全文获取类型
收费全文 | 15381篇 |
免费 | 538篇 |
国内免费 | 141篇 |
专业分类
化学 | 8963篇 |
晶体学 | 333篇 |
力学 | 357篇 |
综合类 | 7篇 |
数学 | 2632篇 |
物理学 | 3768篇 |
出版年
2023年 | 88篇 |
2022年 | 209篇 |
2021年 | 225篇 |
2020年 | 226篇 |
2019年 | 331篇 |
2018年 | 343篇 |
2017年 | 347篇 |
2016年 | 612篇 |
2015年 | 496篇 |
2014年 | 605篇 |
2013年 | 1255篇 |
2012年 | 832篇 |
2011年 | 945篇 |
2010年 | 697篇 |
2009年 | 597篇 |
2008年 | 850篇 |
2007年 | 744篇 |
2006年 | 672篇 |
2005年 | 556篇 |
2004年 | 495篇 |
2003年 | 419篇 |
2002年 | 353篇 |
2001年 | 263篇 |
2000年 | 240篇 |
1999年 | 190篇 |
1998年 | 186篇 |
1997年 | 150篇 |
1996年 | 158篇 |
1995年 | 174篇 |
1994年 | 112篇 |
1993年 | 88篇 |
1992年 | 116篇 |
1991年 | 105篇 |
1990年 | 118篇 |
1989年 | 119篇 |
1988年 | 125篇 |
1987年 | 108篇 |
1986年 | 111篇 |
1985年 | 200篇 |
1984年 | 213篇 |
1983年 | 132篇 |
1982年 | 122篇 |
1981年 | 134篇 |
1980年 | 134篇 |
1979年 | 101篇 |
1978年 | 98篇 |
1977年 | 96篇 |
1976年 | 99篇 |
1975年 | 86篇 |
1974年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
We study interpolation, generated by an abstract method of means, of bilinear operators between quasi-Banach spaces. It is
shown that under suitable conditions on the type of these spaces and the boundedness of the classical convolution operator
between the corresponding quasi-Banach sequence spaces, bilinear interpolation is possible. Applications to the classical
real method spaces, Calderón-Lozanovsky spaces, and Lorentz-Zygmund spaces are presented.
The author is supported by the National Science Foundation under grant DMS 0099881.
The author is supported by KBN Grant 1 P03A 013 26. 相似文献
42.
In this paper, we give a convergence theorem and error estimates for an iteration method under new Kantorovitch-Ostrowski type condition using the information of higher derivatives at initial points. Compared with the corresponding study in [3],the convergence determination is established under one global condition, instead of two , on the function. 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.
Let A be a Weil algebra. The bijection between all natural operators lifting vector fields from m-manifolds to the bundle functor K
A
of Weil contact elements and the subalgebra of fixed elements SA of the Weil algebra A is determined and the bijection between all natural affinors on K
A
and SA is deduced. Furthermore, the rigidity of the functor K
A
is proved. Requisite results about the structure of SA are obtained by a purely algebraic approach, namely the existence of nontrivial SA is discussed. 相似文献
46.
A. Deptuła T. Olczak W. Łada B. Sartowska A.G. Chmielewski C. Alvani P.L. Carconi A. Di Bartolomeo F. Pierdominici S. Casadio 《Journal of Sol-Gel Science and Technology》2003,26(1-3):207-212
Microspheres of Li2TiO3 were fabricated by a classical, inorganic sol-gel process from commercially available TiCl4. Elaborated process consists of the following main steps: (1) dissolving of TiCl4 in concentrated aqueous HCl and addition of LiOH; (2) formation of sol emulsion in 2-ethylhexanol-1 containing the surfactant SPAN-80 (EH); (3) gelation of emulsion drops by extraction of water with partially dehydrated EH; (4) impregnation of gel to Li:Ti molar ratio MR = 2; (5) thermal treatment at 1200°C in order to receive chloride free product. This temperature can be significantly lowered (to 750°C) by dechlorination starting solution TiCl4 by chemical treatment of the with nitric acid to form of nitrate-stabilized titania sols. Tritium release from sol-gel made Li2TiO3 microspheres were found very close to that observed for other traditional materials, however for the first sample process starts slightly earlier. 相似文献
47.
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
48.
49.
A ring is said to be a left essential extension of a reduced ring (domain) if it contains a left ideal which is a reduced ring (domain) and intersects nontrivially every nonzero twosided ideal of the ring. We prove that every ring which is a left essential extension of a reduced ring is a subdirect sum of rings which are essential extensions of domains, but the converse implication does not hold. We give some applications of this result and discuss several related questions.Received: 6 January 2003 相似文献
50.
Orewczyk J. Jasieńska S. Iwanczenko S. 《Journal of Thermal Analysis and Calorimetry》1998,54(1):79-84
This paper presents applications of thermal analysis to observe the course of reduction of acidic pellets, metallurgical substances
whose reducibility and strength are basic parameters of use in blast furnace processes. Both parameters depend on the mineral
composition of the samples. The investigations included determination of the chemical and phase compositions of the initial
samples and reduction products.
Research was conducted on acidic pellets from Połtawa (Poland), applied in the T. Sendzimir Steelworks (Poland), in comparison
with pellets from Brazil, Canada and Lebedyn (Russia).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献