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排序方式: 共有304条查询结果,搜索用时 15 毫秒
271.
Katagiri H Iki N Matsunaga Y Kabuto C Miyano S 《Chemical communications (Cambridge, England)》2002,(18):2080-2081
Thiacalix[4]aniline (4), a cyclic tetramer of p-tert-butylaniline bridged with four sulfides, extracted Au(III) and Pd(II) ions specifically from acidic solutions among 41 metal ions including soft metal ions such as Hg(II), Cd(II), Zn(II), Pb(II), and Cu(II). 相似文献
272.
Yamauchi M Honda Y Matsuki N Watanabe T Date K Hiramatsu H 《The Journal of organic chemistry》1996,61(8):2719-2725
The Diels-Alder reaction of 1,1-dicarbonylethenes 1 with dienes was investigated. The adduct of the reaction of 1, whose two carbonyl groups were different, with cyclopentadiene showed moderate stereoselectivity and this was explained by FMO theory. However, in the Lewis acid-catalyzed addition, the reaction proceeded with high stereoselectivity to give the exo adduct 3x. This might be due to steric hindrance because the benzene ring cannot orient in the plane of the conjugated system in the metal-chelated enedione 6. Applying this principle to (1'R,2'S,5'R)-5-methyl-2-(1-methyl-1-phenylethyl)cyclohexyl 2-benzoylacrylate (1d), we achieved a diastereomeric Diels-Alder reaction to afford 3x-R, whose structure was confirmed by the X-ray crystal analysis. 相似文献
273.
Nobuhiko Yamada 《Tetrahedron letters》2008,49(7):1166-1168
Convenient and efficient procedures for thiirans have been developed via a one-pot reaction of benzoxazolyl β-ketosulfides with NaBH4 and NaOH in MeOH and THF. The reaction is considered to proceed via the spiro intermediate by the ipso-addition of β-hydroxygroup, which is formed by the NaBH4 reduction of β-keto group, to 2-position of benzoxazole group. 相似文献
274.
We have numerically calculated the stability diagram of the higher modes of the Fabry-Perot resonator by direct diagonalization
of the Fox-Li equation. The diagram has an exotic behavior in the small Fresnel number region and its higher modes in our
numerical experiments. 相似文献
275.
Tetsuichiro Iki Masayuki Horiguchi Masami Kurano 《Mathematical Methods of Operations Research》2007,66(3):545-555
In this paper, we are concerned with a new algorithm for multichain finite state Markov decision processes which finds an
average optimal policy through the decomposition of the state space into some communicating classes and a transient class.
For each communicating class, a relatively optimal policy is found, which is used to find an optimal policy by applying the
value iteration algorithm. Using a pattern matrix determining the behaviour pattern of the decision process, the decomposition
of the state space is effectively done, so that the proposed algorithm simplifies the structured one given by the excellent
Leizarowitz’s paper (Math Oper Res 28:553–586, 2003). Also, a numerical example is given to comprehend the algorithm. 相似文献
276.
Hiroyuki Ishii Franois Triozon Nobuhiko Kobayashi Kenji Hirose Stephan Roche 《Comptes Rendus Physique》2009,10(4):283-296
In this contribution, we present a numerical study of quantum transport in carbon nanotubes based materials. After a brief presentation of the computational approach used to investigate the transport coefficient (Kubo method), the scaling properties of quantum conductance in ballistic regime as well as in the diffusive regimes are illustrated. The impact of elastic (impurities) and dynamical disorders (phonon vibrations) are analyzed separately, with the extraction of main transport length scales (mean free path and localization length), as well as the temperature dependence of the nanotube resistance. The results are found in very good agreement with both analytical results and experimental data, demonstrating the predictability efficiency of our computational strategy. To cite this article: H. Ishii et al., C. R. Physique 10 (2009). 相似文献
277.
Nobuhiko P. Kobayashi Sagi Mathai Xuema Li V. J. Logeeswaran M. Saif Islam Andrew Lohn Takehiro Onishi Joseph Straznicky Shih-Yuan Wang R. Stanley Williams 《Applied Physics A: Materials Science & Processing》2009,95(4):1005-1013
A new route to grow an ensemble of indium phosphide single-crystal semiconductor nanowires is described. Unlike conventional
epitaxial growth of single-crystal semiconductor films, the proposed route for growing semiconductor nanowires does not require
a single-crystal semiconductor substrate. In the proposed route, instead of using single-crystal semiconductor substrates
that are characterized by their long-range atomic ordering, a template layer that possesses short-range atomic ordering prepared
on a non-single-crystal substrate is employed. On the template layer, epitaxial information associated with its short-range
atomic ordering is available within an area that is comparable to that of a nanowire root. Thus the template layer locally
provides epitaxial information required for the growth of semiconductor nanowires. In the particular demonstration described
in this paper, hydrogenated silicon was used as a template layer for epitaxial growth of indium phosphide nanowires. The indium
phosphide nanowires grown on the hydrogenerated silicon template layer were found to be single crystal and optically active.
Simple photoconductors and pin-diodes were fabricated and tested with the view towards various optoelectronic device applications
where group III–V compound semiconductors are functionally integrated onto non-single-crystal platforms. 相似文献
278.
Liu Zhenlin Ohtake Hideyuki Izumida Shinji Ono Shingo Sarukura Nobuhiko 《Optical and Quantum Electronics》2000,32(4-5):521-529
The THz-radiation power from InAs reaches sub-mW level in a 1.7-T magnetic field irradiated with femtosecond laser pulses of 1.5-W average power. The THz-radiation power is related almost quadratically both to the magnetic field and to the excitation laser power. Furthermore, the THz-radiation spectrum is found to be controlled by the excitation pulsewidth, chirp direction of the excitation pulse, and the magnetic field. 相似文献
279.
Kajiwara T Katagiri K Hasegawa M Ishii A Ferbinteanu M Takaishi S Ito T Yamashita M Iki N 《Inorganic chemistry》2006,45(13):4880-4882
Dinuclear and cubane-shaped lanthanide cluster complexes containing EuIII)and TbIII were synthesized by step-by-step construction using p-tert-butylsulfonylcalix[4]arene as a cluster-forming ligand. The sulfonylcalixarene adopts a pinched-cone conformation in the dinuclear complexes and a cone conformation in the cubane complexes. Because the calixarene has a large pi-conjugate system expanding over the entire molecule, it behaves as a good antenna chromophore for UV and near-UV light, and a slight conformational change of the calixarene (from cone to pinched-cone and vice versa) has an effect on the energy levels of excited S1 and T1 states. As a result, selectivity is observed in the luminescent properties of dinuclear and cubane-shaped systems of EuIII and TbIII. 相似文献
280.
Zou RQ Jiang L Senoh H Takeichi N Xu Q 《Chemical communications (Cambridge, England)》2005,(28):3526-3528
A novel 3D metal-organic framework with predesigned cubic building blocks and 1D open channels exhibiting significant N2 adsorption has been synthesized and characterized by single crystal X-ray diffraction analysis. 相似文献