全文获取类型
收费全文 | 27669篇 |
免费 | 632篇 |
国内免费 | 168篇 |
专业分类
化学 | 18482篇 |
晶体学 | 222篇 |
力学 | 729篇 |
综合类 | 1篇 |
数学 | 4581篇 |
物理学 | 4454篇 |
出版年
2021年 | 185篇 |
2020年 | 228篇 |
2019年 | 298篇 |
2018年 | 241篇 |
2017年 | 212篇 |
2016年 | 463篇 |
2015年 | 357篇 |
2014年 | 476篇 |
2013年 | 1391篇 |
2012年 | 1254篇 |
2011年 | 1617篇 |
2010年 | 825篇 |
2009年 | 674篇 |
2008年 | 1444篇 |
2007年 | 1498篇 |
2006年 | 1480篇 |
2005年 | 1492篇 |
2004年 | 1305篇 |
2003年 | 1092篇 |
2002年 | 1065篇 |
2001年 | 397篇 |
2000年 | 329篇 |
1999年 | 264篇 |
1998年 | 305篇 |
1997年 | 335篇 |
1996年 | 413篇 |
1995年 | 313篇 |
1994年 | 301篇 |
1993年 | 303篇 |
1992年 | 297篇 |
1991年 | 260篇 |
1990年 | 250篇 |
1989年 | 261篇 |
1988年 | 293篇 |
1987年 | 273篇 |
1986年 | 268篇 |
1985年 | 417篇 |
1984年 | 458篇 |
1983年 | 344篇 |
1982年 | 441篇 |
1981年 | 421篇 |
1980年 | 360篇 |
1979年 | 355篇 |
1978年 | 370篇 |
1977年 | 349篇 |
1976年 | 293篇 |
1975年 | 293篇 |
1974年 | 272篇 |
1973年 | 268篇 |
1972年 | 153篇 |
排序方式: 共有10000条查询结果,搜索用时 539 毫秒
51.
John Pattinson Laidler Glendinning und Lunge 《Fresenius' Journal of Analytical Chemistry》1884,23(1):581-582
Ohne Zusammenfassung 相似文献
52.
A. G. Green S. Rideal Leonard P. Kinnicutt und John U. Nef 《Fresenius' Journal of Analytical Chemistry》1886,25(1):222-223
Ohne Zusammenfassung 相似文献
53.
The enthalpies of formation of simple nonmetal or metalloid oxyanions in aqueous solution are discussed. Archival values are cited and estimates are made. Trends prove evasive. 相似文献
54.
55.
There are few techniques available to numerically solve sixth-order boundary-value problems with two-point boundary conditions. In this paper we show that the Sinc-Galerkin method is a very effective tool in numerically solving such problems. The method is then tested on examples with homogeneous and nonhomogeneous boundary conditions and a comparison with the modified decomposition method is made. It is shown that the Sinc-Galerkin method yields better results.
56.
Jerry Green 《International Journal of Game Theory》2005,33(2):159-180
This paper presents an axiomatic characterization of a family of solutions to two-player quasi-linear social choice problems. In these problems the players select a single action from a set available to them. They may also transfer money between themselves.The solutions form a one-parameter family, where the parameter is a non-negative number, t.The solutions can be interpreted as follows: Any efficient action can be selected. Based on this action, compute for each player a “best claim for compensation”. A claim for compensation is the difference between the value of an alternative action and the selected efficient action, minus a penalty proportional to the extent to which the alternative action is inefficient. The coefficient of proportionality of this penalty is t. The best claim for compensation for a player is the maximum of this computed claim over all possible alternative actions. The solution, at the parameter value t, is to implement the chosen efficient action and make a monetary transfer equal to the average of these two best claims. The characterization relies on three main axioms. The paper presents and justifies these axioms and compares them to related conditions used in other bargaining contexts. In Nash Bargaining Theory, the axioms analogous to these three are in conflict with each other. In contrast, in the quasi-linear social choice setting of this paper, all three conditions can be satisfied simultaneously.This work was supported by the Division of Research at the Harvard Business School. Thanks are due to the Cowles Foundation for Research in Economics at Yale University for its kind hospitality during the Spring of 2002. I have received helpful advice and comments from Youngsub Chun, Ehud Kalai, Herve Moulin, Al Roth, Ilya Segal, Adam Szeidl, Richard Zeckhauser, and other members of the Theory Seminars at Harvard, MIT, Princeton, Rice and Northwestern. 相似文献
57.
58.
We complete our previous(1, 2) demonstration that there is a family of new solutions to the photon and Dirac equations using spatial and temporal circles and four-vector behaviour of the Dirac bispinor. We analyse one solution for a bound state, which is equivalent to the attractive two-body interaction between a charged point particle and a second, which remains at rest. We show this yields energy and angular momentum eigenvalues that are identical to those found by the usual method of solving of the Dirac equation,(4) including fine structure. We complete our previous derivation(2) of QED from a set of rules for the two-body interaction and generalise these. We show that QED may be decomposed into a two-body interaction at every point in spacetime. 相似文献
59.
Jacques Rouzaud MatthewD. Jones Robert Raja BrianF.G. Johnson John MeurigThomas MelindaJ. Duer 《Helvetica chimica acta》2003,86(5):1753-1759
A set of new, air‐stable, RhI‐based heterogeneous asymmetric hydrogenation catalysts have been synthesised, characterised, and tested. Individual members of this new family all exhibit good enantioselectivity. 相似文献
60.
Arthur G. Maki John C. Grecu Brenda Winnewisser Manfred Winnewisser 《Journal of Molecular Spectroscopy》2003,222(2):198-212
High-resolution spectra of 15N12C12C15N and 14N13C13C14N have been measured and analyzed from 200 to 3600 cm−1. All the vibrational levels below 900 cm−1 have been observed and characterized. The Fermi resonance between ν2 and 2ν4 has been studied and the resonance constant has been determined for several cases. Several Σ− states have been directly observed for the first time for each isotopomer, the (0001111)0f, (0011111)0f, and (0002222)0f states. The pattern of the energy levels for clusters of l-type resonance coupled levels, such as 0001131,3, has been determined for cyanogen for the first time. Among other things this involved the determination of the vibrational l-type resonance constant, r45. Many of the power series constants, αi and xij, and higher order constants have been determined. 相似文献