全文获取类型
收费全文 | 789篇 |
免费 | 9篇 |
专业分类
化学 | 644篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 71篇 |
物理学 | 78篇 |
出版年
2020年 | 5篇 |
2016年 | 8篇 |
2014年 | 11篇 |
2013年 | 19篇 |
2012年 | 21篇 |
2011年 | 23篇 |
2010年 | 9篇 |
2008年 | 15篇 |
2007年 | 23篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 21篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 18篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 17篇 |
1994年 | 8篇 |
1993年 | 15篇 |
1992年 | 7篇 |
1991年 | 19篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 31篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 30篇 |
1984年 | 30篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 19篇 |
1980年 | 10篇 |
1979年 | 20篇 |
1978年 | 17篇 |
1977年 | 28篇 |
1976年 | 21篇 |
1975年 | 17篇 |
1974年 | 18篇 |
1973年 | 17篇 |
1972年 | 19篇 |
1971年 | 9篇 |
1968年 | 7篇 |
1966年 | 8篇 |
1961年 | 7篇 |
1956年 | 4篇 |
1930年 | 6篇 |
排序方式: 共有798条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Gottfried Holzwarth 《Zeitschrift für Physik A Hadrons and Nuclei》1966,191(4):354-359
The polarization-asymmetries in the cross-sections for electron-electron and positron-electron scattering are investigated numerically in first order perturbation theory in the range from 1 keV to 10 GeV for all angles with regard to polarization-measurements. 相似文献
55.
56.
We construct stable bundle extensions on elliptically fibered Calabi–Yau threefolds. We show that these bundles can solve the topological anomaly constraint in heterotic string theory without the need for invoking background five-branes. 相似文献
57.
Ana Vidiš Gábor Laurenczy Ernst Küsters Gottfried Sedelmeier Paul J. Dyson 《Journal of Physical Organic Chemistry》2007,20(2):109-114
The effect of pressure on the Diels–Alder reaction was examined in room temperature ionic liquids, followed by high‐pressure FT‐IR spectroscopy using pressures up to 150 MPa. Pressure enhances the kinetic sensitivity of the reaction. The kinetic effect of fluorophobic interactions was examined using ionic liquids with fluorous cations. Ionic liquids in combination with ZnI2 as a Lewis acid catalyst were also studied under high pressure. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
58.
Norbert Haider Gottfried Heinisch Richard Wanko 《Journal of heterocyclic chemistry》1991,28(5):1441-1444
The utility of the aminonitrile 1 as an educt for the preparation of several new examples of heterocyclefused pyridazines (the [1,2,4]triazolo[1′,5′:1,6]pyrimido[4,5-c]pyridazine 7 , the pyrimido[4,5-c]pyridazines 8, 10a,b , and the pyrido[2,3-c]pyridazine 11 ) is demonstrated. 相似文献
59.
Gottfried Mrkl Andreas Pll Norbert G. Aschenbrenner Corinna Schmaus Theodor Troll Peter Kreitmeier Heinrich Nth Martin Schmidt 《Helvetica chimica acta》1996,79(5):1497-1517
Extremely Expanded Tetrathiafulvalenes with Polyene Spacers. Carotinoid Tetrathiafulvalenes. Polymethin-Tetracyanotetrathiafulvalene Radical Cations, a New Class of Violenes The synthesis of extended tetrathiafulvalenes 11 with di-, tetra-, hexa-, octa-, deca- and dodecamethine spacers is described by a PPh3-induced Wittig-reaction-like condensation of the corresponding polyenedials 10 with 2-thio-1,3-dithiole-4,5-dicarbonitrile ( 9 ). By the same procedure, the dimethyloctamethine- and the tetramethyl-hexadecamethine-tetrathiafulvalenes 14 and 15 , respectively, were obtained. The extended tetrathiafulvalenes represent multistep vinylogous redox systems of the ‘violene type’. They can be oxidized to give the cyanine-like radical cations, e.g. 11 sem, 14 sem, and 15 sem, and the dications, e.g. 11 ox, 14 ox, and 15 ox; their UV/VIS/NIR spectra are reported. The crystal and molecular structure of (all-E)-2,2′-(octa-2,4,6-trien-1,8-diylidene)bis[1,3-dithiole-4,5-dicarbonitrile] ( 11e ) was determined: it is a rod-like, planar molecule; in the crystal, it forms staples along the longest molecule axis. The CV measurements confirm that the redox potentials of 11, 14 , and 15 decrease asymptotically with the increasing length of the spacer. Because of the close relationship of the extended tetrathiafulvalenes (ETTF's) to the carotinoids, they are named ‘caroviologenes’; they formally belong to the class of molecular wires. 相似文献
60.
Su XC Man B Beeren S Liang H Simonsen S Schmitz C Huber T Messerle BA Otting G 《Journal of the American Chemical Society》2008,130(32):10486-10487
A new lanthanide tag was designed for site-specific labeling of proteins with paramagnetic lanthanide ions. The tag, 4-mercaptomethyl-dipicolinic acid, binds lanthanide ions with nanomolar affinity, is readily attached to proteins via a disulfide bond, and avoids the problems of diastereomer formation associated with most of the conventional lanthanide tags. The high lanthanide affinity of the tag opens the possibility to measure residual dipolar couplings in a single sample containing a mixture of paramagnetic and diamagnetic lanthanides. Using the DNA-binding domain of the E. coli arginine repressor as an example, it is demonstrated that the tag allows immobilization of the lanthanide ion in close proximity of the protein by additional coordination of the lanthanide by a carboxyl group of the protein. The close proximity of the lanthanide ion promotes accurate determinations of magnetic susceptibility anisotropy tensors. In addition, the small size of the tag makes it highly suitable for studies of intermolecular interactions. 相似文献