-sulfonyldithiocarbimates, K2(RSO2NCS2) [R = 4-IC6H4 (1) and 4-FC6H4 (2)]. These salts reacted with K2[PtCl4] in water/methanol to yield complex anions bis(N-R-sulfonyldithiocarbimato)platinate(II), which were isolated as their tetrabutylammonium salts, (Bu4N)2[Pt(RSO2NCS2)2] [R = 4-IC6H4 (3) and 4-FC6H4 (4)]. The structures of 2–4 were determined by X-ray crystallography. The Pt2+ in both complexes 3 and 4 lies at the inversion centre and the PtS4 moiety has a distorted square-planar configuration. The compounds were also characterized by IR, 1H NMR and 13C NMR spectroscopies, and elemental analyses. The molar conductance data are consistent with the fact that 3 and 4 are dianionic complexes. 相似文献
108.
José M. Goenaga Ana Gayol Raquel G. Concha Miguel Iglesias José M. Resa 《Monatshefte für Chemie / Chemical Monthly》2007,138(5):403-436
Summary. Speeds of sound, densities, and refractive indices of the binary mixtures containing ethanol+(2-methyl-1-propanol, 2-methyl-1-butanol,
1-pentanol, or 3-methyl-1-butanol) were measured at 288.15 ≤ T/K ≤ 323.15 and atmospheric condition in the whole compositional range. The effect of temperature was analyzed by several
chemical terms. 相似文献
109.
110.
Santos Blanco Francisco J Molina Lourdes Castro Maria L Del Moral Raquel Hernandez Ana Jimenez Alma Rus Esther Martinez-Lara Eva Siles Maria A Peinado 《BMC neuroscience》2010,11(1):78