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81.
Dr. Alireza Mashaghi Samaneh Mashaghi Prof. Dr. Ir. Sander J. Tans 《Angewandte Chemie (International ed. in English)》2014,53(39):10390-10393
The folding of complex proteins can be dramatically affected by misfolding transitions. Directly observing misfolding and distinguishing it from aggregation is challenging. Experiments with optical tweezers revealed transitions between the folded states of a single protein in the absence of mechanical tension. Nonfolded chains of the multidomain protein luciferase folded within seconds to different partially folded states, one of which was stable over several minutes and was more resistant to forced unfolding than other partially folded states. Luciferase monomers can thus adopt a stable misfolded state and can do so without interacting with aggregation partners. This result supports the notion that luciferase misfolding is the cause of the low refolding yields and aggregation observed with this protein. This approach could be used to study misfolding transitions in other large proteins, as well as the factors that affect misfolding. 相似文献
82.
Facile Synthesis and Versatile Reactivity of an Unusual Cyclometalated Rhodium(I) Pincer Complex 下载免费PDF全文
Linda S. Jongbloed Prof. Dr. Bas de Bruin Prof. Dr. Joost N. H. Reek Dr. Martin Lutz Dr. Ir. Jarl Ivar van der Vlugt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7297-7305
The synthesis of the reactive PN(CH) ligand 2‐di(tert‐butylphosphanomethyl)‐6‐phenylpyridine ( 1H ) and its versatile coordination to a RhI center is described. Facile C?H activation occurs in the presence of a (internal) base, thus resulting in the new cyclometalated complex [RhI(CO)(κ3‐P,N,C‐ 1 )] ( 3 ), which has been structurally characterized. The resulting tridentate ligand framework was experimentally and computationally shown to display dual‐site proton‐responsive reactivity, including reversible cyclometalation. This feature was probed by selective H/D exchange with [D1]formic acid. The addition of HBF4 to 3 leads to rapid net protonolysis of the Rh?C bond to produce [RhI(CO)(κ3‐P,N,(C?H)‐ 1 )] ( 4 ). This species features a rare aryl C?H agostic interaction in the solid state, as shown by X‐ray diffraction studies. The nature of this interaction was also studied computationally. Reaction of 3 with methyl iodide results in rapid and selective ortho‐methylation of the phenyl ring, thus generating [RhI(CO)(κ2‐P,N‐ 1Me )] ( 5 ). Variable‐temperature NMR spectroscopy indicates the involvement of a RhIII intermediate through formal oxidative addition to give trans‐[RhIII(CH3)(CO)(I)(κ3‐P,N,C‐ 1 )] prior to C?C reductive elimination. The RhIII–trans‐diiodide complex [RhI(CO)(I)2(κ3‐P,N,C‐ 1 )] ( 6 ) has been structurally characterized as a model compound for this elusive intermediate. 相似文献
83.
The class of 3-connected bipartite cubic graphs is shown to contain a non-Hamiltonian graph with only 78 vertices and to have a shortness exponent less than one. 相似文献
84.
V. A. Tafeenko S. V. Medvedev E. Yu. Shishkina G. N. Vorozhtsov Khan Ir. Gvon 《Journal of Structural Chemistry》1992,33(3):471-474
NIOPIK Scientific-Production Association, Moscow. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 3, pp. 157–160, May–June, 1992. 相似文献
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Relative viscosity and concentration 总被引:3,自引:0,他引:3
Ir. R. Rutgers 《Rheologica Acta》1962,2(4):305-348
88.
Catalytic Dibenzocyclooctene Synthesis via Cobalt(III)–Carbene Radical and ortho‐Quinodimethane Intermediates 下载免费PDF全文
Colet te Grotenhuis Naudin van den Heuvel Dr. Ir. Jarl Ivar van der Vlugt Prof. Dr. Bas de Bruin 《Angewandte Chemie (International ed. in English)》2018,57(1):140-145
The metalloradical activation of ortho‐benzallylaryl N‐tosyl hydrazones with [Co(TPP)] (TPP=tetraphenylporphyrin) as the catalyst enabled the controlled exploitation of the single‐electron reactivity of the redox non‐innocent carbene intermediate. This method offers a novel route to prepare eight‐membered rings, using base metal catalysis to construct a series of unique dibenzocyclooctenes through selective Ccarbene?Caryl cyclization. The desired eight‐membered‐ring products were obtained in good to excellent yields. A large variety of aromatic substituents are tolerated. The proposed reaction mechanism involves intramolecular hydrogen atom transfer (HAT) to CoIII–carbene radical intermediates followed by dissociation of an ortho‐quinodimethane that undergoes 8π cyclization. The mechanism is supported by DFT calculations, and the presence of radical‐type intermediates was confirmed by trapping experiments. 相似文献
89.
Donglong Fu Dr. Joel E. Schmidt Dr. Paul Pletcher Pelin Karakiliç Xinwei Ye Carolien M. Vis Prof. Dr. Pieter C. A. Bruijnincx Dr. Matthias Filez Laurens D. B. Mandemaker Prof. Dr. Louis Winnubst Prof. Dr. Ir. Bert M. Weckhuysen 《Angewandte Chemie (International ed. in English)》2018,57(38):12458-12462
Facile fabrication of well‐intergrown, oriented zeolite membranes with tunable chemical properties on commercially proven substrates is crucial to broadening their applications for separation and catalysis. Rationally determined electrostatic adsorption can enable the direct attachment of a b‐oriented silicalite‐1 monolayer on a commercial porous ceramic substrate. Homoepitaxially oriented, well‐intergrown zeolite ZSM‐5 membranes with a tunable composition of Si/Al=25–∞ were obtained by secondary growth of the monolayer. Intercrystallite defects can be eliminated by using Na+ as the mineralizer to promote lateral crystal growth and suppress surface nucleation in the direction of the straight channels, as evidenced by atomic force microscopy measurements. Water permeation testing shows tunable wettability from hydrophobic to highly hydrophilic, giving the potential for a wide range of applications. 相似文献
90.