全文获取类型
收费全文 | 548篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
化学 | 227篇 |
晶体学 | 1篇 |
力学 | 9篇 |
数学 | 98篇 |
物理学 | 229篇 |
出版年
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 12篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 19篇 |
2012年 | 26篇 |
2011年 | 22篇 |
2010年 | 12篇 |
2009年 | 17篇 |
2008年 | 23篇 |
2007年 | 16篇 |
2006年 | 10篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 12篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1986年 | 5篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1971年 | 8篇 |
1966年 | 7篇 |
1939年 | 4篇 |
排序方式: 共有564条查询结果,搜索用时 15 毫秒
41.
We observe pronounced transport anisotropies in magnetotransport experiments performed in the two-dimensional electron system of a Si/SiGe heterostructure. They occur when an in-plane field is used to tune two Landau levels with opposite spin to energetic coincidence. The observed anisotropies disappear drastically for temperatures above 1 K. We propose that our experimental findings may be caused by the formation of a unidirectional stripe phase oriented perpendicular to the in-plane field. 相似文献
42.
Gomez L Slutzky C Ferron J de La Figuera J Camarero J Vazquez De Parga AL de Miguel JJ Miranda R 《Physical review letters》2000,84(19):4397-4400
Generic computer simulations using empiric interatomic potentials suggest a new, collective mechanism that could be responsible for mixing at heteroepitaxial interfaces. Even if single adsorbate atoms diffuse by hopping on the substrate surface and do not mix at the terraces, two-dimensional islands formed by nucleation may become unstable above a certain critical size and explode upwards forming clusters of several atomic layers. This process is accompanied by strong distortions of the underlying atomic layers, and on soft materials it can result in surface etching and incorporation of substrate atoms into the islands. 相似文献
43.
C. Ruwiedel M. Schumacher N. Wermes 《The European Physical Journal C - Particles and Fields》2007,51(2):385-414
The prospects for the measurement of the tensor structure of the vertex between a standard model Higgs boson and two weak
gauge bosons using the distribution of the azimuthal angles between the two tagging jets in the weak boson fusion channel
are studied in a Monte Carlo analysis using the fast simulation of the ATLAS detector. The decay channels H→τ+τ-→ll+4ν, H→τ+τ-→lh+3ν at mH=120 GeV and H→W+W-→llνν at mH=160 GeV are used in the analysis. For a standard model Higgs boson it is found that purely anomalous couplings are expected
to be excluded at a confidence level corresponding to 2σ or more at mH=120 GeV and more than 5σ at mH=160 GeV from 30 fb-1 of data. With a value of 1 roughly reproducing the standard model cross section for a purely anomalous coupling, the standard
deviation in a measurement of a contribution of a CP even anomalous coupling in addition to the standard model coupling is
estimated to be 0.20 at mH=120 GeV and 0.09 at mH=160 GeV. 相似文献
44.
M. Schumacher 《The European Physical Journal A - Hadrons and Nuclei》2007,34(3):293-301
The signs and values of the two-photon couplings F
Mγγ of mesons (M) and their couplings gMNN to the nucleon as entering into the t -channel parts of the difference of the electromagnetic polarizabilities (α - β) and the backward angle spin polarizabilities
γπ are determined. The excellent agreement achieved with the experimental polarizabilities of the proton makes it possible to
make reliable predictions for the neutron. The results obtained are αn = 13.4±1.0 , βn = 1.8±1.0 (10-4fm^3), and γ(n)
π = 57.6±1.8 (10-4fm^4). New empirical information on the flavor wave functions of the f
0(980) - and the a
0(980) -meson is obtained. 相似文献
45.
46.
47.
A method for the systematic cryopreservation of potato apices was developed by the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ) and the Institute for Crop and Grassland Science of the Federal Agricultural Research Centre (FAL, Braunschweig). Designed specifically for routine use in genebanks, this method uses a very simple ultra-rapid freezing approach and was applied to a wide range of varieties within the Federal Centre for Breeding Research on Cultivated Plants (BAZ, Quedlinburg) Potato Collection. After several years of storage in liquid nitrogen, shoot tips from a random sample of 51 varieties were thawed and the survival and shoot regeneration percentages compared to those measured immediately after freezing. There were no major changes in either survival or recovery of frozen apices. Data presented are not the outcome of a systematic experiment but from that accumulated during our work from 1992 to 1999. 相似文献
48.
Katrin Schumacher 《Czechoslovak Mathematical Journal》2009,59(3):637-648
Given a domain Ω of class C
k,1, k ∈ ℕ, we construct a chart that maps normals to the boundary of the half space to normals to the boundary of in the sense
that (∂/∂x
n
)α(x′, 0) = − N(x′) and that still is of class C
k,1. As an application we prove the existence of a continuous extension operator for all normal derivatives of order 0 to k on domains of class C
k,1. The construction of this operator is performed in weighted function spaces where the weight function is taken from the class
of Muckenhoupt weights. 相似文献
49.
50.
The defect formation in the bcc metals W and Mo above annealing stage III and the influence of rare gases on this process
were investigated by means of the perturbed angular correlation technique using111In as radioactive probe. In both metals a relatively high electric field gradient (EFG) could be observed at the indium site,
characterized by the quadrupole interaction frequencies υQ=263 MHz, ν=0 and υQ=220 MHz, ν≈0.15 for W and Mo, respectively. The observations are assigned to the growth of threedimensional vacancy clusters
at the probe atoms with the indium atoms situated in the inner surface of this cavities, thus experiencing the corresponding
surface EFG. 相似文献