全文获取类型
收费全文 | 693篇 |
免费 | 24篇 |
专业分类
化学 | 544篇 |
晶体学 | 1篇 |
力学 | 7篇 |
数学 | 28篇 |
物理学 | 137篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2016年 | 8篇 |
2015年 | 13篇 |
2014年 | 6篇 |
2013年 | 22篇 |
2012年 | 30篇 |
2011年 | 54篇 |
2010年 | 28篇 |
2009年 | 27篇 |
2008年 | 41篇 |
2007年 | 54篇 |
2006年 | 49篇 |
2005年 | 58篇 |
2004年 | 39篇 |
2003年 | 31篇 |
2002年 | 27篇 |
2001年 | 18篇 |
2000年 | 17篇 |
1999年 | 5篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 13篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有717条查询结果,搜索用时 46 毫秒
91.
The decays of 3.25 min 169Hf and 2.05 min 167Hf have been studied with high-resolution Ge(Li) and Si(Li) detectors. The total decay energy of 169Hf determined from our experimental ratio is 3.29+0.05?0.13 MeV. The allowed unhindered character of the main β-branches in the decay of both isotopes allows unique Nilsson model assignments. 相似文献
92.
F.W.N. De Boer P.F.A. Goudsmit B.J. Meijer P. Koldewijn J. Konijn R. Beetz 《Nuclear Physics A》1974,236(2):349-378
The decay of the 21.55 min ground state and of the 24.3 s isomeric state of 162Tm was investigated with semiconductor detectors. The γ-ray spectrum was investigated with a Compton-suppression Ge(Li)-NaI(Tl) arrangement. A Si (Li) detector, mounted in an electron transport solenoid, was used to investigate the conversion electron spectrum. Three-dimensional coincidence measurements were performed with large-volume Ge(Li) detectors. The 162Tm ground state has spin-parity 1? and Nilsson assignment p[411]↓?n[521]↑. An allowed β-transition (log ft ≈ 6.4) was observed to a 2?, 2 octupole vibrational level at 1572.84 keV. The Q-value determined from positon-gamma coincidence measurements is 4705 ± 70keV. The discrepancy of the experimental K /β+ ratio with theoretical predictions might possibly be explained by a large number of unobserved weak γ-rays besides the total of 315 stronger ones observed in this study. The average β-strength function was calculated to be 1.2 × 10?5. Among the 50 levels observed in the decay, the 2+, 4+ and 6+ members of the ground-state band, the 2+, 3+ and 4+ members of the γ-band, several 0+ and 2+ members of the K = 0 β-bands and 1?, 2? and 3? octupole vibrational levels were identified. Parameter values Zγ(0) and Zγ(2) determining the mixing between the γ-band and the ground-state band, allow no conclusive evidence about unequalness of the intrinsic quadrupole moments of the ground states and the γ-band. The Z(0) parameters, determining the mixing between the β-bands and the ground-state band, and X parameters determining the ratio of E0 to E2 transition probabilities, were deduced. A previously unreported 24.3 sec isomer in 162Tm was observed to decay in 10% of the cases by an allowed unhindered (log ft = 4.7) β-ray transition to a level at 1712.20 keV in 162Er. The Nilsson configurations assigned to the isomeric and 1712.20 keV levels are p[523]↑ + n[521]↑5+ and n[523]↓ + n[521]↑4+ respectively. The isomeric level decays in 90% of the cases by an E3 transition (EIT < 125 keV) to a p[404]↓ ?n[521]↑2? level at 66.90 keV in 162Tm, which decays by an (M1+ < 40 % E2) to the 21.55 min 162Tm 1? ground state. 相似文献
93.
R.A. van Calcar M.J.G. Heuts B.K. van Uitert H.A.J. Meijer Tj. Hollander C.Th. Alkemade 《Journal of Quantitative Spectroscopy & Radiative Transfer》1981,26(6):495-502
Prior to power broadening experiments on the Na-D lines in a flame (described in Part II), we investigated the time-dependent spectral and spatial properties of a flashlamp-pumped pulsed dye laser (pulse duration about 800 ns, FWHM), with Rhodamine-6G in methanol as dye liquid and an interference filter combined with a Fabry-Pérot etalon as bandwidth-restricting elements in the cavity. An experimental set-up is described that permits measurements of time-dependent spectra with a time-resolution of 10 ns and a spectral resolution of 2.5 × 105. Results are given for different concentrations of the dye solution and for two different bandwidth settings of the laser. In general the spectral profiles at different moments during the pulse are well described by Gaussian curves. The spatial profiles at different moments during the pulse are best fitted by Lorentzian curves. At small concentrations of the dye solution, the time behaviour of the shift and the bandwidth are in (qualitative) agreement with theoretical predictions, i.e. a narrowing of the bandwidth and a shift to longer wavelengths of the line centre. 相似文献
94.
Paul H. E. Meijer 《Journal of statistical physics》1988,53(1-2):543-548
The simple Flory-Huggins model can be combined with the lattice gas as was done by Tompa and others. Here the same method is used to obtain the van der Waals equation of state for a binary gas-liquid system containing a solute consisting of segmented molecules. The simplified equation of state developed here is useful for the study of the critical properties of such systems, in particular, the dependence of the various parameters on the chain length of the molecules. 相似文献
95.
B. J. Meijer J. Konijn B. Klank J. H. Jett R. A. Ristinen 《Zeitschrift für Physik A Hadrons and Nuclei》1975,275(1):79-93
Levels in179W have been deduced from in-beam gamma and conversion electron studies of the181Ta(p, 3n)179W reaction. The gamma-ray spectrum was studied with Ge(Li) detectors and a crystal diffraction spectrometer; the conversion electrons were measured with a broad range transport solenoid Si(Li) spectrometer. The multipolarities of some 50 transitions could be determined. Coriolis mixing of the Nilsson orbits withN=6 was calculated. 相似文献
96.
97.
98.
J. Hubele P. Kreutz J. C. Adloff M. Begemann-Blaich P. Bouissou G. Imme I. Iori G. J. Kunde S. Leray V. Lindenstruth Z. Liu U. Lynen R. J. Meijer U. Milkau A. Moroni W. F. J. Müller C. Ngô C. A. Ogilvie J. Pochodzalla G. Raciti G. Rudolf H. Sann A. Schüttauf W. Seidel L. Stuttge W. Trautmann A. Tucholski 《Zeitschrift für Physik A Hadrons and Nuclei》1991,340(3):263-270
We have studied the fragmentation of Au projectiles interacting with targets of C, Al and Cu at an incident energy ofE/A=600 MeV. The employed inverse kinematics allowed a nearly complete detection of projectile fragments with chargeZ≧2. The recorded fragmentation events were sorted according to three observables, the multiplicityM lp of light charged particles, the largest atomic numberZ max within an event, and a new observable,Z bound, representing the sum of the atomic numbersZ of all fragments withZ≧2. Using these observables, the impact parameter dependence of the fragmentation process was investigated. For all three targets, a maximum mean multiplicity of 3 to 4 intermediate mass fragments (IMFs) is observed. The corresponding impact parameters range from central collisions for theC target to increasingly peripheral collisions for the heavier targets. It is found that the correlation between the IMF multiplicity andZ bound, extending from evaporation type processes (largeZ bound) to the total disassembly of the projectile (smallZ bound), is independent of the target nucleus. This universal behaviour may suggest an — at least partial — equilibration of the projectile fragment prior to its decay. 相似文献
99.
100.
From known conversion coefficients and angular correlations combined with the γ-ray decay deduced from the 181Ta(p, 2n180W reaction it is found that the 1007 → 104 keV (2− → 2+) transition in 180W has mixing parameters δ1 = −0.16 ± 0.07 and δ2 = −0.64 ± 0.17 for M2/E1 and E3/E1, respectively 相似文献