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The adsorption behavior of proteins in hydrophobic interaction chromatography (HIC) was evaluated by determining the isotherms of a wide range of proteins on various HIC resin systems. Parallel batch experiments were carried out with eleven proteins on three hydrophobic resins with different ligand chemistries and densities. The effects of salt concentration, resin chemistry and protein properties on the isotherms were also examined. The resulting isotherms exhibited unique patterns of adsorption behaviors. For certain protein-resin combinations, a "critical salt behavior" was observed where the amount of protein bound to the resin increased significantly above this salt concentration. Proteins that exhibited this behavior tended to be relatively large with more solvent accessible hydrophobic surface area. Further, calculations indicated that under these conditions the occupied surface area of the adsorbed protein layer could exceed the accessible surface area. The establishment of unique classes of adsorption behavior may shed light on our understanding of the behavior of proteins in HIC systems. 相似文献
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Christopher J. Cramer Armagan Kinal Marta Wloch Piotr Piecuch Laura Gagliardi 《ChemInform》2007,38(1):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. 相似文献
156.
Christopher J. Cramer Anne‐Marie Kelterer Alfred D. French 《Journal of computational chemistry》2001,22(11):1194-1204
Rotational coordinates about the C(3)–O(4) bonds of 2,4‐dioxaheptane (DOH) and 2,4,6‐trioxaheptane (TOH) are compared at correlated levels of electronic structure theory for gauche and trans orientations of the O(2)–C(3) bonds. TOH has overlapping anomeric effects, while DOH does not. The overlapping stereoelectronic effect shows its largest impact on the length of the O(2)–C(3) bond, which is typically 0.02 Å longer in DOH than in TOH. However, the energetic consequences of the overlapping anomeric effect in TOH are very small, as judged by total conformational energies and analysis of delocalization energies within a natural bond orbital framework. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1194–1204, 2001 相似文献
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Giovanni La Macchia Laura Gagliardi Geoffrey S. Carlson Ashley N. Jay Erik Davis Christopher J. Cramer 《Journal of Physical Organic Chemistry》2008,21(2):136-145
Values of σ and σ+, for use in linear free energy relationships, are determined for para hydrogen atoms having nuclear charges other than 1 (nucleomers). Hammett ρ values for a variety of free energies of activation, reaction, and other extrathermodynamic properties (e.g., vibrational frequencies) are computed therefrom and compared to those computed using typical para functional groups. The nucleomer correlations show excellent qualitative agreement with standard correlations but the quantitative agreement is less good, typically underestimating the standard ρ‐value by 10–60%. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Dr. Matthew D. Wodrich Miyeon Chang Simone Gallarati Dr. Łukasz Woźniak Prof. Dr. Nicolai Cramer Prof. Dr. Clemence Corminboeuf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(41):e202200399
Group 9 metals, in particular RhIII complexes with cyclopentadienyl ligands, are competent C−H activation catalysts. Recently, a Cp*RhIII-catalyzed reaction of alkenes with N-enoxyphthalimides showed divergent outcome based on the solvent, with carboamination favored in methanol and cyclopropanation in 2,2,2-trifluoroethanol (TFE). Here, we create selectivity and activity maps capable of unravelling the catalyst-solvent interplay on the outcome of these competing reactions by analyzing 42 cyclopentadienyl metal catalysts, CpXMIII (M=Co, Rh, Ir). These maps not only can be used to rationalize previously reported experimental results, but also capably predict the behavior of untested catalyst/solvent combinations as well as aid in identifying experimental protocols that simultaneously optimize both catalytic activity and selectivity (solutions in the Pareto front). In this regard, we demonstrate how and why the experimentally employed Cp*RhIII catalyst represents an ideal choice to invoke a solvent-induced change in reactivity. Additionally, the maps reveal the degree to which even perceived minor changes in the solvent (e. g., replacing methanol with ethanol) influence the ratio of carboamination and cyclopropanation products. Overall, the selectivity and activity maps presented here provide a generalizable tool to create global pictures of anticipated reaction outcome that can be used to develop new experimental protocols spanning metal, ligand, and solvent space. 相似文献