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71.
Platinum‐Promoted Ga/Al2O3 as Highly Active,Selective, and Stable Catalyst for the Dehydrogenation of Propane
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Jesper J. H. B. Sattler Dr. Ines D. Gonzalez‐Jimenez Dr. Lin Luo Brien A. Stears Dr. Andrzej Malek Dr. David G. Barton Dr. Beata A. Kilos Dr. Mark P. Kaminsky Tiny W. G. M. Verhoeven Eline J. Koers Prof. Dr. Marc Baldus Prof. Dr. Bert M. Weckhuysen 《Angewandte Chemie (International ed. in English)》2014,53(35):9251-9256
A novel catalyst material for the selective dehydrogenation of propane is presented. The catalyst consists of 1000 ppm Pt, 3 wt % Ga, and 0.25 wt % K supported on alumina. We observed a synergy between Ga and Pt, resulting in a highly active and stable catalyst. Additionally, we propose a bifunctional active phase, in which coordinately unsaturated Ga3+ species are the active species and where Pt functions as a promoter. 相似文献
72.
Lidia Jasińska A. Balas J. T. Haponiuk G. Nowaczyk S. Jurga 《Journal of Thermal Analysis and Calorimetry》2007,88(2):419-423
New cross-linked poly(esterurethanes) (PEU) based on unsaturated olygo(alkyleneester)diol
(OAE), 4,4’-diphenylmethane diisocyanate (MDI) and styrene or methyl
methacrylate as curing monomers were prepared. The synthesis of PEU was performed
in two steps. In the first step OAE was obtained from adipic acid, maleic
anhydride and ethylene glycol. In the second step a prepolymer was obtained
in a reaction of OAE with different amounts of 4,4’-diphenylmethane
diisocyanate followed by crosslinking using previously mentioned curing monomers.
The influence of structure of the poly(esterurethanes) on thermal and dynamic
mechanical properties is studied. Thermogravimetric analysis shows that cross-linked
poly(esterurethanes) demonstrate high thermal stability. Moreover the dynamic
mechanical thermal analysis shows that the presence of styrene cross-linking
chains in polymers lead to the phase separation in cross-linked poly(esterurethanes). 相似文献
73.
Selda Kabatas Paola Agüi‐Gonzalez Kim‐Ann Saal Sebastian Jhne Felipe Opazo Silvio O. Rizzoli Nhu T. N. Phan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3476-3481
Boron has been employed in materials science as a marker for imaging specific structures by electron energy loss spectroscopy (EELS) or secondary ion mass spectrometry (SIMS). It has a strong potential in biological analyses as well; however, the specific coupling of a sufficient number of boron atoms to a biological structure has proven challenging. Herein, we synthesize tags containing closo‐1,2‐dicarbadodecaborane, coupled to soluble peptides, which were integrated in specific proteins by click chemistry in mammalian cells and were also coupled to nanobodies for use in immunocytochemistry experiments. The tags were fully functional in biological samples, as demonstrated by nanoSIMS imaging of cell cultures. The boron signal revealed the protein of interest, while other SIMS channels were used for imaging different positive ions, such as the cellular metal ions. This allows, for the first time, the simultaneous imaging of such ions with a protein of interest and will enable new biological applications in the SIMS field. 相似文献
74.
75.
V.I. Afonso D. Bazeia M.A. Gonzalez Len L. Losano J. Mateos Guilarte 《Nuclear Physics B》2009,810(3):427-459
This work deals with the construction of networks of topological defects in models described by a single complex scalar field. We take advantage of the deformation procedure recently used to describe kinklike defects in order to build networks of topological defects, which appear from complex field models with potentials that engender a finite number of isolated minima, both in the case where the minima present discrete symmetry, and in the non-symmetric case. We show that the presence of symmetry guide us to the construction of regular networks, while the non-symmetric case gives rise to irregular networks which spread throughout the complex field space. We also discuss bifurcation, a phenomenon that appear in the non-symmetric case, but is washed out by the deformation procedure used in the present work. 相似文献
76.
Lidia Matesic Julie M. Locke Kara L. Vine Marie Ranson John B. Bremner Danielle Skropeta 《Tetrahedron》2012,68(34):6810-6819
To further expand the structure–cytotoxic activity relationships of isatin derivatives and to reduce flexibility in substituent groups at nitrogen, 20 analogues incorporating a ring system between the N1 and C7 atoms of isatin were prepared using a variety of synthetic strategies. This yielded pyrroloindole-, pyrroloquinoline-, pyrroloacridine-, pyrrolophenanthridine- and benzopyrrolophenanthridine-based systems with embedded isatin moieties, the latter possessing a novel carbon skeleton. These compounds were subsequently assessed for their in vitro cytotoxicity against human U937 lymphoma cells, with the brominated pyrroloacridine dione 27 showing the most promising activity (IC50 3.01 μM) after 24 h. 相似文献
77.
M. Ivković M.A. Gonzalez S. Jovićević M.A. Gigosos N. Konjević 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
The results of an experimental study of the He I 447.1 nm line and its forbidden component at high electron number density are presented and compared with profiles calculated using computer simulation method. Michelson interferometer at 632.8 nm was used to measure plasma electron number density in the range (1–7) × 1023 m− 3 while electron temperatures for the same experimental conditions in the range of 25 000 K to 35 000 K were determined using several spectroscopic techniques. The agreement of experimental overall line shape with computer simulation results is within 10% of what is well within theoretical and experimental uncertainty. This favorable comparison enabled the development of a simple approximate formula for the evaluation of electron number density from the measurement of wavelength separation between peaks of allowed and forbidden lines. This technique of plasma diagnostics is not sensitive to the presence of self-absorption of strong He I allowed line. The derivation of approximate formula with estimated accuracy of 15% was followed by detailed comparison with other experimental and theoretical data. 相似文献
78.
In this paper, we use random walk theory to describe the length dynamics of microtubules, one of the principal components of the cytoskeleton. We present a simple two-state model (growing and shrinking) of microtubule length evolution that incorporates a variable rate of switching between the states. Using the generating function technique, we calculate the mean length of microtubule, its variance and diffusion coefficient. We also report analytical and computer simulation results for the mean number of positive monomers in microtubule, and find good qualitative agreement with experimental data. 相似文献
79.
Lidia Jasinska Cor E. Koning 《Journal of polymer science. Part A, Polymer chemistry》2010,48(24):5907-5915
A new experimental approach for preparing biobased, water‐soluble polyesters (PEs) via titanium(IV) n‐butoxide‐catalyzed bulk polycondensation is presented. In the described method polymers were obtained from isosorbide, maleic anhydride and poly(ethylene glycol) (PEG). The chemical structure of the synthesized PEs was confirmed using 2D NMR spectroscopy and by titration methods. Careful analysis of 2D NMR spectra viz. correlation spectra (COSY), heteronuclear single quantum correlation spectra (HSQC) and heteronuclear multiple‐bond correlation spectra (HMBC) allowed to accomplish the complete proton assignment of isosorbide, PEG, and unsaturated acid residues in the PEs. Moreover, by using NMR spectroscopy the transformation of maleic anhydride into fumaric acid ester and the absence of maleic acid ester units in the final polymer were proven. However, during polycondensation part of the unsaturated bonds has reacted in a Michael addition with isosorbide or PEG. Gel permeation chromatography measurements revealed that the unsaturated PEs have Mn values in the range 3000–5000 g/mol. These PEs, with a low content of carboxylic acid end groups, exhibited sufficient thermal resistance for practical applications, for example, as free radical curable coatings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
80.