全文获取类型
收费全文 | 374篇 |
免费 | 12篇 |
专业分类
化学 | 149篇 |
晶体学 | 2篇 |
力学 | 7篇 |
数学 | 24篇 |
物理学 | 204篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 20篇 |
2011年 | 21篇 |
2010年 | 10篇 |
2009年 | 10篇 |
2008年 | 27篇 |
2007年 | 24篇 |
2006年 | 21篇 |
2005年 | 14篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 5篇 |
2000年 | 15篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1966年 | 3篇 |
1930年 | 2篇 |
排序方式: 共有386条查询结果,搜索用时 15 毫秒
51.
Vidberg and Serene introduced a very useful technique for calculating the low temperature (T « Tc) gap function of a superconductor which bypasses the real-frequency singular integral equations of Eliashberg. Blashke and Blocksdorf recognized and resolved a difficulty with the technique thereby extending it to higher temperatures. We present a much simpler method of doing essentially the same thing and, for a strong-coupling superconductor at a temperature near Tc, compare the gap functions calculated using these methods with the accurate one computed directly from the real-frequency equations. 相似文献
52.
It is shown that the occurrence of electron-exchange processes produces a distinctive effect in the time-resolved electron spin resonance spectra of spin-polarized radicals observed in the continuous presence of a microwave field. The effects observed are consistent with a theory based upon the Bloch equations. 相似文献
53.
D. T. Clark W. J. Feast I. Ritchie W. K. R. Musgrave M. Modena M. Ragazzini 《Journal of polymer science. Part A, Polymer chemistry》1974,12(5):1049-1063
Molecular core binding energies have been measured by ESCA for a series of copolymers of tetrafluoroethylene and ethylene. Detailed analysis of the results demonstrates the utility of ESCA for determination of copolymer compositions and for providing information on important structural features for these copolymers. 相似文献
54.
55.
56.
Denzer W Horrocks SJ Pearson PJ Ritchie GA 《Physical chemistry chemical physics : PCCP》2006,8(16):1954-1962
The translational anisotropy and the polarization of the electronic angular momentum of the O ((1)D2) fragment produced from the 298 nm photodissociation of ozone have been determined using resonance enhanced multiphoton ionization (REMPI) in conjunction with time-of-flight mass spectrometry (TOFMS). The translational anisotropy parameter beta, which is necessarily averaged over the O2 co-fragment rotational distribution, is measured to be 1.08 +/- 0.04. This is consistent with that expected for the (1)B2 <-- (1)A1 transition within an impulsive model if the tangential velocity associated with the zero point motion of the bend is constricted to opening the bond angle. Molecular frame polarization parameters of rank up to k = 4 have been extracted for the O ((1)D2) fragment and the calculated m(J) populations show a strong preference for the absolute value(m(J)) = 1 states. A small coherence term is also observed, a manifestation of the nuclear geometry of the dissociating molecule and the existence of possible non-adiabatic processes in the exit channel. The orientation associated with the mapping of the photon helicity onto the O ((1)D2) electronic angular momentum distribution was observed to have been quenched. However, the parameter gamma1', which describes the contribution to the orientation from a coherent superposition of a parallel and perpendicular excitation where the photofragment angular momentum lies perpendicular to both the recoil velocity and to the transition dipole moment, was determined to be -0.06. 相似文献
57.
Multi-mode absorption spectroscopy, MUMAS, using wavelength modulation and cavity enhancement techniques 总被引:1,自引:0,他引:1
M. L. Hamilton G. A. D. Ritchie Y. Arita P. Ewart 《Applied physics. B, Lasers and optics》2010,100(3):665-673
Multi-mode absorption spectroscopy, MUMAS, has been combined with the techniques of wavelength modulation spectroscopy, WMS, and cavity enhanced absorption spectroscopy, CEAS, to record multiple molecular transitions using a single laser and a single detector. MUMAS signals were recorded using a multi-mode diode laser of the A-band $b^{1}\varSigma _{g}^{+}\leftarrow X^{3}\varSigma _{g}^{-}Multi-mode absorption spectroscopy, MUMAS, has been combined with the techniques of wavelength modulation spectroscopy, WMS,
and cavity enhanced absorption spectroscopy, CEAS, to record multiple molecular transitions using a single laser and a single
detector. MUMAS signals were recorded using a multi-mode diode laser of the A-band
b1\varSigma g+? X3\varSigma g-b^{1}\varSigma _{g}^{+}\leftarrow X^{3}\varSigma _{g}^{-} of molecular oxygen at 760 nm. Direct MUMAS and WMS-MUMAS signals were recorded using a White cell for air and pure oxygen
for pressures in the range 0 to 1 bar. CEAS-MUMAS signals were recorded with and without WMS in an open enhancement cavity
containing laboratory air. Enhancement of the signal-to-noise ratio has been obtained demonstrating the potential for increased
detection sensitivity for gas-sensing applications of MUMAS. 相似文献
58.
P. Atkinson M.B. Ward S.P. Bremner D. Anderson T. Farrow G.A.C. Jones A.J. Shields D.A. Ritchie 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):21
Conventional electron-beam lithographic patterning of GaAs substrates followed by reactive-ion etching of small holes has been successfully used to control the nucleation of InAs dots. We have observed >50% single dot occupancy for holes wide and deep and show that the dot occupancy and dot size can be varied by changing the size of the holes. Luminescence from an array of these site-controlled dots has been demonstrated. Thus this use of substrate patterning is a viable technique to controllably place single dots at pre-determined positions in devices. 相似文献
59.
Patel RB Bennett AJ Cooper K Atkinson P Nicoll CA Ritchie DA Shields AJ 《Physical review letters》2008,100(20):207405
We report an electrically driven semiconductor single-photon source capable of emitting photons with a coherence time of up to 400 ps under fixed bias. It is shown that increasing the injection current causes the coherence time to reduce, and this effect is well explained by the fast modulation of a fluctuating environment. Hong-Ou-Mandel-type two-photon interference using a Mach-Zehnder interferometer is demonstrated using this source to test the indistinguishability of individual photons by postselecting events where two photons collide at a beam splitter. Finally, we consider how improvements in our detection system can be used to achieve a higher interference visibility. 相似文献
60.
In quantum Hall systems, both anticrossings and magnetic phase transitions can occur when opposite-spin Landau levels coincide. Our results indicate that both processes are also possible in quasi-1D quantum wires in an in-plane B field, Bparallel. Crossings of opposite-spin 1D subbands resemble magnetic phase transitions at zero dc source-drain bias, but display anticrossings at high dc bias. Our data also imply that the well-known 0.7 structure may evolve into a spin-hybridized state in finite dc bias. 相似文献