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91.
Bismuth as BiCl4− and BH4− ware successively retained in a column (150 mm × 4 mm, length × i.d.) packed with Amberlite IRA-410 (strong anion-exchange resin). This was followed by passage of an injected slug of hydrochloric acid resulting in bismuthine generation (BiH3). BiH3 was stripped from the eluent solution by the addition of a nitrogen flow and the bulk phases were separated in a gas–liquid separator. Finally, bismutine was atomized in a quartz tube for the subsequent detection of bismuth by atomic absorption spectrometry. Different halide complexes of bismuth (namely, BiBr4−, BiI4− and BiCl4−) were tested for its pre-concentration, being the chloride complexes which produced the best results. Therefore, a concentration of 0.3 mol l−1 of HCl was added to the samples and calibration solutions. A linear response was obtained between the detection limit (3σ) of 0.225 and 80 μg l−1. The R.S.D.% (n = 10) for a solution containing 50 μg l−1 of Bi was 0.85%. The tolerance of the system to interferences was evaluated by investigating the effect of the following ions: Cu2+, Co2+, Ni2+, Fe3+, Cd2+, Pb2+, Hg2+, Zn2+, and Mg2+. The most severe depression was caused by Hg2+, which at 60 mg l−1 caused a 5% depression on the signal. For the other cations, concentrations between 1000 and 10,000 mg l−1 could be tolerated. The system was applied to the determination of Bi in urine of patients under therapy with bismuth subcitrate. The recovery of spikes of 5 and 50 μg l−1 of Bi added to the samples prior to digestion with HNO3 and H2O2 was in satisfactory ranges from 95.0 to 101.0%. The concentrations of bismuth found in six selected samples using this procedure were in good agreement with those obtained by an alternative technique (ETAAS). Finally, the concentration of Bi determined in urine before and after 3 days of treatment were 1.94 ± 1.26 and 9.02 ± 5.82 μg l−1, respectively. 相似文献
92.
93.
94.
Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Duboscq JE Elliot JR Escobar CO Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Ong P Pinfold J Punkar G Purohit MV Santoro AF Shoup AL Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundzia AB Witherell MS 《Physical review D: Particles and fields》1991,43(3):R635-R640
95.
Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Duboscq JE Elliott JR Escobar CO Gibney M Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Pinfold J Punkar G Purohit MV Santoro AF Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundia AB Witherell MS 《Physical review D: Particles and fields》1991,43(7):R2063-R2066
96.
Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Duboscq JE Elliott JR Escobar CO Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Pinfold J Punkar G Purohit MV Ross WR Santoro AF Schmidt DM Shoup AL Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundia AB Witherell MS 《Physical review D: Particles and fields》1991,44(11):R3371-R3374
97.
Anjos JC Appel JA Bean A Bediaga I Bracker SB Browder TE Cremaldi LM Duboscq JE Elliot JR Escobar CO Gibney MC Hartner GF Karchin PE Kumar BR Lima JG Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Pinfold J Punkar G Purohit MV Ross WR Santoro AF Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundzia AB Witherell MS 《Physical review letters》1992,69(20):2892-2895
98.
A. M. Garrido Pedrosa M. J. B. Souza D. M. A. Melo A. S. Araujo 《Journal of Thermal Analysis and Calorimetry》2007,87(2):351-355
The thermo-programmed reduction study of
Pt/WOx–ZrO2 materials
prepared with different tungsten loading were performed by thermogravimetry.
The samples were synthesized by impregnation method and calcined at 600, 700
and 800°C. The characterizations of both un-calcined and calcined materials
were carried out using different techniques: thermal analysis (TG and DTA),
X-ray diffraction (XRD) and thermo-programmed reduction (TPR). TG and DTA
analysis of un-calcined were used to determination of calcination temperatures
of the samples. XRD diffractograms were useful to help us in the determination
of phase presents. TPR profiles showed between three and four events at different
temperatures attributed to platinum reduction and the different stages of
tungsten specie reduction. 相似文献
99.
Summary In the determination of several perhalogenated compounds after gas chromatographic separation on an Apiezon L column, using
a flame ionization detector, all the compounds tested gave linear area-mass plots although the coefficients observed do not
lead to extrapolations which would permit quantitation of perhalogenated compounds for which no standard is available. Of
the compounds tested, dibromodichloromethane, tetrachloroethene and tetrabromoethene gave good linear correlations of area
ratio-mass ratio (using n-decane as the internal standard). Bromotrichloromethane and tetrabromomethane gave continuously
curving area ratio-mass ratio plots which were very reproducible and could be used for graphical interpolation. 相似文献
100.
Kelly C.F. Araújo Cordeiro Kênnia R. Rezende Boniek G. Vaz Wanderson Romão Luciano M. Lião Eric de Souza Gil Valéria de Oliveira 《Tetrahedron letters》2013
This Letter describes glycosylation of 4-Nerolidylcatechol (4-NRC) the major secondary metabolite from Pothomorphe peltata and Pothomorphe umbellata showing remarkable antioxidant, antimalarial, anti-inflammatory, and anti-HIV activities. One step biosynthesis was catalyzed by Cunninghamella echinulata ATCC 9245 and the reaction was undertaken in PDSM medium at 27 °C, 200 rpm for 96 h. After purification by silica gel flash column chromatography the 4-NRC β-glycoside was identified by ultrahigh resolution mass spectrometry and 1H NMR. The antioxidant activity was evaluated by differential pulse voltammetry. 相似文献