全文获取类型
收费全文 | 1363篇 |
免费 | 158篇 |
国内免费 | 44篇 |
专业分类
化学 | 186篇 |
晶体学 | 1篇 |
力学 | 68篇 |
综合类 | 36篇 |
数学 | 777篇 |
物理学 | 497篇 |
出版年
2023年 | 13篇 |
2022年 | 24篇 |
2021年 | 25篇 |
2020年 | 25篇 |
2019年 | 34篇 |
2018年 | 28篇 |
2017年 | 46篇 |
2016年 | 44篇 |
2015年 | 36篇 |
2014年 | 72篇 |
2013年 | 101篇 |
2012年 | 68篇 |
2011年 | 114篇 |
2010年 | 108篇 |
2009年 | 100篇 |
2008年 | 97篇 |
2007年 | 96篇 |
2006年 | 61篇 |
2005年 | 67篇 |
2004年 | 43篇 |
2003年 | 40篇 |
2002年 | 36篇 |
2001年 | 33篇 |
2000年 | 37篇 |
1999年 | 22篇 |
1998年 | 28篇 |
1997年 | 22篇 |
1996年 | 21篇 |
1995年 | 21篇 |
1994年 | 16篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有1565条查询结果,搜索用时 125 毫秒
81.
In this paper we study iterative roots of PM functions, a special class of non-monotone functions. Problem 2 in [W. Zhang, PM functions, their characteristic intervals and iterative roots, Ann. Polon. Math. LXV (1997) 119-128] is solved partly and Theorem 4 in that paper is generalized. 相似文献
82.
Livinus U. Uko 《Journal of Mathematical Analysis and Applications》2008,342(2):909-914
The Kantorovich theorem is a fundamental tool in nonlinear analysis for proving the existence and uniqueness of solutions of nonlinear equations arising in various fields. This theorem was weakened recently by Argyros who used a combination of Lipschitz and center-Lipschitz conditions in place of the Lipschitz conditions of the Kantorovich theorem. In the present paper we prove a weak Kantorovich-type theorem that gives the same conclusions as the previous two results under weaker conditions. Illustrative examples are provided in the paper. 相似文献
83.
Ákos Császár 《Acta Mathematica Hungarica》2005,108(4):351-354
Summary In the paper [5], several operations on generalized topologies are considered. They are not monotone in general, but an old result on monotonicity may be sharpened. 相似文献
84.
声誉是企业的一项重要无形资产,能够增进企业对消费者的吸引力。本文从消费者视野探索企业声誉在电子商务消费者信任建立过程的作用机制。将感知的安全性引入技术接受模型,建立了理论模型及假设,并应用结构方程模型分析软件进行了检验。结果表明,企业声誉通过消费者感知的安全性、有用性和易用性正向影响消费者信任,消费者感知的安全性、易用性也通过感知的有用性影响消费者信任。 相似文献
85.
Wang Haijun 《Numerical Algorithms》2008,48(4):317-325
In this paper, we present new iteration methods with cubic convergence for solving nonlinear equations. The main advantage
of the new methods are free from second derivatives and it permit that the first derivative is zero in some points. Analysis
of efficiency shows that the new methods can compete with Newton’s method and the classical third-order methods. Numerical
results indicate that the new methods are effective and have definite practical utility.
相似文献
86.
Consider an operator equation B(u) − f = 0 in a real Hilbert space. Let us call this equation ill-posed if the operator B′(u) is not boundedly invertible, and well-posed otherwise. The dynamical systems method (DSM) for solving this equation consists of a construction of a Cauchy problem, which has the following properties: (1) it has a global solution for an arbitrary initial data, (2) this solution tends to a limit as time tends to infinity, (3) the limit is the minimal-norm solution to the equation B(u) = f. A global convergence theorem is proved for DSM for equation B(u) − f = 0 with monotone operators B. 相似文献
87.
La Agusu T. Idehara M. Kamada T. Hayashi V. N. Manuilov O. Dumbrajs K. Yatsui W. Jiang 《International Journal of Infrared and Millimeter Waves》2005,26(5):637-655
Designs of cavities for fundamental and high harmonic operation in Large Orbit Gyrotron (LOG) are discussed. The fundamental operation allows one to use beam currents in the range from 200 A to 300 A achieve output power of the order of 9–10 MW at frequency 143.6 GHz. Mode competition calculations show that stable oscillations in the TE1,4 mode using high beam currents are possible even with the pitch factor 1.3 which is significantly lower than the design value 1.55. For the second harmonic operation, the maximum current used for excitation of the TE2,4 mode is 60 A and the optimum magnetic field is 7.6 T. A cavity design for fourth harmonic operation using the TE4,4 mode is also presented. 相似文献
88.
The axioms of iteration 2-theories capture, up to isomorphism, the equational properties of iteration in conjunction with horizontal and vertical composition in all algebraically complete categories. We give a concrete representation of the free iteration 2-theory generated by a 2-signature. 相似文献
89.
90.
Summary The method of iterative target transformation factor analysis (ITTFA) used in conjunction with second derivative peak finding
has shown to be a practical method for the peak deconvolution and reconstruction of HPLC chromatograms and spectra. The second
derivative method of peak finding is acceptable for resolutions above 0.5 for peaks of similar heights. Above 0.5 resolution
the labelling gives correct results where the spectra are substantially different and also when reasonably similar. Below
this value the peak labelling was still accurate where the spectra were different. Solvent effects on the spectra of the compounds
studied are small and do not hinder the peak labelling process. Thus small “local” libraries are feasible.
Presented at the 17th International Symposium on Chromatography, September 25–30, 1988. Vienna, Austria. 相似文献