全文获取类型
收费全文 | 6476篇 |
免费 | 273篇 |
国内免费 | 47篇 |
专业分类
化学 | 4506篇 |
晶体学 | 44篇 |
力学 | 157篇 |
数学 | 1160篇 |
物理学 | 929篇 |
出版年
2023年 | 46篇 |
2022年 | 98篇 |
2021年 | 177篇 |
2020年 | 118篇 |
2019年 | 152篇 |
2018年 | 120篇 |
2017年 | 91篇 |
2016年 | 212篇 |
2015年 | 197篇 |
2014年 | 222篇 |
2013年 | 390篇 |
2012年 | 441篇 |
2011年 | 510篇 |
2010年 | 313篇 |
2009年 | 319篇 |
2008年 | 397篇 |
2007年 | 408篇 |
2006年 | 382篇 |
2005年 | 370篇 |
2004年 | 268篇 |
2003年 | 198篇 |
2002年 | 211篇 |
2001年 | 94篇 |
2000年 | 79篇 |
1999年 | 67篇 |
1998年 | 50篇 |
1997年 | 53篇 |
1996年 | 78篇 |
1995年 | 51篇 |
1994年 | 49篇 |
1993年 | 47篇 |
1992年 | 51篇 |
1991年 | 45篇 |
1990年 | 29篇 |
1989年 | 31篇 |
1988年 | 30篇 |
1987年 | 24篇 |
1986年 | 37篇 |
1985年 | 45篇 |
1984年 | 40篇 |
1983年 | 31篇 |
1982年 | 36篇 |
1981年 | 22篇 |
1980年 | 27篇 |
1979年 | 21篇 |
1978年 | 19篇 |
1977年 | 14篇 |
1976年 | 8篇 |
1975年 | 13篇 |
1974年 | 12篇 |
排序方式: 共有6796条查询结果,搜索用时 265 毫秒
51.
Carmen Izquierdo María Luisa Moyá Jose Luis Usero Julio Casado 《Monatshefte für Chemie / Chemical Monthly》1992,123(5):383-389
Summary A simple working method for the estimation of the aggregation numbers and core radii from weight measurements of sodium bis-2-ethylhexylsulphosuccinate (aerosol-OT orAOT)/decane/water microemulsions of several compositions is proposed.Starting out from the hypotheses that (i) the density of the water inside the droplets is the same as that of free water, (ii) all the surfactant is localized as interface, and (iii) the penetration of the organic phase into the interface is negligible, values for the aggregation number and core radii comparable to those determined using more sophisticated methods were obtained.The results/methodological simplicity ratio may be of great advantage in kinetic work on reaction mechanisms in microemulsions.
Abschätzung von Aggregationszahl und Radius von Mikroemulsionen
Zusammenfassung Es wird eine einfache Methode zur Abschätzung von Aggregationszahl und Core-Radius von Mikroemulsionen aus Gewichtsmessungen von Natriumbis-2-ethylhexylsulphosuccinat (aerosol-OT oderAOT)/Decan/Wasser-Mikroemulsionen verschiedener Zusammensetzung vorgeschlagen. Unter den Annahmen, daß (i) die Dichte von Wasser innerhalb der Aggregationen die gleiche als bei freiem Wasser ist, (ii) das ganze Emulsionsmittel in der Grenzfläche vorliegt und (iii) das Eindringen der organischen Phase in die Grenzfläche vernachlässigbar ist, können Werte für Aggregationszahlen und Core-Radien erhalten werden, die durchaus mit entsprechenden Werten aus aufwendigeren Methoden vergleichbar sind. Das Leistungsverhältnis (Ergebnisse/geringer Aufwand) ist sehr vorteilhaft und macht die Methode für kinetische Arbeiten zur Bestimmung von Reaktionsmechanismen in Mikroemulsionen interessant.相似文献
52.
53.
Rodrigo París Jos Luis de la Fuente 《Journal of polymer science. Part A, Polymer chemistry》2006,44(18):5304-5315
Functional spontaneous gradient copolymers of allyl methacrylate (A) and butyl acrylate (B) were synthesized via atom transfer radical polymerization. The copolymerization reactions were carried out in toluene solutions at 100 °C with methyl 2‐bromopropionate as the initiator and copper bromide with N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalyst system. Different aspects of the statistical reaction copolymerizations, such as the kinetic behavior, crosslinking density, and gel fraction, were studied. The gel data were compared with Flory's gelation theory, and the sol fractions of the synthesized copolymers were characterized by size exclusion chromatography and nuclear magnetic resonance spectroscopy. The copolymer composition, demonstrating the gradient character of the copolymers, and the microstructure were analyzed. The experimental data agreed well with data calculated with the Mayo–Lewis terminal model and Bernoullian statistics, with monomer reactivity ratios of 2.58 ± 0.37 and 0.51 ± 0.05 for A and B, respectively, an isotacticity parameter for A of 0.24, and a coisotacticity parameter of 0.33. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5304–5315, 2006 相似文献
54.
55.
56.
Rastislav Varga Arcady Zhukov Michail Ipatov Juan Maria Blanco Julian Gonzalez Valentina Zhukova Pavol Vojtanik 《Journal of magnetism and magnetic materials》2006
The effect of the glass coating on the single domain wall potential in amorphous glass-coated Fe-based microwire has been studied by the switching field distribution technique. The thermoactivated mechanism model is used to describe the thermally activated switching through the complex energy barrier in amorphous FeSiB microwires. Glass removal leads to the increase of the probability of the thermally activated switching pointing to the decrease of the energy barrier. 相似文献
57.
58.
In this article, local optimality in multiobjective combinatorial optimization is used as a baseline for the design and analysis
of two iterative improvement algorithms. Both algorithms search in a neighborhood that is defined on a collection of sets
of feasible solutions and their acceptance criterion is based on outperformance relations. Proofs of the soundness and completeness
of these algorithms are given. 相似文献
59.
Mikhael Balabane Thierry Cazenave Luis Vázquez 《Communications in Mathematical Physics》1990,133(1):53-74
We prove the existence of stationary states for nonlinear Dirac equations of the form (E) $$i\sum\limits_{\mu = 0}^3 {\gamma ^\mu \partial _\mu \psi - M\psi + F\left( {\bar \psi \psi } \right)\psi = 0,} $$ whereM>0 andF is a singular self-interaction. In particular, in the model case whereF(s)=?s ?α, for some 0<α<1, and for every ω>M, there exists a solution of (E) of the form ψ(t, x)=e iωt?(x), wherex 0=t andx=(x 1,x 2,x 3), such that ? has compact support. IF 0<α<1/3, then ? is of classC 1. If 1/3<α<1, then ? is continuously differentiable, except on some sphere {|x|=R}, where |??| is infinite. 相似文献
60.