全文获取类型
收费全文 | 2056篇 |
免费 | 80篇 |
国内免费 | 3篇 |
专业分类
化学 | 1099篇 |
晶体学 | 34篇 |
力学 | 118篇 |
数学 | 504篇 |
物理学 | 384篇 |
出版年
2023年 | 20篇 |
2022年 | 24篇 |
2021年 | 24篇 |
2020年 | 58篇 |
2019年 | 69篇 |
2018年 | 75篇 |
2017年 | 64篇 |
2016年 | 123篇 |
2015年 | 79篇 |
2014年 | 97篇 |
2013年 | 357篇 |
2012年 | 96篇 |
2011年 | 103篇 |
2010年 | 93篇 |
2009年 | 82篇 |
2008年 | 69篇 |
2007年 | 68篇 |
2006年 | 76篇 |
2005年 | 38篇 |
2004年 | 46篇 |
2003年 | 24篇 |
2002年 | 32篇 |
2001年 | 30篇 |
2000年 | 16篇 |
1999年 | 26篇 |
1998年 | 23篇 |
1997年 | 30篇 |
1996年 | 15篇 |
1995年 | 18篇 |
1994年 | 19篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1975年 | 10篇 |
1973年 | 5篇 |
1971年 | 5篇 |
1927年 | 5篇 |
排序方式: 共有2139条查询结果,搜索用时 15 毫秒
161.
We consider several statistical models defined on the Farey fractions. Two of these models may be regarded as spin chains, with long-range interactions, while another arises in the study of multifractals associated with chaotic maps exhibiting intermittency. We prove that these models all have the same free energy. Their thermodynamic behavior is determined by the spectrum of the transfer operator (Ruelle–Perron–Frobenius operator), which is defined using the maps (presentation functions) generating the Farey tree. The spectrum of this operator was completely determined by Prellberg. It follows that these models have a second-order phase transition with a specific heat divergence of the form C [ ln2
]–1. The spin chain models are also rigorously known to have a discontinuity in the magnetization at the phase transition. 相似文献
162.
Two-center nuclear attraction integrals over Slater type orbitals with integer and noninteger principal quantum numbers in nonlined up coordinate systems have been calculated by means of formulas in our previous work (T. Özdoan and M. Orbay, Int. J. Quant. Chem. 87 (2002) 15). The computer results for integer case are in best agreement with the prior literature. On the other hand, the results for noninteger case are not compared with the literature due to the scarcity of the literature, but also compared with the limit of integer case and good agreements are obtained. The proposed algorithm for the calculation of two-center nuclear attraction integrals over Slater type orbitals with noninteger principal quantum numbers in nonlined-up coordinate systems permits to avoid the interpolation procedure used to overcome the difficulty introduced by the presence of noninteger principal quantum numbers. Finally, numerical aspects of the presented formulae are analyzed under wide range of quantum numbers, orbital exponents and internuclear distances. 相似文献
163.
We investigate the groups of equivalence transformations for first-order balance equations involving an arbitrary number of dependent and independent variables. We obtain the determining equations and find their explicit solutions. The approach to this problem is based on a geometric method that depends on Cartan's exterior differential forms. The general solutions of the determining equations for equivalence transformations for first-order systems are applied to a class of the Maxwell equations of electrodynamics. 相似文献
164.
In this paper, new codes of dimension 8 are presented which give improved bounds on the maximum possible minimum distance of ternary linear codes. These codes belong to the class of quasi-twisted (QT) codes, and have been constructed using a stochastic optimization algorithm, tabu search. Twenty three codes are given which improve or establish the bounds for ternary codes. In addition, a table of upper and lower bounds for d
3(n, 8) is presented for n 200. 相似文献
165.
The problem of embedding of linear spaces in finite projective planes has been examined by several authors ([1], [2], [3], [4], [5], [6]). In particular, it has been proved in [1] that a linear space which is the complement of a projective or affine subplane of order m is embeddable in a unique way in a projective plane of order n. In this article, we give a generalization of this result by embedding linear spaces in a finite projective plane of order n, which are complements of certain regularA-affine linear spaces with respect to a finite projective plane. 相似文献
166.
Ozlem Karahan Duygu Avci Vİktorya Avİyente 《Journal of polymer science. Part A, Polymer chemistry》2011,49(14):3058-3068
A series of alkyl α‐hydroxymethacrylate derivatives with various secondary functionalities (ether, ester, carbonate, and carbamate) and terminal groups (alkyl, cyano, oxetane, cyclic carbonate, phenyl and morpholine) were synthesized to investigate the effect of intermolecular interactions, H‐bonding, π–π interactions, and dipole moment on monomer reactivity. All of the monomers except one ester and one ether derivative are novel. The polymerization rates, determined by using photo‐DSC, showed the average trend (aromatic carbamate > hydroxyl > ester > carbonate ~ aliphatic carbamate ~ ether), with several exceptions due to the differences in terminal groups. There is a correlation between the chemical shift differences of the double bond carbons, the calculated dipole moments, and the reactivities only for nonhydrogen bonded monomers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
167.
Samed Atak Merve İçli‐Özkut Ahmet M. Önal Atilla Cihaner 《Journal of polymer science. Part A, Polymer chemistry》2011,49(20):4398-4405
Optical and electrochemical properties of regiosymmetric and soluble alkylenedioxyselenophene‐based electrochromic polymers, namely poly(3,3‐dibutyl‐3,4‐dihydro‐2H‐selenopheno[3,4‐b][1,4]dioxephine) (PProDOS‐C4), poly(3,3‐dihexyl‐3,4‐dihydro‐2H‐selenopheno[3,4‐b][1,4]dioxephine) (PProDOS‐C6), and poly(3,3‐didecyl‐3,4‐dihydro‐2H‐selenopheno[3,4‐b][1,4]dioxephine) (PProDOS‐C10), are highlighted. It is noted that these unique polymers have low bandgaps (1.57–1.65 eV), and they are exceptionally stable under ambient atmospheric conditions. Polymer films retained 82–97% of their electroactivity after 5000 cycles. The percent transmittance of PProDOS‐Cn (n = 4, 6, 10) films found to be between 55 and 59%. Furthermore, these novel soluble PProDOS‐Cn polymers showed electrochromic behavior: a color change form pure blue to highly transparent state in a low switching time (1.0 s) during oxidation with high coloration efficiencies (328–864 cm2 C?1) when compared to their thiophene analogues. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
168.
169.
Powerful recombination centers resulting from reactions of hydrogen with carbon–oxygen defects in n‐type Czochralski‐grown silicon (Phys. Status Solidi RRL 8/2017)
下载免费PDF全文
![点击此处可从《固体物理学:研究快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)