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921.
Michael Höft Jochen Weinzierl Rolf Judaschke 《International Journal of Infrared and Millimeter Waves》2002,23(7):1127-1146
Holography is a promising technique for power combining applications in the frequency range of short millimeter and submillimeter waves. In this paper, quasi-optical holographic power combining circuits are investigated. An equivalent network is utilized which rigorously models horn arrays and biperiodic dielectric structures in order to design computer-generated holograms. We apply the network model to a 5-element quasi-optical power combiner and demonstrate its capability. The hologram is designed for 150 GHz and has an efficiency of 92.5 % with a 90 % bandwidth of 5.3 %. With the aid of a broadband waveguide power divider and a vector field measurement system, the circuit is analyzed. 相似文献
922.
Wang Yongqian Liao Xianbo Diao Hongwei Cheng Wenchao Li Guohua Chen Changyong Zhang Shibin Xu Yanyue Chen Weide Kong Guanglin 《中国科学A辑(英文版)》2002,45(10):1320-1328
A set of a-SiOx:H (0.52 <x< 1.58) films are fabricated by plasma-enhanced-chemical-vapor-deposition (PECVD) method at the substrate temperature
of 250°C. The microstructure and local bonding configurations of the films are investigated in detail using micro-Raman scattering,
X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). It is found that the films are
structural inhomogeneous, with five phases of Si, Si2O:H, SiO:H, Si2O3:H and SiO2 that coexist. The phase of Si is composed of nonhydrogenated amorphous silicon (a-Si) clusters that are spatially isolated.
The average size of the clusters decreases with the increasing oxygen concentration x in the films. The results indicate that
the structure of the present films can be described by a multi-shell model, which suggests that a-Si cluster is surrounded
in turn by the subshells of Si2O:H, SiO:H, Si2O3:H, and SiO2. 相似文献
923.
1 IntroductionForsolvingstiffinitialvalueproblemsforsystemsofODEsy′=f(y) ,y(t0 ) =y0 ,t0 <t≤T ,y0 ,y∈Rm,f :Ω Rm →Rm (1 .1 )manyparticularone blockmethodsoftheformYn+1= AYn+h( B0 F(Yn) + B1F(Yn+1) ) , A =A Im, Bi=Bi Im,A ,Bi∈Rr×r,Yn =(YTnr,… ,yT(n+1)r- 1) T,F(Yn) =(fT(ynr) ,… ,fT(y(n+1)r- 1) ) T,yj≈ y(tj) ,… 相似文献
924.
Recent experiments revealed that the dielectric dispersion spectrum of fission yeast cells in a suspension was mainly composed of two sub-dispersions. The low-frequency sub-dispersion depended on the cell length, while the high-frequency one was independent of it. The cell shape effect was simulated by an ellipsoidal cell model but the comparison between theory and experiment was far from being satisfactory. Prompted by the discrepancy, we proposed the use of spectral representation to analyze more realistic cell models. We adopted a shell-spheroidal model to analyze the effects of the cell membrane. It is found that the dielectric property of the cell membrane has only a minor effect on the dispersion magnitude ratio and the characteristic frequency ratio. We further included the effect of rotation of dipole induced by an external electric field, and solved the dipole-rotation spheroidal model in the spectral representation.Good agreement between theory and experiment has been obtained. 相似文献
925.
章利用基于三次B样条插值的边界元方法,对振动体外部声辐射问题进行了研究,对CHIEF法及其改进方法作了进一步的改进,提出在加权余量意义下,通过把内部Helmholtz积分方程与其对内点坐标取导后的方程式作线性叠加,在域外构作的一个小体积块上进行积分以形成补充方程,经与表面Helmholtz积分方程相结合,来求解任意频率下的声辐射问题,并以脉动球和摆动球作为算例,说明本提出的方法能够有效地克服在特殊频率处解的非唯一性问题。 相似文献
926.
环上矩阵的广义Moore-Penrose逆 总被引:14,自引:0,他引:14
本文给出带有对合的有1的结合环上一类矩阵的广义Moore-Penrose逆存在的充要条件,而这类矩阵概括了左右主理想整环,单Artin环上所有矩阵。 相似文献
927.
V. T. Plaksiy O. N. Suchoruchko B. P. Yefimov A. P. Kasyanenko 《International Journal of Infrared and Millimeter Waves》2002,23(4):645-650
Bismuth, antimony and its alloys are the typical representatives of a class of semimetals, which electric conductance is lower in 102-103 times, than of usual well conducting an electrical current metals. The alloys bismuth with antimony have semi-conductor properties in wide area of compositions at temperatures below 77 °K. The semimetals are rather perspective materials from the point of view of their probable application in various devices [1,2,3].In present time the semimetal alloys BiSb have wide application in thermoelectric generators and refrigerators. In work [3] the opportunity of use of semimetals BiSb with percentage content of Bi and Sb from 8 % up to 25 % was shown as high-sensitivity and of small inertion indicators of the mm range radiation where thermoelectric effect is used. The principle of action of such indicators is based on occurrence of temperature gradient in a semimetal crystal BiSb that has two contacts of the various area with flowing electrical current. Basic element of such device is the dot contact metal - semimetal. One of the main characteristics is volt-watt sensitivity of metal-semimetal BiSb contact which calculating is shown in present work. 相似文献
928.
929.
930.
利用溶胶凝胶法在SiO2Si衬底上沉积高取向的V2O5薄膜,在压强低于2Pa,温度高于400℃的条件下,对V2O5薄膜进行真空烘烤,获得了电阻率变化3个数量级以上、弛豫宽度为62℃的VO2多晶薄膜.以X射线衍射(XRD)、扫描电子显微镜(SEM)图和电阻率转换特性等实验结果为依据,详细分析了溶胶凝胶薄膜在真空烘烤时从V2O5向VO2的转化,它经历了从VnO2n+1(n=2,3,4,6)到VO2的过程.实验证明,根据选择合适的成膜热处理条件和真空烘烤条件是实现溶胶凝胶V2O5结构向VO2结构成功转换的关键
关键词:
溶胶-凝胶法 氧化钒薄膜 VO2膜转换特性 相似文献