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1.
2.
Ground state conformation for all possible geometrical isomers of hedycaryol was estimated by the molecular mechanics calculations. All isomers are indicated to exist in more than two conformations and the parallel conformation (TC or TT) is most stable for all isomers. 相似文献
3.
Akemi Umeyama Chihiro Ohta Yukari Shino Minori Okada Yukari Nakamura Tatsuya Hamagaki Hiroshi Imagawa Masami Tanaka Aki Ishiyama Masato Iwatsuki Kazuhiko Otoguro Satoshi Ōmura Toshihiro Hashimoto 《Tetrahedron》2014
During the search for new antitrypanosomal drug leads, three new antitrypanosomal compounds, hexatenuins A–C (1–3), were isolated from the fruiting body of Hexagonia tenuis. 1 and 3 possessed an unusual malonate half-ester functional group at C-3 position, and 1 and 2 had a spirostructure in the side-chain. Their structures were elucidated using MS analyses, extensive 2D-heteronuclear NMR data interpretation. Compounds 1–3 showed in vitro antitrypanosomal activity against Trypanosoma brucei brucei with IC50 values of 0.57, 8.60 and 5.62 μg/ml, respectively. 相似文献
4.
Jun-Ichi Aihara Sumio Oe Mitsuho Yoshida Eiji Ōsawa 《Journal of computational chemistry》1996,17(12):1387-1394
Thermodynamic and kinetic stabilities of 73 C84 fullerene isomers were estimated from the MM3 heats of formation and the recently defined bond resonance energies (BREs), respectively. The BRE represents the contribution of a given π bond in a molecule to the topological resonance energy (TRE). All π bonds shared by two pentagons turned out to be highly reactive without exceptions. C84 fullerene isomers with such π bonds must be incapable of survival during harsh synthetic processes. Thus, the isolated pentagon rule (IPR) proved to be applicable to such large fullerene cages. For sufficiently large fullerenes like C84, some isolated-pentagon isomers are also predicted to be very unstable with highly antiaromatic π bonds. © 1996 by John Wiley & Sons, Inc. 相似文献
5.
6.
Takashi Okazaki Seiji Ōkubo Yūichi Hoshino Kanji Fujii 《Physics letters. [Part B]》1979,85(1):107-110
The validity of the assumption that decays into mesons proceed via ω, φ and ?0 poles followed by cascade decays is examined. is well reproduced by using and the B → ωπ helicity structure. The structure of OZI-violating transitions including the electromagnetic contribution is examined, and compared with the data on inclusive decay. 相似文献
7.
The title problem was discussed to facilitate the formulation of constitutive models of cyclic plasticity under general states of loading. A series of plastic strain controlled cyclic tests was performed by applying combined axial force and torque to thin-walled tubular specimens of Type 316 stainless steel at room temperature. These tests consist of cyclic loading along uniaxial, torsional, cruciform, stellate in eight directions, square and circular plastic strain paths with a constant amplitude of equivalent plastic strain.The results of these tests showed that the strain-hardening depends markedly on the shape of the plastic strain path, and that the strain-hardening (measured by equivalent stress amplitudes) in the saturated state is significant in the order of circular, square, stellate, cruciform and proportional paths. It was also observed that these saturated values were independent of the less significant plastic strain cycles experienced in the past. Finally, the characteristic features of strain-hardening mechanisms under non-proportional loadings were discussed in some detail on the basis of the present results. 相似文献
8.
A. Schenck A. Amato F.N. Gygax M. Pinkpank P. Ahmet M. Ablitz R. Settai Y. Ōnuki 《Hyperfine Interactions》1997,104(1-4):105-111
We report on ZF and TF‐studies of PrCu2 above the induced Jahn–Teller transition at 7.3 K. Generally a two‐component signal is found, one showing inhomogeneous the
other one homogeneous, temperature dependent line broadening. In ZF the former component is well represented by a Gaussian
Kubo–Toyabe function with \varDelta \simeq 6.5\,μs-1 at 7.5 K, corresponding to a field width of 76 G. This is about 30 times larger than what is calculated to arise from the
141Pr‐nuclear dipole moments alone, pointing to strong hyperfine enhanced features. TF‐field scans at 12 K revealed that the
enhancement is suppressed in external fields exceeding 1 kG. In parallel the Knight shift drops from very large values well
above 10% at 100 G to shifts of the order of 1% above 1 kG. A scaling of the Knight shifts with the corresponding relaxation
rates seems to imply that the strange field dependence below 1 kG is associated with the magnetic susceptibility of the muons’s
nearest neighbour Pr3+‐ions, a result for which we have no explanation yet to offer.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Hiroyuki Kawai Yoichi Hayakawa Masaya Nakagawa Kazuo Furihata Haruo Seto Noboru Ōtake 《Tetrahedron letters》1984,25(18):1937-1940
Based on 1H- and 13C-NMR and mass spectral analysis and chemical degradation, the structures of degradation products of arugomycin (arugorol, AG1, AG2 and AG3) have been determined as shown in Fig. 1. 相似文献
10.
Internal rotation of cannabidiol (1), its mono-(2) and dimethyl (3) derivatives has been studied by 1H and 13C dynamic NMR spectroscopy. The free energy of activation for the rotation of C3-C2, bond that we have observed for cannabidiol of 14.7 kcal/mol at 22° in CDCl3 is in contrast with values previously reported in the literature. Molecular mechanics simulation of the rotation of C3-C2, bond of a model structure (4) well reproduced the presently determined barrier height. Analysis of the calculated rotational transition state structure revealed severe nonbonded C2H/O and C 8/O interactions as the source of barrier. Calculations of other model structures indicate general occurrence of restricted rotation about the pivot bond of phenylcyclohexanes appropriately substituted at β-carbon of cyclohexane ring and at ortho position of phenyl ring. The fully substituted 2,6-dimethyl-1-(o,o'-dimethylphenyl) cyclohexane (10) is predicted to show atropisomerism. 相似文献