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11.
12.
Mihaela Frunza Gabriela Lisa M. I. Popa N. D. Miron Denisa Ileana Nistor 《Journal of Thermal Analysis and Calorimetry》2008,93(2):373-379
The thermal behavior of the new inorganic-organic nanohybrid materials obtained by intercalation of chloramphenicol and salicylate
into layered double hydroxides (LDHs) by direct synthesis method, anion exchange reaction and the reconstruction method was
evaluated by dynamic thermogravimetric analysis in air, at heating rates of 5°C min−1. The XRD patterns of the samples are characteristic for those of well crystallized solids with layered double hydroxide structures.
The FTIR spectroscopy results show the presence of the organic compound within the network structure of the synthesized LDHs.
The kinetic parameters (reaction order (n) apparent activation energy (E
a) and pre-exponential factor (lnA) were calculated by the Coats-Redfern method. The compensation effects were determined. 相似文献
13.
Yang Luo Tuo Li Fang Yu Tal Kramer Ileana M. Cristea 《Journal of the American Society for Mass Spectrometry》2010,21(1):34-46
Current biological studies have been advanced by the continuous development of robust, accurate, and sensitive mass spectrometric
technologies. The MALDI LTQ Orbitrap is a new addition to the Orbitrap configurations, known for their high resolving power
and accuracy. This configuration provides features inherent to the MALDI source, such as reduced spectra complexity, forgiveness
to contaminants, and sample retention for follow-up analyses with targeted or hypothesis-driven questions. Here we investigate
its performance for characterizing the composition of isolated protein complexes. To facilitate the assessment, we selected
two well characterized complexes from Saccharomyces cerevisiae, Apl1 and Nup84. Manual and automatic MS and MS/MS analyses readily resolved their compositions, with increased confidence
of protein identification compared with our previous reports using MALDI QqTOF and MALDI IT. CID fragmentation of singly-charged
peptides provided sufficient information for conclusive identification of the isolated proteins. We then assessed the resolution,
accuracy, and sensitivity provided by this instrument in the context of analyzing the isolated protein assemblies. Our analysis
of complex mixtures of singly-charged ions up to m/z 4000 showed that (1) the resolving power, inversely proportional to the square root of m/z, had over four orders of magnitude dynamic range; (2) internal calibration led to improved accuracy, with an average absolute
mass error of 0. 5 ppm and a distribution centered at 0 ppm; and (3) subfemtomole sensitivity was achieved using both CHCA
and DHB matrices. Additionally, our analyses of a synthetic phosphorylated peptide in mixtures showed subfemtomole level of
detection using neutral loss scanning. 相似文献
14.
Celia Regaño Romina Marín Abdelilah Alla José I. Iribarren Antxon Martínez De Ilarduya Sebastián Muñoz‐Guerra 《Journal of Polymer Science.Polymer Physics》2007,45(1):116-125
The crystal structure and crystallization behavior of a series of poly(ester amide)s derived from L ‐tartaric acid, 1,6‐hexanediamine, and 6‐amino‐1‐hexanol were examined. The study included aregic polymers containing 5, 10, and 20% of ester groups in addition to the syndioregic polymer containing equal amounts of amide and ester groups. X‐ray diffraction data revealed that all the aregic poly(ester amide)s adopt the same crystal structure as the parent polyamide made of L ‐tartaric acid, and 1,6‐hexanediamine. In this structure, chains are slightly compressed and arranged as in the α‐form of nylon 66. Solid‐state nuclear magnetic resonance (NMR) revealed that ester groups are excluded from the crystal phase except for the case of the syndioregic polymer. Isothermal crystallization kinetics was analyzed according to the Avrami theory. Crystallization rates were found to decrease regularly with increasing contents in ester groups and with increasing crystallization temperature. Avrami exponent values close to 2 were found whereas spherulitic morphologies were observed by optical microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 116–125, 2007 相似文献
15.
Ileana Streinu 《Computational Geometry》2005,31(3):195-206
We exhibit a family of graphs which can be realized as pseudo-visibility graphs of pseudo-polygons, but not of straight-line polygons. The example is based on the characterization of vertex-edge pseudo-visibility graphs of O'Rourke and Streinu [Proc. ACM Symp. Comput. Geometry, Nice, France, 1997, pp. 119–128] and extends a recent result of the author [Proc. ACM Symp. Comput. Geometry, Miami Beach, 1999, pp. 274–280] on non-stretchable vertex-edge visibility graphs. We construct a pseudo-visibility graph for which there exists a unique compatible vertex-edge visibility graph, which is then shown to be non-stretchable. The construction is then extended to an infinite family. 相似文献
16.
This paper is devoted to the applications of classical topological degrees to nonlinear problems involving various classes of operators acting between ordered Banach spaces. In this framework, the Leray-Schauder, Browder-Petryshyn, and Amann-Weiss degree theories are considered, and several existence results are obtained. The non-Archimedean case is also discussed. 相似文献
17.
The 4-triangles longest-side partition of triangles and linear refinement algorithms 总被引:3,自引:0,他引:3
In this paper we study geometrical properties of the iterative 4-triangles longest-side partition of triangles (and of a 3-triangles partition), as well as practical algorithms based on these partitions, used both directly for the triangulation refinement problem, and as a basis for point insertion strategies in Delaunay refinement algorithms. The 4-triangles partition is obtained by joining the midpoint of the longest side with the opposite vertex and the midpoints of the two remaining sides. By means of simple geometrical arguments we show that the iterative partition of obtuse triangles systematically improves the triangles (while they remain obtuse) in the following sense: the sequence of smallest angles monotonically increases while the sequence of largest angles monotonically decreases in an amount (at least) equal to the smallest angle of each iteration. This allows us to improve the known bound on the smallest angle (without making use of previous results), and to obtain a better a priori bound on the number of similarly distinct triangles, as a function of the geometry of the initial triangle. Numerical evidence, showing that the practical behavior of the 4-triangles partition is in complete agreement with this theory, is included. A 4-triangles refinement algorithm is also discussed and illustrated. Furthermore, we show that the time cost of the algorithm is linear independently of the size of the triangulation.
18.
Menegazzo I Fries A Mammi S Galeazzi R Martelli G Orena M Rinaldi S 《Chemical communications (Cambridge, England)》2006,(47):4915-4917
Starting from (3S,4R,1'S)-3-amino-2-oxo-1-[1'-(4-methoxyphenylethyl)]pyrrolidine carboxylic acid (2), the first synthesis of a beta-foldamer containing pyrrolidin-2-one rings is described, whose 12-helix conformation is assigned by NMR analysis and confirmed by molecular dynamics (MD) simulations. 相似文献
19.
20.
F. Caballero-Briones J.L. Peña A. Iribarren S. Jiménez-Sandoval 《Journal of Non》2008,354(31):3756-3761
Crystalline and microcrystalline Cd-Te-O samples have been obtained by RF reactive sputtering from a CdTe target using N2O as oxidant. The growth conditions were substrate temperatures of 323 K, 573 K and 773 K and cathode voltage of −400 V, corresponding to 30 W of forward power. The samples were studied by micro-Raman spectroscopy, X-ray diffraction and optical transmittance. The films are remarkably transparent in the visible range, with transmittances about 88% at 400 nm and band gap energies above the absorption edge of the glass substrates. Although only the samples prepared at 773 K present defined diffraction peaks, the analysis of the Raman spectra indicate that samples prepared at 323 K and 573 K have a defined microstructure indeed. The spectra fitting performed by comparison with pattern compounds demonstrate that Cd-Te-O films are formed of Te-O units similar to those present in metal oxide-doped tellurite glasses, such as TeO3 and TeO3 + 1 linked through Cd-O bonds. As the substrate temperature increases the microstructure evolves from a γ-TeO2 richer state to CdxTeyOz. In the crystalline sample the main phase identified was CdTeO3 even though evidence of other phases was observed. 相似文献