全文获取类型
收费全文 | 2443篇 |
免费 | 63篇 |
国内免费 | 16篇 |
专业分类
化学 | 1585篇 |
晶体学 | 16篇 |
力学 | 43篇 |
数学 | 475篇 |
物理学 | 403篇 |
出版年
2022年 | 24篇 |
2021年 | 28篇 |
2020年 | 26篇 |
2019年 | 36篇 |
2018年 | 23篇 |
2017年 | 25篇 |
2016年 | 37篇 |
2015年 | 32篇 |
2014年 | 42篇 |
2013年 | 108篇 |
2012年 | 83篇 |
2011年 | 131篇 |
2010年 | 80篇 |
2009年 | 65篇 |
2008年 | 116篇 |
2007年 | 93篇 |
2006年 | 110篇 |
2005年 | 105篇 |
2004年 | 118篇 |
2003年 | 102篇 |
2002年 | 87篇 |
2001年 | 22篇 |
2000年 | 40篇 |
1999年 | 29篇 |
1997年 | 20篇 |
1996年 | 59篇 |
1994年 | 39篇 |
1993年 | 27篇 |
1992年 | 29篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 22篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 21篇 |
1985年 | 42篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 31篇 |
1981年 | 30篇 |
1980年 | 31篇 |
1979年 | 27篇 |
1978年 | 33篇 |
1977年 | 31篇 |
1976年 | 21篇 |
1975年 | 29篇 |
1974年 | 34篇 |
1973年 | 28篇 |
1970年 | 20篇 |
1968年 | 19篇 |
排序方式: 共有2522条查询结果,搜索用时 0 毫秒
41.
Auerbach LB Burman RL Caldwell DO Church ED Cochran AK Donahue JB Fazely AR Garvey GT Gunasingha RM Imlay RL Kahrimanis G Louis WC Majkic R Malik A McIlhany KL Metcalf WJ Mills GB Rupnik D Sandberg VD Smith D Somodi RF Stancu I Strossman WD Sung M Tayloe R VanDalen GJ Vernon W Wadia N White DH Yellin S Yi H;LSND Collaboration 《Physical review letters》2004,92(9):091801
We observe a net beam excess of 8.7+/-6.3(stat)+/-2.4(syst) events, above 160 MeV, resulting from the charged-current reaction of nu(micro) and/or nu;(mu) on C and H in the LSND detector. No beam-related muon background is expected in this energy regime. Within an analysis framework of pi(0)-->nu(mu)nu;(mu), we set a direct upper limit for this branching ratio of Gamma(pi(0)-->nu(mu)nu;(mu))/Gamma(pi(0)-->all)<1.6 x 10(-6) at 90% confidence level. 相似文献
42.
Humberto Bustos Rodriguez Dagoberto Oyola Lozano Yebrayl A. Rojas Martínez Germán A. Pérez Alcázar Stefan Flege Adam G. Balogh Louis J. Cabri Michael Tubrett 《Hyperfine Interactions》2007,175(1-3):195-206
X-ray diffraction (XRD), Mössbauer spectrometry (MS), secondary ions mass spectroscopy (SIMS) and laser-ablation microprobe–inductively coupled plasma–mass spectrometry (LAM–ICP–MS) were used to study mineral samples of Colombian auriferous ores collected from the “El Diamante” mine, located in the municipality of Guachavez-Nariño, in Colombia. The samples were prepared as polished thin sections and polished sections. From XRD data, quartz, sphalerite and pyrite were detected and their respective cell parameters were estimated. From MS analyses, pyrite, arsenopyrite and chalcopyrite were identified; their respective hyperfine parameters and respective texture were deduced. Multiple regions of approximately 200 × 200 μm in each sample were analyzed with SIMS; the occurrence of “invisible gold” associated mainly with pyrite and secondarily with arsenopyrite could thus be assigned. It was also found that pyrite is of the arsenious type. Spots from 30 to 40 μm in diameter were analyzed with LAM–ICP–MS for pyrite, arsenopyrite and sphalerite; Au is “homogeneously” distributed inside the structure of the arsenious pyrite and the arsenopyrite (not as inclusions); the chemical composition indicates similarities of this “invisible gold”, forming a solid solution with arsenious pyrite and arsenopyrite. One hundred nineteen and 62 ppm of ‘invisible gold’ was quantified in 21 spots analyzed on pyrite and in 14 spots on arsenopyrite, respectively. 相似文献
43.
We describe two experiments in which we investigate the synchronization of coupled periodic oscillators. Each experimental system consists of two identical coupled electronic periodic oscillators that display bursts of desynchronization events similar to those observed previously in coupled chaotic systems. We measure the degree of synchronization as a function of coupling strength. In the first experiment, high-quality synchronization is achieved for all coupling strengths above a critical value. In the second experiment, no high-quality synchronization is observed. We compare our results to the predictions of the several proposed criteria for synchronization. We find that none of the criteria accurately predict the range of coupling strengths over which high-quality synchronization is observed. (c) 2000 American Institute of Physics. 相似文献
44.
45.
46.
J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda B. Grelaud G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier B. Louis F. Mané C. Paulot R. Riskalla Ph. Roy F. Rumpf G. Szklarz Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret R. Baldini S. Calcaterra G. Capon D. Bisello G. Busetto S. Limentani M. Nigro L. Pescara M. Posocco P. Sartori L. Stanco DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,36(3):369-376
The radiative decayJ/ψ → γ π+ π? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe +e? storage rings at Orsay. The π+ π? mass spectrum shows a cleanf 2 (1270) signal, and the possible presence of two other states at thef 2 (1720) andf 4 (2030) masses. For thef 2 (1270), the branching ratio BR(J/ψ →γf)xBR(f→π+ π?) is measured to be (7.50±0.30±1.12)×10?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed. 相似文献
47.
Atiya MS Chiang IH Frank JS Haggerty JS Ito MM Kycia TF Li KK Littenberg LS Sambamurti A Stevens A Strand RC Louis WC Akerib DS Marlow DR Meyers PD Selen MA Shoemaker FC Smith AJ Blackmore EW Bryman DA Felawka L Kitching P Konaka A Kuno Y Macdonald JA Numao T Padley P Poutissou JM Poutissou R Roy J Soluk R Turcot AS 《Physical review letters》1993,70(17):2521-2524
48.
BIT Numerical Mathematics - 相似文献
49.
Louis Marchildon 《Foundations of Physics》2004,34(1):59-73
In a recently proposed interpretation of quantum mechanics, U. Mohrhoff advocates original and thought-provoking views on space and time, the definition of macroscopic objects, and the meaning of probability statements. The interpretation also addresses a number of questions about factual events and the nature of reality. The purpose of this note is to examine several issues raised by Mohrhoff's interpretation, and to assess whether it helps providing solutions to the long-standing problems of quantum mechanics. 相似文献
50.
Liu F Phipps A Horowitz S Ngo K Cattafesta L Nishida T Sheplak M 《The Journal of the Acoustical Society of America》2008,123(4):1983-1990
This paper presents the development of an acoustic energy harvester using an electromechanical Helmholtz resonator (EMHR). The EMHR consists of an orifice, cavity, and a piezoelectric diaphragm. Acoustic energy is converted to mechanical energy when sound incident on the orifice generates an oscillatory pressure in the cavity, which in turns causes the vibration of the diaphragm. The conversion of acoustic energy to electrical energy is achieved via piezoelectric transduction in the diaphragm of the EMHR. Moreover, the diaphragm is coupled with energy reclamation circuitry to increase the efficiency of the energy conversion. Lumped element modeling of the EMHR is used to provide physical insight into the coupled energy domain dynamics governing the energy reclamation process. The feasibility of acoustic energy reclamation using an EMHR is demonstrated in a plane wave tube for two power converter topologies. The first is comprised of only a rectifier, and the second uses a rectifier connected to a flyback converter to improve load matching. Experimental results indicate that approximately 30 mW of output power is harvested for an incident sound pressure level of 160 dB with a flyback converter. Such power level is sufficient to power a variety of low power electronic devices. 相似文献