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541.
Pedro P. Carvalhinha Anderson Flôres José A. D. Rodrigues Suzana M. Ratusznei Marcelo Zaiat Eugenio Foresti 《Applied biochemistry and biotechnology》2010,162(6):1708-1724
An investigation was performed regarding the application of a mechanically stirred anaerobic sequencing batch biofilm reactor containing immobilized biomass on inert polyurethane foam (AnSBBR) to the treatment of soluble metalworking fluids to remove organic matter and produce methane. The effect of increasing organic matter and reactor fill time, as well as shock load, on reactor stability and efficiency have been analyzed. The 5-L AnSBBR was operated at 30?°C in 8-h cycles, agitation of 400 rpm, and treated 2.0 L effluent per cycle. Organic matter was increased by increasing the influent concentration (500, 1,000, 2,000, and 3,000 mg chemical oxygen demand (COD)/L). Fill times investigated were in the batch mode (fill time 10 min) and fed-batch followed by batch (fill time 4 h). In the batch mode, organic matter removal efficiencies were 87%, 86%, and 80% for influent concentrations of 500, 1,000, and 2,000 mgCOD/L (1.50, 3.12, and 6.08 gCOD/L.d), respectively. At 3,000 mgCOD/L (9.38 gCOD/L.d), operational stability could not be achieved. The reactor managed to maintain stability when a shock load twice as high the feed concentration was applied, evidencing the robustness of the reactor to potential concentration variations in the wastewater being treated. Increasing the fill time to 4 h did not improve removal efficiency, which was 72% for 2,000 mgCOD/L. Thus, gradual feeding did not improve organic matter removal. The concentration of methane formed at 6.08 gCOD/L was 5.20 mmolCH4, which corresponded to 78% of the biogas composition. The behavior of the reactor during batch and fed-batch feeding could be explained by a kinetic model that considers organic matter consumption, production, and consumption of total volatile acids and methane production. 相似文献
542.
We consider the Dirichlet problem for a class of anisotropic degenerate elliptic equations. 相似文献
543.
Daviso E Janssen GJ Alia A Jeschke G Matysik J Tessari M 《Journal of the American Chemical Society》2011,133(42):16754-16757
Several techniques rely on electron-nuclear interactions to boost the polarization of nuclear spins in the solid phase. Averaging out of anisotropic interactions as a result of molecular tumbling strongly reduces the applicability of such hyperpolarization approaches in liquids. Here we show for the first time that anisotropic electron-nuclear interactions in solution can survive sufficiently long to generate nuclear spin polarization by the solid-state photo-CIDNP mechanism. A 10,000-fold NMR signal increase in solution was observed for a giant biomolecular complex of a photosynthetic membrane protein with a tumbling correlation time in the submicrosecond regime, corresponding to a molecular weight close to 1 MDa. 相似文献
544.
Detection of phosphorylation states by intermolecular sensitization of lanthanide-peptide conjugates
E Pazos M Goličnik JL Mascareñas M Eugenio Vázquez 《Chemical communications (Cambridge, England)》2012,48(76):9534-9536
The luminescence of a designed peptide equipped with a coordinatively-unsaturated lanthanide complex is modulated by the phosphorylation state of a serine residue in the sequence. While the phosphorylated state is weakly emissive, even in the presence of an external antenna, removal of the phosphate allows coordination of the sensitizer to the metal, yielding a highly emissive supramolecular complex. 相似文献
545.
Favretto D Cosmi E Ragazzi E Visentin S Tucci M Fais P Cecchetto G Zanardo V Viel G Ferrara SD 《Analytical and bioanalytical chemistry》2012,402(3):1109-1121
A number of metabolic abnormalities have been observed in pregnancies complicated by intrauterine growth restriction (IUGR).
Metabolic fingerprinting and clinical metabolomics have recently been proposed as tools to investigate individual phenotypes
beyond genomes and proteomes and to advance hypotheses on the genesis of diseases. Non-targeted metabolomic profiling was
employed to study fetal and/or placental metabolism alterations in IUGR fetuses by liquid chromatography high-resolution mass
spectrometry (LC-HRMS) analysis of cord blood collected soon after birth. Samples were collected from 22 IUGR and 21 appropriate
for gestational age (AGA) fetuses. Birth weight differed significantly between IUGR and AGA fetuses (p < 0.001). Serum samples were immediately obtained and deproteinized by mixing with methanol at room temperature and centrifugation;
supernatants were lyophilized and reconstituted in water for analysis. LC-HRMS analyses were performed on an Orbitrap mass
spectrometer linked to a Surveyor Plus LC. Samples were injected into a 1.0 × 150-mm Luna C18 column. Spectra were collected
in full-scan mode at a resolution of approximately 30,000. Data were acquired over the m/z range of 50–1,000, with measurements performed in duplicate. To observe metabolic variations between the two sets of samples,
LC-HRMS data were analyzed by a principal component analysis model. Many features (e.g., ionic species with specific retention
times) differed between the two classes of samples: among these, the essential amino acids phenylalanine, tryptophan, and
methionine were identified by comparison with available databases. Logistic regression coupled to a receiver-operating characteristic
curve identified a cut-off value for phenylalanine and tryptophan, which gave excellent discrimination between IUGR and AGA
fetuses. Non-targeted LC-HRMS analysis of cord blood collected at birth allowed the identification of significant differences
in relative abundances of essential amino acids between IUGR and AGA fetuses, emerging as a promising tool for studying metabolic
alterations. 相似文献
546.
D Sadhukhan C Rizzoli E Garribba CJ Gómez-García A Yahia-Ammar LJ Charbonnière S Mitra 《Dalton transactions (Cambridge, England : 2003)》2012,41(38):11565-11568
A mixed valent copper complex [Cu(II)Cu(I)(L)(μ-SCN)(μ(3)-SCN)](n) (LH = N'-((pyridin-2-yl)methylene)acetohydrazide) has been synthesized and characterized. It is a unique example of a 2D mixed valent Cu(II)-Cu(I) interlinked molecular assembly with a very unusual bridging property of the hydrazone ligand. An extraordinary in situ partial Cu(II)→ Cu(I) reduction is observed in this system at room temperature. 相似文献
547.
The hyperfine coupling constant (A in units of energy or A' in units of magnetic field) and zero-field splitting (D in units of energy or D' in units of magnetic field) in the ESR spectrum of Mn(2+) in calcite were determined. The spreading of the non-central allowed transitions |3/2, m --> |5/2, m, |1/2, m --> |3/2, m, |-3/2, m --> |-1/2, m and |-5/2, m --> |-3/2, m was analysed and the experimental transitions were attributed. Particular relevance was given to the difference between the two types of resonances, shoulder or divergence, and to their origin (M, m). The analysis explains the presence of a weak shoulder between each of the five central doublets |-1/2, m --> |1/2, m. Six independent methods for calculating the hyperfine coupling constant and five methods for calculating the zero-field splitting, based on the analysis of the allowed and forbidden transitions, were provided. The values of the hyperfine coupling constant range from -93.9 to -94.6 G and those of the zero-field splitting range from -79.5 to -80.5 G. A critical evaluation of the advantages and drawbacks of the 11 methods is included: the best value for A' is -94.30 G and that for D' is -79.95 G. 相似文献
548.
Muzzalupo R Gente G La Mesa C Caponetti E Chillura-Martino D Pedone L Saladino ML 《Langmuir : the ACS journal of surfaces and colloids》2006,22(14):6001-6009
Mixtures composed of water, sodium dodecyl sulfate (SDS), and a bolaform surfactant with two aza-crown ethers as polar headgroups (termed Bola C-16) were investigated by modulating the mole ratios between the components. The two surfactants have ionic and nonionic, but ionizable, headgroups, respectively. The ionization is due to the complexation of alkali ions by the aza-crown ether unit(s). Structural, thermodynamic, and transport properties of the above mixtures were investigated. Results from surface tension, translational self-diffusion, and small angle neutron scattering (SANS) are reported and discussed. Interactions between the two surfactants to form mixed micelles result in a combination of electrostatic and hydrophobic contributions. These effects are reflected in the size and shape of the aggregates as well as in transport properties. The translational diffusion of the components in mixed micelles, in particular, depends on the Bola C-16/SDS mole ratio. Nonideality of mixing of the two components was inferred from the dependence of the critical micelle concentration, cmc, on the mole fraction of Bola C-16. This behavior is also reflected in surface adsorption and in the area per polar headgroup at the air-water interface. SANS data analysis for the pure components gives results in good agreement with previous findings. An analysis of data relative to mixed systems allows us to compute some structural parameters of the mixed aggregates. The dependence of aggregation numbers, nu(T), on the Bola C-16/SDS mole ratio displays a maximum that depends on the overall surfactant content and is rationalized in terms of the nonideality of mixing. Aggregates grow perpendicularly to the major rotation axis, as formerly observed in the Bola C-16 system, and become progressively ellipsoidal in shape. 相似文献
549.
Zangrando R Armelao L Bottaro G Gross S Seraglia R Tondello E Traldi P 《Rapid communications in mass spectrometry : RCM》2006,20(18):2681-2688
The hydrolysis and polycondensation reactions of Al(OBu(s))3 have been studied by laser desorption/ionization (LDI), performed on the solid samples originating from different aluminum alkoxide solutions, prepared using the usual operating conditions employed in the sol-gel synthesis of Al2O3-based materials. CHCl3, CH3OH and CH3OH/H2O mixture were used as solvents. In the latter case different H2O/Al(OBu(s))3 molar ratios were adopted, i.e. 1:1, 1:2, and 1:4. The obtained hydrolysis and polycondensation species consist of polynuclear species containing < or =12 aluminum atoms. In the CHCl3 solutions, the formation of the observed hydrolysis products has been ascribed to the reaction with water present in the atmosphere during the LDI sample preparation and/or present at trace level in the solvent. When methanol is used as a solvent, extensive methanolysis reactions take place, thus originating oligomers with CH3O and OH substituents. The kinetics of formation of the various polynuclear species are dependent on the reaction environment and the reaction is faster in the presence of methanol. It is worth noticing that, regardless of the hydrolysis process, the polycondensation products can be considered as originating from a common tetrameric core [Al4O4(OBu)2(OH)2] around which different building blocks are condensed to form various oxo-polymeric species. 相似文献
550.