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11.
The effect of a market factor on information flow between stocks using the minimal spanning tree 总被引:1,自引:0,他引:1
We empirically investigated the effects of market factors on the information flow created from N(N−1)/2 linkage relationships among stocks. We also examined the possibility of employing the minimal spanning tree (MST) method, which is capable of reducing the number of links to N−1. We determined that market factors carry important information value regarding information flow among stocks. Moreover, the information flow among stocks showed time-varying properties according to the changes in market status. In particular, we noted that the information flow increased dramatically during periods of market crises. Finally, we confirmed, via the MST method, that the information flow among stocks could be assessed effectively with the reduced linkage relationships among all links among stocks from the perspective of the overall market. 相似文献
12.
Photonic crystal fiber coupler 总被引:3,自引:0,他引:3
Fiber couplers made with photonic crystal fibers (PCF) are reported. Two types of PCF were fabricated by means of stacking a group of silica tubes around a silica rod and drawing them. The fiber couplers were made by use of the fused biconical tapered method. With a fiber that had five hexagonally stacked layers of air holes, a 33/67 coupling ratio was obtained, and with a one-layer four-hole fiber, a 48/52 coupling ratio was obtained. The fabrication processes and the characteristics of the PCFs and the PCF couplers are presented. 相似文献
13.
We propose one- and two-wavelength methods of absolute measurement of diffraction-grating spacings based on the Littman configuration for autocollimation. The one-wavelength method has been applied to measure the spacing of a grating with a nominal value of 2160grooves/mm . The grating spacing was measured to be 463.16 nm, with an experimental standard deviation of 0.24 nm. It has been demonstrated that the both methods can provide direct traceability in the submicrometer region in terms of wavelength standards for applications in the field of nanometrology. 相似文献
14.
This communication provides a comparison between the backscattering coefficients computed using Gaussian versus non-Gaussian surface statistics. The computations are performed for a class of surface height distributions and surface correlation functions. Results indicate that the coherent component of the scattering coefficient is strongly dependent upon the surface height distribution. The noncoherent component also depends on the surface height distribution and the surface root mean square (rms) slope when the rms surface height is large relative to the incident wavelength. On the other hand, when the surface rms height is moderate or small, the noncoherent component is sensitive mainly to the surface height correlation function. 相似文献
15.
Building Pb nanomesas with atomic-layer precision 总被引:1,自引:0,他引:1
Jiang CS Li SC Yu HB Eom D Wang XD Ebert P Jia JF Xue QK Shih CK 《Physical review letters》2004,92(10):106104
We demonstrate a novel scheme for manipulating metallic nanostructures involving a macroscopic number of atoms, yet with precise control in their local structures. The scheme entails a two-step process: (a) a triggering step using a scanning tunneling microscope, followed by (b) self-driven and self-limiting mass-transfer process. By using this scheme, we construct Pb nanomesas on Si(111) substrates whose thickness can be controlled with atomic-layer precision. The kinetic barrier for the mass transfer and the underlying mechanism behind this novel manipulation are determined. 相似文献
16.
Modeling of ultrasonic testing has been paid a great attention in nondestructive evaluation community recently since it can provide thorough understanding of underlying physics of ultrasonic testing. As a result, there have been developed various modeling approaches up to now. Especially, many practical models have been developed based on either the multi-Gaussian beam or the Rayleigh-Sommerfeld integral. This paper discusses the modeling of ultrasonic testing with oblique incidence at the near critical angles using these two approaches. The theoretical models that can predict the reflection signals from side drilled cylindrical holes in solid specimen immersed in water are developed. Then, the theoretical predictions for the oblique incidence at the near critical angles are compared to the experiments for the investigation of model behavior. 相似文献
17.
The problem of a leaky coaxial cable with narrow transverse slots is solved by using the Fourier transform and mode-matching techniques. The characteristics of far-field radiation and near-field coupling are presented in terms of numerically fast convergent series. Our theoretical results are compared with experimental data to confirm favorable agreement 相似文献
18.
Tae-Hyoung Kim Keane J. Hanyong Eom Kim C.H. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2007,15(7):821-829
The impact of the reverse short-channel effect (RSCE) on device current is stronger in the subthreshold region due to reduced drain-induced barrier lowering (DIBL) and the exponential dependency of current on threshold voltage. This paper describes a device-size optimization method for subthreshold circuits utilizing RSCE to achieve high drive current, low device capacitance, less sensitivity to random dopant fluctuations, better subthreshold swing, and improved energy dissipation. Simulation results using ISCAS benchmark circuits show that the critical path delay, power consumption, and energy consumption can be improved by up to 10.4%, 34.4%, and 41.2%, respectively. 相似文献
19.
T.Y. Kwon Y.B. Kim K. Eom D.S. Yoon H.L. Lee T.S. Kim 《Applied Physics A: Materials Science & Processing》2007,88(4):627-632
Electrical properties of piezoelectric thick films with controlled microstructure were investigated. In order to enhance the
electromechanical properties (e.g. d31, d33) of a thick film by control of its microstructure, a mixed powder, referred to as BNP, consisting of both nano-sized and
micro-sized piezoelectric particles, was employed as a starting precursor in the film fabrication process. According to a
scanning electron microscopy study, it is shown that a BNP thick film exhibits the densest homogeneous microstructures. According
to surface area measurements, the BNP thick film was sufficiently densified without an additional infiltration process of
Pb(Zr1-xTix)O3 sol for densification. The screen-printed BNP thick film possesses a dielectric constant and a remanent polarization much
higher than those of a thick film composed of only micro-sized piezoelectric particles by a factor of more than two. This
suggests the potential application of the BNP thick film, in conjunction with a silicon substrate, to a micromachined monolithic
PZT thick film device on the silicon substrate.
PACS 85.40.Xx; 85.85.+j; 85.50.-n; 77.65.-j; 68.37.-d 相似文献
20.
Electromagnetic wave penetration into the two-dimensional (2-D) rectangular cavity with multiple slots in an infinite conducting plane with a finite thickness is investigated. The Fourier transform and the mode-matching technique are used to obtain simultaneous equations, which are solved to represent the scattered and the penetrated fields in series forms that are suitable for numerical computations 相似文献