全文获取类型
收费全文 | 1643篇 |
免费 | 3篇 |
国内免费 | 6篇 |
专业分类
化学 | 622篇 |
晶体学 | 17篇 |
力学 | 96篇 |
数学 | 218篇 |
物理学 | 699篇 |
出版年
2021年 | 18篇 |
2020年 | 22篇 |
2019年 | 24篇 |
2018年 | 48篇 |
2017年 | 38篇 |
2016年 | 38篇 |
2015年 | 19篇 |
2014年 | 48篇 |
2013年 | 54篇 |
2012年 | 45篇 |
2011年 | 47篇 |
2010年 | 68篇 |
2009年 | 68篇 |
2008年 | 59篇 |
2007年 | 55篇 |
2006年 | 39篇 |
2005年 | 36篇 |
2004年 | 41篇 |
2003年 | 35篇 |
2002年 | 47篇 |
2001年 | 36篇 |
2000年 | 37篇 |
1999年 | 21篇 |
1998年 | 22篇 |
1997年 | 30篇 |
1996年 | 29篇 |
1994年 | 19篇 |
1992年 | 19篇 |
1990年 | 22篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1984年 | 22篇 |
1983年 | 25篇 |
1982年 | 23篇 |
1981年 | 19篇 |
1980年 | 21篇 |
1979年 | 19篇 |
1978年 | 21篇 |
1977年 | 40篇 |
1976年 | 29篇 |
1975年 | 16篇 |
1974年 | 19篇 |
1973年 | 20篇 |
1972年 | 28篇 |
1971年 | 21篇 |
1970年 | 17篇 |
1969年 | 19篇 |
1968年 | 22篇 |
1967年 | 35篇 |
1966年 | 20篇 |
排序方式: 共有1652条查询结果,搜索用时 15 毫秒
91.
D. P. Kostomarov F. S. Zaitsev A. G. Shishkin S. V. Stepanov 《Moscow University Computational Mathematics and Cybernetics》2010,34(4):191-197
We consider problems of the visualization and automation of routine tasks that arise in the process of a computational experiment.
We describe ScopeShell, a state-of-the-art universal platform independent graphic interface for computational codes that includes
data visualization and the monitoring of calculations on distributed computing systems. We describe the concept behind ScopeShell,
along with the interface’s functionality and methods of application. The ScopeShell system is used to support computational
experiments in the field of controlled thermonuclear fusion. The system considerably increases the efficiency of research
requiring the application of voluminous computer codes. 相似文献
92.
A. V. Bokov V. M. Byakov L. A. Kulikov Yu. D. Perfiliev S. V. Stepanov 《Hyperfine Interactions》2017,238(1):95
Being the main cause of cancer, almost all chemical carcinogens are strong electrophiles, that is, they have a high affinity for the electron. We have shown that positron annihilation lifetime spectroscopy (PALS) is able to detect chemical carcinogens by their inhibition of positronium (Ps) formation in liquid media. Electrophilic carcinogens intercept thermalized track electrons, which are precursors of Ps, and as a result, when they are present Ps atom does not practically form. Available biophysical data seemingly indicate that frozen solutions model better an intracellular medium than the liquid ones. So it is reasonable to use emission Mössbauer spectroscopy (EMS) to detect chemical carcinogens, measuring the yield of 57Fe2+ions formed in reactions of Auger electrons and other secondary electrons they produced with 57Fe3+. These reactions are similar to the Ps formation process in the terminal part the positron track: e++ e? =>Ps. So EMS and PALS are complementary methods for detection of carcinogenic compounds. 相似文献
93.
Eugene Stepanov 《Proceedings of the American Mathematical Society》2002,130(2):433-442
It is shown that the relaxation of the integral functional involving argument deviations
in weak topology of a Lebesgue space (where and are standard measure spaces, the latter with nonatomic measure), coincides with its convexification whenever the matrix of measurable functions : satisfies the special condition, called unifiability, which can be regarded as collective nonergodicity or commensurability property, and is automatically satisfied only if . If, however, either 1$"> or 1$">, then it is shown that as opposed to the classical case without argument deviations, for nonunifiable function matrix one can always construct an integrand so that the functional itself is already weakly lower semicontinuous but not convex.
94.
A. A. Babin D. V. Kartashov A. M. Kiselev V. V. Lozhkarev A. M. Sergeev A. A. Solodov A. N. Stepanov 《JETP Letters》2002,76(9):548-552
The propagation of an intense (I≤106 W/cm2) femtosecond laser radiation with a duration of ~100 fs through gas-filled dielectric capillaries was studied. The radiation with a power up to 0.2 TW propagates along the paths up to 20 cm with a transmission efficiency of ~45%. The beam transverse structure at the output is close to the capillary fundamental mode under gas-ionization conditions. The transformation of pulse spectrum was studied as a function of input intensity. It is demonstrated experimentally that the pulse is compressed to a duration of ~30 fs due to the compensation of ionization-induced self-phase modulation in a linear dispersive element at the capillary output. 相似文献
95.
Gonnelli RS Daghero D Ummarino GA Stepanov VA Jun J Kazakov SM Karpinski J 《Physical review letters》2002,89(24):247004
We present the results of the first directional point-contact spectroscopy experiments in high-quality MgB2 single crystals. Because of the directionality of the current injection into the samples, the application of a magnetic field allowed us to separate the contributions of the sigma and pi bands to the total conductance of our point contacts. By using this technique, we were able to obtain the temperature dependency of each gap independent of the other. The consequent, strong reduction of the error on the value of the gap amplitude as a function of temperature allows a stricter test of the predictions of the two-band model for MgB2. 相似文献
96.
The energy of plasma oscillations of free charge carriers in bismuth crystals ?ωp can be qual to the band gap at the L point of the Brillouin zone E gL as a result of doping with an acceptor impurity. Variation in the edge shape and splitting of the minimum in the plasma reflection are observed in experimental studies of reflection under normal incidence of radiation on the crystal. An analysis of the totality of available experimental data shows that the above special features are caused by interaction of elementary excitations (such as the plasma oscillations) with band-to-band transitions. It became possible for the first time to ascertain the composition of the bismuth crystals for which the condition ?ωp=E gL is satisfied and observe the variation in the characteristics of the plasma oscillations of free charge carriers, which occurs as a result of electron-plasmon interaction. 相似文献
97.
We suggest a novel method for significant improvement of fiber Bragg grating (FBG) spectral characteristics based on compensation of repeatable errors during the grating writing process. The method is based on an open loop scheme in which a test grating is written first and then a corrected design is obtained and implemented by writing another (compensated) grating. The results are presented for a FBG dispersion compensator. 相似文献
98.
V. Burjan J. Cejpek J. Fojtu V. Kroha D. V. Aleksandrov B. G. Novatskii D. N. Stepanov 《Zeitschrift für Physik A Hadrons and Nuclei》1996,356(1):281-286
The analogue of the 0+ ground state in118Sn has been observed in the compound nucleus118Sb through117Sn(p,nγ)117Sb reaction. The neutron decays of this analogue resonance have been studied from the deexcitingγ-rays of the residual nucleus117Sb. From off resonance excitation functions, spin assignments have been made to states in117Sb, on the basis of Hauser-Feshbach formalism. The resonance parameters of the isobaric analogue resonance have been determined, including the total, proton and neutron decay widths. 相似文献
99.
100.
Using birefringent crystals such as LiNbO3: Fe, reading and writing of holograms at different wavelengths and so nondestructive readout of information may be accomplished. 相似文献