全文获取类型
收费全文 | 4235篇 |
免费 | 447篇 |
国内免费 | 244篇 |
专业分类
化学 | 518篇 |
晶体学 | 7篇 |
力学 | 593篇 |
综合类 | 61篇 |
数学 | 1834篇 |
物理学 | 1913篇 |
出版年
2023年 | 34篇 |
2022年 | 48篇 |
2021年 | 75篇 |
2020年 | 98篇 |
2019年 | 90篇 |
2018年 | 79篇 |
2017年 | 94篇 |
2016年 | 127篇 |
2015年 | 99篇 |
2014年 | 171篇 |
2013年 | 322篇 |
2012年 | 182篇 |
2011年 | 266篇 |
2010年 | 184篇 |
2009年 | 245篇 |
2008年 | 233篇 |
2007年 | 256篇 |
2006年 | 235篇 |
2005年 | 218篇 |
2004年 | 186篇 |
2003年 | 185篇 |
2002年 | 169篇 |
2001年 | 160篇 |
2000年 | 157篇 |
1999年 | 122篇 |
1998年 | 99篇 |
1997年 | 99篇 |
1996年 | 90篇 |
1995年 | 59篇 |
1994年 | 54篇 |
1993年 | 47篇 |
1992年 | 53篇 |
1991年 | 60篇 |
1990年 | 41篇 |
1989年 | 32篇 |
1988年 | 28篇 |
1987年 | 39篇 |
1986年 | 23篇 |
1985年 | 17篇 |
1984年 | 24篇 |
1983年 | 13篇 |
1982年 | 18篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有4926条查询结果,搜索用时 62 毫秒
11.
Becky Lavi Abraham Marmur 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):409-414
An equation for the kinetics of partial drop spreading is proposed. This equation was empirically derived from experimental data for the spreading kinetics of partially wetting liquids in terms of the wet area versus time. The equation has the form of an exponential power law (EPL), and transforms into the well-known power law for complete wetting, when the equilibrium contact angle approaches zero. The EPL fits very well available experimental data. To lend additional support to the validity of this generalized equation, it will be demonstrated that when it is transformed to present the dynamic contact angle (DCA), it fits very well DCA experimental data for other wetting processes, such as capillary flow and tape coating. 相似文献
12.
Some features of software implementation of the Pulay scaling procedure are considered. The advantages of the single value decomposition method for maintaining well-conditionality of the scale factor determination problem are demonstrated. The necessity of using a rational number of scale factors is shown. The possibility of obtaining transferable scale factors with the Pulay method and thus predict the vibrational spectra of related compounds is emphasized. 相似文献
13.
A. Bourgeat O. Gipouloux E. Marui‐Paloka 《Mathematical Methods in the Applied Sciences》2004,27(4):381-403
In this paper, we study the global behaviour of an underground waste disposal in order to have an accurate upscaled model suitable for the computations involved in safety assessment processes. We start from a detailed model describing the transport of pollutant leaking from a high number of units. Using the method of homogenization, going to the limit, we obtain first a macroscopic model where the sources are now appearing globally. Then we compute a first‐order matched asymptotic expansion and we give the error estimates for this approximation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
14.
The refraction holodiagram RHD is analyzed here with respect to the law of refraction. Particularly, we study the surface that exactly conjugates by refraction a virtual point source with a real image or conversely. By using the total optical path as a parameter we build a diagram that consists in a family of Descartes ovals of the apple type that contains the Pascal's limaçon as a particular extreme case and the spherical surface with the Weierstrass points as another. These representations permit the straightforward application of Fermat's principle in the case of arbitrary refracting surfaces and show the shape of generalized Fresnel's zones in the intersections with any surface. Snell's law is applied to rays incident on the apple type surfaces to find out the conditions for exact conjugation. Sensitivity to optical path variations is also discussed. The RHD curves family can be represented in a Cartesian way where the ovals appear as equally spaced straight lines. 相似文献
15.
R. Norvaisa 《Lithuanian Mathematical Journal》2005,45(4):447-457
We give a characterization of Gaussian chaos laws on Banach function spaces which do not contain ℓ
∞
n
's uniformly. The result is applied to describe the convergence in law of U-processes with sample paths in certain Banach function spaces.
__________
Published in Lietuvos Matematikos Rinkinys, Vol. 45, No. 4, pp. 553–566, October–December, 2005. 相似文献
16.
A model of two interacting (chemically different) linear polymer chains is solved exactly using the real-space renormalization
group transformation on a family of Sierpinski gasket type fractals and on a truncated 4-simplex lattice. The members of the
family of the Sierpinski gasket-type fractals are characterized by an integer scale factorb which runs from 2 to ∞. The Hausdorff dimensiond
F of these fractals tends to 2 from below asb → ∞. We calculate the contact exponenty for the transition from the State of segregation to a State in which the two chains are entangled forb = 2-5. Using arguments based on the finite-size scaling theory, we show that forb→∞, y = 2 - v(b) d
F, wherev is the end-toend distance exponent of a chain. For a truncated 4-simplex lattice it is shown that the system of two chains
either remains in a State in which these chains are intermingled in such a way that they cannot be told apart, in the sense
that the chemical difference between the polymer chains completely drop out of the thermodynamics of the system, or in a State
in which they are either zipped or entangled. We show the region of existence of these different phases separated by tricritical
lines. The value of the contact exponenty is calculated at the tricritical points. 相似文献
17.
本文研究了A型暂留稳定过程在无穷远处的收敛速度,给出了一个重对数律.同时我们也得出了这类过程在起始点附近的一些性质.这些性质推广了[1]中的结果 相似文献
18.
S. Moss de Oliveira P. M. C. de Oliveira F. C. de Sá Barreto 《Journal of statistical physics》1995,78(5-6):1619-1627
Using the finite-size scaling renormalization group, we obtain the two-dimensional flow diagram of the Blume-Capel model forS=1 andS=3/2. In the first case our results are similar to those of mean-field theory, which predicts the existence of first- and second-order transitions with a tricritical point. In the second case, however, our results are different. While we obtain in theS=1 case a phase diagram presenting a multicritical point, the mean-field approach predicts only a second-order transition and a critical endpoint. 相似文献
19.
Djamel Meraghni Abdelhakim Necir 《Methodology and Computing in Applied Probability》2007,9(4):557-572
The characteristic exponent α of a Lévy-stable law S
α
(σ, β, μ) was thoroughly studied as the extreme value index of a heavy tailed distribution. For 1 < α < 2, Peng (Statist. Probab. Lett. 52: 255–264, 2001) has proposed, via the extreme value approach, an asymptotically normal estimator for the location parameter μ. In this paper, we derive by the same approach, an estimator for the scale parameter σ and we discuss its limiting behavior.
相似文献
20.
Piotr Rybka 《Journal of Differential Equations》2002,181(2):340-366
We study the behavior of solutions of the modified Stefan problem in the plane for polygonal interfaces. We are particularly interested in a solution near a singularity of either the loss of a facet or the breaking of a facet. We establish precise regularity results if a facet disappears. We use them to establish the existence of a weak solution with singular data, i.e., when some of the zero-crystalline-curvature facets have zero length. 相似文献