全文获取类型
收费全文 | 170篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 64篇 |
晶体学 | 7篇 |
力学 | 5篇 |
数学 | 52篇 |
物理学 | 49篇 |
出版年
2020年 | 6篇 |
2019年 | 3篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 8篇 |
2008年 | 14篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1948年 | 1篇 |
1943年 | 1篇 |
1938年 | 1篇 |
1935年 | 1篇 |
1934年 | 1篇 |
1933年 | 1篇 |
1930年 | 2篇 |
1929年 | 2篇 |
1926年 | 2篇 |
1886年 | 2篇 |
排序方式: 共有177条查询结果,搜索用时 0 毫秒
171.
Monoids and acts which may have zero elements are considered. In Section 1 we construct a O-wreath product of monoids. In
2 we prove the theorem that the endomorphism monoid of a free act over a monoid with zero can be represented as a O-wreath
product. Considering monoids with tero we are interested in their annihilator properties. In 3 we give necessary and sufficient
conditions for a O-wreath product of monoids to be a right (left) Baer (Rickart) monoid. In 4 we obtain as a consequence corresponding
conditions for the endomorphism monoid of a free act over a monoid with zero. 相似文献
172.
A. Knauer I. Rechenberg F. Bugge S. Gramlich G. Oelgardt A. Oster M. Weyers 《Journal of Crystal Growth》1997,170(1-4):281-286
The luminescence properties of In1−xGaxAsyP1−y layers and heterostructures grown lattice matched to GaAs by metalorganic vapour-phase epitaxy (MOVPE) were studied and correlated to the crystalline properties. For laser structures emitting around 800 nm a red-shift of the emission from the active layer (y = 0.72) grown at 680°C together with an anomalous temperature behaviour and excitation dependence of the bandgap is observed. Although some degree of ordering is observed for thick layers of this composition, polarization dependent photoluminescence does not indicate ordering of the quantum well to be the main reason for this excitation dependence. Instead, interfacial In-rich layers are found to be responsible. The thickness of these interfacial layers strongly depends on substrate misorientation and growth conditions. 相似文献
173.
Li CK Séguin FH Frenje JA Rygg JR Petrasso RD Town RP Landen OL Knauer JP Smalyuk VA 《Physical review letters》2007,99(5):055001
The spatial structure and temporal evolution of megagauss magnetic fields generated by interactions of up to 4 laser beams with matter were studied with an innovative, time-gated proton radiography method that produces images of unprecedented clarity because it uses an isotropic, truly monoenergetic back-lighter (14.7-MeV protons from D3He nuclear fusion reactions). Quantitative field maps reveal precisely and directly, for the first time, changes in the magnetic topology due to reconnection in a high-energy-density plasma (n(e) approximately 10(20)-10(22) cm(-3), T(e) approximately 1 keV). 相似文献
174.
This review gives the first comprehensive overview of the rapidly emerging young class of 4-phenylanthraquinones isolated from the three genera Bulbine, Bulbinella, and Kniphofia, all from the plant family Aphodelaceae: their occurrence, structural elucidation (with particular emphasis on the phenomenon of axial chirality), partial and total synthesis, their pharmacological (i.a., antimalarial and antitumoral) activities, and their biosynthetic origin (from acetate units). Particular emphasis is given to the stereostructure of knipholone, the most abundant of these naturally occurring phenylanthraquinones. The most recent highlight is the discovery of the first dimeric representatives, named joziknipholones, involving interesting phenomena of--partially or fully restricted--rotation at the sp2-sp2 and sp2-sp3 axes. 相似文献
175.
Li CK Séguin FH Frenje JA Rygg JR Petrasso RD Town RP Amendt PA Hatchett SP Landen OL Mackinnon AJ Patel PK Smalyuk VA Sangster TC Knauer JP 《Physical review letters》2006,97(13):135003
Electromagnetic (E/B) fields generated by the interaction with plasmas of long-pulse, low-intensity laser beams relevant to inertial confinement fusion have been measured for the first time using novel monoenergetic proton radiography methods. High-resolution, time-gated radiography images of a plastic foil driven by a 10(14) W/cm(2) laser implied B fields of approximately 0.5 MG and E fields of approximately 1.5 x 10(8) V/m. Simulations of these experiments with LASNEX+LSP have been performed and are in overall (though not exact) agreement with the data both for field strengths and for spatial distributions; this is the first direct experimental test of the laser-generated B-field package in LASNEX. The experiments also demonstrated that laser phase plates substantially reduce medium-scale chaotic field structure. 相似文献
176.
A. Knauer Dipl.-Phys. Dr. J. Kräusslich Dr. R. Kittner R. Staske Dipl.-Phys. Dr. A. Bärwolff 《Crystal Research and Technology》1990,25(4):441-449
The variation of the lattice constant was determined across (001) InP wafers from 〈111〉 grown LEC INP: S and InP: Sn + Ga + As monocrystals. The variation correlates to the free carrier distribution. The enrichment of dopants results in lattice spacing in the crystal core (especially for InP: Sn + Ga + As), which occupy a larger region as dopant enrichment do. 相似文献
177.
Investigation of the distribution of dislocations intersecting the free surface of (1, 0, 0), Si-doped Bridgman-grown GaAs wafers. The defect densities were determined by using molten KOH as the defect-revealing etch. Their distribution can well be described by the compound Poisson-gamma distribution. The corresponding formula for the chip-yield is derived and it is shown, under which conditions it goes over into that for the simple Poisson distribution. Further, it is shown how the finite dimension of failures can be taken into account. 相似文献