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71.
Cluster size effects of SiO2 thin film formation with size-selected O2 gas cluster ion beams (GCIBs) irradiation on Si surface were studied. The cluster size varied between 500 and 20,000 molecules/cluster. With acceleration voltage of 5 kV, the SiO2 thickness was close to the native oxide thickness by irradiation of (O2)20,000 (0.25 eV/molecule), or (O2)10,000 (0.5 eV/molecule). However, it increased suddenly above 1 eV/molecule (5000 molecules/cluster), and increased monotonically up to 10 eV/molecule (500 molecules/cluster). The SiO2 thickness with 1 and 10 eV/molecule O2-GCIB were 2.1 and 5.0 nm, respectively. When the acceleration voltage was 30 kV, the SiO2 thickness has a peak around 10 eV/molecule (3000 molecules/cluster), and it decreased gradually with increasing the energy/molecule. At high energy/molecule, physical sputtering effect became more dominant process than oxide formation. These results suggest that SiO2 thin film formation can be controlled by energy per molecule. 相似文献
72.
H. Imao M. Tarek K. Michishio Y. Enomoto T. Shimoyama Y. Kanai N. Kuroda A. Mohri H. Higaki H. Saitoh H. A. Torii Y. Nagata H. Toyoda Y. Matsuda Y. Nagashima Y. Yamazaki 《Hyperfine Interactions》2009,194(1-3):71-76
Our group “ASACUSA MUSASHI” has established an efficient way for accumulating antiprotons and extracting them as intense ultra-slow mono-energetic beams at the CERN-AD facility. This novel beam opens new frontiers for investigating a variety of physics. For realizing H? spectroscopy and the test for charge-parity-time symmetry, we have also developed the cusp trap, a combination of an anti-Helmholz superconducting coil and a multi-ring electrode trap, for trapping both antiprotons and positrons and then synthesizing antihydrogens. Recently, the cusp trap was practically used to accumulate antiprotons. The last piece for synthesizing antihydrogens in the cusp trap is the positron accumulator. We have developed a compact system to effectively accumulate positrons based on N2 gas-buffer scheme with a specially designed high precision cylindrical multi-ring electrode trap. The recent progress of the developing work is an important milestone for upcoming antihydrogen science of ASACUSA MUSASHI. 相似文献
73.
A novel dicyanoheptafulvene 9 annulated by two spiro[4,5]deca-1,3-dienes was synthesized by the reaction of dispirocyclopentaazulenium cation 8 with bromomalononitrile. Although 9 was found to have a nonplanar heptafulvene structure by its X-ray crystallographic analysis, it is still capable of π-conjugation and thus shows appreciable contribution of the dipolar resonance form 9B based on its spectroscopic data. The degree of the contribution was further evaluated for various dicyanoheptafulvenes in terms of the partial sum of atomic charges of the dicyanomethylene group in the calculated structures besides the interplanar angles of the heptafulvene part and the length of the exocyclic double bond in the crystal structures. 相似文献
74.
Because microperforated panels (MPPs), which can be made from various materials, provide wide-band sound absorption, they are recognized as one of the next-generation absorption materials. Although MPPs are typically placed in front of rigid walls, MPP space sound absorbers without a backing structure, including three-dimensional cylindrical MPP space absorbers (CMSAs) and rectangular MPP space absorbers (RMSAs), are proposed to extend their design flexibility and easy-to-use properties. On the other hand, improving the absorption performance by filling the back cavity of typical MPP absorbers with porous materials has been shown theoretically, and three-dimensional MPP space absorbers should display similar improvements. Herein the effects of porous materials inserted into the cavities of CMSAs and RMSAs are experimentally investigated and a numerical prediction method using the two-dimensional boundary element method is proposed. Consequently, CMSAs and RMSAs with improved absorption performances are illustrated based on the experimental results, and the applicability of the proposed prediction method as a design tool is confirmed by comparing the experimental and numerical results. 相似文献
75.
The sensing characteristics of an amperometric NOx sensor with yttria-stabilized zirconia and a La-based perovskite-type oxide
sensing electrode were examined. La1-xSrxMO3 (M = Co, Mn, x = 0, 0.2, 0.4, 0.6) were synthesized using the spray pyrolysis method. The NO2 response of a sensor fabricated with La1-xSrxMnO3 increased with increasing amount of Sr, and the trend was in contrast to that of the sensors fabricated with La1-xSrxCoO3. LaSr0.2MnO3 was determined to be the most appropriate material for the sensor in terms of a high NO2 response and low O2 current. In order to discuss the effects of Sr addition to La-based perovskite oxides for the sensor, NO adsorption and desorption
properties of oxides and the relationship between the oxidation number of the B-site cation and Sr substitution were examined
using temperature-programmed desorption and X-ray photoelectron spectroscopy, respectively. 相似文献
76.
Hélène Tissoux Pierre Voinchet Fréderic Lacquement François Prognon Davinia Moreno Christophe Falguères Jean-Jacques Bahain Shin Toyoda 《Radiation measurements》2012,47(9):894-899
Electron Spin Resonance (ESR) can be used as a method to estimate the age of sediment deposition using the paramagnetic centre related to aluminium impurities in quartz. This so-called Al-centre can be partially optically bleached and its signal intensity decreases in relation to time exposure to solar light, until it reaches a plateau value corresponding to a residual signal. This signal can be attributed to “Deep Aluminium Traps” (DAT) which cannot be reset by an exposure to sunlight. In this study, we have investigated the behaviour of the DAT signal in samples from different origins and ages. The intensity of the DAT signal has been isolated from the total aluminium signal by the exposure of different quartz samples to simulated solar light. We observed that the DAT intensities were sample dependant and therefore it should be determined for each sample. Moreover, DAT intensities of Pleistocene volcanic quartz increase with gamma laboratory irradiation, whereas DAT intensities of sedimentary quartz do not vary with added artificial doses. This suggests that DAT in quartz extracted from sediments must be inherited from the primary source of the quartz, and were saturated at the time of sedimentation. We thereby validate the ESR dating of quartz sediment protocol used so far. 相似文献
77.
Electronic structures in coupled two quantum dots by 3D-mesh Hartree-Fock-Kohn-Sham calculation 总被引:2,自引:0,他引:2
T. Matsuse T. Hama H. Kaihatsu N. Toyoda T. Takizawa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):391-394
To study the electronic structures of quantum dots in the framework of self-interaction-free including three dimensional effects,
we adopt the theory of nonlocal effective potential introduced by Kohn and Sham [#!ks65!#]. For utilizing the advantageous
point of the real space (3D) mesh method to solve the original nonlinear and nonlocal Hartree-Fock-Kohn-Sham (HFKS)-equation,
we introduce a linearization of the equation in the local form by introducing the local Coulomb potentials which depend on
explicitly the two single particle states. In practice, for solving the local form HFKS-equation, we use the Car-Parrinello-like
relaxation method and the Coulomb potentials are obtained by solving the Poisson equation under proper boundary conditions.
Firstly the observed energy gap between triplet- and singlet-states of N = 4 in DBS [#!tarucha96!#] is discussed to reproduce the addition energies and chemical potentials depending the magnetic
field. Next the coupling between two-quantum dots in TBS [#!aht97!#] is studied by adding the square barrier between two dots.
The spin-degeneracy [#!aht97!#] measured in gate-voltage depending on magnetic field is well reproduced in the limit of small
mismatch. Finally, the electronic states in the ring structure are calculated and discussed how the ring size and magnetic
field affect to the structures.
Received 30 November 2000 相似文献
78.
K. Obata K. Sugioka T. Akane N. Aoki K. Toyoda K. Midorikawa 《Applied Physics A: Materials Science & Processing》2001,73(6):755-759
A collinear irradiation system of F2 and KrF excimer lasers for high-quality and high-efficiency ablation of hard materials by the F2 and KrF excimer lasers’ multi-wavelength excitation process has been developed. This system achieves well-defined micropatterning
of fused silica with little thermal influence and little debris deposition. In addition, the dependence of ablation rate on
various conditions such as laser fluence, irradiation timing of each laser beam, and pulse number is examined to investigate
the role of the F2 laser in this process. The multi-wavelength excitation effect is strongly affected by the irradiation timing, and an extremely
high ablation rate of over 30 nm/pulse is obtained between -10 ns and 10 ns of the delay time of F2 laser irradiation. The KrF excimer laser ablation threshold decreases and its effective absorption coefficient increases
with increasing F2 laser fluence. Moreover, the ablation rate shows a linear increase with the logarithm of KrF excimer laser fluence when the
F2 laser is simultaneously irradiated, while single KrF excimer laser ablation shows a nonlinear increase. The ablation mechanism
is discussed based on these results.
Received: 16 July 2001 / Accepted: 27 July 2001 / Published online: 2 October 2001 相似文献
79.
80.
The synthesis and spectroscopic characterization of the title complexes correspond to isoelectronic system of o-quinodi-methane complex are described. 相似文献