全文获取类型
收费全文 | 11878篇 |
免费 | 357篇 |
国内免费 | 26篇 |
专业分类
化学 | 7170篇 |
晶体学 | 171篇 |
力学 | 229篇 |
数学 | 1932篇 |
物理学 | 2759篇 |
出版年
2022年 | 108篇 |
2021年 | 174篇 |
2020年 | 208篇 |
2019年 | 224篇 |
2018年 | 300篇 |
2017年 | 300篇 |
2016年 | 425篇 |
2015年 | 360篇 |
2014年 | 445篇 |
2013年 | 863篇 |
2012年 | 643篇 |
2011年 | 724篇 |
2010年 | 580篇 |
2009年 | 479篇 |
2008年 | 589篇 |
2007年 | 506篇 |
2006年 | 456篇 |
2005年 | 345篇 |
2004年 | 315篇 |
2003年 | 259篇 |
2002年 | 270篇 |
2001年 | 195篇 |
2000年 | 178篇 |
1999年 | 179篇 |
1998年 | 131篇 |
1997年 | 115篇 |
1996年 | 150篇 |
1995年 | 109篇 |
1994年 | 119篇 |
1993年 | 110篇 |
1992年 | 102篇 |
1991年 | 89篇 |
1990年 | 98篇 |
1989年 | 74篇 |
1988年 | 70篇 |
1987年 | 59篇 |
1985年 | 89篇 |
1984年 | 92篇 |
1983年 | 77篇 |
1982年 | 86篇 |
1981年 | 75篇 |
1980年 | 69篇 |
1979年 | 71篇 |
1978年 | 76篇 |
1977年 | 81篇 |
1976年 | 95篇 |
1975年 | 79篇 |
1974年 | 63篇 |
1973年 | 61篇 |
1972年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
72.
73.
Physical simulation was used to study pollution dispersion in a street canyon. The street canyon model was designed to study the effect of measuring flow and concentration fields. A method of C02-laser photoacoustic spectrometry was applied for detection of trace concentration of gas pollution. The advantage of this method is its high sensitivity and broad dynamic range, permitting monitoring of concentrations from trace to saturation values. Application of this method enabled us to propose a simple model based on line permeation pollutant source, developed on the principle of concentration standards, to ensure high precision and homogeneity of the concentration flow. Spatial measurement of the concentration distribution inside the street canyon was performed on the model with reference velocity of 1.5 m/s. 相似文献
74.
M. Smi?anská J. Hladky M. Novák M. Vecko A. N. Aleev V. A. Arefiev V. P. Balandin V. K. Berdyshev V. K. Birulev A. S. Chvyrov et al. 《Czechoslovak Journal of Physics》1990,40(12):1293-1305
We present results of the exclusive diffractive reaction np 0K0p at 0·08 < |t|< 0·53 GeV2/c2 and momenta between 30–70 GeV/c at the Serpukhov neutron beam. Thet-dependence is exp (Bt) withB= 11·4± 2·3 (GeV/c)–2 and it exhibits the diffractive minimum at ¦t¦ 0·28 GeV2/c2 for 0K0 massesM < 1·8 GeV/c2.B decreases with increasingM. Correlation with the beam direction is observed in the rest frame of the 0K0 system: the cross section rises for the forward-going 0. The rise is more pronounced for higherM. The cross section of reaction np 0K0p for 0<|t|< 0·53 GeV2/c2 is 10·3 ± 2·5 ± 2·8 b. 相似文献
75.
Wagner SR Hinshaw DA Ong RA Snyder A Abrams G Adolphsen CE Akerlof C Alexander JP Alvarez M Amidei D Baden AR Ballam J Barish BC Barklow T Barnett BA Bartelt J Blockus D Bonvicini G Boyarski A Boyer J Brabson B Breakstone A Brom JM Bulos F Burchat PR Burke DL Butler F Calvino F Cence RJ Chapman J Cords D Coupal DP DeStaebler HC Dorfan DE Dorfan JM Drell PS Feldman GJ Fernandez E Field RC Ford WT Fordham C Frey R Fujino D Gan KK Gidal G Gladney L Glanzman T Gold MS Goldhaber G Green A 《Physical review letters》1990,64(10):1095-1098
76.
77.
The paper deals with the regime of advanced Bénard instabilities (described usually by the Lorenz system) in a more general system formulated firstly by Obukhov. It has been shown that triplet co-operation leads to characteristic courses where some new regularities occur. 相似文献
78.
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
79.
D. Macko V. Hajko Jr. J. Billy P. Makroczy V. Kavečanský O. Hudák 《Czechoslovak Journal of Physics》1988,38(12):1383-1386
Quasicrystalline Al-14 at. % Mn alloy was prepared by melt-spinning and its structural and electrical properties were studied. This alloy consists of icosahedral grains with sizes from 1 to 4 m and of crystalline aluminium phase. The electrical resistivity was almost temperature independent with a value of about 765 n gWm at 4·2 K. 相似文献
80.
F. Štěrba J. Lipták Nguyen An Ninh J. Štěrbová J. Starý 《Czechoslovak Journal of Physics》1988,38(7):741-754
Excitation functions for the55Mn(p, p )55Mn,55Mn(p, n )55Fe and55Mn(p, )56Fe reactions are studied for proton beam energyE
p=1·3–2 MeV. The excitation functions are established from yield functions for -rays emitted from the first excited states of final nuclei. Many resonances are observed and competition of their decay into all three output channels is analysed. Spin-parity assignment for some resonant states in the56Fe compound nucleus is deduced.Participated partly in the course of his work on a Thesis.The authors wish to thank the staff of the Van de Graaff accelerator at Charles University in Prague for the efficient operation of the machine and dr. I. Wilhelm for the valuable technical help in the early period of the experimental work. One of us (N. A. N.) acknowledges the staff of the Dept. of Nuclear Physics of Charles University in Prague for the excellent working conditions. 相似文献