全文获取类型
收费全文 | 15012篇 |
免费 | 458篇 |
国内免费 | 322篇 |
专业分类
化学 | 9345篇 |
晶体学 | 104篇 |
力学 | 420篇 |
综合类 | 30篇 |
数学 | 2019篇 |
物理学 | 3874篇 |
出版年
2022年 | 161篇 |
2021年 | 191篇 |
2020年 | 184篇 |
2019年 | 181篇 |
2018年 | 176篇 |
2017年 | 142篇 |
2016年 | 340篇 |
2015年 | 307篇 |
2014年 | 371篇 |
2013年 | 801篇 |
2012年 | 641篇 |
2011年 | 738篇 |
2010年 | 529篇 |
2009年 | 511篇 |
2008年 | 677篇 |
2007年 | 720篇 |
2006年 | 587篇 |
2005年 | 604篇 |
2004年 | 593篇 |
2003年 | 587篇 |
2002年 | 629篇 |
2001年 | 445篇 |
2000年 | 407篇 |
1999年 | 314篇 |
1998年 | 225篇 |
1997年 | 207篇 |
1996年 | 229篇 |
1995年 | 241篇 |
1994年 | 234篇 |
1993年 | 181篇 |
1992年 | 171篇 |
1991年 | 180篇 |
1990年 | 192篇 |
1989年 | 158篇 |
1988年 | 145篇 |
1987年 | 138篇 |
1986年 | 130篇 |
1985年 | 222篇 |
1984年 | 240篇 |
1983年 | 165篇 |
1982年 | 181篇 |
1981年 | 154篇 |
1980年 | 156篇 |
1979年 | 147篇 |
1978年 | 124篇 |
1977年 | 166篇 |
1976年 | 144篇 |
1975年 | 122篇 |
1974年 | 113篇 |
1973年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Blank B Bey A Canchel G Dossat C Fleury A Giovinazzo J Matea I Adimi N De Oliveira F Stefan I Georgiev G Grévy S Thomas JC Borcea C Cortina D Caamano M Stanoiu M Aksouh F Brown BA Barker FC Richter WA 《Physical review letters》2005,94(23):232501
The nucleus 54Zn has been observed for the first time in an experiment at the SISSI/LISE3 facility of GANIL in the quasifragmentation of a 58Ni beam at 74.5 MeV/nucleon in a (nat)Ni target. The fragments were analyzed by means of the ALPHA-LISE3 separator and implanted in a silicon-strip detector where correlations in space and time between implantation and subsequent decay events allowed us to generate almost background free decay spectra for about 25 different nuclei at the same time. Eight 54Zn implantation events were observed. From the correlated decay events, the half-life of 54Zn is determined to be 3.2(+1.8)(-0.8) ms. Seven of the eight implantations are followed by two-proton emission with a decay energy of 1.48(2) MeV. The decay energy and the partial half-life are compared to model predictions and allow for a test of these two-proton decay models. 相似文献
952.
Sansone G Benedetti E Caumes JP Stagira S Vozzi C Pascolini M Poletto L Villoresi P De Silvestri S Nisoli M 《Physical review letters》2005,94(19):193903
By using a self-referencing technique, we have experimentally measured the influence of the carrier-envelope phase of femtosecond light pulses on the phase of the electric field of the radiation produced by high-order harmonic generation. We show that, in particular experimental conditions, the temporal evolution of the electric field of the attosecond pulses, is directly controlled by the carrier-envelope phase of the driving pulses. 相似文献
953.
Agnello M Beer G Benussi L Bertani M Bianco S Botta E Bressani T Busso L Calvo D Camerini P Cerello P Dalena B De Mori F D'Erasmo G Di Santo D Fabbri FL Faso D Feliciello A Filippi A Filippini V Fiore EM Fujioka H Gianotti P Grion N Lucherini V Marcello S Maruta T Mirfakhrai N Morra O Nagae T Olin A Outa H Pace E Palomba M Pantaleo A Panzarasa A Paticchio V Piano S Pompili F Rui R Simonetti G So H Tomassini S Toyoda A Wheadon R Zenoni A;FINUDA Collaboration 《Physical review letters》2005,94(21):212303
We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e(+)e(-) collider DAPhiNE. Almost monochromatic K(-)'s produced through the decay of phi(1020) mesons are used to observe K(-) absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K(-)pp through its two-body decay into a Lambda hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115(+6)(-5)(stat)(+3)(-4)(syst) MeV and 67(+14)(-11)(stat)(+2)(-3)(syst) MeV, respectively. 相似文献
954.
We discuss the zero field superconducting phase transition in a finite system of magnetically coupled superconducting layers. Transverse screening is modified by the presence of other layers resulting in topological excitations with fractional flux. Vortex stacks trapping a full flux and present at any finite temperature undergo a dissociation transition which corresponds to the depairing of fractional-flux vortices in individual layers. We propose an experiment with a bilayer system allowing us to identify the dissociation of bound vortex molecules. 相似文献
955.
Javidi B Ferraro P Hong SH De Nicola S Finizio A Alfieri D Pierattini G 《Optics letters》2005,30(2):144-146
We present three-dimensional (3D) image fusion by use of digital holography. We demonstrate experimentally that, through the image fusion technique with multiresolution wavelet decomposition, it is possible to increase the details and contrast of 3D reconstructed images obtained by multiwavelength digital holography. Although there is substantial activity in the fields of image fusion and holography, to the best of our knowledge, this is the first report of 3D image fusion by use of digital holography. 相似文献
956.
We demonstrate the possibility of extending the well-established metrological performance of optical frequency-comb synthesizers to the mid-IR region by phase locking the pump and signal lasers of a difference-frequency source to two near-IR teeth of an optical comb. An uncertainty of 800 Hz (1.1 x 10(-11)) in the absolute frequencies of CO2 transitions near 4.2 microm has been measured by cavity-enhanced saturated-absorption spectroscopy. Prospects for the creation of a new dense set of high-quality molecular frequency standards in the IR are discussed. 相似文献
957.
D.T. Petkie B.P. Winnewisser R.A.H. Butler F.C. De Lucia 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,92(2):129-141
The results of millimeter and submillimeter wave rotational spectroscopy are used to simulate the complex structure of the 2ν9-ν9 and ν5-ν9 hot bands. The comparison data were obtained with a high-resolution Bruker FTIR. The combination of the quality of these data and the complexity of the spectra of these interacting states represents a stringent test for the simulation. It is shown that the agreement is very good and that this approach is generally advantageous. From this simulation, the ratios of the transition dipole moments for the 2ν9-ν9 and ν5-ν9 hot bands with respect to the ν9 fundamental band were found to be 1.38(11) and 0.67(20), respectively. Using these results, the calculated integrated band intensities for the hot bands at were determined to be and . These results were used to successfully simulate high-resolution stratospheric spectra obtained from a balloon flight of the FIRS-2 spectrometer. The more general problem of the rotation-vibration database and the optimal use of both microwave and infrared data to define it is discussed. It is concluded that it is best if the combination of data takes place at the level of the original spectra. 相似文献
958.
The liquid-gas system is expected to exhibit distinct dynamic behavior in the fluid's critical region (model H). We present molecular dynamics simulations of a Lennard-Jones fluid model starting from specially designed, near-equilibrium, initial conditions. By following the fluid's relaxation towards equilibrium, we calculate the requisite transport coefficients in the critical region. The results yield the scaling behavior of the thermal diffusion coefficient D(T) approximately xi(-1.023+/-0.018) (xi is the correlation length) and a nonconventional divergent heat conductivity, all of which are in accord with mode-coupling and renormalization group predictions, as well as some experimental data. 相似文献
959.
The scaling of the average gyration radius of polymers as a function of their length can be experimentally determined from ensemble measurements, such as light scattering, and agrees with analytical estimates. Ensemble techniques, yet, do not give access to the full probability distributions. Single molecule techniques, instead, can deliver information on both average quantities and distribution functions. Here we exploit the high resolution of atomic force microscopy over long DNA molecules adsorbed on a surface to measure the average end-to-end distance as a function of the DNA length, and its full distribution function. We find that all the scaling exponents are close to the predicted 3D values (upsilon=0.589+/-0.006 and delta=2.58+/-0.77). These results suggest that the adsorption process is akin to a geometric projection from 3D to 2D, known to preserve the scaling properties of fractal objects of dimension df<2. 相似文献
960.
The empirical validity of the locality (LOC) principle of relativity is used to argue in favour of a local hidden variable theory (HVT) for individual quantum processes. It is shown that such a HVT may reproduce the statistical predictions of quantum mechanics (QM), provided the reproducibility of initial hidden variable states is limited. This means that in a HVT limits should be set to the validity of the notion of counterfactual definiteness (CFD). This is supported by the empirical evidence that past, present, and future are basically distinct. Our argumentation is contrasted with a recent one by Stapp resulting in the opposite conclusion, i.e. nonlocality or the existence of faster-than-light influences. We argue that Stapps argumentation still depends in an implicit, but crucial, way on both the notions of hidden variables and of CFD. In addition, some implications of our results for the debate between Bohr and Einstein, Podolsky and Rosen are discussed. 相似文献