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91.
A major research field in mechanistic systems biology is represented by the development of methods for investigating the structural and dynamic features of systems with multiple interacting components, in order to understand their function. A combination of NMR techniques can be used in such respect, among which the employment of paramagnetic metal ions, 13C direct detection, and solid-state NMR, possibly supported by other techniques like small angle X-ray scattering. Among the results, the information on the conformational heterogeneity experienced by multicomponent systems in solution can be mentioned. The structural and functional characterization of large biological systems, not affordable with standard solution NMR techniques, can be tackled through a synergistic use of solution and MAS solid-state NMR. 13C direct detection NMR spectroscopy is on the other hand advantageous for improving the quality and quantity of observed nuclear signals, for their intrinsically smaller linewidths and larger signal breadth. Details on these approaches are reviewed here. 相似文献
92.
Pietro Baraldi Gian Carlo Franchini Andrea Marchetti Gavino Sanna Lorenzo Tassi Alessandro Ulrici Giulia Vaccari 《Journal of solution chemistry》2000,29(5):489-504
Thermodynamic interactions in the ethane-1,2-diol (1) + 1,2-dimethoxyethane(2) + water (3) ternary system have been investigated in terms of the excessmolar volume, derived from density measurements at 19 different temperaturesfrom –10;dg to 80;dgC. Fourteen three-component mixtures have been considered,covering the entire composition range. The excess molar volumes are discussedin terms of conformational changes induced in each component by the presenceof another one. The results obtained support the hypothesis of the absence of anythree-component complex adducts under all experimental conditions investigated. 相似文献
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94.
The conformation in the crystalline state and in solution of the sterically congested tetramethylpiperidinederived amide group of the symmetric diamide I formed from 2,2,6,6-tetramethylpiperidine ( b ) and 1,2,5-thiadiazole-3,4-dicarbonyl dichloride ( c ), and of the mixed diamide II derived from b , c , and piperidine ( a ) has been investigated. In crystals, as observed with II , this group is strongly bent out-of-plane at both the N-atom and the carbonyl C-atom, and there is also a sizable twisting around the amide bond. Furthermore, the amide bond is abnormally long (1.37 Å). In CD2Cl2 (or CDCl3) solution, the group is apparently planar in its ground-state conformation, but the energy barrier to rotation around the amide bond is low. This conclusion is based on low-temperature 1H-NMR measurements on I , II , and on the symmetric diamide III derived from a and c . 相似文献
95.
Martino Ambrosini Nikla Baricordi Simonetta Benetti Carmela De Risi Gian P. Pollini Vinicio Zanirato 《Tetrahedron: Asymmetry》2009,20(18):2145-2148
The Favorskii rearrangement of suitable α-chloro derivatives of commercially available (+)- and (−)-carvone, and (−)-menthone served efficiently to prepare the title compounds featuring delicious fruity, floral olfactory notes. 相似文献
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97.
S. Banerjee S. N. Ganguli A. Gurtu R. Raghavan K. Shankar Y. Goldschmidt-Clermont R. T. Ross S. Squarcia K. Dziunikowska T. Haupt P. Girtler D. Kuhn G. Koul Devanand P. V. K. S. Baba Gian Singh K. W. J. Barnham J. Wells P. R. S. Wright F. Mandl M. Markytan M. Bardadin-Otwinowska M. Szczekowski 《Zeitschrift fur Physik C Particles and Fields》1986,31(3):409-416
Results are presented on inclusive production of ∑+(1385) and ∑?(1385) inK ? p interactions at 110 GeV/c. The inclusive and topological cross sections have been estimated and compared with published results at lower energies. The inclusive cross section of ∑+(1385) seems to decrease with c.m. energy, while that of the ∑?(1385) is nearly constant. The mean charged multiplicity associate to Σ(1385) increases with c.m. energy. The ∑+(1385) is produced both in the target fragmentation region and in the central region where ∑?(1385) is predominantly produced in the central region. Approximately 16% of the Λ's stem from the decay of ∑±(1385) and the kinematic distributions of these Λ's are not very different from the inclusive Λ's. 相似文献
98.
Gian Paulo G. Freschi Carolina D. Freschi José A. Gomes Neto 《Mikrochimica acta》2008,161(1-2):129-135
Different kinds of modifiers and coatings on the integrated platform of transversely heated graphite atomizer (THGA) have
been tested for the simultaneous determination of two group of elements: the first, the more volatile, formed by arsenic,
bismuth, lead, antimony and selenium; the second, the less volatile, formed by cobalt, chromium, cupper, iron and manganese
in milk by electrothermal atomic absorption spectrometry. Different Rh-modifiers were studied, such as Rh-coated platforms
(Rh), carbide plus rhodium coated platforms (W-Rh, Zr-Rh), carbide-coated platforms (W and Zr) with co-injection of RhCl3, solutions and uncoated platforms with injection of solutions of Pd(NO3)2, Mg(NO3)2, and RhCl3. Milk samples were diluted 1:10 in 1.0% HNO3 and injected into the tube. The mass of modifier deposited and co-injected in the tube and the use of end capped tubes were
also evaluated in order to improve the electrothermal behavior of analytes. Integrated platform pretreated with W plus co-injection
RhCl3 for first group and pretreated with W-Rh for second group were elected. For 20 μL injected samples the analytical curves
in the 5.0–20.0 μg L−1 concentration range have good linear correlation coefficients (r > 0.998). Relative standard deviations (n = 12) are <6% and the calculated characteristic masses are between 5 pg and 62 pg.
Correspondence: Gian Paulo G. Freschi, Faculdade de Ciências Exatas e Tecnologia, Universidade Federal da Grande Dourados,
PO Box 332, 79.804-970, Dourados-MS, Brazil; Instituto de Química, Universidade Estadual Paulista, PO Box 355, 14801-970 Araraquara-SP,
Brazil 相似文献
99.
100.