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1.
Reactions of the hydrated electron, H atoms, 2-propanol, and methanol radicals with the TiO2 nano-particles have been studied either directly or by competition kinetics. The radicals were produced by radiolysis of 2-propanol, t-butanol, or methanol aqueous solutions in acid pH's. The reactions involve electron injection to the conduction band. As expected, the t-butanol radical is inert towards TiO2 under our conditions, while the other reducing radicals react with TiO2. The reactivity decreases in the order: eaq−>H>CH3COHCH3>CH2OH. Two TiO2 nanocrystallite sizes, with average diameters of 1.0 and 4.7 nm were compared. For equal concentrations (in terms of TiO2 molecules), the rate of electron injection shows relatively little dependency on particle size. The rates of interfacial electron transfer and transfer coefficient are also reported. 相似文献
2.
3.
Agnes Kurucz 《Algebra Universalis》2002,47(4):409-424
We show that in many cases the decision problems for varieties of cylindric algebras are much harder than those for the corresponding relation algebra reducts. We also give examples of varieties of cylindric and relation algebras which are algorithmically more complicated than the subvarieties of their representable algebras. 相似文献
4.
Szantai E Ronai Z Szilagyi A Sasvari-Szekely M Guttman A 《Journal of chromatography. A》2005,1079(1-2):41-49
The investigation of the genetic background and phenotype structures of complex diseases, such as cardiovascular or psychiatric disorders and tumors, is one of the most scrutinized fields of the post genomic era. Besides the multiplex analysis of genetic markers and polymorphisms throughout the whole genome, more and more attention is focused on the interaction between the etiological factors of these traits. Haplotype determination, rather than multiplex genotyping seems to be one of the first building blocks of this endeavor. This review focuses on the importance and theoretical background of haplotyping, and summarizes the recent examples of novel and emerging haplotyping techniques by capillary gel electrophoresis based DNA fragment analysis, a powerful tool for the examination of the inheritance of complex traits. 相似文献
5.
Agnes G. Nagy 《Journal of organometallic chemistry》1985,291(3):335-340
Polarizations, polarization ranges and ratios of polarization ranges for vinylene groups in seven series, namely chalcone derivatives, ferrocene analogues of chalcone, stilbene derivatives, ferrocene analogues of stilbene, and styrene derivatives, were studied. The polarization ranges spanning the intervals between 13C NMR chemical shifts of the derivatives substituted by p-NO2 and p-NMe2 groups are compared in these related compounds. The influence of the side-chain groups in the vinylene moiety and of the sign of the polarization on the substituent-effect are discussed. 相似文献
6.
Tamas Benko Agnes Szanyi Peter Mizsey Zsolt Fonyo 《Central European Journal of Chemistry》2006,4(1):92-110
The sustainable development and consumption need more efficient use of natural resources. As a consequence, the use of industrial
solvents demands their recovery instead of end-of-pipe treatment. It is not always clear, however, which treatment alternative
should be applied. Based on an industrial case study, the environmental and economic evaluation and comparison of the treatment
alternatives of a non-ideal solvent mixture containing azeotropes is investigated for determining the preferable option. For
the recovery of the industrial solvent mixture, two different separation alternatives are evaluated: a less effective alternative
and a novel design based on hybrid separation tools. An end-of-pipe treatment alternative, incineration, is also considered
and the split of the solvent mixtures between recovery and incineration is investigated. The environmental evaluation of the
alternatives is carried out using ‘Eco-indicator 99 life-cycle impact assessment methodology’. Economic investigation is also
accomplished. The economic features clearly favour the total recovery, however, the environmental evaluation detects that
if a recovery process of low efficiency is applied, its environmental burden can be similar or even higher than that of the
incineration. This motivates engineers to design more effective recovery processes and reconsider the evaluation of process
alternatives at environmental decision making. 相似文献
7.
8.
Ibrahim Y Alsharaeh E Dias K Meot-Ner Mautner M El-Shall MS 《Journal of the American Chemical Society》2004,126(40):12766-12767
We studied the stepwise hydration and solvent-mediated deprotonation of the benzene*+ cation (Bz*+) and found several unusual features. The solvent binding energies DeltaH on-1,n for the reactions Bz*+(H2O)n-1 + H2O --> Bz*+(H2O)n are nearly constant at 9 +/- 1 kcal mol-1 for n = 1 to 8. We observed a remarkable sudden decrease in the entropy of association accompanying the formation of Bz*+(H2O)7 and Bz*+(H2O)8, indicating strong orientational restraint in the hydration shells of these clusters consistent with the formation of cagelike structures. We observed the size-dependent deprotonation of Bz*+ in a cooperative multibody process, where n H2O molecules (n >/= 4) can remove a proton from Bz*+ to form protonated water clusters. We measured, for the first time, the temperature dependence of such a process and found a negative temperature coefficient of a magnitude unprecedented in any chemical reaction, of the form k = AT-67+/- 4, or in an Arrhenius form having an activation energy of -34 +/- 1 kcal mol-1. The temperature effect may be explained by Bz*+ and four H2O molecules needing to be assembled from gas-phase components to form the reactive species. Such large temperature effects may be therefore general in solvent cluster-mediated reactions. 相似文献
9.
The thermodynamic and extra-thermodynamic dependencies of five types of cytochrome c in water-acetonitrile mixtures of different composition in the presence of immobilised n-octyl ligands as a function of temperature from 278 K to 338 K have been investigated. The corresponding enthalpic, entropic and heat capacity parameters, deltaHdegrees assoc, deltaS degrees assoc and delta C degrees p, have been evaluated from the observed non-linear Van't Hoff plots of these globular proteins in these heterogeneous systems. The relationships between the free energy dependencies, various molecular parameters and extra-thermodynamic dependencies (empirical correlations) of these protein-non-polar ligand interactions have also been examined. Thus, the involvement of enthalpy-entropy compensation effects has been documented for the binding of these cytochrome cs to solvated n-octyl ligands. Moreover, the results confirm that this experimental approach permits changes in molecular surface area due to the unfolding of these proteins on association with non-polar ligands as a function of temperature to be correlated with other biophysical properties. This study thus provides a general procedure whereby the corresponding free energy dependencies of globular proteins on association with solvated non-polar ligands in heterogeneous two-phase systems can be quantitatively evaluated in terms of fundamental molecular parameters. 相似文献
10.
Abu-Youssef MA Drillon M Escuer A Goher MA Mautner FA Vicente R 《Inorganic chemistry》2000,39(22):5022-5027
The reaction of manganese(II) and pyridine derivatives such as 3-methylpyridine (3-Mepy) and 3,4-dimethylpyridine (3,4-Dmepy) led to the new one-dimensional systems trans-[Mn(3-Mepy)2(N3)2]n (1) and trans-[Mn(3,4-Dmepy)2(N3)2]n (2). Compound 1 crystallizes in the monoclinic system, space group P2(1)/n, a = 11.201(3) A, b = 14.499(4) A, c = 14.308(4) A, Z = 6, and compound 2 crystallizes in the triclinic system, space group P1, a = 11.502(4) A, b = 14.246(5) A, c = 16.200(8) A, Z = 6. The two compounds show the same general one-dimensional arrangement of double azido bridges between neighboring manganese atoms with the unprecedented -Mn-(mu(1,3)-N3)2-Mn-(mu(1,3)-N3)2-Mn-(mu(1,1)-N3)2-Mn- sequence. Susceptibility and magnetization measurements reveal a ferrimagnetic-like behavior derived from the topology of the chain. A model of the Heisenberg chain, comprising classical spins coupled through alternating exchange interactions J1J1J2... is proposed to describe the magnetic behavior. 相似文献