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141.
Low-energy boron clusters are characterized by two-dimensional geometry. Aromaticity of these planar boron clusters was established in terms of topological resonance energy (TRE). All planar boron clusters were found to be highly aromatic with large positive TREs even if they have 4n pi-electrons. Aromaticity must therefore be the origin of unusual planar or quasi-planar geometry. Thus, the aromaticity concept is as useful in boron chemistry as it is in general organic chemistry. It is evident that the Hückel 4n + 2 rule of aromaticity should not be applied to such polycyclic pi-systems. Some of the boron clusters are in the triplet electronic state to attain higher aromaticity. Multivalency and electron deficiency of boron atoms are responsible for lowering the energies of low-lying pi molecular orbitals and then for enhancing aromaticity. For polycyclic pi-systems, paratropicity does not always indicate antiaromaticity. 相似文献
142.
[reaction: see text] Aminomethano[60]fullerene was synthesized for the first time as a trifluoromethanesulfonic acid salt by applying the Curtius rearrangement of azidocarbonylmethano[60]fullerene as the key reaction. Aminomethano[60]fullerene thus obtained was found to be able to react with various acyl chlorides to afford the corresponding amides. 相似文献
143.
144.
N. Kawamura K. Nagamine T. Matsuzaki K. Ishida S. N. Nakamura Y. Matsuda M. Tanase M. Kato K. Kurosawa H. Sugai K. Kudo N. Takeda G. H. Eaton 《Hyperfine Interactions》2001,138(1-4):235-240
A systematic study on muon catalyzed fusion (μCF) was conducted in solid deuterium and tritium (D–T) mixture. A variety of
experimental conditions were investigated, i.e., tritium concentrations from 20 to 70%, temperatures from 5 to 16 K. A preliminary
analysis result suggests a steep decrease in the dtμ-molecule formation rate with decreasing temperature, and also an increase in the probability for a muon reactivation after
an α-sticking phenomenon.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
145.
T Suzuki S Miyanari Y Tsubata T Fukushima T Miyashi Y Yamashita K Imaeda T Ishida T Nogami 《The Journal of organic chemistry》2001,66(1):216-224
N,N'-Dicyanonaphthoquinodiimines fused with a pyrazine ring 1 were prepared from the corresponding quinones 4. The new acceptors 1 have a planar pi-system and undergo reversible two-stage 1e-reduction. Quaternization of the pyridyl substituent in 1d-f gave pyridinium derivatives 2d+, 2e+, and R-3+, respectively, which are stronger acceptors that undergo three-stage 1e-reduction. Upon electrochemical reduction of these cations, novel radicals 2d., 2e., and R-3. were generated and isolated as stable solids. The molecular geometries determined by X-ray analysis indicated that these radicals adopt a zwitterionic structure, in which the unpaired electron is located on the quinodiimine unit but not on the pyridyl group. These novel radicals undergo facile and reversible 1e-oxidation as well as two-stage 1e-reduction. The observed amphotericity endows the radicals with electrical conductivities (10(-5) to 10(-9) S cm-1), and these thus represent a new motif for single-component organic semiconductors. 相似文献
146.
147.
K. Nishiyama K. Ishida K. Nagamine T. Matsuzaki Y. Kuno H. Shirakawa R. Kiefl J. H. Brewer 《Hyperfine Interactions》1986,32(1-4):551-556
The state of the muon in cis-polyacetylene was studied by muon spin rotation method under high transverse magnetic field.
The most of the muons are found to be in muonium substituted radical state. The hyperfine coupling constant was determined
to be 91 MHz with a line width of 10 MHz. 相似文献
148.
Tamio Kamidate Yasunori Hashimoto Hirofumi Tani Akihiko Ishida 《Analytical sciences》2002,18(3):273-276
The uptake of Cu2+ was investigated using various types of liposomes composed of phosphatidylcholine (PC), cholesterol (Chol) and dicethylphosphate (DCP). DCP played a role as a ligand for Cu2+. Multilamellar vesicles (MLVs) were more effective for the uptake of Cu2+ compared to unilamellar vesicles prepared by the extrusion technique. The uptake efficiency of MLVs for Cu2+ was dependent on the molar ratio of DCP in MLVs. The uptake percent of Cu2+ was 92% using MLVs having a PC:DCP:Chol molar ratio of 4:3:3; 95% of the total vesicle Cu2+ was bound to DCP of the outer membrane surface of the MLVs, and the remaining 5% of the total Cu2+ was distributed into the interior side of the MLVs. MLVs having a PC:DCP:Chol molar ratio of 4:3:3 were also effective as separation media for Mn2+, Co2+, Ni2+ and Zn2+. The uptake efficiency of the MLVs for the transition-metal ions increased in the order Co2+ < Zn2+ < Ni2+ < Mn2+ < Cu2+. 相似文献
149.
The equations of state of CeCu2Si2 and CeCu2Ge2 to about 60 GPa, as well as that of CeNi2Ge2 to 22 GPa and the valence state of Ce in CeCu2Ge2 to 20 GPa have been studied at room temperature in a diamond-anvil cell using synchrotron radiation sources. In each compound, the ambient-pressure phase (tetragonal ThCr2Si2-type structure) persisted to the highest pressure studied. The unit cell volumes of CeNi2Ge2 at ∼5 GPa and CeCu2Ge2 at ∼7 GPa, respectively, approached that of CeCu2Si2 taken at ambient pressure. From the equation-of-state data, the bulk modulus was derived to be 112.0±5.1 GPa for CeCu2Si2, 125.6±4.3 GPa for CeCu2Ge2, and 178.4±14.3 GPa for CeNi2Ge2. The valence state of Ce in CeCu2Ge2 remained trivalent throughout the pressure range investigated. 相似文献
150.
K. Asayama Y. Kitaoka G. -Q. Zheng K. Ishida Y. Tokunaga H. Mukuda T. Ohno 《Applied magnetic resonance》2000,19(3-4):305-319
This paper introduces nuclear magnetic resonance works in the strongly correlated super-conductors: heavy-Fermion, high-T C superconductors and Sr2RuO4. The analyses strongly support the spin-fluctuation-mediated superconductivity model in a high-T C superconductor. 相似文献