全文获取类型
收费全文 | 198230篇 |
免费 | 2085篇 |
国内免费 | 586篇 |
专业分类
化学 | 107622篇 |
晶体学 | 3234篇 |
力学 | 8137篇 |
综合类 | 7篇 |
数学 | 20006篇 |
物理学 | 61895篇 |
出版年
2020年 | 1606篇 |
2019年 | 1709篇 |
2018年 | 2206篇 |
2017年 | 2227篇 |
2016年 | 3407篇 |
2015年 | 1986篇 |
2014年 | 3007篇 |
2013年 | 7929篇 |
2012年 | 6178篇 |
2011年 | 7573篇 |
2010年 | 5305篇 |
2009年 | 5096篇 |
2008年 | 6821篇 |
2007年 | 6740篇 |
2006年 | 6675篇 |
2005年 | 6221篇 |
2004年 | 5574篇 |
2003年 | 5128篇 |
2002年 | 5079篇 |
2001年 | 5655篇 |
2000年 | 4191篇 |
1999年 | 3378篇 |
1998年 | 2933篇 |
1997年 | 2853篇 |
1996年 | 2652篇 |
1995年 | 2553篇 |
1994年 | 2311篇 |
1993年 | 2314篇 |
1992年 | 2582篇 |
1991年 | 2618篇 |
1990年 | 2503篇 |
1989年 | 2513篇 |
1988年 | 2453篇 |
1987年 | 2399篇 |
1986年 | 2267篇 |
1985年 | 2964篇 |
1984年 | 3147篇 |
1983年 | 2644篇 |
1982年 | 2983篇 |
1981年 | 2725篇 |
1980年 | 2740篇 |
1979年 | 2771篇 |
1978年 | 3017篇 |
1977年 | 2942篇 |
1976年 | 2872篇 |
1975年 | 2775篇 |
1974年 | 2637篇 |
1973年 | 2809篇 |
1972年 | 1802篇 |
1967年 | 1467篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
In this paper, the authors studied certain properties of the estimate of Liang and Krishnaiah (1985, J. Multivariate Anal. 16, 162–172) for multivariate binary density. An alternative shrinkage estimate is also obtained. The above results are generalized to general orthonormal systems. 相似文献
123.
124.
Summary The main purpose of this paper is to introduce the concepts of η-sets, ηζ-sets,η-continuity and ηζ-continuity and to obtain
a decomposition of continuity. 相似文献
125.
Zarubitskii O. G. Budnik V. G. Omel'chuk A. A. Melekhin V. T. Opanasyuk V. P. Zakharchenko N. F. 《Russian Journal of Applied Chemistry》2002,75(4):558-561
Electrochemical separation of lead-silver alloys into the constituents by thin-layer electrolysis in molten electrolytes, with bismuth as metal separator, is studied. It is proposed to determine the extent of component recovery by potentiometry. 相似文献
126.
The procedure for calculating the dispersion of the refractive and absorption indices and thickness of an optical film, based on measurements of spectral dependence of the transmittance, is described. The film parameters are calculated using a solution of the approximation problem. The effect of the film model on the calculated values of the refractive and absorption indices is analyzed. 相似文献
127.
128.
The process of harmonic wave propagation is investigated in a semi-infinite rigidly-clamped elastic layer. An analytic solution of the problem is obtained by the superposition method. The wave field expansion in the form of a normal mode series for a corresponding infinite waveguide is established. According to residue theory, the explicit form of the expansion coefficients is established with physical requirements of the radiation conditions taken into account.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 19, pp. 3–10, 1988. 相似文献
129.
O. Babelon 《Communications in Mathematical Physics》2006,266(3):819-862
The classical Volterra model, equipped with the Faddeev-Takhtajan Poisson bracket provides a lattice version of the Virasoro algebra. The Volterra model being integrable, we can express the dynamical variables in terms of the so-called separated variables. Taking the continuum limit of these formulae, we obtain the Virasoro generators written as determinants of infinite matrices, the elements of which are constructed with a set of points lying on an infinite genus Riemann surface. The coordinates of these points are separated variables for an infinite set of Poisson commuting quantities including L
0. The scaling limit of the eigenvector can also be calculated explicitly, so that the associated Schroedinger equation is in fact exactly solvable. 相似文献
130.
Neodymium-substituted Bi4Ti3O12 (BNdT) thin films were prepared by a chemical solution deposition technique on platinum- coated silicon substrates. All of
the samples were annealed at the relatively low temperature of 600 °C by a rapid thermal annealing process in different atmospheres,
such as O2, air, and nitrogen, and vacuum. Irrespective of different annealing atmospheres, all of the BNdT thin films exhibit good
ferroelectric properties, such as a saturated hysteresis loop, good fatigue endurance, and low leakage current density. A
large remanent polarization (Pr) of ∼48 μC/cm2 with an electric field of 240 kV/cm was observed from the BNdT thin film annealed in O2 atmosphere. The BNdT thin films annealed in nitrogen and vacuum, at reduced oxygen partial pressures, exhibit smaller Pr than that annealed in oxygen. The difference of Pr of the BNdT thin films annealed in different atmospheres may originate from differences in the grain sizes and the number
of oxygen vacancies.
PACS 77.55.+f; 77.80.-e; 77.80.Fm; 81.15.-z 相似文献