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991.
Reflection and transmission of an incident plane wave at five types of possible interfaces between two dipo-lar gradient elastic solids are studied in this paper. First, the explicit expressions of monopolar tractions and dipolar trac-tions are derived from the postulated function of strain energy density. Then, the displacements, the normal derivative of displacements, monopolar tractions, and dipolar tractions are used to create the nontraditional interface conditions. There are five types of possible interfaces based on all possible combinations of the displacements and the normal derivative of displacements. These interfacial conditions with consid-eration of microstructure effects are used to determine the amplitude ratio of the reflection and transmission waves with respect to the incident wave. Further, the energy ratios of the reflection and transmission waves with respect to the incident wave are calculated. Some numerical results of the reflection and transmission coefficients are given in terms of energy flux ratio for five types of possible interfaces. The influences of the five types of possible interfaces on the energy parti-tion between the refection waves and the transmission waves are discussed, and the concept of double channels of energy transfer is first proposed to explain the different influences of five types of interfaces. 相似文献
992.
T. Hayat M. Waqas M. Ijaz Khan A. Alsaedi S.A. Shehzad 《Chinese Journal of Physics (Taipei)》2017,55(2):318-330
Here magnetohydrodynamic (MHD) two-dimensional (2D) flow of an incompressible Burgers material bounded by a permeable stretched surface is addressed. The boundary layer flow equations are modelled. Heat transfer is discussed for power law heat flux at the surface and heat source. Convergent series solutions are constructed. Clarification of different emerging variables is presented through graphs of velocity, temperature and local Nusselt number. The present solutions are matched with the available published work in a limiting case. 相似文献
993.
利用脉冲激光沉积法(PLD),在质量流量比为1∶3的氧气和氩气的混合气氛下,在STO(001) 基片上制备了外延的YBa2Cu3O7-δ(YBCO)超导薄膜.尽管薄膜表面分布有亚微米到微米量级颗粒,但与传统PLD制备YBCO的方法相比,大颗粒的密度要小得多.直流电阻和磁化率测量法同时证明了YBCO薄膜的超导转变温度(Tc)大于90 K. 在40 K时,零场临界电流密度(Jc)为63.8 MA/cm2,在5.2 T时达到最大钉扎力密度(Fpmax)387.9 GN/m3;在65 K时,零场Jc为28.3 MA/cm2,在2.6 T时Fpmax达到71.3 GN/m3;在77 K时,零场Jc为8.7 MA/cm2,在0.91 T时Fpmax达到12.1 GN/m3.研究结果为氧气和氩气混合气氛下PLD方法制备YBCO薄膜提供了重要实验数据. 相似文献
994.
A family of flux‐continuous, locally conservative, finite‐volume schemes has been developed for solving the general geometry‐permeability tensor (petroleum reservoir‐simulation) pressure equation on structured and unstructured grids and are control‐volume distributed (textit Comput. Geo. 1998; 2 :259–290; Comput. Geo. 2002; 6 :433–452). The schemes are applicable to diagonal and full tensor pressure equation with generally discontinuous coefficients and remove the O(1) errors introduced by standard reservoir‐simulation schemes (two‐point flux approximation) when applied to full tensor flow approximation. The family of flux‐continuous schemes is quantified by a quadrature parameterization (Int. J. Numer. Meth. Fluids 2006; 51 :1177–1203). Improved convergence (for two‐ and three‐dimensional formulation) using the quadrature parameterization has been observed for the family of flux‐continuous control‐volume distributed multi‐point flux approximation (CVD‐MPFA) schemes (Ph.D. Thesis, University of Wales, Swansea, U.K., 2007). In this paper family of flux‐continuous (CVD‐MPFA) schemes are used as a part of numerical upscaling procedure for upscaling the fine‐scale grid information (permeability) onto a coarse grid scale. A series of data‐sets (SPE, 2001) are tested where the upscaled permeability tensor is computed on a sequence of grid levels using the same fixed range of quadrature points in each case. The refinement studies presented involve:
- (i) Refinement comparison study: In this study, permeability distribution for cells at each grid level is obtained by upscaling directly from the fine‐scale permeability field as in standard simulation practice.
- (ii) Refinement study with renormalized permeability: In this refinement comparison, the local permeability is upscaled to the next grid level hierarchically, so that permeability values are renormalized to each coarser level. Hence, showing only the effect of increased grid resolution on upscaled permeability, compared with that obtained directly from the fine‐scale solution.
- (iii) Refinement study with invariant permeability distribution: In this study, a classical mathematical convergence test is performed. The same coarse‐scale underlying permeability map is preserved on all grid levels including the fine‐scale reference solution.
995.
996.
首次以LiF-H3BO3为助熔剂,用顶部籽晶法,生长出尺寸为12 mm×13mm×5mm的Ba2B5O9Cl透明单晶.通过热性能分析证实该晶体为非同成分熔融化合物,属于正交晶系,空间群Pnn2,晶胞参数为a=1.1576(2) nm,b=1.1619(2)nm,c =0.66874(13) nm,V=0.8994(3) nm3,Z=4.该晶体中含有BO3和BO3基团,具有三维网状的晶体结构.Ba2B5O9Cl粉末的非线性光学效应约为KDP的3.5倍,同时还进行了红外、漫反射光谱性能的研究. 相似文献
997.
Enhancement effect of asymmetry on the thermal conductivity of double-stranded chain systems 下载免费PDF全文
Using nonequilibrium molecular dynamics simulations, we study the thermal conductivity of asymmetric double chains. We couple two different single chains through interchain coupling to build three kinds of asymmetric double-stranded chain system: intrachain interaction, external potential, and mass asymmetric double chains. It is reported that asymmetry is helpful in improving the thermal conductivity of the system. We first propose double-heat flux channels to explain the influence of asymmetric structures on the thermal conductivity. The phonon spectral behaviour and finite size effect are also included. 相似文献
998.
Heat transport mechanisms of low Mach number turbulent channel flow with spanwise wall oscillation 下载免费PDF全文
Jian Fang·Li-Peng Lu National Key Laboratory of Science Technology on Aero-Engines School of Jet Propulsion Beihang University Beijing China Liang Shao Laboratory of Fluid Mechanics Acoustics Ecole Centrale de Lyon Lyon France 《Acta Mechanica Sinica》2010,26(3):391-399
Large eddy simulation (LES) of low Mach num- ber compressible turbulent channel flow with spanwise wall oscillation (SWO) is carried out. The flow field is analyzed with emphases laid on the heat transport as well as its rela- tion with momentum transport. When turbulent coherent structures are suppressed by SWO, the turbulent transports are significantly changed, however the momentum and heat transports change in the same manner, which gives the evi- dence of inherently consistent transport mechanisms between momentum and heat in turbulent boundary layers. The Reynolds analogies of all the flow cases are quite good, which confirms again the fact that the transport mechanisms of momentum and heat are consistent, which gives theoreti- cal support for controlling the wall heat flux control by using the drag reducing techniques. 相似文献
999.
1000.
For a mesoscopic radio frequency superconducting quantum
interference device (rfSQUID), at a degeneracy point, the system
reduces to a quantum two-state system which can be used as a flux
qubit. When the noise environment is equivalent to a harmonic
oscillators bath, by virtue of an operator-norm measure for the
short time decoherence, this paper investigates the initial
decoherence of the flux qubit operating in the ohmic noise
environment and illustrates its property by means of the numerical
evaluation. 相似文献