全文获取类型
收费全文 | 154548篇 |
免费 | 838篇 |
国内免费 | 485篇 |
专业分类
化学 | 64843篇 |
晶体学 | 2043篇 |
力学 | 9947篇 |
综合类 | 1篇 |
数学 | 39526篇 |
物理学 | 39511篇 |
出版年
2022年 | 629篇 |
2021年 | 872篇 |
2020年 | 965篇 |
2019年 | 1104篇 |
2018年 | 11932篇 |
2017年 | 11855篇 |
2016年 | 8135篇 |
2015年 | 1850篇 |
2014年 | 1997篇 |
2013年 | 3555篇 |
2012年 | 6599篇 |
2011年 | 13653篇 |
2010年 | 8206篇 |
2009年 | 8584篇 |
2008年 | 9482篇 |
2007年 | 11517篇 |
2006年 | 2959篇 |
2005年 | 3695篇 |
2004年 | 3735篇 |
2003年 | 4012篇 |
2002年 | 3116篇 |
2001年 | 2469篇 |
2000年 | 1907篇 |
1999年 | 1400篇 |
1998年 | 1312篇 |
1997年 | 1176篇 |
1996年 | 1084篇 |
1995年 | 944篇 |
1994年 | 884篇 |
1993年 | 903篇 |
1992年 | 916篇 |
1991年 | 995篇 |
1990年 | 925篇 |
1989年 | 961篇 |
1988年 | 874篇 |
1987年 | 824篇 |
1986年 | 795篇 |
1985年 | 910篇 |
1984年 | 1003篇 |
1983年 | 854篇 |
1982年 | 875篇 |
1981年 | 784篇 |
1980年 | 747篇 |
1979年 | 812篇 |
1978年 | 924篇 |
1977年 | 930篇 |
1976年 | 824篇 |
1975年 | 790篇 |
1974年 | 800篇 |
1973年 | 785篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Howard Robinson 《Acta Analytica》2005,20(3):7-10
Nicholas Nathan tries to resist the current version of the causal argument for sense-data in two ways. First he suggests that,
on what he considers to be the correct re-construction of the argument, it equivocates on the sense of proximate cause. Second
he defends a form of disjunctivism, by claiming that there might be an extra mechanism involved in producing veridical hallucination,
that is not present in perception. I argue that Nathan’s reconstruction of the argument is not the appropriate one, and that,
properly interpreted, the argument does not equivocate on proximate cause. Furthermore, I claim that his postulation of a
modified mechanism for hallucinations is implausibly ad hoc. 相似文献
7.
Large eddy simulations of two basic configurations (decay of isotropic turbulence, and the academic plane channel flow) with heat transfer have been performed comparing several convection numerical schemes, in order to discuss their ability to evaluate temperature fluctuations properly. Results are compared with the available incompressible heat transfer direct numerical simulation data. It is shown that the use of regularizing schemes (such as high order upwind type schemes) for the temperature transport equation in combination with centered schemes for momentum transport equation gives better results than the use of centred schemes for both equations. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
8.
O. V. Shramkova 《Technical Physics》2004,49(2):232-237
Magnetoplasma waves and inhomogeneous (complex) waves in an infinite semiconductor superlattice in a magnetic field are studied, and dispersion curves are obtained. It is shown analytically and numerically that, in periodic structures, among inhomogeneous waves, there are many complex waves for which the imaginary part of the wave vector is greater than the real part. The effect of dissipation in a medium on the dispersion curves of magnetoplasma waves is examined. The dependence of the minimum phase velocity on the collision frequency and the magnetic field strength is studied. 相似文献
9.
10.
K. P. O. Mahesh M. Sivakumar Y. Yamamoto Y. Tsujita H. Yoshimizu S. Okamoto 《Journal of Polymer Science.Polymer Physics》2004,42(18):3439-3446
A crystalline δ form of a syndiotactic polystyrene (sPS) membrane was prepared from a solution of sPS (1 wt %) and p‐chlorotoluene (p‐CT) by a solution‐casting method. The mesophase (δ empty form) of sPS was obtained by the extraction of the guest solvent from the δ form of sPS by a stepwise solvent‐extraction method. The sPS/p‐CT mesophase membrane [p‐CT (A‐M)] was used for the sorption of 1 mol % p‐CT for different times and for the sorption of different concentrations of p‐CT, chlorobenzene (CB), p‐xylene (p‐X), toluene, and chloroform for 48 h. The presence of solvents in the sPS membrane was confirmed by IR analysis. A thermal study revealed that the sorption amount of 1 mol % p‐CT increased with increasing immersion time, and the sorption amounts of different solvents increased with increasing solvent concentration. Differential scanning calorimetry results showed that the desorption peak temperature increased as the amount of the solvent increased in the clathrated sPS membrane. Wide‐angle X‐ray diffraction results showed that 2θ at 8.25° was slightly shifted toward 8°, and there was no change in the peak position at 10° for p‐CT (A‐M), which was immersed in different solvents (1 mol %); however, the intensity of 2θ at 10° was not similar for all the samples. Among the solvents used for the sorption studies at 1 mol %, p‐CT (A‐M) could sorb more p‐CT and CB than p‐X, toluene, and chloroform. The solvent sorption isotherm was the Langmuir sorption mechanism. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3439–3446, 2004 相似文献