全文获取类型
收费全文 | 408篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学 | 238篇 |
晶体学 | 1篇 |
力学 | 7篇 |
数学 | 73篇 |
物理学 | 97篇 |
出版年
2022年 | 7篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 13篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 16篇 |
2011年 | 27篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 12篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1969年 | 4篇 |
1932年 | 4篇 |
1924年 | 2篇 |
1909年 | 2篇 |
1885年 | 2篇 |
排序方式: 共有416条查询结果,搜索用时 31 毫秒
411.
J. Meijer S. Pezzagna T. Vogel B. Burchard H.H. Bukow I.W. Rangelow Y. Sarov H. Wiggers I. Plümel F. Jelezko J. Wrachtrup F. Schmidt-Kaler W. Schnitzler K. Singer 《Applied Physics A: Materials Science & Processing》2008,91(4):567-571
Decreasing structure sizes in both conventional and quantum solid state devices require novel fabrication methods: we present
a technology which allows to implant ions through a small hole in the tip of an atomic force microscope. This technique offers
a maskless addressing of small structures using different projectiles at kinetic energies between 0.5 and 5.0 keV. Our method
aims to implant single atomic ions, molecular ions or charged nanoparticles with nm resolution. We test the method by implanting
N+ ions into diamond and generating nitrogen-vacancy color centers. The system is operated with a conventional ion gun. However,
in future we will employ an ion trap as a deterministic source of cold single ions.
PACS 03.67.-a; 29.25.Ni; 61.72.Ji; 81.16.Rf; 85.40.Ry 相似文献
412.
Bostedt C Thomas H Hoener M Eremina E Fennel T Meiwes-Broer KH Wabnitz H Kuhlmann M Plönjes E Tiedtke K Treusch R Feldhaus J de Castro AR Möller T 《Physical review letters》2008,100(13):133401
The interaction of intense extreme ultraviolet femtosecond laser pulses (lambda = 32.8 nm) from the FLASH free electron laser (FEL) with clusters has been investigated by means of photoelectron spectroscopy and modeled by Monte Carlo simulations. For laser intensities up to 5x10(13) W/cm(2), we find that the cluster ionization process is a sequence of direct electron emission events in a developing Coulomb field. A nanoplasma is formed only at the highest investigated power densities where ionization is frustrated due to the deep cluster potential. In contrast with earlier studies in the IR and vacuum ultraviolet spectral regime, we find no evidence for electron emission from plasma heating processes. 相似文献
413.
Stork H Ditter M Plösser H Privalov AF Fujara F 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,192(2):173-176
A new design of a mechanical field-cycling setup, operating in the wide temperature range up to 1200 K has been implemented. The sample is moved by a stepping motor in the stray field of a superconducting magnet inside a furnace of homogeneous temperature profile. For a field range from 0.75 to 7 T (transfer length 24 cm), the transfer time is less than 100 ms. The temperature profile is homogenized to better than 1% of the absolute set temperature. The main objective of this design is to extend the T1 relaxation dispersion range covered by electronic field-cycling to higher frequencies. 相似文献
414.
Alessandro Ballestrero Benedikt Biedermann Simon Brass Ansgar Denner Stefan Dittmaier Rikkert Frederix Pietro Govoni Michele Grossi Barbara Jäger Alexander Karlberg Ezio Maina Mathieu Pellen Giovanni Pelliccioli Simon Plätzer Michael Rauch Daniela Rebuzzi Jürgen Reuter Vincent Rothe Christopher Schwan Hua-Sheng Shao Pascal Stienemeier Giulia Zanderighi Marco Zaro Dieter Zeppenfeld 《The European Physical Journal C - Particles and Fields》2018,78(8):671
Vector-boson scattering processes are of great importance for the current run-II and future runs of the Large Hadron Collider. The presence of triple and quartic gauge couplings in the process gives access to the gauge sector of the Standard Model (SM) and possible new-physics contributions there. To test any new-physics hypothesis, sound knowledge of the SM contributions is necessary, with a precision which at least matches the experimental uncertainties of existing and forthcoming measurements. In this article we present a detailed study of the vector-boson scattering process with two positively-charged leptons and missing transverse momentum in the final state. In particular, we first carry out a systematic comparison of the various approximations that are usually performed for this kind of process against the complete calculation, at LO and NLO QCD accuracy. Such a study is performed both in the usual fiducial region used by experimental collaborations and in a more inclusive phase space, where the differences among the various approximations lead to more sizeable effects. Afterwards, we turn to predictions matched to parton showers, at LO and NLO: we show that on the one hand, the inclusion of NLO QCD corrections leads to more stable predictions, but on the other hand the details of the matching and of the parton-shower programs cause differences which are considerably larger than those observed at fixed order, even in the experimental fiducial region. We conclude with recommendations for experimental studies of vector-boson scattering processes. 相似文献
415.
Ranime El-Nabouch Joseph Pastor Quoc-Bao Bui Olivier Plé 《Comptes Rendus Mecanique》2018,346(2):98-109
The present paper is concerned with the simulation of the Casagrande test carried out on a rammed earth material for wall-type structures in the framework of Limit Analysis (LA). In a preliminary study, the material is considered as a homogeneous Coulomb material, and existing LA static and kinematic codes are used for the simulation of the test. In each loading case, static and kinematic bounds coincide; the corresponding exact solution is a two-rigid-block mechanism together with a quasi-constant stress vector and a velocity jump also constant along the interface, for the three loading cases. In a second study, to take into account the influence of compressive loadings related to the porosity of the material, an elliptic criterion (denoted Cohesive Cam–Clay, CCC) is defined based on recent homogenization results about the hollow sphere model for porous Coulomb materials. Finally, original finite element formulations of the static and mixed kinematic methods for the CCC material are developed and applied to the Casagrande test. The results are the same than above, except that this time the velocity jump depends on the compressive loading, which is more realistic but not satisfying fully the experimental observations. Therefore, the possible extensions of this work towards non-standard direct methods are analyzed in the conclusion section. 相似文献
416.
Deborah S. B. S. Silva Haley Ecker Johnisa Walcott Rebecca Weeden Adriana Medina Juliette M. Gorson 《Electrophoresis》2023,44(13-14):1037-1046
Deoxyribonucleic acid (DNA) methylation patterns can be used to identify the type of tissue or body fluid found at a crime scene. However, tissue-related methylation levels have not been analyzed in individuals with different illnesses and medical conditions in forensic-specific studies. The primary goal of this study was to investigate if certain clinical phenotypes can alter the methylation levels of CpG sites in genes involved in tissue typing. Four studies with focus on DNA methylation analysis on individuals with different clinical conditions were selected from the Gene Expression Omnibus database. Then, a list of 137 CpG sites was compiled for further investigation. Statistical tests were performed to compare the beta-values results obtained for the control groups and the individuals affected by medical conditions. For each study, CpG sites that presented significant statistical differences between patients and control group were identified and it was possible to notice that DNA methylation levels can be affected in sites with potential forensic use. Although the observed DNA methylation variation (less than 10% difference) in this study would likely not cause any issues in body fluid identification, the results are important to show that this type of analysis should be taken into consideration when investigating and further validating body fluid markers. The CpG sites identified in this study should be further investigated by future studies on body fluids identification, and due to the significant difference in methylation levels in samples from affected individuals, caution must be taken before including these sites in tissue identification investigations. 相似文献