首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   80篇
  免费   1篇
  国内免费   2篇
化学   54篇
力学   2篇
数学   9篇
物理学   18篇
  2023年   1篇
  2021年   2篇
  2019年   1篇
  2018年   6篇
  2016年   3篇
  2015年   2篇
  2014年   2篇
  2013年   8篇
  2012年   6篇
  2011年   11篇
  2010年   5篇
  2009年   5篇
  2008年   8篇
  2007年   4篇
  2006年   2篇
  2005年   3篇
  2003年   1篇
  2002年   3篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1990年   1篇
排序方式: 共有83条查询结果,搜索用时 296 毫秒
21.
A new kind of decoherence in quantum computer memory, called intrinsic decoherence, is investigated in some details, which is caused by discontinuous and stochastic unitary evolution of qubits in quantum computers on a sufficient short time scale. It is found that the intrinsic decoherence leads to quasi-periodic decaying oscillations of the state fidelity of qubits in the time evolution. Schemes to reduce the intrinsic decoherence are proposed.  相似文献   
22.
In this work, the investigation of the interface state density and series resistance from capacitance–voltage (CV) and conductance–voltage (G/ωV) characteristics in In/SiO2/p-Si metal–insulator–semiconductor (MIS) structures with thin interfacial insulator layer have been reported. The thickness of SiO2 film obtained from the measurement of the oxide capacitance corrected for series resistance in the strong accumulation region is 220 Å. The forward and reverse bias CV and G/ωV characteristics of MIS structures have been studied at the frequency range 30 kHz–1 MHz at room temperature. The frequency dispersion in capacitance and conductance can be interpreted in terms of the series resistance (Rs) and interface state density (Dit) values. Both the series resistance Rs and density of interface states Dit are strongly frequency-dependent and decrease with increasing frequency. The distribution profile of RsV gives a peak at low frequencies in the depletion region and disappears with increasing frequency. Experimental results show that the interfacial polarization contributes to the improvement of the dielectric properties of In/SiO2/p-Si MIS structures. The interface state density value of In/SiO2/p-Si MIS diode calculated at strong accumulation region is 1.11×1012 eV−1 cm−2 at 1 MHz. It is found that the calculated value of Dit (≈1012 eV−1 cm−2) is not high enough to pin the Fermi level of the Si substrate disrupting the device operation.  相似文献   
23.
24.
This study aimed to investigate the effect of resin impregnation on the interfacial shear strength (IFSS), thermogravimetric (TG) and fourier transform infrared (FT-IR) of sugar palm (Arenga pinnata) fibres. In addition, the effect of resin impregnation on the mechanical properties of sugar palm fibre reinforced unsaturated polyester (UP) composites was also studied. The fibres were impregnated with UP via vacuum resin impregnation process at a pressure of 600 mmHg for 5 min. Composites of 10, 20, 30, 40 and 50 % fibre loadings were fabricated and tested for tensile and flexural properties. It was observed that the impregnation process caused the fibres to be enclosed by UP resin and this gave a strong influence to the increase of its interfacial bonding by the increase of its IFSS from single fibre pull-out test. It was also observed with TG and FT-IR spectra that the impregnated fibre had lower moisture uptake than the control and there was no significant increase in thermal stability of the impregnated fibre. The sequence of fibre decomposition started from the evaporation of moisture, hemicelluloses, cellulose, lignin and finally ash content and the presence of these components were proven by FT-IR spectra. For the composite specimens, due to the high interfacial bonding of the impregnated fibre and the matrix, the impregnated composites showed consistently higher tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus and toughness than the control samples. It was also observed that 30 % fibre loading gave optimum properties.  相似文献   
25.
As higher radiation levels are associated with granodiorite area and the maps are more practical to interpret the results of radiological survey, the distributions of the specific activities of 226Ra, 232Th, 40K in soil-granite samples and indoor 222Rn activities throughout the granodiorite area of Bergama (Pergamon) were mapped in detail. Samples from the granites and soils underlying Kozak-Bergama (Pergamon) granodiorite area were collected and analyzed by HPGe gamma spectrometry system, while indoor radon levels in 20 dwellings of rural areas at this area were measured by the alpha track etch integrated method. This paper represents the baseline maps of natural radioactivity levels (226Ra, 232Th, 40K and 222Rn) and corresponding absorbed dose rates from outdoors terrestrial gamma radiation.  相似文献   
26.
We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below ~10 GeV/c(2). This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c(2) and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.  相似文献   
27.
Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped GaSb grown by the liquid encapsuled Czochralski technique are carried out as functions of temperature (35-350 K) and magnetic field (0-1.35 T). The power law model is used to explain the temperature-dependent resistivity. The magnetic-field-dependent data are analysed using the quantitative mobility spectrum analysis technique. The effect of individual band parameters (nL, nr, μL, μr, p and μp) on both the electron and magneto transports have been discussed. The EL - Er energy separation between the L and conduction band edges is also derived.  相似文献   
28.
The synthesis of novel metal-free (H2-Pz) and metalloporphyrazines (MgPz and CoPz), peripherally substituted with eight aza-15-crown-5 moieties, is described. The novel compounds were characterized by elemental analysis, i.r, 1H and 13C-n.m.r, UV–vis and m.s. spectral data.  相似文献   
29.
Cyclic codes over an infinite family of rings are defined. The general properties of cyclic codes over these rings are studied, in particular nontrivial one-generator cyclic codes are characterized. It is also proved that the binary images of cyclic codes over these rings under the natural Gray map are binary quasi-cyclic codes of index 2 k . Further, several optimal or near optimal binary codes are obtained from cyclic codes over R k via this map.  相似文献   
30.
The electrical and interface state properties of Au/perylene-monoimide (PMI)/n-Si Schottky barrier diode have been investigated by current–voltage (IV) and capacitance–voltage (CV) measurements at room temperature. A good rectifying behavior was seen from the IV characteristics. The series resistance (Rs) values were determined from IV and CV characteristics and were found to be 160 Ω and 53 Ω, respectively. The barrier height (Φb) of Au/PMI/n-Si Schottky diode was found to be 0.694 eV (IV) and 0.826 eV (CV). The ideality factor (n) was obtained to be 4.27 from the forward bias IV characteristics. The energy distribution of interface state density (Nss) of the PMI-based structure was determined, and the energy values of Nss were found in the range from Ec ? 0.508 eV to Ec ? 0.569 eV with the exponential growth from midgap toward the bottom of the conduction band. The values of the Nss without Rs are 2.11 × 1012 eV?1 cm?2 at Ec ? 0.508 eV and 2.00 × 1012 eV?1 cm?2 at Ec ? 0.569 eV. Based on the above results, it is clear that modification of the interfacial potential barrier for metal/n-Si structures has been achieved using a thin interlayer of the perylene-monomide.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号