全文获取类型
收费全文 | 42199篇 |
免费 | 1445篇 |
国内免费 | 135篇 |
专业分类
化学 | 22031篇 |
晶体学 | 240篇 |
力学 | 1183篇 |
综合类 | 5篇 |
数学 | 7464篇 |
物理学 | 12856篇 |
出版年
2023年 | 270篇 |
2021年 | 344篇 |
2020年 | 541篇 |
2019年 | 451篇 |
2018年 | 610篇 |
2017年 | 596篇 |
2016年 | 1167篇 |
2015年 | 900篇 |
2014年 | 1046篇 |
2013年 | 2340篇 |
2012年 | 1911篇 |
2011年 | 2072篇 |
2010年 | 1453篇 |
2009年 | 1201篇 |
2008年 | 1958篇 |
2007年 | 1823篇 |
2006年 | 1716篇 |
2005年 | 1509篇 |
2004年 | 1336篇 |
2003年 | 1063篇 |
2002年 | 959篇 |
2001年 | 890篇 |
2000年 | 727篇 |
1999年 | 525篇 |
1998年 | 453篇 |
1997年 | 447篇 |
1996年 | 541篇 |
1995年 | 490篇 |
1994年 | 509篇 |
1993年 | 514篇 |
1992年 | 572篇 |
1991年 | 387篇 |
1990年 | 403篇 |
1989年 | 371篇 |
1988年 | 340篇 |
1987年 | 365篇 |
1986年 | 330篇 |
1985年 | 533篇 |
1984年 | 497篇 |
1983年 | 424篇 |
1982年 | 444篇 |
1981年 | 448篇 |
1980年 | 432篇 |
1979年 | 421篇 |
1978年 | 406篇 |
1977年 | 410篇 |
1976年 | 378篇 |
1975年 | 371篇 |
1974年 | 362篇 |
1973年 | 307篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Günter F. Steinke 《Results in Mathematics》2007,51(1-2):111-126
Polster and Steinke [Result. Math., 46 (2004), 103–122] determined the possible Kleinewillingh?fer types of flat Laguerre planes. These types reflect transitivity
properties of groups of certain central automorphisms. We exclude three more types from the list given there with respect
to Laguerre homotheties. This yields a complete determination of all possible single types with respect to Laguerre homotheties
that can occur in flat Laguerre planes. Building on results by M?urer and Hartmann to characterize ovoidal or miquelian Laguerre
planes we further characterize certain flat Laguerre planes in terms of their Kleinewillingh?fer types.
Received: January 16, 2007. Revised: July 26, 2007. 相似文献
52.
The vibrational dynamics of protein folding is analyzed in the framework of Tsallis statistics. We employ exact expressions
for classical harmonic oscillators by considering the unnormalized constraints. As q→1, we show that these approximations agree with the result of Gaussian network model. 相似文献
53.
54.
Keller Teichmann Hans Pfeiffer W. Langenbeck A. Reid Heinrich Menzel Th. Höpner W. Mühlsteph M. Ulmann Geib R. E. Liesegang 《Colloid and polymer science》1939,87(1):100-104
Ohne Zusammenfassung 相似文献
55.
56.
57.
58.
A Raney-Ag catalyst was prepared by leaching out aluminium from a Raney Ag-Al alloy with NaOH solution. The kinetics of leaching
has been investigated in a stirred-batch-reactor at various temperatures by using alloy particles of different sizes. The
kinetic model best fitting the experimental results has been determined.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
59.
Kerstin Paech Adrian Dumitru Jürgen Schaffner-Bielich Stefan Schramm Horst Stöcker Gebhard Zeeb Detlef Zschiesche 《Acta Physica Hungarica A》2004,21(2-4):151-156
The measured particle ratios in central heavy-ion collisions are investigated within a chemical and thermal equilibrium chiral SU(3) σ?ω approach. Contrary to the commonly adopted non-interacting gas calculations, the chiral SU(3) model predicts modified effective hadron masses and effective chemical potentials in the medium and a transition to a chirally restored phase at high temperatures or chemical potentials. the influence of three different types of phase transitions is investigated. We show that the deduced freeze-out values considerably depend on the underlying model while the quality of the fit is approximately the same. 相似文献
60.
Starch belongs to the polyglucan group. This type of polysaccharide shows a broad β-relaxation process in dielectric spectra at low temperatures, which has its molecular origin in orientational motions of sugar rings via glucosidic linkages. This chain dynamic was investigated for α(1,4)-linked starch oligomers with well-defined chain lengths of 2, 3, 4, 6, and 7 anhydroglucose units (AGUs) and for α(1,4)-polyglucans with average degrees of polymerization of 5, 10, 56, 70, and so forth (up to 3000; calculated from the mean molecular weight). The activation energy (Ea) of the segmental chain motion was lowest for dimeric maltose (Ea = 49.4 ± 1.3 kJ/mol), and this was followed by passage through a maximum at a degree of polymerization of 6 (Ea = 60.8 ± 1.8 kJ/mol). Subsequently, Ea leveled off at a value of about 52 ± 1.5 kJ/mol for chains containing more than 100 repeating units. The results were compared with the values of cellulose-like oligomers and polymers bearing a β(1,4)-linkage. Interestingly, the shape of the Ea dependency on the chain length of the molecules was qualitatively the same for both systems, whereas quantitatively the starch-like substances generally showed higher Ea values. Additionally, and for comparison, three cyclodextrins were measured by dielectric relaxation spectroscopy. The ringlike molecules, with 6, 7, and 8 α(1,4)-linked AGUs, showed moderately different types of dielectric spectra. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 188–197, 2004 相似文献