全文获取类型
收费全文 | 52535篇 |
免费 | 1721篇 |
国内免费 | 32篇 |
专业分类
化学 | 33430篇 |
晶体学 | 263篇 |
力学 | 1682篇 |
综合类 | 1篇 |
数学 | 8111篇 |
物理学 | 10801篇 |
出版年
2023年 | 384篇 |
2022年 | 325篇 |
2021年 | 534篇 |
2020年 | 717篇 |
2019年 | 680篇 |
2018年 | 1055篇 |
2017年 | 868篇 |
2016年 | 1611篇 |
2015年 | 1464篇 |
2014年 | 1485篇 |
2013年 | 3054篇 |
2012年 | 3555篇 |
2011年 | 3636篇 |
2010年 | 2186篇 |
2009年 | 1799篇 |
2008年 | 3150篇 |
2007年 | 3144篇 |
2006年 | 2788篇 |
2005年 | 2731篇 |
2004年 | 2330篇 |
2003年 | 1873篇 |
2002年 | 1626篇 |
2001年 | 978篇 |
2000年 | 810篇 |
1999年 | 584篇 |
1998年 | 443篇 |
1997年 | 405篇 |
1996年 | 524篇 |
1995年 | 332篇 |
1994年 | 376篇 |
1993年 | 384篇 |
1992年 | 407篇 |
1991年 | 358篇 |
1990年 | 340篇 |
1989年 | 337篇 |
1988年 | 282篇 |
1987年 | 270篇 |
1986年 | 253篇 |
1985年 | 429篇 |
1984年 | 398篇 |
1983年 | 269篇 |
1982年 | 367篇 |
1981年 | 350篇 |
1980年 | 328篇 |
1979年 | 303篇 |
1978年 | 294篇 |
1976年 | 299篇 |
1975年 | 270篇 |
1974年 | 274篇 |
1973年 | 269篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
José A. Anquela Teresa Cortés Miguel Gómez-Lozano Mercedes Siles-Molina 《Acta Mathematica Hungarica》2004,103(3):177-196
We investigate the basic properties of the different socles that can be considered in not necessarily semiprime associative
systems. Among other things, we show that the socle defined as the sum of minimal (or minimal and trivial) inner ideals is
always an ideal. When trivial inner ideals are included, this inner socle contains the socles defined in terms of minimal
left or right ideals.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
52.
Hydrogels of N‐vinylimidazole (VI) and sodium styrenesulfonate (SSS) were synthesized in aqueous solution by radical crosslinking copolymerization with N,N′‐methylene‐bis(acrylamide) as crosslinker. Swelling in several saline solutions was measured for hydrogel samples synthesized with different comonomer concentrations (CT = 10, 25, or 40%) and with SSS mole fractions covering a broad range (fSSS = 0–0.7), while the crosslinker ratio was 2 wt % in all cases. The degree of swelling in aqueous solution with a specific ionic strength (μ), plotted versus the SSS composition of the feed, shows a minimum for any set of samples synthesized with a fixed CT. The dependence of swelling on μ shows both polyelectrolyte (fSSS beyond the minimum) and antipolyelectrolyte behaviors (in the low fSSS limit). It was found that the nonGaussian factor of the crosslinking density and the polymer‐solvent interaction parameter increase with fSSS for any CT. Moreover, in the low fSSS limit, the osmotic swelling pressure is governed not only by the ionic contribution, but also by the polymer‐solvent mixing and, the concentration of mobile counterions inside the gel is not proportional to the net fixed charge but to the addition of cationic and anionic side groups, what discards the formation of ionic pairs. The antipolyelectrolyte effect is interpreted as due to the increasing protonation of VI as μ goes up. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1683–1693, 2007 相似文献
53.
E. Sh. Finkel'shtein N. V. Ushakov N. A. Pritula E. A. Andreev N. A. Platé 《Russian Chemical Bulletin》1992,41(1):185-187
The thermally initiated and platinum-catalyzed polymerization of 1-silacyclobutanes with substitutents containing a trimethylsilyl group was carried out. Soluble, high-molecular-weight, heterochain siltrimethylene polymers were obtained, containing trimethylsilyl groups removed from the main chain by various bridges.A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 117912 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 223–225, January, 1992. 相似文献
54.
Details are given of a new method allowing an exact calculation of the spontaneous magnetization in the corner as well as along the edge at an arbitrary distance of the corner for a rectangular planar Ising ferromagnet. 相似文献
55.
F. Grisch P. Bouchardy M. Péalat B. Chanetz T. Pot M. C. Coët 《Applied physics. B, Lasers and optics》1993,56(1):14-20
Rotational temperature and nitrogen number density are measured in the shock wave/boundary layer interaction region in the vicinity of a two-dimensional compression corner disposed in a low pressure, 55 K, Mach 10 hypersonic air flow. Spatially-resolved data are recorded using a nonlinear optical technique named dual-line coherent anti-Stokes Raman scattering (DLCARS). Averaged temperature and density profiles are compared with those predicted by a Navier-Stokes solver. Good agreement is found. 相似文献
56.
Summary. This paper introduces and analyzes the convergence properties of a method that computes an approximation to the invariant
subspace associated with a group of eigenvalues of a large not necessarily diagonalizable matrix. The method belongs to the
family of projection type methods. At each step, it refines the approximate invariant subspace using a linearized Riccati's
equation which turns out to be the block analogue of the correction used in the Jacobi-Davidson method. The analysis conducted
in this paper shows that the method converges at a rate quasi-quadratic provided that the approximate invariant subspace is
close to the exact one. The implementation of the method based on multigrid techniques is also discussed and numerical experiments
are reported.
Received June 15, 2000 / Revised version received January 22, 2001 / Published online October 17, 2001 相似文献
57.
58.
59.
We prove global existence of solutions to the continuous nonhomogeneous Smoluchowski equation for coagulation rates satisfying a more general structure condition than the Galkin–Tupchiev monotony hypothesis considered in (Ph. Laurençot, S. Mischler, Arch. Rational Mech. Anal. 162 (1) (2002) 45–99). The Smoluchowski coagulation rate fulfils this condition as well as some rates which vanish on the diagonal. Under the condition of positivity of the coagulation rate outside of the diagonal we prove that solutions tend to 0 in the large time asymptotic. These results depend on a new estimate from below for the dissipation rate of the Lp-norm, p>1. To cite this article: S. Mischler, M. Rodriguez Ricard, C. R. Acad. Sci. Paris, Ser. I 336 (2003). 相似文献
60.
M. Dubé C. Daneault V. Vuorinen M. Alava M. Rost 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):15-26
We investigate the structure and dynamics of the interface between
two immiscible liquids in a three-dimensional disordered porous
medium. We apply a phase-field model that includes explicitly
disorder and discuss both spontaneous and forced imbibition.
The structure of the interface is dominated by a length scale
ξ× which arises from liquid conservation. We further show
that disorder in the capillary and permeability act on different
length scales and give rise to different scalings and
structures of the interface properties. We conclude with a
range of applications. 相似文献