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111.
112.
Ichthyosan A and V are two highly elastoviscous glycan complexes present in the aqueus and vitreus [here aqueus and vitreus
are used as nouns as was suggested by Balazs and Denlinger in The eye, vol 1A. Vegetative physiology and biochemistry, 3rd
edn. Academic Press, New York, pp 533–589, 1984] of the fish eye. Ichthyosan A, with its high elastic properties, surrounds
and stabilizes the lens of the eye. Ichthyosan V, within the collagen fibers, serves as a structure stabilizer of the gel
vitreus. These two molecular complexes are non-covalent aggregates composed of hyaluronan, a chondroitin-proteoglycan (sulfate
free), and a keratan-like molecule. The ratio of hyaluronan to chondroitin–proteoglycan varies in the two ichthyosans. Electrophoretic
separation methods (both free and gel electrophoresis) demonstrate that the hyaluronan–proteoglycan aggregates move as one
molecular entity. The average molecular weight of the ichthyosan varies from 5.2 to 13.0 million in various species. Aquatic
mammals do not have ichthyosan in their eyes. 相似文献
113.
Paul Armand Joël Benoist Dominique Orban 《Computational Optimization and Applications》2008,41(1):1-25
We introduce a framework in which updating rules for the barrier parameter in primal-dual interior-point methods become dynamic.
The original primal-dual system is augmented to incorporate explicitly an updating function. A Newton step for the augmented
system gives a primal-dual Newton step and also a step in the barrier parameter. Based on local information and a line search,
the decrease of the barrier parameter is automatically adjusted. We analyze local convergence properties, report numerical
experiments on a standard collection of nonlinear problems and compare our results to a state-of-the-art interior-point implementation.
In many instances, the adaptive algorithm reduces the number of iterations and of function evaluations. Its design guarantees
a better fit between the magnitudes of the primal-dual residual and of the barrier parameter along the iterations. 相似文献
114.
Maryam Tabrizian Armand Soldera Michel Couturier C. Geraldine Bazuin 《Liquid crystals》1995,18(3):475-482
The thermotropism of 1-n-alkyl-(4-methyl and 4-tolyl)pyridinium bromides were compared for alkyl chain lengths ranging from n = 12 to 22 carbons. A smectic A mesophase is present in both series for the longer chain compounds, n ≥ 16, with the clearing temperature being similar for both series but increasing rapidly with chain length. The series with the elongated mesogen also possesses an ordered mesophase identified as smectic G. The transition between this mesophase and the SA or isotropic phase in the 4-tolyl series, and the transition to and from the crystalline phase in both series, are affected relatively little by the alkyl chain length. It seems that the SA mesophase is governed primarily by the amphiphilic character of the substances, whereas elongation of the ionic head group is responsible for the appearance of a more ordered mesophase at intermediate temperatures. 相似文献
115.
Bubacco L van Gastel M Benfatto M Tepper AW Canters GW 《Micron (Oxford, England : 1993)》2004,35(1-2):143-145
The structural basis that define the physiological functions of binuclear copper enzymes is discussed in the frame of the data generated by a broad spectroscopic approach, spanning from paramagnetic NMR and pulsed EPR to x-ray absorption spectroscopies. The structural features discussed for the different oxidation and ligation states accessible to a binuclear copper sites are the coordination geometry for the first and second shell, the metal-metal distance and the role of the bridging exogenous ligand(s). A structural model will be presented to rationalize both the differentiation in function within the protein families and the reaction mechanism of those proteins that are enzymatically active. 相似文献
116.
Patrone L Palacin S Charlier J Armand F Bourgoin JP Tang H Gauthier S 《Physical review letters》2003,91(9):096802
The transport properties of two oligothiophene derivatives, that differ only by the chemical group coupling to gold, are compared. It is shown that the role of the coupling group in the transport properties can be decoupled from that of the conjugated body of the molecules and that Se is a better electronic coupling group than S. These results are accounted for semiquantitatively within the frame of the scattering theory of transport, using results from ultraviolet photoemission spectroscopy experiments as inputs for the position in energy of the molecular orbitals with respect to the Fermi level of the electrodes. 相似文献
117.
We report that, when a train of confined droplets flowing through a channel reaches a junction, the droplets either are alternately distributed between the different outlets or all collect into the shortest one. We argue that this behavior is due to the hydrodynamic feedback of droplets in the different outlets on the selection process occurring at the junction. A "mean field" model, yielding semiquantitative results, offers a first guide to predict droplet traffic in branched networks. 相似文献
118.
119.
Starting from 3-bromo-, 1-iodo- and 4-iodo-9-oxo-fluorene three symmetrical bifluorenonyls and the corresponding hydrocarbons 3,3′-, 1,1′- and 4,4′-bifluorenyls are prepared. An attempt to obtain the non-symmetrical 1,2′-bifluorenyl is also described. 相似文献
120.
Esther Oliveros Monique Riviere Armand Lattes 《Magnetic resonance in chemistry : MRC》1976,8(12):601-606
The structures of imines and oxaziridines derived from 2-methyl and 2,6-dimethyl cyclohexanone have been determined by 1H n.m.r. spectroscopy. The preferred conformation of all the oxaziridines we examined was found to have the nitrogen atom in equatorial position. 相似文献