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251.
Results of determination of selected imidazolium ionic liquids by isotachophoresis (ITP) with conductometric detection was presented. The effects of the molar mass of different ionic liquids on electrophoretic mobility was observed. The presented method was validated and basic validation parameters were determined. Limit of detection (LOD) in a 10 and 25 ng/L for anions and cations, respectively, is very satisfied. Thanks to its low cost and high rate, the presented method can be used in qualitative routine analysis as an alternative technique to liquid chromatography. 相似文献
252.
Przemysław Górka 《Periodica Mathematica Hungarica》2016,72(2):243-247
We prove an Ergodic Theorem in variable exponent Lebesgue spaces, whenever the exponent is invariant under the transformation. Moreover, a counterexample is provided which shows that the norm convergence fails to hold for an arbitrary exponent. 相似文献
253.
Oxidation of trispicolinatoruthenate(II) complex by hydrogen peroxide leads to the formation of mer-trispicolinatoruthenium(III) in acidic or neutral solutions. Kinetics of the reaction were studied under a large excess of
H2O2 at constant pH. The initial rate method gives a rate expression of the form:
- d[\textRu(\textII)]/\textdt = kII [\textH2 \textO2 ][\textRu(\textII)] - \hbox{d}[{\text{Ru}}({\text{II}})]/{\text{d}}t = k^{II} [{\text{H}}_{2} {\text{O}}_{2} ][{\text{Ru}}({\text{II}})] but the overall process examined till completion is far more complex. The rate of the reaction decreases with increasing
pH to be practically completely retarded in alkaline media. The key step in the proposed reaction mechanism is the picolinato
chelate ring opening followed by the substitution of the coordinated water by H2O2 and two-electron intramolecular ruthenium(II) oxidation. Formation of the final ruthenium(III) complex is assigned rather
to the ruthenium(IV) reduction by H2O2 than ruthenium(II)–ruthenium(IV) comproportionation. The obtained results show the much slower rate of the trispicolinatoruthenate(II)
oxidation by hydrogen peroxide or dioxygen than the mer-trispicolinatoruthenium(III) reduction by such bioreductants as cytochrome cII or some cobalt(II) reductants. 相似文献
254.
Eldon R. Rene Przemys?aw Bernat Jerzy D?ugoński Maria C. Veiga Christian Kennes 《Applied biochemistry and biotechnology》2012,168(6):1351-1371
Biodegradation of styrene by Exophiala sp. was tested at different initial concentrations (19.3?C170.6?mg?l?1), pH (2.8?C8.7), and temperatures (19.8?C45.1?°C), for 120?h according to a 23 full-factorial central composite design. The specific growth rate (SGR, per hour) and specific styrene utilization rate (SUR, milligrams of styrene per milligram of biomass per hour) values were used as the response variables for optimization purposes. The interactions between concentration and temperature (P?=?0.022), and pH and temperature (P?=?0.010) for SGR, and interactions between concentration and temperature (P?=?0.012) for SUR were found to be statistically significant. The optimal values for achieving high SGR (0.15?h?1) and SUR (0.3622?mg styrene mg?1 biomass h?1) were calculated from the regression model equation. Those values are C o ?=?89.1?mg?l?1, pH?=?5.4, and T?=?31.5?°C for SGR and C o ?=?69.2?mg?l?1, pH?=?5.5, and T?=?32.4?°C for SUR. It was also observed that the Exophiala strain degrades styrene via phenylacetic acid, involving initial oxidation of the vinyl side chain. Besides, in the presence of styrene, changes in the fatty acids profile were also observed. It is hypothesized that an increasing amount of linoleic acid (18:2) may be involved in the protection of the fungus against toxic substrate. 相似文献
255.
Sarnicka A Starynowicz P Lisowski J 《Chemical communications (Cambridge, England)》2012,48(16):2237-2239
Reaction of 4-tert-butyl-2,6-diformylphenol with (1R,2R)- or (1S,2S)-1,2-diaminocyclohexane in the presence of 1 equivalent of Zn(2+) ions leads to selective formation of a chiral 2+2 macrocycle. Application of 0.5 equivalent of Zn(2+) ions under the same conditions leads to selective formation of a chiral 3+3 macrocycle, which forms a cavitand-shaped trinuclear double-decker complex with Zn(II). 相似文献
256.
Przemysław Zalewski Judyta Cielecka-Piontek Anna Jelińska 《Central European Journal of Chemistry》2012,10(1):121-126
The stability-indicating LC assay method was developed and validated for quantitative determination of cefoselis sulphate
in the presence of degradation products formed during the forced degradation studies. An isocratic, RP-HPLC method was developed
with C-18 (250 × 4.6 mm, 5 μm) column and 12 mM ammonium acetate-acetonitrile (95:5 V/V) as a mobile phase. The flow rate of the mobile phase was 1.0 mL min−1. Detection wavelength was 260 nm and temperature was 30°C. Cefoselis similarly to other cephalosporins was subjected to stress
conditions of degradation in aqueous solutions including hydrolysis, oxidation, photolysis and thermal degradation. The developed
method was validated with regard to linearity, accuracy, precision, selectivity and robustness. The method was applied successfully
for identification and determination of cefoselis sulphate in pharmaceuticals and during kinetic studies. 相似文献
257.
Michał Michalak Maciej Stodulski Sebastian Stecko Magdalena Woźnica Olga Staszewska-Krajewska Przemysław Kalicki Bartłomiej Furman Jadwiga Frelek Marek Chmielewski 《Tetrahedron》2012,68(52):10806-10817
The methodology of construction of N,4-diaryl substituted β-lactam framework, based on the Kinugasa cycloaddition/rearrangement sequence is presented. The series of protected chiral propargyl alcohols was treated with diaryl nitrones to afford mainly the cis-I adduct, providing direct access to the highly-functionalized azetitidin-2-one derivatives with a well-defined stereochemistry. Under the optimized reaction conditions, the unprotected chiral propargylic alcohols were also found to be suitable precursors of β-lactams. The absolute configuration of adducts was determined by CD or HPLC-CD technique, which was shown to be reliable method of determination of the configuration at C-4 of 4-aryl-substituted azetidin-2-ones. Epimerization of the cis adduct to the respective trans isomer could be easily done by the oxidation of hydroxyl group next to the four-membered β-lactam ring to the ketone, followed by a base-mediated epimerization of the malonyl fragment. 相似文献
258.
1H and 13C NMR spectra of 2-acyl-substituted cyclohexane-1,3-diones (acyl = formyl, 1; 2-nitrobenzoyl, 2; 2-nitro-4-trifluoromethylbenzoyl, 3) and lithium sodium and potassium salts of 1 have been measured. The compound 3, known as NTBC, is a life-saving medicine applied in tyrosinemia type I. The optimum molecular structures of the investigated objects in solutions have been found using the DFT method with B3LYP functional and 6-31G** and/or 6-311G(2d,p) basis set. The theoretical values of the NMR parameters of the investigated compounds have been calculated using GIAO DFT B3LYP/6-311G(2d,p) method. The theoretical data obtained for compounds 1-3 have been exploited to interpret their experimental NMR spectra in terms of the equilibrium between different tautomers. It has been found that for these triketones an endo-tautomer prevails. The differences in NMR spectra of the salts of 1 can be rationalized taking into account the size of the cation and the degree of salt dissociation. It seems that in DMSO solution the lithium salt exists mainly as an ion pair stabilized by the chelation of a lithium cation with two oxygen atoms. The activation free energy the of formyl group rotation for this salt has been estimated to be 51.5 kJ/mol. The obtained results suggest that in all the investigated objects, including the free enolate ions, all atoms directly bonded to the carbonyl carbons lie near the same plane. Some observations concerning the chemical shift changes could indicate strong solvation of the anion of 1 by water molecules. Implications of the results obtained in this work for the inhibition mechanism of (4-hydroxyphenyl) pyruvate dioxygenase by NTBC are commented upon. 相似文献
259.
Weak convergence of products of sums of independent and non-identically distributed random variables
Przemys?aw Matu?a Iwona St?pień 《Journal of Mathematical Analysis and Applications》2009,353(1):49-54
We study limit properties in the sense of weak convergence in the space D[0,1] of certain processes based on products of sums of independent and non-identically distributed random variables. The obtained results extend and generalize results known in the i.i.d. case. 相似文献
260.
We investigate the properties of harmonic functions defined on a metric measure space. Especially, sequences of harmonic functions
are examined, i.e. their convergence and compactness. Moreover, Harnack‘s inequality is shown. 相似文献