全文获取类型
收费全文 | 1354篇 |
免费 | 50篇 |
国内免费 | 5篇 |
专业分类
化学 | 854篇 |
晶体学 | 6篇 |
力学 | 22篇 |
数学 | 273篇 |
物理学 | 254篇 |
出版年
2021年 | 13篇 |
2020年 | 22篇 |
2019年 | 19篇 |
2018年 | 12篇 |
2016年 | 28篇 |
2015年 | 25篇 |
2014年 | 38篇 |
2013年 | 61篇 |
2012年 | 64篇 |
2011年 | 57篇 |
2010年 | 56篇 |
2009年 | 39篇 |
2008年 | 69篇 |
2007年 | 50篇 |
2006年 | 57篇 |
2005年 | 40篇 |
2004年 | 31篇 |
2003年 | 29篇 |
2002年 | 33篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 18篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 22篇 |
1992年 | 32篇 |
1991年 | 16篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 24篇 |
1984年 | 23篇 |
1983年 | 15篇 |
1982年 | 20篇 |
1981年 | 20篇 |
1980年 | 21篇 |
1979年 | 16篇 |
1978年 | 26篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1975年 | 16篇 |
1974年 | 22篇 |
1971年 | 9篇 |
1970年 | 17篇 |
1969年 | 12篇 |
排序方式: 共有1409条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
E. Schlenker A. Bakin H. Schmid W. Mader H. Bremers A. Hangleiter H.-H. Wehmann M. Al-Suleiman J. Lüdke M. Albrecht A. Waag 《Applied Physics A: Materials Science & Processing》2008,91(3):375-378
The structural and magnetic properties of Mn-doped ZnO nanopowder are investigated and compared to undoped ZnO crystals. Mn
incorporation leads to an increase in the lattice constants as revealed by X-ray diffraction measurements. An inhomogeneous
distribution of the Mn atoms within the nanopowder was detected by energy-dispersive X-ray and electron-energy-loss spectroscopy
measurements. Magnetic features are investigated by means of SQUID magnetometry on ensembles of powder particles as well as
by magnetic force microscopy to study the behavior of single grains.
PACS 75.50.Pp; 75.75.+a; 78.55.Et 相似文献
135.
R. Albrecht T. C. Awes P. Beckmann F. Berger M. A. Bloomer D. Bock R. Bock G. Claesson G. Clewing L. Dragon A. Eklund R. L. Ferguson A. Franz S. Garpman R. Glasow H. Å. Gustafsson H. H. Gutbrod M. Hartig G. Hölker J. Idh P. Jacobs K. H. Kampert B. W. Kolb P. Kristiansson H. Löhner I. Lund F. E. Obenshain A. Oskarsson I. Otterlund T. Peitzmann S. Persson F. Plasil A. M. Poskanzer M. Purschke H. G. Ritter B. Roters S. Saini R. Santo H. R. Schmidt R. Schmidt S. P. Sørensen K. Steffens P. Steinhauser E. Stenlund D. Stüken M. L. Tincknell A. Twyhues G. R. Young 《Zeitschrift fur Physik C Particles and Fields》1992,53(2):225-237
Correlations between positive pions are investigated in the target fragmentation region of 200A GeV16O+nucleus collisions. The pions are measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The target mass dependence of the radii and the correlation strength extracted by interferometry is studied. A new approach to the fit of the correlation function is introduced. The correlation strength and both invariant and transverse radii increase with decreasing target mass. The transverse radius for16O+C reactions appears to be much larger than the geometrical radius of the nuclei involved. For the Au target only a small fraction of the measured pions contributes to the apparent correlation. Hints for a much larger second component in16O+Au reactions are observed. Rescattering phenomena may provide a clue to understand these phenomena. 相似文献
136.
137.
138.
Albrecht J Matveev AT Strempfer J Habermeier HU Shantsev DV Galperin YM Johansen TH 《Physical review letters》2007,98(11):117001
Anisotropic penetration of magnetic flux in MgB(2) films grown on vicinal sapphire substrates is investigated using magneto-optical imaging. Regular penetration above 10 K proceeds more easily along the substrate surface steps, the anisotropy of the critical current being 6%. At lower temperatures the penetration occurs via abrupt dendritic avalanches that preferentially propagate perpendicular to the surface steps. This inverse anisotropy in the penetration pattern becomes dramatic very close to 10 K where all flux avalanches propagate in the strongest pinning direction. The observed behavior is fully explained using a thermomagnetic model of the dendritic instability. 相似文献
139.
Carbazole Dendrimers as Solution‐Processable Thermally Activated Delayed‐Fluorescence Materials 下载免费PDF全文
Assist. Prof. Ken Albrecht Assist. Prof. Kenichi Matsuoka Assoc. Prof. Katsuhiko Fujita Prof. Kimihisa Yamamoto 《Angewandte Chemie (International ed. in English)》2015,54(19):5677-5682
Recently, thermally activated delayed fluorescence (TADF) materials have received increasing attention as effective emitters for organic light‐emitting diodes (OLEDs). However, most of them are usually employed as dopants in a host material. In this report, carbazole dendrimers with a triphenyl‐s‐triazine core are reported, which are the first solution‐processable, non‐doped, high‐molecular‐weight TADF materials. The dendrimers were obtained by a new and facile synthetic route using the tert‐butyldimethylsilyl moiety as a protecting group. All dendrimers showed TADF in toluene. Measurements of the temperature‐dependent luminescence lifetime revealed that spin‐coated neat films also showed TADF with moderate quantum yields. OLED devices incorporating these dendrimers as spin‐coated emitting layers gave external quantum efficiencies of up to a 3.4 %, which suggests that this device is harvesting triplet excitons. This result indicates that carbazole dendrimers with attached acceptors are potential TADF materials owing to their polarized electronic structure (with HOMO–LUMO separation). 相似文献
140.