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771.
Hydroxy radical-initiated poly(methyl methacrylate) and polystyrene have been reacted with o-sulfobenzoic anhydride to produce dye-active sulfonate groups and these were measured by a dye-partition technique with methylene blue. The important advantages over chlorosulfonic acid, previously employed in the dye-partition analysis for the conversion of hydroxy into sulfate groups, are that o-sulfobenzoic anhydride does not react at sites other than the hydroxy functionality and that it introduces the dye-active moiety (sulfonate) into the polymer via a hydrolytically more stable linkage. 相似文献
772.
We study separated nets Y that arise from primitive substitution tilings of Rd. We show that the question whether Y is a bounded displacement of Zd or not can be reduced, in many cases, to a simple question on the eigenvalues and eigenspaces of the substitution matrix. 相似文献
773.
Chiral Anion Phase Transfer of Aryldiazonium Cations: An Enantioselective Synthesis of C3‐Diazenated Pyrroloindolines
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Dr. Hosea M. Nelson Solomon H. Reisberg Hunter P. Shunatona Jigar S. Patel Prof. Dr. F. Dean Toste 《Angewandte Chemie (International ed. in English)》2014,53(22):5600-5603
Herein is reported the first asymmetric utilization of aryldiazonium cations as a source of electrophilic nitrogen. This is achieved through a chiral anion phase‐transfer pyrroloindolinization reaction that forms C3‐diazenated pyrroloindolines from simple tryptamines and aryldiazonium tetrafluoroborates. The title compounds are obtained in up to 99 % yield and 96 % ee. The air‐ and water‐tolerant reaction allows electronic and steric diversity of the aryldiazonium electrophile and the tryptamine core. 相似文献
774.
Maiti D Lee DH Narducci Sarjeant AA Pau MY Solomon EI Gaoutchenova K Sundermeyer J Karlin KD 《Journal of the American Chemical Society》2008,130(21):6700-6701
A discrete peroxynitrite-copper(II) complex, [(TMG3tren)CuII(-OONO)]+ (3), has been generated in solution (ESI-MS, m/z = 565.15; tetragonal EPR) by reacting *NO(g) with superoxo complex [(TMG3tren)CuII(O2*-)]+ (2). Complex 3 undergoes a thermal transformation to give CuII-nitrite complex [(TMG3tren)CuII(-ONO)]+ (4) (X-ray) along with ca. 0.5 molar equiv dioxygen. A DFT calculation derived structure with cyclic bidentate k2-O,O'-OONO bound peroxynitrite moiety and dx2-y2 ground state is proposed. Experiments using 18O2 suggest that the adjacent peroxo oxygen atoms in 3 are derived from molecular oxygen. Further, 18O2 containing 3 undergoes O-O bond cleavage to form singly 18-O-labeled 4. The results suggest the viability of biological CuI/O2/(*NO) peroxynitrite formation and chemistry, that is, not coming from free superoxide plus *NO reaction. 相似文献
775.
Xie X Gorelsky SI Sarangi R Garner DK Hwang HJ Hodgson KO Hedman B Lu Y Solomon EI 《Journal of the American Chemical Society》2008,130(15):5194-5205
776.
V. Alagarsamy P. Parthiban V. Raja Solomon K. Dhanabal S. Murugesan G. Saravanan G. V. Anjana 《Journal of heterocyclic chemistry》2008,45(3):709-715
777.
Vanapalli SA Iacovella CR Sung KE Mukhija D Millunchick JM Burns MA Glotzer SC Solomon MJ 《Langmuir : the ACS journal of surfaces and colloids》2008,24(7):3661-3670
We study fluidic assembly and packing of spherical particles in rectilinear microchannels that are terminated by a flow constriction. First, we introduce a method for active assembly of particles in the confined microchannels by triggering a local constriction in the fluid channel using a partially closed membrane valve. This microfluidic valve allows active, on-demand particle assembly as opposed to previous passive assembly methods based on terminal channels and weirs. Second, we study the three-dimensional assembly and packing of particles against a weir in confined rectilinear microchannels. The packings result in achiral particle chains with alternating (zigzag) structure. This structure is characterized by a single, repeated bond angle whose components projected into the frame of the channel are quantified by confocal microscopy and image processing. Brownian dynamics simulation of the packing comprehensively delineates the range of bond angles possible in narrow, rectilinear microchannels as well as the complex dependence of these angles on the relative dimensions of the channel and particles. The simulations of the three-dimensional packings are accurately modeled by a compact theory based on trigonometric relationships. The experimentally measured bond angles show excellent agreement with the simulations, thereby validating the functional dependence of the achiral packing bond angles on channel dimensions. This functional relationship is immediately useful for the design of anisotropic particles by microfluidic synthesis. 相似文献
778.
Many of the active sites involved in electron transfer (ET) in biology have more than one metal and are mixed valent in at least one redox state. These include Cu(A), and the polynuclear Fe-S clusters which vary in their extent of delocalization. In this tutorial review the relative contributions to delocalization are evaluated using S K-edge X-ray absorption, magnetic circular dichroism and other spectroscopic methods. The role of intra-site delocalization in ET is considered. 相似文献
779.
Crystallographic and NMR spectroscopic studies on allyl complexes of lithium, potassium and magnesium containing an O-donor functionality are described. 相似文献
780.