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321.
A time-domain topological sensitivity (TS) approach is developed for elastic-wave imaging of media of arbitrary geometry. The TS, which quantifies the sensitivity of the misfit cost functional to the creation at a specified location of an infinitesimal hole, is expressed in terms of the time convolution of the free field and a supplementary adjoint field as a function of that specified location. Following previous studies performed under (mostly) static or time-harmonic conditions, the TS field is here considered as a natural and computationally efficient approach for defining a defect indicator function. This study emphasizes the implementation and exploitation of TS fields using standard displacement-based FEM approaches, a straightforward task once the correct sensitivity formulation is available. A comprehensive set of numerical experiments on 3D and 2D elastodynamic and acoustic configurations is reported, allowing to assess and highlight many features of the proposed TS-based fast qualitative identification such as its ability to identify multiple defects and its robustness against data noise. 相似文献
322.
Audrey Favrelle Véronique Bonnet Catherine Sarazin Florence Djedaïni-Pilard 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):15-20
A new class of mono-substituted amphiphilic cyclodextrins was synthesized in a one-step lipase catalysed amidification. Microbial and animal lipases were able to catalyse this reaction. Depending on the acyl donors, various hydrophobic moieties have been grafted on methylated β-cyclodextrin. Azoninyl-methylated-β-cyclodextrin derivatives were also obtained by reaction of acetaldehyde and modified cyclodextrins in presence of dedicated lipase. 相似文献
323.
Sylvestre Bonnet Dr. Jie Li Maxime A. Siegler Dr. Lars S. von Chrzanowski Dr. Anthony L. Spek Prof. Dr. Gerard van Koten Prof. Dr. Robertus J. M. Klein Gebbink Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(14):3340-3343
Feel the pinch! Planar–chiral, cationic, ruthenium–palladium complexes based on η6,η1‐coordinated ECE′ pincer ligands are synthesized as racemic mixtures by reacting ECE′–palladium complexes and [Ru(C5R5)(MeCN)3]+ arenophiles (R=H or Me). Chiral resolution of the cationic complexes was achieved by using the chiral counterion [Δ‐TRISPHAT]?, and solving the X‐ray crystal structure of one diastereoisomer (shown here).
324.
Anke Wilhelm-MoutonSusan L. Bonnet Yuanqing DingXing-Cong Li Daneel Ferreira Jan H. van der Westhuizen 《Journal of photochemistry and photobiology. A, Chemistry》2012,227(1):18-24
A new method to open the heterocyclic ring of flavan-3-ols via photolytic cleavage of the ether bond, with stereoselective trapping of the intermediates with phloroglucinol to obtain phloroglucinol grafted derivatives of flavan-3-ols, was developed. Photolysis of catechin and epicatechin, respectively, in the presence of phloroglucinol yielded the enantiomeric (1S,2S)- and (1R,2R)-1,3-di(2,4,6-trihydroxyphenyl)-1-(3,4-dihydroxyphenyl)propan-2-ols, respectively. The absolute configuration at C-1 and C-2 was determined by electronic circular dichroism (experimental and calculated) and these results confirmed that the trapping mechanism is controlled by the C-3 configuration of the flavan-3-ol. 相似文献
325.
Pierre Murat Romaric Bonnet Angéline Van der Heyden Dr. Nicolas Spinelli Dr. Pierre Labbé Prof. Dr. David Monchaud Dr. Marie‐Paule Teulade‐Fichou Dr. Pascal Dumy Prof. Dr. Eric Defrancq Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(20):6106-6114
A new biomolecular device for investigating the interactions of ligands with constrained DNA quadruplex topologies, using surface plasmon resonance (SPR), is reported. Biomolecular systems containing an intermolecular‐like G‐quadruplex motif 1 (parallel G‐quadruplex conformation), an intramolecular G‐quadruplex 2 , and a duplex DNA 3 have been designed and developed. The method is based on the concept of template‐assembled synthetic G‐quadruplex (TASQ), whereby quadruplex DNA structures are assembled on a template that allows precise control of the parallel G‐quadruplex conformation. Various known G‐quadruplex ligands have been used to investigate the affinities of ligands for intermolecular 1 and intramolecular 2 DNA quadruplexes. As anticipated, ligands displaying a π‐stacking binding mode showed a higher binding affinity for intermolecular‐like G‐quadruplexes 1 , whereas ligands with other binding modes (groove and/or loop binding) showed no significant difference in their binding affinities for the two quadruplexes 1 or 2 . In addition, the present method has also provided information about the selectivity of ligands for G‐quadruplex DNA over the duplex DNA. A numerical parameter, termed the G‐quadruplex binding mode index (G4‐BMI), has been introduced to express the difference in the affinities of ligands for intermolecular G‐quadruplex 1 against intramolecular G‐quadruplex 2 . The G‐quadruplex binding mode index (G4‐BMI) of a ligand is defined as follows: G4‐BMI=KDintra/KDinter, where KDintra is the dissociation constant for intramolecular G‐quadruplex 2 and KDinter is the dissociation constant for intermolecular G‐quadruplex 1 . In summary, the present work has demonstrated that the use of parallel‐constrained quadruplex topology provides more precise information about the binding modes of ligands. 相似文献
326.
Elementary gas‐phase reactions of the bimolecular type A + B → Products are characterized by the second‐order kinetic law , where [A] and [B] are the concentrations of A and B species, t is the time, and k is the rate constant, usually estimated by means of Eyring equation. Here, we show that its dynamical derivation, as such, is not consistent with the second‐order law. This contradiction is however removed by introducing a correlation between what we call potentially reactive pairs. A new presentation of the dynamical derivation of Eyring equation is finally proposed on the basis of the previous findings. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem 110:2355–2359, 2010 相似文献
327.
Bonnet L 《The Journal of chemical physics》2010,133(17):174108
The standard classical expression of the state-resolved photodissociation cross section is not consistent with an efficient Bohr quantization of product internal motions. A new and strictly equivalent expression not suffering from this drawback is proposed. This expression opens the way to more realistic classical simulations of direct polyatomic photodissociations in the quantum regime where only a few states are available to the products. 相似文献
328.
Roland Bonnet 《哲学杂志》2013,93(33):3055-3083
AbstractThe interfacial structure of a lamellar Al(α)-Al2Cu(θ) eutectic obtained by directional solidification is investigated using conventional transmission electron microscopy (TEM) and high-resolution TEM. The average lamellar habit plane is close to (2 3 3)α and lie 10° from the atomically densest planes (1 1 1)α//(2 –1 1)θ. Networks of linear contrasted features are observed along the interfaces, the lines being separated each other’s in a wide range of spacings, typically 6–500 nm. These features are identified as interfacial dislocations with 1/2<1 1 0>α Burgers vectors from image contrast analysis. According to previous works, they are associated with ledge-like defects, the heights of which can reach 3 nm. The high-resolution TEM images do not confirm the presence of atomic terraces parallel to the atomically dense plane (1 1 1)α or the habit plane (2 3 3)α. The interface ensures the quasi-continuity of atomically dense planes, which is a configuration corresponding to the plane-matching model. It is suggested that α/θ interfaces can be considered as semi-coherent but in a particular sense since, according to our analysis, the theoretical length misfits between the fcc and bct lattices are too large to explain the presence of some loose dislocation networks. Their general irregular geometry suggests that these dislocation networks behave like non-equilibrated low-angle grain boundaries superposed on the α–θ interfaces. 相似文献
329.
A theoretical study of H(2) and D(2) desorbing from Cu(111) is reported. The study makes use of the LEPS PES of Dai and Zhang [J. Chem. Phys. 1995, 102, 6280]. The LEPS parameters have been modified in order to lower the barrier threshold in conformity with accurate ab initio electronic structure calculations. The topological study of the modified PES by the CHAIN method reveals unambiguously that the transition state (TS) is located at the top of a unique early barrier along the desorption path. The adsorbed H atoms are supposed to be in thermal equilibrium with the metal surface. Batches of classical trajectories (CT) are then carried out from the TS onto the products with their initial conditions canonically distributed and the effect of their possible recrossing of the TS taken into account according to Keck's method [Discuss. Faraday Soc. 1962, 33, 173]. Product state distributions are then calculated using the Gaussian weighting procedure [Chem. Phys. Lett. 2004, 397, 106] to account for the quantization of the vibration motion of the desorbed diatom. These distributions are in overall good agreement with experimental measurements. On average, the early barrier to desorption results in a significant vibrational excitation of the final diatom and a strong deexcitation of its rotational angular momentum J from the TS onto the products. Moreover, the orientation of the rotation plane is roughly random for low values of J (both cartwheel and helicopter motions are observed) while it is more likely parallel to the metal surface for large values of J (predominance for helicopter motion). These findings are analyzed in some details. 相似文献
330.
Bonnet E Borderie B Le Neindre N Raduta AR Rivet MF Bougault R Chbihi A Frankland JD Galichet E Gagnon-Moisan F Guinet D Lautesse P Łukasik J Marini P Pârlog M Rosato E Roy R Spadaccini G Vigilante M Wieleczko JP Zwieglinski B;INDRA ALADIN Collaborations 《Physical review letters》2010,105(14):142701
Fragment partitions of fragmenting hot nuclei produced in central and semiperipheral collisions have been compared in the excitation energy region 4-10?MeV per nucleon where radial collective expansion takes place. It is shown that, for a given total excitation energy per nucleon, the amount of radial collective energy fixes the mean fragment multiplicity. It is also shown that, at a given total excitation energy per nucleon, the different properties of fragment partitions are completely determined by the reduced fragment multiplicity (i.e., normalized to the source size). Freeze-out volumes seem to play a role in the scalings observed. 相似文献