全文获取类型
收费全文 | 741篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
化学 | 310篇 |
晶体学 | 3篇 |
力学 | 30篇 |
数学 | 70篇 |
物理学 | 341篇 |
出版年
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2016年 | 21篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 24篇 |
2012年 | 17篇 |
2011年 | 21篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 21篇 |
2007年 | 24篇 |
2006年 | 22篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 17篇 |
2002年 | 29篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1997年 | 6篇 |
1996年 | 19篇 |
1995年 | 13篇 |
1994年 | 21篇 |
1993年 | 29篇 |
1992年 | 19篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 14篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1975年 | 14篇 |
1974年 | 11篇 |
1973年 | 12篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有754条查询结果,搜索用时 656 毫秒
61.
S. F. Peterson F. Tera G. H. Morrison 《Journal of Radioanalytical and Nuclear Chemistry》1969,2(1-2):115-125
Isotopic ion exchange for the rapid separation of radioactive mixtures has been further extended through the use of an acetone-water-hydrochloric
acid system. Distribution data were obtained for 27 elements in the range of 15–90% acetone, 0.3N HCl indicating a number of new separations. The approach was used for the separation of several radioisotopes from short
half-life magnesium matrix for activation analysis. The separations were completed in less than 5 minutes.
Research supported by the Advanced Research Projects Agency. 相似文献
62.
J. Bartke M. Deutschmann H.G. Kirk P. Sixel L. Becker H. Vogt R. Hartmann H. Plothow D. Kocher D.R.O. Morrison P. Porth K. Eskreys K. Olkiewicz K. Doroba T. Hofmokl 《Nuclear Physics B》1977,120(1):1-13
Interactions in which the baryon is emitted forwards in the c.m.s. are studied in 8 and 16 GeV/cπ+p collisions. These interactions are interpreted as representing baryon exchange. The properties of such off-shell N annihilation events are studied. It is found that the multiplicity distribution of the multi-pion system as a function of the effective mass for events with |upp| < 1 GeV2 is the same as for real annihilations. 相似文献
63.
64.
65.
A computer-based method is developed to perform the numerical analysis of the measured adsorption isotherm in order to determine the quantitative distribution of potential energies displayed by a solid substrate for a physically-adsorbed gas. The characteristic adsorptive energies of the basal planes of graphite and of boron nitride for argon and nitrogen are determined as examples of the use of the method. As more such values are put on record the method becomes suitable for the qualitative analysis of substrates. 相似文献
66.
C.G. Ryan I. Morrison D.L. Kennedy A.E. Stuchbery H.H. Bolotin 《Nuclear Physics A》1980,342(3):373-384
The lifetimes of 9 states in 63Cu up to an excitation energy of 2092 keV have been determined by means of the Doppler-shift attenuation method using the reaction. A search was made for a suitable set of M1 and E2 single-particle matrix elements for use with shell-model eigenstates throughout the Ni, Cu and Zn isotopes. The theoretical predictions for the level spectroscopy and electromagnetic transitions and static moments in 63Cu are in satisfactory agreement with the experimental findings. 相似文献
67.
The particle-hole model is presented for nuclei with closed core±2 nucleons. This model, as applied to 6Li, 14N, 14C and 18O, gives overall agreement with experiment for the low-lying and GDR states. 相似文献
68.
Hanson RJ Macomber HK Morrison AC Boucher MA 《The Journal of the Acoustical Society of America》2005,117(1):400-412
The purpose of the work reported here is to further experimentally explore the wide variety of behaviors exhibited by driven vibrating wires, primarily in the nonlinear regime. When the wire is driven near a resonant frequency, it is found that most such behaviors are significantly affected by the splitting of the resonant frequency and by the existence of a "characteristic" axis associated with each split frequency. It is shown that frequency splitting decreases with increasing wire tension and can be altered by twisting. Two methods are described for determining the orientation of characteristic axes. Evidence is provided, with a possible explanation, that each axis has the same orientation everywhere along the wire. Frequency response data exhibiting nonlinear generation of transverse motion perpendicular to the driving direction, hysteresis, linear generation of perpendicular motion (sometimes tubular), and generation of motion at harmonics of the driving frequency are exhibited and discussed. Also reported under seemingly unchanging conditions are abrupt large changes in the harmonic content of the motion that sometimes involve large subharmonics and harmonics thereof. Slow transitions from one stable state of vibration to another and quasiperiodic motions are also exhibited. Possible musical significance is discussed. 相似文献
69.
Plane-wave density functional theory has been applied to determine the strengths of hydrogen bonds in the phase I crystal structures of ammonia and urea. For ammonia, each component of the trifurcated hydrogen bond has been found to be almost as strong as a standard N-H.N interaction, and for urea the strengths of the two different N-H.O interactions have been determined by a quantum mechanical technique for the first time. 相似文献
70.
We study self-collimation and beam splitting in low-refractive-index photonic crystals created within chalcogenide glass. We propose a beam splitter structure that allows direct experimental verification of photonic-crystal effects at optical wavelengths in a straightforward and definitive manner. The beam splitter provides angular separation of 90° using a highly compact spatial footprint, thus delivering direct application in highly integrated photonic devices. 相似文献