全文获取类型
收费全文 | 86174篇 |
免费 | 2039篇 |
国内免费 | 185篇 |
专业分类
化学 | 48630篇 |
晶体学 | 977篇 |
力学 | 2478篇 |
综合类 | 3篇 |
数学 | 13085篇 |
物理学 | 23225篇 |
出版年
2022年 | 630篇 |
2021年 | 865篇 |
2020年 | 1050篇 |
2019年 | 986篇 |
2018年 | 1549篇 |
2017年 | 1361篇 |
2016年 | 2479篇 |
2015年 | 1896篇 |
2014年 | 2169篇 |
2013年 | 4786篇 |
2012年 | 4597篇 |
2011年 | 4826篇 |
2010年 | 3335篇 |
2009年 | 2988篇 |
2008年 | 4101篇 |
2007年 | 3884篇 |
2006年 | 3500篇 |
2005年 | 3355篇 |
2004年 | 3014篇 |
2003年 | 2496篇 |
2002年 | 2250篇 |
2001年 | 2315篇 |
2000年 | 1959篇 |
1999年 | 1487篇 |
1998年 | 1157篇 |
1997年 | 1044篇 |
1996年 | 1116篇 |
1995年 | 897篇 |
1994年 | 938篇 |
1993年 | 855篇 |
1992年 | 961篇 |
1991年 | 883篇 |
1990年 | 916篇 |
1989年 | 810篇 |
1988年 | 817篇 |
1987年 | 761篇 |
1986年 | 710篇 |
1985年 | 884篇 |
1984年 | 889篇 |
1983年 | 684篇 |
1982年 | 720篇 |
1981年 | 719篇 |
1980年 | 595篇 |
1979年 | 681篇 |
1978年 | 652篇 |
1977年 | 649篇 |
1976年 | 675篇 |
1975年 | 585篇 |
1974年 | 576篇 |
1973年 | 607篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
61.
J. Song H. Jiang Z.J. Liu D.Y. Khang Y. Huang J.A. Rogers C. Lu C.G. Koh 《International Journal of Solids and Structures》2008,45(10):3107-3121
A finite-deformation theory is developed to study the mechanics of thin buckled films on compliant substrates. Perturbation analysis is performed for this highly nonlinear system to obtain the analytical solution. The results agree well with experiments and finite element analysis in wavelength and amplitude. In particular, it is found that the wavelength depends on the strain. Based on the accurate wavelength and amplitude, the membrane and peak strains in thin films, and stretchability and compressibility of the system are also obtained analytically. 相似文献
62.
P. Kolář 《Czechoslovak Journal of Physics》1989,39(11):1317-1320
Conclusions The sets (3) and (4) of condensates have been compared using the QCD sum rules (2) with indefinite weight functions. A bad matching between both sets of condensates and experimental data has been obtained. The standard values (3) appear to be closer to data but some increase ofQ is necessary to improve the agreement. Only higher values ofm
0
2
could change the results of this analysis. It is interesting that negative values ofm
0
2
considerably improve the agreement with data; note that this quantity cannot be determined with a sufficient accuracy. We conclude that the QCD sum rules (2) cannot definitely determine a privileged set of condensates.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday. 相似文献
63.
Time structure of iodine laser pulse in the free running mode of operation was studied using the power amplifier of laser system PERUN as the laser oscillator. Two characteristic shapes of laser pulse correspond to different regimes of laser operation, the existence of which is ascribed to the critical concentration of I2 molecules. Simultaneously an additional chemical pumping was proved at least in the initial phase of photodissociation and in a late-time lasing after the end of flashlamps pumping light. 相似文献
64.
Z.J. Yang T.H. Johansen H. Bratsberg G. Helgesen A.T. Skjeltorp 《Physica C: Superconductivity and its Applications》1989,160(5-6):461-465
Based on a dipole-dipole interaction model, we discuss the levitation force and related vibration problems to understand the effects of flux pinning in type-II superconductors, and the applications of levitation in superconducting systems. 相似文献
65.
Thermodynamic fluctuations in systems that are in nonequilibrium steady states are always spatially long ranged, in contrast to fluctuations in thermodynamic equilibrium. In the present paper we consider a fluid subjected to a stationary temperature gradient. Two different physical mechanisms have been identified by which the temperature gradient causes long-ranged fluctuations. One cause is the presence of couplings between fluctuating fields. Secondly, spatial variation of the strength of random forces, resulting from the local version of the fluctuation-dissipation theorem, has also been shown to generate long-ranged fluctuations. We evaluate the contributions to the long-ranged temperature fluctuations due to both mechanisms. While the inhomogeneously correlated Langevin noise does lead to long-ranged fluctuations, in practice, they turn out to be negligible as compared to nonequilibrium temperature fluctuations resulting from the coupling between temperature and velocity fluctuations. 相似文献
66.
67.
68.
Yu. B. Bolkhovityanov S. Ts. Krivoshchapov A. I. Nikiforov B. Z. Ol’shanetskii O. P. Pchelyakov L. V. Sokolov S. A. Teys 《Physics of the Solid State》2004,46(1):64-66
Different techniques for the fabrication of structures containing ensembles of ultrasmall germanium nanoclusters distributed with a high density over the substrate surface are discussed. How to control the morphology and ordering of these ensembles is also discussed. 相似文献
69.
A. Baeza M. Fernández M. Herranz F. Legarda C. Miró A. Salas 《Journal of Radioanalytical and Nuclear Chemistry》2004,260(2):321-326
We studied the effectiveness of potable water treatment processes that consist of the stages of coagulation-flocculation-decantation,
using iron-based coagulants, in eliminating gamma-emitting man-made radioisotopes of cesium, strontium, and americium from
two natural waters with different degrees of mineralization. The resulting decontamination was found to depend on the chemical
behavior of each of the radionuclides considered, on the pH at which the process of coagulation is carried out, and on the
concentration of the other stable cations present.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
70.
X. H. Li Y. Z. Meng S. J. Wang A. Varada Rajulu S. C. Tjong 《Journal of Polymer Science.Polymer Physics》2004,42(4):666-675
The composites of biodegradable poly(propylene carbonate) (PPC) reinforced with short Hildegardia populifolia natural fiber were prepared by melt mixing followed by compression molding. The mechanical properties, thermal properties, and morphologies of the composites were studied via static and dynamic mechanical measurements, thermogravimetric analysis, and scanning electron microscopy (SEM) techniques, respectively. Static tensile tests showed that the stiffness and tensile strength of the composites increased with an increasing fiber content. However, the elongation at break and the energy to break decreased dramatically with the addition of short fiber. The relationship between the experimental results and the compatibility or interaction between the PPC matrix and fiber was correlated. SEM observations indicated good interfacial contact between the short fiber and PPC matrix. Thermogravimetric analysis revealed that the introduction of short Hildegardia populifolia fiber led to a slightly improved thermooxidative stability of PPC. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 666–675, 2004 相似文献