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101.
Kunimitsu Kataoka Yasuhiko Takahashi Norihito Kijima Hiroshi Hayakawa Junji Akimoto Ken-ichi Ohshima 《Solid State Ionics》2009,180(6-8):631-635
Single crystals of Li4 + xTi5O12 were prepared by means of electrochemical Li-ion intercalation technique using parent Li4Ti5O12 single crystals. The obtained Li4 + xTi5O12 (x = 1.35) crystallizes in the cubic spinel-related type structure, space group Fd3?m, and lattice parameters of a = 8.346(2) Å and V = 581.3(5) Å3 and Z = 8. The Li-ion intercalated sites were successfully determined to be both the 8a and 16c sites by using the difference Fourier synthesis map. The structure was determined by single-crystal X-ray structure analysis and refined to the conventional value of R = 3.7% for 132 independent observed reflections. The chemical composition has been determined to be Li5.35Ti5O12 from the result of site-population refinements. In addition, theoretical electron density distributions and total energy were calculated for three postulated compounds of “Li4.5Ti4.5O12” and “Li4.5 + xTi4.5O12” with x = 1.5 and 3.0. 相似文献
102.
Junji Awaka Norihito Kijima Hiroshi Hayakawa Junji Akimoto 《Journal of solid state chemistry》2009,182(8):2046-2052
We have successfully synthesized a high-purity polycrystalline sample of tetragonal Li7La3Zr2O12. Single crystals have been also grown by a flux method. The single-crystal X-ray diffraction analysis verifies that tetragonal Li7La3Zr2O12 has the garnet-related type structure with a space group of I41/acd (no. 142). The lattice constants are a=13.134(4) Å and c=12.663(8) Å. The garnet-type framework structure is composed of two types of dodecahedral LaO8 and octahedral ZrO6. Li atoms occupy three crystallographic sites in the interstices of this framework structure, where Li(1), Li(2), and Li(3) atoms are located at the tetrahedral 8a site and the distorted octahedral 16f and 32g sites, respectively. The structure is also investigated by the Rietveld method with X-ray and neutron powder diffraction data. These diffraction patterns are identified as the tetragonal Li7La3Zr2O12 structure determined from the single-crystal data. The present tetragonal Li7La3Zr2O12 sample exhibits a bulk Li-ion conductivity of σb=1.63×10−6 S cm−1 and grain-boundary Li-ion conductivity of σgb=5.59×10−7 S cm−1 at 300 K. The activation energy is estimated to be Ea=0.54 eV in the temperature range of 300–560 K. 相似文献
103.
Kiyoshi Fukuhara Akiko Ohno Kohei Imai Kazunori Anzai Haruhiro Okuda 《Tetrahedron letters》2009,50(50):6989-1796
The reaction of ninhydrin with (+)-catechin in the presence of TMSOTf resulted in condensation product 1, which consists of a 2:1 mixture of epimers at the C-2 position. The antioxidative radical-scavenging activity of 1 against the galvinoxyl radical, acting as an oxyl radical, was significantly enhanced compared to (+)-catechin. Our results offer a new method for chemical modification of a natural phenolic antioxidant. 相似文献
104.
We analyzed the dynamic evolution of an ensemble of electrons performing macroscopic resonant tunneling for room-temperature millimeter-sized Coulomb oscillation in Ni-Nb-Zr-H glassy alloys as a function of the cluster size and boundary length using a one-dimensional Kronig-Penny model with a stepwise potential. The reflection coefficient showed a stagnant chaos around a narrow torus for a superlattice with a cluster size of 0.55 nm and a boundary distance of 0.23 nm. The transmission and reflection coefficients showed stationary chaotic behavior in periodic units with decreasing boundary distance rather than increasing cluster size. 相似文献
105.
Isao Saraoka Shinobu Kato Takayuki Chujo Hiroyasu Sato Koichi Fukuhara Hiroatsu Matsuura 《Journal of inclusion phenomena and macrocyclic chemistry》1995,22(1):59-69
4,13-Diaza-15-crown-5 and three of its sodium complexes (bromide, iodide and thiocyanate) were studied using Raman and IR spectroscopy and normal coordinate calculations, following the corresponding study on the sodium complexes of 4,13-diaza-18-crown-6 in the preceding paper. Complex formation was again accompanied by a characteristic shift of the bands, especially of those in the 800–900 cm–1 region. The complexes of 4-13-diaza-15-crown-5 were distinct from those of 4-13-diaza-18-crown-6, in that both of the bands at 830 and 890 cm–1 of the parent azacrown were affected on complex formation and in that only the 11 complex was formed. Normal mode calculations were made to predict conformations of the azacrown ring of the parent 4,13-diaza-15-crown-5 and its sodium complexes. Attention was paid to the different extent of mismatch in size of a sodium ion and azacrown cavities. 相似文献
106.
We consider a hyperbolic version of Eells-Sampson's equation:
. This equation is semilinear with respect to space derivative and time derivative. Letu
(x) be the solution with initial data u(0) and
(0), and putv
(t,x)=u
(t,x). We show that when the resistance ,V
(t,x) converges to a solution of the original parabolic Eells-Sampson's equation:
. Note thatv
t(0)=
(0) diverges when . We show that this phenomena occurs in more general situations.This article was processed by the author using the Springer-Verlag
Pjourlg macro package. 相似文献
107.
Minoru Sakurai Norihito Aoyama Masaki Kitagawa Yoshio Inoue Riichiro Chûjô 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(1):55-62
The binding process of the paracyclophane 1 with benzene is classified into two types; namely simple fit and induced fit. In the former case, it is assumed that the geometry of the host is fixed to that in the free state during complexation. On the basis of the MMP2 calculations, the induced fit type process, allowing all motional freedoms of the host and the guest, is essential in forming the stable inclusion complex with benzene. By the use of van der Waals potential maps, it is confirmed that the force-field inside the cavity of the host is effective for the inclusion of benzene. 相似文献
108.
Shintani R Tokunaga N Doi H Hayashi T 《Journal of the American Chemical Society》2004,126(20):6240-6241
A rhodium-catalyzed asymmetric 1,4-addition reaction has been applied to the synthesis of 2-aryl-4-piperidones. While other conventional nucleophiles fail, organozinc reagents have been successfully utilized for the construction of these useful compounds in very good yield and enantiomeric excess. 相似文献
109.
3,5-Ethenoporphyrin is a π-extended porphyrin containing a fused ethene unit between the meso- and β-positions, exhibiting unique contribution of macrocyclic antiaromaticity. We have recently reported that its analogue, etheno-fused diporphyrin, underwent thermal [2 + 2] cycloaddition to furnish X-shaped cyclobutane-linked tetraporphyrins. Here we demonstrate that the cyclobutane-ring formation is dynamically redox-active. Namely, the tetraporphyrin underwent two-step four-electron oxidation to afford two etheno-fused diporphyrin dications. The reduction of the resulting dication regenerated the cyclobutane-linked tetraporphyrin. The dication was sufficiently stable to allow its isolation under ambient conditions. The structure of the dication has been confirmed by 1H NMR spectroscopy and X-ray diffraction analysis. Importantly, the simultaneous double C–C bond cleavage in the cyclopropane ring in the tetraporphyrin is exceptional among dynamic redox (dyrex) systems to achieve large structural changes, thus offering new insights for the design of novel redox-active functional organic materials for electrochromic dyes, organic batteries, and organic memories.A four-electron oxidation of an X-shaped tetraporphyrin affords stable etheno-fused diporphyrin dications through double C–C bond cleavage. The reduction of the dication recovers the tetraporphyrin via a thermal [2 + 2] cycloaddition. 相似文献
110.
Conformational states of poly(oxyethylene) chain in aqueous solution are examined in connection with hydrophilic property of nonionic surfactants. The Raman spectra in various states are analyzed on the basis of comprehensive normal coordinate treatment. The poly(oxyethylene) chain is more ordered in more dilute aqueous solution. This conformational ordering is further promoted by lowering temperature. The ordered structure, which is similar, at least in part, to that in the solid state, is substantiated by the hydrogen bonds making the gauche conformation of the OCH2-CH2O group more favorable. The hydration has no significant effect on the conformation of the CH2O-CH2CH2 group. 相似文献