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1.
The interaction between azathioprine (AZ) and bovine serum albumin (BSA) is mainly due to hydrophobic binding according to the dependence of the binding constant on the ionic strength obtained by equilibrium dialysis. The binding constant and partition coefficient of AZ were smaller than those of warfarin, phenylbutazone and ibuprofen. Little variation in the proton chemical shift of AZ was observed whether there was an absence or presence of BSA (7.25 x 10(-5) M). The spin-lattice relaxation time (T1) of AZ decreased in the presence of BSA to 6-22%. The spin-spin relaxation rate (1/T2) of AZ increased 16-24 times for the methyl group and the imidazole ring and 8-13 times for the purine ring in the presence of BSA. The ratio of the spin-spin relaxation rate of the free AZ to the bound AZ ((1/T2)b/(1/T2)f) of the methyl group and the imidazole ring was 2-3 times larger than that of the purine ring. The binding of AZ to BSA was concluded to be mainly at the methyl group on the imidazole ring of AZ. 相似文献
2.
An m‐covering of a graph G is a spanning subgraph of G with maximum degree at most m. In this paper, we shall show that every 3‐connected graph on a surface with Euler genus k ≥ 2 with sufficiently large representativity has a 2‐connected 7‐covering with at most 6k ? 12 vertices of degree 7. We also construct, for every surface F2 with Euler genus k ≥ 2, a 3‐connected graph G on F2 with arbitrarily large representativity each of whose 2‐connected 7‐coverings contains at least 6k ? 12 vertices of degree 7. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 26–36, 2003 相似文献
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Syun-ichi Kiyooka Yushi Takeshita Yoshinori Tanaka Takafumi Higaki Yosuke Wada 《Tetrahedron letters》2006,47(26):4453-4456
A dicationic ((−)-sparteine)palladium complex underwent a superior catalytic enantioselective aldol reaction of aldehydes with 1-phenyl-1-trimethylsilyloxyethene performing satisfactorily, starting with ((−)-sparteine)PdCl2 and AgSbF6 as catalyst precursors (1 mol % loading) in the presence of 3 Å molecular sieves over the reaction. 相似文献
6.
Mitsunori Oda Yosuke Fukuchi Satoshi Ito Nguyen Chung Thanh Shigeyasu Kuroda 《Tetrahedron letters》2007,48(52):9159-9162
Reactions of pyrrolidine with 2 equiv of aldehydes without any catalyst in a pressurized vessel at 140–200 °C yielded 1,3-disubstituted pyrroles. -Branched aldehydes gave fairly good yields of the corresponding products by this method, which provides a facile non-oxidative procedure for synthesizing 1,3-dialkylpyrroles from inexpensive pyrrolidine and aldehydes. 相似文献
7.
Yosuke Aoki 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2006,82(7):251-256
Addition of azurocidin, a protein in granulocytes similar to serine proteases but has no protease activity because of replacement of the active serine residue by glycine, to the incubation mixture containing medullasin induced elastinolytic activity of medullasin. Both medullasin and human leukocyte elastase were already shown to have negligible elastinolytic activity (Aoki, Y. et al. J. Biochem. 114, 122, 1993). Elastinolytic activity of medullasin was induced dose-dependently by the addition of azurocidin. Medullasin activity determined by using apo-ornithine transaminase or casein as substrates or that by N-methoxy-succinyl-(Ala)2-Pro-Val-p-nitroanilide as substrate remained unchanged when azurocidin was added to the tube containing medullasin. Therefore, azurocidin is considered to cause an appearance of elastinolytic activity of medullasin without affecting the protease activity of it. 相似文献
8.
Katsuhiro Ota 《Graphs and Combinatorics》1988,4(1):333-354
An edge of a 3-connected graph is calledcontractible if its contraction results in a 3-connected graph. Ando, Enomoto and Saito proved that every 3-connected graph of order at least five has |G|/2 or more contractible edges. As another lower bound, we prove that every 3-connected graph, except for six graphs, has at least (2|E(G)| + 12)/7 contractible edges. We also determine the extremal graphs. Almost all of these extremal graphsG have more than |G|/2 contractible edges. 相似文献
9.
We have produced recombinant gamma-chain variant fibrinogens, gamma308K, gamma308I, and gamma308A simultaneously with wild-type fibrinogen, gamma-308N, by genetic protein engineering using Chinese hamster ovary cells. Although all three variant fibrinogens are a result of a single amino acid substitution, the aberrant gamma-chains of gamma308K and gamma308I fibrinogens migrated faster than gamma308N. Furthermore, plasmic digestion profiles were examined in the presence of 5 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) or 1 mM CaCl2. In the presence of EGTA, the three variant fibrinogens were digested into D1 and D2 fragments slightly faster than wild type. In addition, the D2 fragment derived from gamma308K was further digested into D3 by plasmin much faster than that from gamma308N. These data suggest that cleavage of gamma356Lys-gamma357Ala bond by plasmin in gamma308K, gamma308I, and gamma308A is slightly accelerated and the gamma302Lys-gamma303Phe bond is cleaved by plasmin rapidly in only the gamma308K variant. Furthermore, the substitution of Lys for gamma308Asn results in the generation of a new plasmin cleavage site between gamma308Lys and gamma309Gly in the presence of EGTA. In conclusion, a substitution at residue gamma308Asn may cause a conformational change in the gammachain of fragment D affecting polymerization and plasmin cleavage. 相似文献
10.
Abstract— As a model for studies involving biologic systems, rates of hematoporphyrin and protopor-phyrin-sensitized photooxidation of tryptophan were measured in water-methanol mixtures. Absorption and fluorescence-emission spectra associated with solutions of porphyrins in different water-methano! mixtures were also examined. The optimal rate of photooxidation by hematoporphyrin occurred in 30% methanol; by protoporphyrin, in 60% methanol. Absorption spectra were examined to characterize dispersion of hematoporphyrin into monomeric form in 90% methanol, and the dimer formation which predominates in 30% methanol. With the more hydrophobic protoporphyrin, an absorption spectrum characteristic of drug monomer was seen in 100% methanol, a dimer spectrum was observed in 60% methanol. At methanol concentrations < 60%, we observed impaired photooxidation and another alteration in the absorption pattern apparently reflecting drug aggregation beyond the dimer stage. Fluorescence emission maxima of both porphyrins were blue-shifted with increasing solvent dielectric constant, but an additional blue shift was detected in an aqueous environment which was apparently related to porphyrin aggregation. Absorption and fluorescence-emission spectra appear helpful for characterizing environmental determinants of porphyrin-sensitized photooxidation. 相似文献