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51.
Iva Juranovi? Cindri? Michaela Zeiner Michaela Kröppl Gerhard Stingeder 《Microchemical Journal》2011,99(2):364-369
Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the determination of minor and major elements present in apple juices. Prior to ICP-AES measurement, samples were diluted with nitric acid or digested in a microwave assisted digestion system. The differences in the measured element concentrations after application of different types of sample preparation procedures are discussed. The direct measurement compared to closed microwave dissolution was found to be the best sample preparation procedure. Prior to the measurements the ICP-AES method was validated and optimized for the determination of elements in apple juices. For diluted apple juice samples the lowest limits of detection (LOD) were obtained for Ba and Cd (< 20 μg L− 1), moderate ones for Cu, Mn, Ni, Fe, Ag, Ca, Cr, Zn, Mg, and Sr (20–100 μg L− 1), and the highest LODs for K, Pb, Na, and Al (> 110 μg L− 1). The results obtained for the repeatability (< 0.9%), the intermediate precision (< 4.5%), the day-to-day reproducibility (< 5.2%), and the overall uncertainty of measurement (approx. 4–7%) for all elements analyzed demonstrated the good applicability of the proposed method. Differences in major element content in fresh and commercial apple juice are discussed. 相似文献
52.
Cecioni S Faure S Darbost U Bonnamour I Parrot-Lopez H Roy O Taillefumier C Wimmerová M Praly JP Imberty A Vidal S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(7):2146-2159
The design of multivalent glycoconjugates has been developed over the past decades to obtain high-affinity ligands for lectin receptors. While multivalency frequently increases the affinity of a ligand for its lectin through the so-called "glycoside cluster effect", the binding profiles towards different lectins have been much less investigated. We have designed a series of multivalent galactosylated glycoconjugates and studied their binding properties towards two lectins, from plant and bacterial origins, to determine their potential selectivity. The synthesis was achieved through copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) under microwave activation between propargylated multivalent scaffolds and an azido-functionalised carbohydrate derivative. The interactions of two galactose-binding lectins from Pseudomonas aeruginosa (PA-IL) and Erythrina cristagalli (ECA) with the synthesized glycoclusters were studied by hemagglutination inhibition assays (HIA), surface plasmon resonance (SPR) and isothermal titration microcalorimetry (ITC). The results obtained illustrate the influence of the scaffold's geometry on the affinity towards the lectin and also on the relative potency in comparison with a monovalent galactoside reference probe. 相似文献
53.
Transitions within the tunneling multiplet of CH(4) in phase II have been measured in an experiment at the backscattering instrument BASIS of the Neutron Source SNS. They all involve transitions from or to T-states. A statistical model is put forward which accounts for local departures from tetrahedral symmetry at the sites of ordered molecules. Different from previous work, in which discrete sets of overlap matrix elements have been studied, now large numbers of elements as well as the ensemble of T-states are considered. The observed neutron spectra can be explained rather well, all based on the pocket state formalism of A. Hu?ller [Phys. Rev. B 16, 1844 (1977)]. A completely new result is the observation and simulation of transitions between T-states, which give rise to a double peaked feature close to the elastic position and which reflect the disorder in the system. CH(2)D(2) molecules in the CH(4) matrix are largely responsible for the disorder and an interesting topic for their own sake. The simple model presented may lend itself to a broader application. 相似文献
54.
Révész A Schröder D Svec J Wimmerová M Sindelar V 《The journal of physical chemistry. A》2011,115(41):11378-11386
Electrospray ionization mass spectrometry (ESI-MS) is used to probe the binding of small anions to the macrocycle of bambus[6]uril. For the halide ions, the experimental patterns suggest F(-) < Cl(-) < Br(-) < I(-), which is consistent with the order of anion binding found in the condensed phase. Parallel equilibrium studies in the condensed phase establish the association constants of halide anions and bambus[6]uril in mixed solvents. A detailed analysis of the mass spectrometric data is used to shed light on the correlations between the binding constants in the condensed phase and the ion abundances observed using ESI-MS. From the analysis it becomes apparent that ESI-MS can indeed represent the situation in solution to some extent, but the sampling in the gas-phase experiment is not 1:1 compared to that in solution. 相似文献
55.
Maria Michaela Porzio 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(16):5359-5382
We prove existence, uniqueness, regularity results and estimates describing the behavior (both for large and small times) of a solution u of some nonlinear parabolic equations of Leray-Lions type including the p-Laplacian. In particular we show how the summability of the initial datum u0 and the value of p influence the behavior of the solution u, producing ultracontractive or supercontractive estimates or extinction in finite time or different kinds of decay estimates. 相似文献
56.
Shmilovits-Ofir M Miller Y Gerber RB 《Physical chemistry chemical physics : PCCP》2011,13(19):8715-8722
Vibrational energy flow and conformational transitions following excitation of the OH stretching mode of the most stable conformer of glycine are studied by classical trajectories. "On the fly" simulations with the PM3 semiempirical electronic structure method for the potential surface are used. Initial conditions are selected to correspond to the ν=1 excitation of the OH stretch. The main findings are: (1) An an equilibrium-like ratio is established between the populations of the 3 lowest-lying conformers after about 10 picoseconds. (2) There is a high probability throughout the 150 ps of the simulations for finding the molecule in geometries far from the equilibrium structures of the lowest-energy conformers. (3) Energy from the initial excited OH (ν=1) stretch flows preferentially to 5 other vibrational modes, including the bending motion of the H atom. (4) RRK theory yields conformational transition rates that deviate substantially from the classical trajectory results. Possible implication of these results for vibrational energy flow and conformational transitions in small biological molecules are discussed. 相似文献
57.
58.
1-Azido-3-phenalenones 5 with acyl substituents in position 2, obtained by acylation and azidation of 1-hydroxy-3-phenalenones 1 , cyclized by thermolysis to give phenaleno[1,2-c]isoxazol-7-ones 9 . The thermolysis conditions were studied by differential scanning calorimetry. 相似文献
59.
We prove existence and uniqueness results for non-linear elliptic equations with lower order terms, L1 data, and mixed boundary conditions that include as particular cases the Dirichlet and the Neumann problems.
Mathematics Subject Classification (2000) 35J25, 35D05, 35J70, 35J60 相似文献
60.