全文获取类型
收费全文 | 3971篇 |
免费 | 110篇 |
国内免费 | 8篇 |
专业分类
化学 | 2546篇 |
晶体学 | 24篇 |
力学 | 114篇 |
综合类 | 5篇 |
数学 | 423篇 |
物理学 | 977篇 |
出版年
2024年 | 7篇 |
2023年 | 31篇 |
2022年 | 125篇 |
2021年 | 120篇 |
2020年 | 98篇 |
2019年 | 115篇 |
2018年 | 121篇 |
2017年 | 84篇 |
2016年 | 169篇 |
2015年 | 108篇 |
2014年 | 141篇 |
2013年 | 254篇 |
2012年 | 253篇 |
2011年 | 294篇 |
2010年 | 207篇 |
2009年 | 220篇 |
2008年 | 250篇 |
2007年 | 229篇 |
2006年 | 179篇 |
2005年 | 130篇 |
2004年 | 125篇 |
2003年 | 96篇 |
2002年 | 97篇 |
2001年 | 73篇 |
2000年 | 59篇 |
1999年 | 36篇 |
1998年 | 38篇 |
1997年 | 33篇 |
1996年 | 23篇 |
1995年 | 13篇 |
1994年 | 40篇 |
1993年 | 34篇 |
1992年 | 35篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 16篇 |
1980年 | 11篇 |
1979年 | 18篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1975年 | 10篇 |
1973年 | 10篇 |
排序方式: 共有4089条查询结果,搜索用时 15 毫秒
81.
82.
Background
Several studies have shown that Stroop interference is stronger in children than in adults. However, in a standard Stroop paradigm, stimulus interference and response interference are confounded. The purpose of the present study was to determine whether interference at the stimulus level and the response level are subject to distinct maturational patterns across childhood. Three groups of children (6–7 year-olds, 8–9 year-olds, and 10–12 year-olds) and a group of adults performed a manual Color-Object Stroop designed to disentangle stimulus interference and response interference. This was accomplished by comparing three trial types. In congruent (C) trials there was no interference. In stimulus incongruent (SI) trials there was only stimulus interference. In response incongruent (RI) trials there was stimulus interference and response interference. Stimulus interference and response interference were measured by a comparison of SI with C, and RI with SI trials, respectively. Event-related potentials (ERPs) were measured to study the temporal dynamics of these processes of interference.Results
There was no behavioral evidence for stimulus interference in any of the groups, but in 6–7 year-old children ERPs in the SI condition in comparison with the C condition showed an occipital P1-reduction (80–140 ms) and a widely distributed amplitude enhancement of a negative component followed by an amplitude reduction of a positive component (400–560 ms). For response interference, all groups showed a comparable reaction time (RT) delay, but children made more errors than adults. ERPs in the RI condition in comparison with the SI condition showed an amplitude reduction of a positive component over lateral parietal (-occipital) sites in 10–12 year-olds and adults (300–540 ms), and a widely distributed amplitude enhancement of a positive component in all age groups (680–960 ms). The size of the enhancement correlated positively with the RT response interference effect.Conclusion
Although processes of stimulus interference control as measured with the color-object Stroop task seem to reach mature levels relatively early in childhood (6–7 years), development of response interference control appears to continue into late adolescence as 10–12 year-olds were still more susceptible to errors of response interference than adults. 相似文献83.
M. Melo O. Frazão A.L.J. Teixeira L.A. Gomes J.R. Ferreira da Rocha H.M. Salgado 《Applied physics. B, Lasers and optics》2003,77(1):139-142
In this paper, we present a continuous-wave tunable fibre ring laser operating in the L-band. A bi-directional pumped L-band erbium-doped fibre amplifier provides gain to the loop. Tunability is achieved by bending a single-mode fibre taper using a micrometer drive, controlling in this way the spectral cavity losses. Laser emission is achieved between 1587 and 1606 nm, and low variation of the output laser power is observed over all the tuning range. PACS 42.55.Wd; 42.60.Da 相似文献
84.
Humberto César Chaves Fernandes Arthur Rodrigo Barros da Rocha 《International Journal of Infrared and Millimeter Waves》2003,24(7):1171-1176
The use of photonic materials has been used in the theory of optical waves. The PBG (Photonic Band Gap) theory and material, was developed recently for optical frequencies and can be easily applied to millimeter waves, microwaves and planar antenna frequencies. The presence of photonic materials as substrate in antennas has some good characteristics such as, supression of light spontaneous emission and suppression of surface waves, allowing the application in planar antenna array. In this work an elaborate analysis using the full wave Transverse Transmission Line - TTL method, that provides efficient and concise results is applied to the planar antennas array with PBG substrate. 相似文献
85.
86.
87.
Alves GA Amato S Anjos JC Appel JA Bracker SB Cremaldi LM Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Kaplan D Karchin PE Kwan S Leedom I Lueking LH Luste GJ Mantsch PM de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Rafatian A dos Reis AC Reucroft S Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wu Z 《Physical review letters》1993,70(6):722-725
88.
89.
90.