全文获取类型
收费全文 | 8663篇 |
免费 | 185篇 |
国内免费 | 10篇 |
专业分类
化学 | 4947篇 |
晶体学 | 193篇 |
力学 | 185篇 |
数学 | 1362篇 |
物理学 | 2171篇 |
出版年
2022年 | 128篇 |
2021年 | 193篇 |
2020年 | 120篇 |
2019年 | 170篇 |
2018年 | 162篇 |
2017年 | 161篇 |
2016年 | 284篇 |
2015年 | 215篇 |
2014年 | 291篇 |
2013年 | 665篇 |
2012年 | 446篇 |
2011年 | 476篇 |
2010年 | 383篇 |
2009年 | 364篇 |
2008年 | 428篇 |
2007年 | 412篇 |
2006年 | 371篇 |
2005年 | 305篇 |
2004年 | 263篇 |
2003年 | 253篇 |
2002年 | 210篇 |
2001年 | 163篇 |
2000年 | 142篇 |
1999年 | 108篇 |
1998年 | 115篇 |
1997年 | 92篇 |
1996年 | 88篇 |
1995年 | 117篇 |
1994年 | 71篇 |
1993年 | 59篇 |
1992年 | 76篇 |
1991年 | 48篇 |
1990年 | 74篇 |
1989年 | 68篇 |
1988年 | 68篇 |
1987年 | 60篇 |
1986年 | 69篇 |
1985年 | 107篇 |
1984年 | 118篇 |
1983年 | 70篇 |
1982年 | 70篇 |
1981年 | 78篇 |
1980年 | 87篇 |
1979年 | 58篇 |
1978年 | 65篇 |
1977年 | 71篇 |
1976年 | 64篇 |
1975年 | 59篇 |
1974年 | 50篇 |
1973年 | 43篇 |
排序方式: 共有8858条查询结果,搜索用时 31 毫秒
41.
Zdzisław Denkowski Leszek Gasiński Nikolaos S. Papageorgiou 《Journal of Global Optimization》2006,34(3):317-337
We study a resonant semilinear elliptic hemivariational inequality. Under some assumptions of strong resonance on the Clarke
subdifferential of the superpotential, and using nonsmooth critical point theory, the existence of a nontrivial solution of
the problem is shown.
This paper has been partially supported by the State Committee for Scientific Research of Poland (KBN) under research grants
no. 2 P03A 003 25 and no. 4 T07A 027 26. 相似文献
42.
The internal conical refraction of a Bessel beam of arbitrary order is studied theoretically. It is shown that a beam of the order m of arbitrary polarization in the general case is partially converted to Bessel beams of the order m ± 1 with orthogonal circular polarizations. Conditions for complete conversion of a beam of the order m to a Bessel beam of the order m?1 or m+1 are determined. 相似文献
43.
We give characterizations of continuous distributions in terms of moments of order statistics when the sample size is random.
In particular, we characterize uniform, exponential, Pareto, and logistic distributions. Special cases of a random sample
size (logarithmic series, geometrical, truncated binomial, truncated negative binomial, and truncated Poisson distribution)
are also considered.
Proceedings of the XVII Seminar on Stability Problems for Stochastic Models, Kazan, Russia, 1995, Part I. 相似文献
44.
Janusz Mierczyński Wenxian Shen Xiao-Qiang Zhao 《Journal of Differential Equations》2004,204(2):471-510
The purpose of this paper is to investigate uniform persistence for nonautonomous and random parabolic Kolmogorov systems via the skew-product semiflows approach. It is first shown that the uniform persistence of the skew-product semiflow associated with a nonautonomous (random) parabolic Kolmogorov system implies that of the system. Various sufficient conditions in terms of the so-called unsaturatedness and/or Lyapunov exponents for uniform persistence of the skew-product semiflows are then provided. Among others, it is shown that if the associated skew-product semiflow has a global attractor and its restriction to the boundary of the state space has a Morse decomposition which is unsaturated or whose external Lyapunov exponents are positive, then it is uniformly persistent. More specific conditions are discussed for uniform persistence in n-species, particularly 3-species, random competitive systems. 相似文献
45.
JPC – Journal of Planar Chromatography – Modern TLC - Emodin and twelve phenolic acids (ellagic, gallic, protocatechuic, homoprotocatechuic, caffeic, p-hydroxybenzoic, p-coumaric,... 相似文献
46.
47.
Joanna Tarasińska 《Applications of Mathematics》2003,48(1):67-72
Two estimates of the regression coefficient in bivariate normal distribution are considered: the usual one based on a sample and a new one making use of additional observations of one of the variables. They are compared with respect to variance. The same is done for two regression lines. The conclusion is that the additional observations are worth using only when the sample is very small. 相似文献
48.
49.
Grzegorz M. Salamończyk 《Tetrahedron letters》2003,44(40):7449-7453
An efficient synthesis of antiviral dendritic prodrug candidates, water-soluble, polyanionic conjugates of 1st and 2nd generation thiophosphate dendrimers with acyclovir, is described. 相似文献
50.
Hubert Grudzński 《Reports on Mathematical Physics》2004,53(3):331-338
New elements of the dual cone of the set of fermion N-representable 2-density operators are proposed. So far, the explicit form of the corresponding necessary conditions for N-representability is obtained for N = 3. In this case the new condition is stronger than the known B- and C-conditions for 3-representability. The results provide evidence that in the spectral decomposition of the N-representable 2-density operator there exists an intrinsic relation between the eigenvalue and the corresponding eigenfunction. 相似文献