全文获取类型
收费全文 | 204379篇 |
免费 | 1968篇 |
国内免费 | 593篇 |
专业分类
化学 | 102547篇 |
晶体学 | 3343篇 |
力学 | 9307篇 |
综合类 | 5篇 |
数学 | 22535篇 |
物理学 | 69203篇 |
出版年
2021年 | 1658篇 |
2020年 | 1805篇 |
2019年 | 2002篇 |
2018年 | 2703篇 |
2017年 | 2603篇 |
2016年 | 3777篇 |
2015年 | 2314篇 |
2014年 | 3626篇 |
2013年 | 9103篇 |
2012年 | 7256篇 |
2011年 | 8751篇 |
2010年 | 6052篇 |
2009年 | 5914篇 |
2008年 | 7923篇 |
2007年 | 8099篇 |
2006年 | 7738篇 |
2005年 | 6903篇 |
2004年 | 6433篇 |
2003年 | 5665篇 |
2002年 | 5510篇 |
2001年 | 6434篇 |
2000年 | 4943篇 |
1999年 | 3804篇 |
1998年 | 3039篇 |
1997年 | 3049篇 |
1996年 | 2810篇 |
1995年 | 2623篇 |
1994年 | 2480篇 |
1993年 | 2360篇 |
1992年 | 2707篇 |
1991年 | 2687篇 |
1990年 | 2616篇 |
1989年 | 2408篇 |
1988年 | 2458篇 |
1987年 | 2456篇 |
1986年 | 2287篇 |
1985年 | 2966篇 |
1984年 | 3225篇 |
1983年 | 2636篇 |
1982年 | 2805篇 |
1981年 | 2775篇 |
1980年 | 2641篇 |
1979年 | 2731篇 |
1978年 | 2828篇 |
1977年 | 2824篇 |
1976年 | 2895篇 |
1975年 | 2677篇 |
1974年 | 2648篇 |
1973年 | 2786篇 |
1972年 | 1768篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Summary The interceluster organization of a two-dimensional colloidal system undergoing diffusion-limited cluster-cluster aggregation
is considered. During this process the system evolves into a stationary, scaling state. In this state the organization arises
from effective intercluster repulsion due to the mutually exclusive depletion zones surrounding each cluster. It is shown
that in the scaling regime the relevant size of the depletion zones is determined by the separation between clusters, rather
than the cluster size.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
992.
C. P. Painuli B. P. Bahuguna B. D. Indu M. D. Tiwari 《International Journal of Theoretical Physics》1992,31(1):81-108
The theory of first-, second-, and third-order Raman scattering is investigated for isotopically disordered anharmonic crystals. The theory of time-dependent thermodynamic Zubarev Green's functions is adopted to obtain the Raman tensor, intensity of Raman lines, and differential cross sections of various orders of scatterings. It is observed that each class of scattering can be separated into diagonal and nondiagonal parts. The first-order and nondiagonal parts are absent in the case of chemically pure crystals. The diagonal parts are separated into anharmonic and interference terms. The interference terms arise due to the interactions of anharmonic phonons with the local phonons. The temperature and defect dependencies are discussed in detail along with the nature of continuous and line spectra. It is proposed that very high-power laser sources will reveal the third-order spectra, and that the resulting structure can be explained with the help of temperature-dependent one-, two-, and three-phonon density of states. 相似文献
993.
Two previously unknown metabolites of halofantrine, a candidate anti-malarial drug, have been isolated by thin-layer chromatography from the plasma of dogs administered a single oral dose of 60 mg/kg. Their identifies were investigated after trimethylsilylation by gas chromatography-mass spectrometry under electron-impact and negative-ion chemical ionization conditions. The structural assignment was further confirmed by using a combination of elemental composition analysis of all the isotope peaks at low mass resolution and isotope pattern matching. These two metabolites were formed by modification of the dibutylaminopropyl side-chain of the parent compound involving deamination and oxidation or reduction. 相似文献
994.
995.
Frank T. D. 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,37(2):139-142
The European Physical Journal B - We compute autocorrelation functions from nonlinear Fokker-Planck equations that describe nonlinear families of Markov diffusion processes and illustrate this... 相似文献
996.
The pseudopotential augmented-plane-wave method was used to study the surface structure of thin copper films with monolayers of Co, Ni, and Cs. Local densities of electron states, distributions of charge densities in the layers, and electron energy spectra are analyzed. The effect of adsorbates on the electronic properties of the Cu(001) surface and work function are discussed. Satisfactory agreement with available experimental data has been obtained. 相似文献
997.
Mathematical Notes - We consider functions f(z), z ∈ D ? ?, determining the mappings w = f(z) that, at the points ζ of the domain D, have the same dilatation ratio along the... 相似文献
998.
999.
In survival or reliability studies, the mean residual life or life expectancy is an important characteristic of the model. Whereas the failure rate can be expressed quite simply in terms of the mean residual life and its derivative, the inverse problem—namely that of expressing the mean residual life in terms of the failure rate—typically involves an integral of a complicated expression. In this paper, we obtain simple expressions for the mean residual life in terms of the failure rate for certain classes of distributions which subsume many of the standard cases. Several results in the literature can be obtained using our approach. Additionally, we develop an expansion for the mean residual life in terms of Gaussian probability functions for a broad class of ultimately increasing failure rate distributions. Some examples are provided to illustrate the procedure. 相似文献
1000.
We obtain global heat kernel bounds for semigroups which need not be ultracontractive by transferring them to appropriately chosen weighted spaces where they become ultracontractive. Our construction depends upon two assumptions: the classical Sobolev imbedding and a “desingularizing” (L1,L1) bound on the weighted semigroup. 相似文献