全文获取类型
收费全文 | 1532篇 |
免费 | 40篇 |
国内免费 | 1篇 |
专业分类
化学 | 1014篇 |
晶体学 | 5篇 |
力学 | 51篇 |
数学 | 137篇 |
物理学 | 366篇 |
出版年
2021年 | 13篇 |
2020年 | 21篇 |
2016年 | 20篇 |
2015年 | 30篇 |
2014年 | 26篇 |
2013年 | 50篇 |
2012年 | 54篇 |
2011年 | 68篇 |
2010年 | 34篇 |
2009年 | 34篇 |
2008年 | 55篇 |
2007年 | 65篇 |
2006年 | 56篇 |
2005年 | 32篇 |
2004年 | 23篇 |
2003年 | 30篇 |
2002年 | 38篇 |
2001年 | 23篇 |
2000年 | 27篇 |
1999年 | 23篇 |
1998年 | 27篇 |
1997年 | 25篇 |
1996年 | 27篇 |
1995年 | 37篇 |
1994年 | 30篇 |
1993年 | 39篇 |
1992年 | 22篇 |
1991年 | 27篇 |
1990年 | 18篇 |
1989年 | 22篇 |
1988年 | 33篇 |
1987年 | 32篇 |
1986年 | 24篇 |
1985年 | 30篇 |
1984年 | 36篇 |
1983年 | 21篇 |
1982年 | 21篇 |
1981年 | 26篇 |
1980年 | 10篇 |
1979年 | 24篇 |
1978年 | 24篇 |
1977年 | 16篇 |
1976年 | 21篇 |
1975年 | 21篇 |
1974年 | 17篇 |
1973年 | 26篇 |
1972年 | 16篇 |
1970年 | 10篇 |
1968年 | 9篇 |
1966年 | 9篇 |
排序方式: 共有1573条查询结果,搜索用时 31 毫秒
101.
J. N. Kavanagh F. J. Currell D. J. Timson M. H. Holzscheiter N. Bassler R. Herrmann K. M. Prise G. Schettino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(1):209-214
Radiotherapy employs ionizing radiation to induce lethal DNA lesions in
cancer cells while minimizing damage to healthy tissues. Due to their
pattern of energy deposition, better therapeutic outcomes can, in theory, be
achieved with ions compared to photons. Antiprotons have been proposed to
offer a further enhancement due to their annihilation at the end of the
path. The work presented here aimed to establish and validate an
experimental procedure for the quantification of plasmid and genomic DNA
damage resulting from antiproton exposure. Immunocytochemistry was used to
assess DNA damage in directly and indirectly exposed human fibroblasts
irradiated in both plateau and Bragg peak regions of a 126 MeV antiproton
beam at CERN. Cells were stained post irradiation with an anti-γ-H2AX antibody. Quantification of the
γ-H2AX foci-dose relationship is consistent with a linear increase in the Bragg peak region. A qualitative analysis of the
foci
detected in the Bragg peak and plateau
region indicates significant differences highlighting the different severity
of DNA lesions produced along the particle path. Irradiation of desalted
plasmid DNA with 5 Gy antiprotons at the Bragg peak resulted in a significant
portion of linear plasmid in the resultant solution. 相似文献
102.
K. Suzuki P. Bühler L. Fabbietti N. Herrmann P. Kienle M. Kis Y. Leifels J. Marton E. Widmann T. Yamazaki J. Zmeskal 《Hyperfine Interactions》2009,193(1-3):189-194
We search for the most fundamental kaonic nuclear state, K ??? pp by employing the reaction p?+?p→K ?+??+?X at 3.0 GeV incident beam energy. The experiment makes use of the SIS-18 synchrotron and the ~4π acceptance FOPI apparatus in the cave-B at the GSI, Darmstadt, Germany and aims to collect full kinematics information of the reaction. We look for a signature of the X (?≡?K ??? pp) in both missing mass spectrum by measuring K ?+?, and invariant mass spectrum by measuring decay particles; X?→?Λ?+?p. The experiment is planned to take place in 2009. 相似文献
103.
Claudia Strobel Adriano A. Torrano Rudolf Herrmann Marcelina Malissek Christoph Bräuchle Armin Reller Lennart Treuel Ingrid Hilger 《Journal of nanoparticle research》2014,16(1):1-16
Until now, the potential effects of titanium dioxide (TiO2) nanoparticles on endothelial cells are not well understood, despite their already wide usage. Therefore, the present work characterizes six TiO2 nanoparticle samples in the size range of 19 × 17 to 87 × 13 nm, which are commonly present in sun protection agents with respect to their physicochemical properties (size, shape, ζ-potential, agglomeration, sedimentation, surface coating, and surface area), their interactions with serum proteins and biological impact on human microvascular endothelial cells (relative cellular dehydrogenase activity, adenosine triphosphate content, and monocyte chemoattractant protein-1 release). We observed no association of nanoparticle morphology with the agglomeration and sedimentation behavior and no variations of the ζ-potential (?14 to ?19 mV) in dependence on the surface coating. In general, the impact on endothelial cells was low and only detectable at concentrations of 100 μg/ml. Particles containing a rutile core and having rod-like shape had a stronger effect on cell metabolism than those with anatase core and elliptical shape (relative cellular dehydrogenase activity after 72 h: 60 vs. 90 %). Besides the morphology, the nanoparticle shell constitution was found to influence the metabolic activity of the cells. Upon cellular uptake, the nanoparticles were localized perinuclearly. Considering that in the in vivo situation endothelial cells would come in contact with considerably lower nanoparticle amounts than the lowest-observable adverse effects level (100 μg/ml), TiO2 nanoparticles can be considered as rather harmless to humans under the investigated conditions. 相似文献
104.
We proved in an earlier work that any existence variety of regular algebras is generated by its simple unital Artinian members,
while any existence variety of Arguesian sectionally complemented lattices is generated by its simple members of finite length.
A characterization of the class of simple unital Artinian members [members of finite length, respectively] of such varieties
is given in the present paper. 相似文献
105.
Simal F Delfosse S Demonceau A Noels AF Denk K Kohl FJ Weskamp T Herrmann WA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(13):3047-3052
Air-stable and readily available ruthenium benzylidene complexes of the general type [RuCl2(=CHPh)(L)(L')] (L, L' = PCy3 and/or N-heterocyclic carbene) constitute a new class of catalyst precursors for atom-transfer radical polymerization (ATRP) of methyl methacrylate and styrene, and provide an unprecedented example for the involvement of ruthenium alkylidenes in radical reactions. They promote the polymerization of various monomers with good to excellent yields, and in a controlled way with methyl methacrylate and styrene. Variations of their basic structural motif provide insights into the essential parameters responsible for catalytic activity. The ligands L (PCy3 and/or N-heterocyclic carbene) turned out to play a particularly important role in determining the rate of the polymerizations. A similarly pronounced influence is exerted by the substituents on the N-heterocyclic carbene. Our results indicate that the catalysts decompose quickly under ATRP conditions, and polymerizations are mediated by both [RuCl2(=CHPh)(L)(L')] complexes and ruthenium species bereft of the benzylidene moiety, through a pathway in which both tricyclohexylphosphane and/or N-heterocyclic carbene ligands remain bound to the metal center. Polymerization of n-butyl acrylate and vinyl acetate is not controlled and most probably takes place through a redox-initiated free-radical process. 相似文献
106.
Herrmann J Griebner U Zhavoronkov N Husakou A Nickel D Knight JC Wadsworth WJ Russell PS Korn G 《Physical review letters》2002,88(17):173901
We report on an experimental study of supercontinuum generation in photonic crystal fibers with low-intensity femtosecond pulses, which provides evidence for a novel spectral broadening mechanism. The observed results agree with our theoretical calculations carried out without making the slowly varying envelope approximation. Peculiarities of the measured spectra and their theoretical explanation demonstrate that the reason for the white-light generation in photonic crystal fibers is fission of higher-order solitons into redshifted fundamental solitons and blueshifted nonsolitonic radiation. 相似文献
107.
108.
The compaction of granular packings or soils is a collective process which for higher densities becomes increasingly slower
reaching glassy behaviour. We present a study of this problem from various points of view, in particular we will represent
the evolving force network that percolates through the system by an inverse fiber rupture model.
Received 15 March 2002 and Received in final form 29 July 2002 相似文献
109.
Nicodemi M Coniglio A Herrmann HJ 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,59(6):6830-6837
This paper presents the study of density fluctuations in a model for vibrated granular media. Their microscopic origin is shown to be linked to the microscopic disorder in grains packing. Varying vibrations amplitude and duration, several regimes are found for density relaxation. Its power spectrum is well described by power laws. 相似文献
110.
D. Hildebrandt H. Grote A. Herrmann M. Laux P. Pech H.-D. Reiner H. Wolff 《等离子体物理论文集》1988,28(1):85-95
It is shown that the efflux of impurities injected into the core plasma can be detected by collector probes in the scrape-off plasma. The time evolution, orientation and radial dependences of these effluxes allow to conclude on the impurity confinement in the core plasma and the scrape-off plasma. Moreover, recycling effects can also be measured. 相似文献