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排序方式: 共有244条查询结果,搜索用时 15 毫秒
191.
Dr. Manuel Tropiano Dr. Octavia A. Blackburn James A. Tilney Leila R. Hill Dr. Matteo P. Placidi Dr. Rebecca J. Aarons Dr. Daniel Sykes Dr. Michael W. Jones Dr. Alan M. Kenwright Dr. John S. Snaith Dr. Thomas Just Sørensen Prof. Dr. Stephen Faulkner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16566-16571
A study of the anion‐binding properties of three structurally related lanthanide complexes, which all contain chemically identical anion‐binding motifs, has revealed dramatic differences in their anion affinity. These arise as a consequence of changes in the substitution pattern on the periphery of the molecule, at a substantial distance from the binding pocket. Herein, we explore these remote substituent effects and explain the observed behaviour through discussion of the way in which remote substituents can influence and control the global structure of a molecule through their demands upon conformational space. Peripheral modifications to a binuclear lanthanide motif derived from α,α′‐bis(DO3 Ayl)‐m‐xylene are shown to result in dramatic changes to the binding constant for isophthalate. In this system, the parent compound displays considerable conformational flexibility, yet can be assumed to bind to isophthalate through a well‐defined conformer. Addition of steric bulk remote from the binding site restricts conformational mobility, giving rise to an increase in binding constant on entropic grounds as long as the ideal binding conformation is not excluded from the available range of conformers. 相似文献
192.
Dr. Karel J. Hartlieb Dr. Wei‐Guang Liu Dr. Albert C. Fahrenbach Anthea K. Blackburn Dr. Marco Frasconi Dr. Nema Hafezi Dr. Sanjeev K. Dey Dr. Amy A. Sarjeant Charlotte L. Stern Prof. William A. Goddard III Prof. J. Fraser Stoddart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(8):2736-2745
The promiscuous encapsulation of π‐electron‐rich guests by the π‐electron‐deficient host, cyclobis(paraquat‐p‐phenylene) (CBPQT4+), involves the formation of 1:1 inclusion complexes. One of the most intensely investigated charge‐transfer (CT) bands, assumed to result from inclusion of a guest molecule inside the cavity of CBPQT4+, is an emerald‐green band associated with the complexation of tetrathiafulvalene (TTF) and its derivatives. This interpretation was called into question recently in this journal based on theoretical gas‐phase calculations that reinterpreted this CT band in terms of an intermolecular side‐on interaction of TTF with one of the bipyridinium (BIPY2+) units of CBPQT4+, rather than the encapsulation of TTF inside the cavity of CBPQT4+. We carried out DFT calculations, including solvation, that reveal conclusively that the CT band emerging upon mixing TTF with CBPQT4+ arises from the formation of a 1:1 inclusion complex. In support of this conclusion, we have performed additional experiments on a [2]rotaxane in which a TTF unit, located in the middle of its short dumbbell, is prevented sterically from interacting with either one of the two BIPY2+ units of a CBPQT4+ ring residing on a separate [2]rotaxane in a side‐on fashion. This [2]rotaxane has similar UV/Vis and 1H NMR spectroscopic properties with those of 1:1 inclusion complexes of TTF and its derivatives with CBPQT4+. The [2]rotaxane exists as an equimolar mixture of cis‐ and trans‐isomers associated with the disubstituted TTF unit in its dumbbell component. Solid‐state structures were obtained for both isomers, validating the conclusion that the TTF unit, which gives rise to the CT band, resides inside CBPQT4+. 相似文献
193.
Lambert MH Blackburn RK Seaton TD Kassel DB Kinder DS Leesnitzer MA Bickett DM Warner JR Andersen MW Badiang JG Cowan DJ Gaul MD Petrov KG Rabinowitz MH Wiethe RW Becherer JD McDougald DL Musso DL Andrews RC Moss ML 《Combinatorial chemistry & high throughput screening》2005,8(4):327-339
We report a systematic analysis of the P1' and P2' substrate specificity of TNF-alpha converting enzyme (TACE) using a peptide library and a novel analytical method, and we use the substrate specificity information to design novel reverse hydroxamate inhibitors. Initial truncation studies, using the amino acid sequence around the cleavage site in precursor-TNF-alpha, showed that good turnover was obtained with the peptide DNP-LAQAVRSS-NH2. Based on this result, 1000 different peptide substrates of the form Biotin-LAQA-P1'-P2'-SSK(DNP)-NH2 were prepared, with 50 different natural and unnatural amino acids at P1' in combination with 20 different amino acids at P2'. The peptides were pooled, treated with purified microsomal TACE, and the reaction mixtures were passed over a streptavidin affinity column to remove unreacted substrate and the N-terminal biotinylated product. C-terminal cleavage products not binding to streptavidin were subjected to liquid chromatography/mass spectrometry analysis where individual products were identified and semiquantitated. 25 of the substrates were resynthesized as discrete peptides and assayed with recombinant TACE. The experiments show that recombinant TACE prefers lipophilic amino acids at the P1' position, such as phenylglycine, homophenylalanine, leucine and valine. At the P2' position, TACE can accommodate basic amino acids, such as arginine and lysine, as well as certain non-basic amino acids such as citrulline, methionine sulfoxide and threonine. These substrate preferences were used in the design of novel reverse hydroxamate TACE inhibitors with phenethyl and 5-methyl-thiophene-methyl side-chains at P1', and threonine and nitro-arginine at P2'. 相似文献
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Reductions of 2-substituted quinoline--boranes by sodium bis-(2-methoxyethoxy)aluminum dihydride lead to 1,2,3,4-tetrahydroquinolines by hydride attack at C-4 and subsequent reduction of the resulting enamine. 相似文献
196.
Simon R. Blackburn 《Designs, Codes and Cryptography》1997,11(3):223-234
We show that an algorithm designed to solve the Welch–Berlekamp key equation may also be used to solve a more general problem, which can be regarded as a finite analogue of a generalized rational interpolation problem. As a consequence, we show that a single algorithm exists which can solve both Berlekamp's classical key equation (usually solved by the Berlekamp–Massey algorithm) and the Welch–Berlekamp key equation which arise in the decoding of Reed–Solomon codes. 相似文献
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Saheed Bukola Zhaodong Li Jason Zack Christopher Antunes Carol Korzeniewski Glenn Teeter Jeffrey Blackburn Bryan Pivovar 《Journal of Energy Chemistry》2021,(8):419-430
We report near-zero crossover for vanadium cross-permeation through single-layer graphene immobilized at the interface of two Nafion(R) polymer electrolyte memb... 相似文献