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181.
Natalya V. Likhanova Rafael Martínez‐Palou M. Aurora Veloz Diana J. Matías Victor E. Reyes‐Cruz Herbert Höpfl Octavio Olivares 《Journal of heterocyclic chemistry》2007,44(1):145-153
An efficient and fast procedure for the synthesis of 2‐(2‐pyridyl)azoles is described using ionic liquids as catalysts under microwave irradiation. The X‐ray crystallographic analyses for three of the four synthesized compounds are presented. Potentiodynamic polarization studies were carried out to analyze the electrochemical behavior of the compounds in corrosive acidic media. Of the four derivatives, one compound was detected to be an effective corrosion inhibitor prototype for oil refinery environments. 相似文献
182.
Surface characterization of electrodeposited silver on activated carbon for bactericidal purposes 总被引:1,自引:0,他引:1
Ortiz-Ibarra H Casillas N Soto V Barcena-Soto M Torres-Vitela R de la Cruz W Gómez-Salazar S 《Journal of colloid and interface science》2007,314(2):562-571
The use of an electrochemical reactor operated under different flow conditions to deposit silver from aqueous AgNO(3) solutions and tartaric acid as an organic additive on a commercial activated carbon with ultimate bactericidal applications in water purification processes is presented. The characterization of carbon/silver samples was studied by BET, FTIR, X-ray diffraction, XPS, and SEM techniques. The bactericidal activity of the carbon/silver samples was tested on drinking water samples inoculated with E. coli. A reduction of carbon surface area was detected and was caused by increased amounts of silver deposited on carbon samples. Adherent silver deposits were obtained on the carbon/silver samples. X-ray diffraction studies of carbon with electrodeposited silver showed two different preferential deposition planes, [111] and [220]. The FTIR results confirm the presence of carboxyl, phenolic, quinone, and ether surface groups. The XPS results suggest the formation of Ag(2)O and AgO surface species and confirm the reduction of silver to the metallic form. Antimicrobial activity toward E. coli indicated reductions by up to 7 orders of magnitude in the log CFU/mL in just 10 min contact time and for silver contents of 2.47 wt%. 相似文献
183.
Kudlay A Gibbs JM Schatz GC Nguyen ST de la Cruz MO 《The journal of physical chemistry. B》2007,111(7):1610-1619
An associative equilibrium theory describing the sharp melting behavior of polymer-DNA hybrids is developed. The theory considers linear polymers with attached DNAs on each polymer that serve as "stickers" and with a two-state model governing the DNA melting equilibrium. For three or more oligonucleotides on each polymer, solutions of polymer-DNA hybrids are found to undergo phase separation at sufficiently low temperatures. The dense phase dissolves as temperature increases, which leads to a sharp increase in the fraction of non-hybridized DNA near the phase transition temperature, in agreement with experimental absorbance profiles at 260 nm. The melting temperature is predicted to have the same dependence on salt concentration as a solution of unattached DNAs and be weakly sensitive to the concentration of DNA in solution. The melting temperature is predicted to be higher than that of unattached DNA in solution, with the magnitude of the increase sensitive to the DNA hybridization cooperativity. The theoretical predictions are generally in good quantitative agreement with new experimental data (also presented here), which show the effect of the polymer-DNA hybrid length and salt concentration on the melting profiles. 相似文献
184.
A new protein phosphatase inhibitor, 19-epi-okadaic acid, was isolated from the marine dinoflagellate Prorocentrum belizeanum. Its structure and conformation in solution has been determined, and important differences were found when compared with the lead compound okadaic acid. The new metabolite showed nanomolar activities, and its selectivity for PP2A versus PP1 surpasses that shown by okadaic acid 10-fold, making it one of the most selective inhibitors of this class. 相似文献
185.
F. J. Egea González M. L. Castro Cano J. L. Martínez Vidal C. R. Glass M. Cruz Márquez 《Chromatographia》1999,50(5-6):293-298
Summary An analytical method for the determination of the potential and actual exposure of agricultural workers to procymidone has
been developed. The methodology is based on the whole body technique, using Tyvek Pro-Tech and Sontara as sampling media,
and uses hexane extraction, GC-ECD analysis and GC-MSD confirmation. The validation of the analytical method has been carried
out incorporating the matrix of coverall in all steps when calculating parameters such as retention time window, limits of
detection and quantification, linear ranges and precision. A field sampling strategy has also been developed and the method
has been applied to the evaluation of the potential and actual dermal exposure of an applicator and an assistant in normal
working conditions. 相似文献
186.
R. C. Viscovini F. C. Cruz J. C. S. Moraes A Scalabrin D. Pereira 《International Journal of Infrared and Millimeter Waves》1999,20(2):193-201
We have used Fourier Transform spectral data on the C-O stretching mode of 13CD3OD in order to perform a vibro-rotational analysis for this molecule. We have estimated a few molecular parameters of the ground and C-O stretching vibrational modes. Based on these parameters, and by using the Kwan-Dennison model, we propose assignments for a number of far-infrared laser transitions of 13CD3OD. 相似文献
187.
S. Castillo A. Cruz V. Bertin E. Poulain J. S. Arellano G. Del Angel 《International journal of quantum chemistry》1997,62(1):29-45
The H2 interaction with the Pd dimer and trimer were studied using multiconfigurational self-consistent field (MC-SCF) calculations with the relativistic effective core potential (RECP); the correlation energy correction was included in the extended multireference configuration interaction (MRCI), variational and perturbative to second order. Here, we considered the Pd2 first six states: 3Σ+u, 1Σ+g, 3Πg, 3Δxy, 1Σ+u, and 3Σ+g. For them, the four geometrical approaches included were the side-on H2 toward Pd2, for the hydrogen molecule in and out the Pd dimer plane; the perpendicular end-on H2 toward Pd2; and the perpendicular end-on Pd2 to H2. The Pd2 ground state is 3Σ+u, which only captures H2 in the C2v end-on approach, softly relaxing the H(SINGLE BOND)H bond. The closed-shell 1Σ+g captures the H2 molecule in all the approaches considered: The side-on approach of this state presents deep wells and relaxes the H(SINGLE BOND)H bond, and the end-on approach captures H2 with a relatively longer H(SINGLE BOND)H distance and also a deep well. The 3Πg state was the only one which did not capture H2. For the triangular Pd3 clusters, H2 was approached in the C2v symmetry in and out of the Pd3 plane. In the triangular case, H2 was absorbed in both spin states, with deep wells and relaxing the H(SINGLE BOND)H distance. The linear Pd3 singlet and triplet states capture outside of the Pd3 and break the H(SINGLE BOND)H bond. © 1997 John Wiley & Sons, Inc. 相似文献
188.
Elso M. Cruz Xabier Lopez Martín Sarobe Fernando P. Cossío Jesus M. Ugalde 《Journal of computational chemistry》1997,18(1):9-19
A G2 search of the triplet [H4, Si, P]+ potential energy surface (PES) was carried out, along with a study of a number of mechanisms for the reaction of the P+ (3P) ion with silane. The most stable isomer, which corresponds to the species resulting from transferring three hydrogen atoms from the silicon to the phosphorus atom, lies 67.3 kcal/mol below the reactants' level. The P+(SINGLE BOND)SiH4 ion-molecule complex also has remarkable stability, 20.4 kcal/mol. Bond properties were calculated and are discussed for all the stable species found on the PES. Various exothermic reaction paths were also fully characterized. The abstractions of a hydrogen molecule and a hydrogen atom, yielding species with P(SINGLE BOND)Si bonds, have comparable kinetic hindrance, although release of molecular hydrogen was found to be more exothermic. Finally, hydrogen and/or charge transfer reactions between P+ (3P) and silane are also discussed. © 1997 by John Wiley & Sons, Inc. 相似文献
189.
Yesenia Mendoza García Ana Luiza Coeli Cruz Ramos Afonso Henrique de Oliveira Júnior Ana Cardoso Clemente Filha Ferreira de Paula Angelita Cristine de Melo Moacir Alves Andrino Mauro Ramalho Silva Rodinei Augusti Raquel Linhares Bello de Araújo Eurico Eduardo Pinto de Lemos Júlio Onsio Ferreira Melo 《Molecules (Basel, Switzerland)》2021,26(23)
Myrciaria floribunda, also known as rumberry, is a tree native to the Brazilian Atlantic Forest, where its fruits have the potential for commercial use. This study evaluates the antioxidant potential, determines the phytochemical profile, and chemically characterizes the rumberry fruit. Accessions were sampled from the Rumberry Active Germplasm Bank of the Federal University of Alagoas, Brazil. Physical characteristics, chemical characteristics, and phenolic compound content were analyzed. Chemical profile characterization was carried out using PSMS. Accessions had an average weight of 0.86 g. Accession AC137 presented a higher pulp yield (1.12 g). AC132 and AC156 had larger fruits, AC137 showed greater firmness (5.93 N), and AC160 had a higher and total phenolic content ratio (279.01 ± 11.11). Orange-colored accessions scored higher in evaluated parameters, except for AC160 for phenolic content. Thirty-two compounds were identified on positive ionization mode and 42 compounds on negative ionization mode using PSMS. Flavonoids, followed by the derivatives of benzoic acid, sugars, and phenylpropanoids, were the most prominent. Myricitrin, quercitrin, and catechin stand out as flavonoids that have been reported in previous studies with antioxidant and antimicrobial properties, in addition to health and therapeutical benefits, demonstrating the potential of the rumberry fruit. 相似文献
190.
Gabriela Rocha‐Botello Roberto Olvera‐Guillen Jorge Herrera‐Ordonez Martha Cruz‐Soto David Victoria‐Valenzuela 《大分子反应工程》2019,13(5)
Kinetic aspects of the vinyl acetate ab initio batch emulsion polymerization using poly(vinyl alcohol) to produce polymer nanoparticles are studied. The initial nucleation step is followed by limited coagulation and then by the generation of new particles. It seems that this is the first report of secondary nucleation phenomenon occurring in the system under study in batch mode. To explain this phenomenon, a mathematical model that allows to determine whether certain polymerization conditions and the presence/absence of a steric barrier, can lead or not to significant secondary nucleation is developed. It is deduced that the effect of such steric barrier on the free‐radical entry process plays a key role on the observed phenomenon. 相似文献