全文获取类型
收费全文 | 11801篇 |
免费 | 428篇 |
国内免费 | 4篇 |
专业分类
化学 | 6293篇 |
晶体学 | 67篇 |
力学 | 221篇 |
综合类 | 23篇 |
数学 | 2470篇 |
物理学 | 3159篇 |
出版年
2021年 | 140篇 |
2020年 | 162篇 |
2019年 | 140篇 |
2018年 | 229篇 |
2017年 | 262篇 |
2016年 | 543篇 |
2015年 | 408篇 |
2014年 | 411篇 |
2013年 | 918篇 |
2012年 | 527篇 |
2011年 | 648篇 |
2010年 | 427篇 |
2009年 | 339篇 |
2008年 | 364篇 |
2007年 | 293篇 |
2006年 | 227篇 |
2005年 | 214篇 |
2004年 | 220篇 |
2003年 | 222篇 |
2002年 | 259篇 |
2001年 | 207篇 |
2000年 | 242篇 |
1999年 | 237篇 |
1998年 | 195篇 |
1997年 | 155篇 |
1996年 | 146篇 |
1995年 | 152篇 |
1994年 | 121篇 |
1993年 | 100篇 |
1992年 | 132篇 |
1991年 | 113篇 |
1990年 | 113篇 |
1989年 | 121篇 |
1988年 | 113篇 |
1987年 | 95篇 |
1985年 | 121篇 |
1984年 | 108篇 |
1983年 | 103篇 |
1982年 | 100篇 |
1981年 | 95篇 |
1980年 | 103篇 |
1979年 | 95篇 |
1978年 | 110篇 |
1977年 | 112篇 |
1976年 | 95篇 |
1974年 | 102篇 |
1973年 | 101篇 |
1968年 | 95篇 |
1966年 | 91篇 |
1965年 | 108篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
Mariano Giaquinta Giuseppe Modica Jiří souček 《Archive for Rational Mechanics and Analysis》1989,106(2):97-159
Summary In this paper we introduce some new classes of functions, among these a class of weak diffeomorphisms. In these classes we prove by direct methods the existence of minimizers for several kinds of variational integrals. In particular, we prove the existence of one-to-one orientation-preserving maps that minimize suitable energies associated with hyperelastic materials. The minimizers are also proved to satisfy equilibrium equations. Finally radial deformations are discussed in connection with cavitation. 相似文献
94.
Linear mode conversion of waves near the maxima or minima of the density in a warm magnetized plasma
Behaviour of the h. f. electrostatic waves near the plasma or upper hybrid resonances was studied in the case that these resonances are situated at the maxima or minima of the plasma density. Supposing the parabolic density profile in these regions we obtained the connection formulae for the WKB solutions. In a weakly inhomogeneous magnetoplasma the effect of the parabolic profile manifests itself only in narrow frequency band centred at the resonance frequency corresponding to the extreme value of the density. The whole process can be then described by only two coefficients, viz. the power conversion and power transmission coefficients. 相似文献
95.
K. Rohlena K. Mašek E. G. Balabanova I. Paulička 《Czechoslovak Journal of Physics》1988,38(6):622-637
Systematic calculations of maximum inversion were performed for iodine photodissociation laser in dependence on the mixture composition. The flash-lamp radiation was modelled as emanating from an optically thin Xe plasma. Duration of the pumping pulse is about 300 s. The sensitivity of the model to the values of kinetic constants was also tested. 相似文献
96.
J. Kvapil B. Perner Jos Kvapil B. Mánek K. Hamal M. Košelja V. Kubeček 《Czechoslovak Journal of Physics》1988,38(11):1281-1287
YAP:Nd, Cr grown under Ar-H2 or Ar-He-H2 atmosphere possesses good energy transfer from Cr3+ to Nd3+ but suffers from the colour centre formation. The centre formation was completely prevented using further admixture of Ce3+ and 10–4–10–3 wt. % Fe. Small luminescence quenching of Cr3+ or Nd3+ due to iron ions is negligible in the presence of Ce3+. The crystals may be also heavily doped with Nd3+ because the increased pumping efficiency compensates the shortening of the luminescence lifetime. YAP: Nd, Ce, Cr, Fe is advisible active laser material particularly for all the types of pulsed lasers. 相似文献
97.
Mária Hvastijová Jiří Kohout Helmut Köhler 《Monatshefte für Chemie / Chemical Monthly》1992,123(6-7):493-500
Summary New dicyanamide complexes of the typeM[N(CN)2]2
L
2 (M=Cu or Ni;L=2-, 3-, 4-aminopyridine, 2-amino-5-nitropyridine) and Co[N(CN)2]2 (2-amino-5-nitropyridine)2 were prepared and studied by spectroscopic methods as well as by room-temperature magnetic moments. The results show that the Cu(II) complexes have elongated pseudooctahedral structures while the Ni(II) and Co(II) complexes are octahedral. In most cases the N(CN)2 groups are in bridging function and through their cyanide nitrogens, or-more rarely-amide and cyanide nitrogens connect the basic structure units into polymeric conglomerates. In the Cu(II) systems exchange coupling is seen from the eff value or ESR spectrum.
Professor Viktor Gutmann zum 70. Geburtstag gewidmet 相似文献
98.
S. Vepřek 《Plasma Chemistry and Plasma Processing》1992,12(3):219-235
Impurity release from the first wall and components facing the hot plasma in Tokamak devices for controlled fusion research and the concomitant pollution of the plasma lead to enhanced energy losses and deuterium-tritium luel dilution. Both these effects can prevent reaching the ignition conditions. The recently developed technique for large areain situ deposition of boron carbide protective coatings by means of plasma-induced chemical vapor deposition enables one to significantly improve the purity of the fusion plasma. The prospects of approaching the scientific break-even in the large machines of the Tokarnak type has been increased.Extended version of an invited paper presented at the 10th International Symposium on Boron, Borides, and Related Compounds, Albuquerque, New Mexico, August 1990.The term Tokarnak is an abbreviation of the Russian name toroidal magnetic chamber. 相似文献
99.
We discuss productions of scalar gluonium candidates in the radiativeJ/ decays. The branching ratios of such productions are estimated on the basis of the Euler-Heisenberg effective Lagrangian for gluon-photon couplings. We mention that these estimates cannot be expected to be accurate to better than within a factor 2. We show that the radiativeJ/ decays probably invalidate gluoniumgg interpretation of the GAMS meson F0(1590) and a narrow 0++ stateS lying below 1 GeV. However, a possible wide scalar effective gluonium candidate(920) is shown not to be excluded by the data on the decayJ/. We also find that the experimental data about radiativeJ/ decays presumably agree with a recently suggested interpretation of F0(1590) as being approximately a half-and-half mixture of pure 0++ gluoniumgg andSU(3)f singlet quarkoniumq¯q states. 相似文献
100.
The characteristic length scales for the transport in disordered metals are discussed. Based on a phenomenological model of phase randomising scattering processes, the influence of the phase coherence length on the conductance of ballistic systems is studied. It is argued that the frequency dependence of the conductance of quasi-one dimensional systems can be used in order to determine not only the statistical average but the whole distribution function of the phase coherence length. Various cases of distributions, the -function, the exponential, and the Gamma distribution, are discussed. It is shown that due to quantum coherence effects deviations from the classical (Drude) behavior of the conductance exist. For independent scattering processes the probability distribution function is given by the Poisson distribution function. In this case an expression for the conductance can be derived which contains the ballistic transport, and the result for the exponential distribution. 相似文献