全文获取类型
收费全文 | 314603篇 |
免费 | 3757篇 |
国内免费 | 1091篇 |
专业分类
化学 | 170790篇 |
晶体学 | 4462篇 |
力学 | 13041篇 |
综合类 | 7篇 |
数学 | 36272篇 |
物理学 | 94879篇 |
出版年
2020年 | 1985篇 |
2019年 | 1957篇 |
2018年 | 1965篇 |
2017年 | 1876篇 |
2016年 | 3861篇 |
2015年 | 3236篇 |
2014年 | 4423篇 |
2013年 | 13984篇 |
2012年 | 10734篇 |
2011年 | 13368篇 |
2010年 | 8272篇 |
2009年 | 8261篇 |
2008年 | 12340篇 |
2007年 | 12583篇 |
2006年 | 12222篇 |
2005年 | 11160篇 |
2004年 | 10045篇 |
2003年 | 8856篇 |
2002年 | 8706篇 |
2001年 | 10115篇 |
2000年 | 7720篇 |
1999年 | 6126篇 |
1998年 | 4905篇 |
1997年 | 4744篇 |
1996年 | 4778篇 |
1995年 | 4368篇 |
1994年 | 4119篇 |
1993年 | 3945篇 |
1992年 | 4435篇 |
1991年 | 4297篇 |
1990年 | 4014篇 |
1989年 | 3833篇 |
1988年 | 4123篇 |
1987年 | 3792篇 |
1986年 | 3682篇 |
1985年 | 5326篇 |
1984年 | 5399篇 |
1983年 | 4384篇 |
1982年 | 4757篇 |
1981年 | 4802篇 |
1980年 | 4551篇 |
1979年 | 4668篇 |
1978年 | 4670篇 |
1977年 | 4649篇 |
1976年 | 4604篇 |
1975年 | 4515篇 |
1974年 | 4358篇 |
1973年 | 4530篇 |
1972年 | 2570篇 |
1971年 | 1883篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
881.
882.
C. Torres O. Alejos C. de Francisco J.M. Muñoz P. Hernández-Gómez 《Applied Physics A: Materials Science & Processing》2003,77(3-4):543-547
This paper describes a robust and fast fitting procedure applicable for relaxing processes that cannot be understood as a discrete sum of single processes but require an activation energy distribution. The method is based on a set of closed-form expressions that allow the computation of the relaxation parameters directly from the isochronal curves obtained experimentally. The usefulness of this method is checked by analyzing the isochronal curves given by a theoretical energy distribution and the magnetic disaccommodation spectra observed in yttrium iron garnet (YIG) samples. PACS 02.60.Ed; 75.60.Lr; 75.50.Gg 相似文献
883.
Brenda J. Latka 《Journal of Graph Theory》2003,42(3):165-192
A finite tournament T is tight if the class of finite tournaments omitting T is well‐quasi‐ordered. We show here that a certain tournament N5 on five vertices is tight. This is one of the main steps in an exact classification of the tight tournaments, as explained in [10]; the third and final step is carried out in [11]. The proof involves an encoding of the indecomposable tournaments omitting N5 by a finite alphabet, followed by an application of Kruskal's Tree Theorem. This problem arises in model theory and in computational complexity in a more general form, which remains open: the problem is to give an effective criterion for a finite set {T1,…,Tk} of finite tournaments to be tight in the sense that the class of all finite tournaments omitting each of T1,…,Tk is well‐quasi‐ordered. © 2003 Wiley Periodicals, Inc. J Graph Theory 42: 165–192, 2003 相似文献
884.
Raj Gandhi Kamales Kar S. Uma Sankar Abhijit Bandyopadhyay Rahul Basu Pijushpani Bhattacharjee Biswajoy Brahmachari Debrupa Chakraborti M. Chaudhury J. Chaudhury Sandhya Choubey E. J. Chun Atri Desmukhya Anindya Datta Gautam Dutta Sukanta Dutta Anjan Giri Sourendu Gupta Srubabati Goswami Namit Mahajan H. S. Mani A. Mukherjee Biswarup Mukhopadhyaya S. N. Nayak M. Randhawa Subhendu Rakshit Asim K. Ray Amitava Raychaudhuri D. P. Roy Probir Roy Suryadeep Roy Shiv Sethi G. Sigl Arunansu Sil N. Nimai Singh Mark Vagins Urjit Yagnik 《Pramana》2003,60(2):405-409
This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in
long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed. 相似文献
885.
J. Haslinger T. Kozubek K. Kunisch G. Peichl 《Journal of Mathematical Analysis and Applications》2004,290(2):665-685
This contribution combines a shape optimization approach to free boundary value problems of Bernoulli type with an embedding domain technique. A theoretical framework is developed which allows to prove continuous dependence of the primal and dual variables in the resulting saddle point problems with respect to the domain. This ensures the existence of a solution of a related shape optimization problem in a sufficiently large class of admissible domains. 相似文献
886.
Paul A. Binding Patrick J. Browne Bruce A. Watson 《Journal of Mathematical Analysis and Applications》2004,291(1):246-261
Three inverse problems for a Sturm-Liouville boundary value problem −y″+qy=λy, y(0)cosα=y′(0)sinα and y′(1)=f(λ)y(1) are considered for rational f. It is shown that the Weyl m-function uniquely determines α, f, and q, and is in turn uniquely determined by either two spectra from different values of α or by the Prüfer angle. For this it is necessary to produce direct results, of independent interest, on asymptotics and oscillation. 相似文献
887.
L.A. Carvalho dos Santos J. Hounie 《Journal of Mathematical Analysis and Applications》2004,299(2):465-493
We study Hardy spaces on the boundary of a smooth open subset or Rn and prove that they can be defined either through the intrinsic maximal function or through Poisson integrals, yielding identical spaces. This extends to any smooth open subset of Rn results already known for the unit ball. As an application, a characterization of the weak boundary values of functions that belong to holomorphic Hardy spaces is given, which implies an F. and M. Riesz type theorem. 相似文献
888.
J. Browkin 《Journal of Number Theory》2004,109(2):379-389
The aim of the paper is to determine all free separable quadratic algebras over the rings of integers of quadratic fields in terms of the properties of the fundamental unit in the real case. The paper corrects some earlier published results on the subject. 相似文献
889.
890.
By means of a new force sensor based on optical beam deflection (OBD), the mechanical effects of laser-matter interaction underwater at different incident laser energy are investigated in detail. The experimental results show that a target underwater is impacted in turn by laser-plasma ablation force and high-speed liquid-jet impulse induced by bubbles collapse in the vicinity of a solid boundary. Furthermore, the amplitudes of the two forces increase monotonously with laser energy. According to the ablation force detected by the experiment and the theoretical relationship between laser intensity and ablation pressure, the value of liquid-jet impact against a solid boundary can be easily obtained. In addition, based on the model of a collapsing bubble, some characteristic parameters, such as the liquid-jet impact velocity, the maximum bubble radius, the bubble energy can also be obtained at different laser energy, which are valuable in the corresponding research fields. 相似文献