全文获取类型
收费全文 | 38115篇 |
免费 | 1297篇 |
国内免费 | 7篇 |
专业分类
化学 | 21635篇 |
晶体学 | 168篇 |
力学 | 774篇 |
数学 | 6237篇 |
物理学 | 10605篇 |
出版年
2023年 | 204篇 |
2021年 | 296篇 |
2020年 | 495篇 |
2019年 | 318篇 |
2018年 | 436篇 |
2017年 | 417篇 |
2016年 | 981篇 |
2015年 | 831篇 |
2014年 | 938篇 |
2013年 | 2047篇 |
2012年 | 1615篇 |
2011年 | 1950篇 |
2010年 | 993篇 |
2009年 | 814篇 |
2008年 | 1858篇 |
2007年 | 1838篇 |
2006年 | 1619篇 |
2005年 | 1445篇 |
2004年 | 1143篇 |
2003年 | 975篇 |
2002年 | 938篇 |
2001年 | 760篇 |
2000年 | 680篇 |
1999年 | 467篇 |
1998年 | 420篇 |
1997年 | 412篇 |
1996年 | 519篇 |
1995年 | 462篇 |
1994年 | 486篇 |
1993年 | 558篇 |
1992年 | 464篇 |
1991年 | 350篇 |
1990年 | 405篇 |
1989年 | 320篇 |
1988年 | 332篇 |
1987年 | 339篇 |
1986年 | 301篇 |
1985年 | 487篇 |
1984年 | 474篇 |
1983年 | 426篇 |
1982年 | 450篇 |
1981年 | 446篇 |
1980年 | 414篇 |
1979年 | 368篇 |
1978年 | 416篇 |
1977年 | 399篇 |
1976年 | 350篇 |
1975年 | 329篇 |
1974年 | 311篇 |
1973年 | 328篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Marco Möller 《Results in Mathematics》2004,46(3-4):271-360
53.
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
54.
Thomas Pautzsch Elisabeth Klemm 《Journal of polymer science. Part A, Polymer chemistry》2004,42(12):2911-2919
Poly{bis(4,4′‐tert‐butyl‐2,2′‐bipyridine)–(2,2′‐bipyridine‐5,5′‐diyl‐[1,4‐phenylene])–ruthenium(II)bishexafluorophosphate} ( 3a ), poly{bis(4,4′‐tert‐butyl‐2,2′‐bipyridine)–(2,2′‐bipyridine‐4,4′‐diyl‐[1,4‐phenylene])–ruthenium(II)bishexafluorophosphate} ( 3b ), and poly{bis(2,2′‐bipyridine)–(2,2′‐bipyridine‐5,5′‐diyl‐[1,4‐phenylene])–ruthenium(II)bishexafluorophosphate} ( 3c ) were synthesized by the Suzuki coupling reaction. The alternating structure of the copolymers was confirmed by 1H and 13C NMR and elemental analysis. The polymers showed, by ultraviolet–visible, the π–π* absorption of the polymer backbone (320–380 nm) and at a lower energy attributed to the d–π* metal‐to‐ligand charge‐transfer absorption (450 nm for linear 3a and 480 nm for angular 3b ). The polymers were characterized by a monomodal molecular weight distribution. The degree of polymerization was approximately 8 for polymer 3b and 28 for polymer 3d . © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2911–2919, 2004 相似文献
55.
Thomas Pautzsch Lars Blankenburg Elisabeth Klemm 《Journal of polymer science. Part A, Polymer chemistry》2004,42(3):722-732
A series of novel π-conjugated polymers containing ruthenium bipyridine complexes was synthesized by a cross-coupling reaction and characterized. These polymers exhibit absorption maxima around 330–350 nm (π-π*) and 460–500 nm metal-to-ligand charge transfer (MLCT), respectively. They are soluble in common organic solvents, and all polymers can be converted into transparent films. We investigated the influence of different donating and acceptor diethynylarenes of the ultraviolet-visible spectra. The oxidation potential, which was measured by cyclic- and square-wave voltametry, showed a typical Ru2+/3+ exhibited at 1.25 V versus the saturated calomel electrode. The polymers were further characterized with photoluminescence measurements. When excited at 442 nm ( 11a ), the polymer exhibited an emission peak at 690 nm. This peak was attributed to the MLCT states. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 722–732, 2004 相似文献
56.
Periodica Mathematica Hungarica - As it is well-known a Minkowski space is a finite dimensional real vector space equipped with a Minkowski functional F. If the square of the Minkowski functional... 相似文献
57.
I. P. Kuranova K. M. Polyakov E. A. Smirnova W. E. Höhne V. S. Lamzin R. Meijer 《Crystallography Reports》2003,48(6):953-958
Crystals of Saccharomyces cerevisiae inorganic pyrophosphatase suitable for X-ray diffraction study were grown by cocrystallization of the enzyme with cobalt chloride and imidodiphosphate. Saccharomyces cerevisiae is a metal-dependent enzyme which catalyzes hydrolysis of inorganic pyrophosphate to orthophosphate. The three-dimensional structure of this enzyme was solved by the molecular-replacement method and refined at 1.8 Å resolution to an R factor of 19.5%. Cobalt and phosphate ions were revealed in the active centers of both identical subunits (A and B) of the pyrophosphatase molecule. In subunit B, a water molecule was found between two cobalt ions. It is believed that this water molecule acts as an attacking nucleophile in the enzymatic cleavage of the pyrophosphate bond. It was demonstrated that cobalt ions and a phosphate group occupy only part of the potential binding sites (two chemically identical and crystallographically independent subunits have different binding sites). The arrangement of ligands and the structure of the nucleophile-binding site are discussed in relation to the mechanism of action of the enzyme and the nature of the metal activator. 相似文献
58.
59.
60.