全文获取类型
收费全文 | 470篇 |
免费 | 25篇 |
国内免费 | 8篇 |
专业分类
化学 | 281篇 |
晶体学 | 1篇 |
力学 | 17篇 |
数学 | 77篇 |
物理学 | 127篇 |
出版年
2022年 | 5篇 |
2021年 | 15篇 |
2020年 | 10篇 |
2019年 | 16篇 |
2018年 | 8篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 18篇 |
2014年 | 19篇 |
2013年 | 22篇 |
2012年 | 26篇 |
2011年 | 31篇 |
2010年 | 17篇 |
2009年 | 24篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 20篇 |
2002年 | 12篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1995年 | 6篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1966年 | 2篇 |
1964年 | 4篇 |
排序方式: 共有503条查询结果,搜索用时 81 毫秒
61.
The spin-lattice relaxation rate of gallium isotopes in a melt was shown by NMR to increase considerably with a decrease in
gallium particle size. The dominant relaxation mechanism of gallium embedded in an synthetic opal matrix changes from magnetic
dipole to electrical quadrupole. The increase in the correlation time of atomic motion in gallium particles with a decrease
in their size was estimated. For gallium in opal, the correlation time was found to increase by more than an order of magnitude.
It was shown that a variation in atomic mobility becomes noticeable already in gallium particles about 5 μm in size.
__________
Translated from Fizika Tverdogo Tela, Vol. 45, No. 12, 2003, pp. 2242–2246.
Original Russian Text Copyright ? 2003 by Tien, Charnaya, Sedykh, Kumzerov. 相似文献
62.
The temperature dependences of the integrated intensity and of the Knight shift of 199Hg NMR signals are measured for liquid and solid mercury introduced into porous carbon and silica gel. A decrease in the temperature of completion of crystallization and a small temperature hysteresis (from 4 to 9 K) between melting and crystallization are observed. The melting temperature of mercury in pores coincides with that in the bulk. The 199Hg NMR signal from crystalline mercury under the condition of restricted geometry is observed for the first time. It is established that the Knight shift for liquid and crystalline mercury in pores is smaller than in the bulk. 相似文献
63.
The conduction properties of lecithin bilayer membranes in iodine-containing solutions are examined from a potentiodynamic experimental approach. Voltammetric data obtained by using a variety of forms (derived from charge-transfer type interactions) of iodide implicate the triiodide ion as the charge carrier accounting for the diffusion-limited voltammetric response whereas the charge transport of iodide seems to be limited by transmembrane diffusion. The data are used to support one of the many proposed mechanisms for conductance of iodide in membranes. 相似文献
64.
65.
Chao-Kuang Chen ProfessorTzu-Li Tien Postgraduate Student 《Applied mathematics and computation》1996,80(2-3):225-244
Usually a linear differential equation is used to represent continuous dynamic systems, but a linear difference equation is used to represent discrete dynamic systems. AGO is one of the most important characteristics of grey theory, and its main purpose is to reduce the randomness of data. A linear differential equation, instead of a linear difference equation, is used to replace the grey differential equation to analyze discrete systems in this paper. Approximating a k-order derivative by operating after spline curve fitting of 1-AGO data, a model is directly established by means of the least square method. ARIMA models are used to analyze the leading indicator in advance, and the Fourier series with suitably chosen values of parameters is used in the fitting of leading indicator. This model is called the GDM(2, 2, 1) model. 相似文献
66.
M.A. Brosmer C.L. Tien 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,33(5):521-532
The spectral absorptivity of the v3 and v4 fundamental and the v1 + v4 combination bands of methane have been measured at low resolution for temperatures between 290 and 850 K. Spectral mean (narrow-band) parameters for the fundamental bands have been correlated from the Elsasser model, while total band absorptance data for all three bands have been correlated using the Edwards exponential wide band model. A total emissivity chart has been developed, based on the wide band absorption models. 相似文献
67.
Hsien-Ju Tien Long-Li Lai Yao-Kueng Lee Che-Ping Chuang Mou-Yung Yeh Tian-Shung Wu 《中国化学会会志》1988,35(3):237-240
A new method to prepare 3,3′-ethylenebissydnone (40%), 3,3′-tetramethylenebissydnone (37%) and 3,3′-hexamethylenebissydnone (43%) from the corresponding alkylene diamine with paraformaldehyde and potassium cyanide were investigated. Some new bissydone: ?3,3′-trimethylenebissydnone (6%), 3,3′-(4,4′-diphenyl)bissydnonylmethane (9%) and 3,3′-(4,4′-diphenyi)bissydnonyl ether (28%) were synthesized from the corresponding diamine, paraformaldehyde, sodium bisulfite and potassium cyanide. Biological test of 3,3′-(4,4′-diphenyl)bissydnonylmethane shows significant response for coronary dilgtion test, inhibition of collagen induced platelet aggregation and moderate carditropic response. 3,3′-(4,4′-Diphenyl)bissydnonyl ether also shows inhibition of collagen induced platelet aggregation and moderate carditropic response. 相似文献
68.
69.
Tien Cuong?Dinh Romain?DujardinEmail author Nessim?Sibony 《Mathematische Annalen》2005,333(4):703-739
We construct the Green current for a random iteration of horizontal-like mappings in . This is applied to the study of a polynomial map with the following properties:
i. infinity is f-attracting;
ii. f contracts the line at infinity to a point not in the indeterminacy set.
We study for such mappings the escape rates near infinity, i.e. the set of possible values of the function We show in particular that the set of possible values can contain an interval.
On the other hand the Green current T of f can be decomposed into pieces associated to an itinerary defined by the indeterminacy points. This allows us to prove that
exists ||T||-a.e. and we give its value in terms of explicit quantities depending on f. 相似文献
70.
The resistance-network representation for radiative heat transfer is developed for a planar absorbing-scattering medium on the basis of the two-flux model and the linear anisotropic scattering model. Particular attention is given to the scattering effect due to particulates such as flame soot or smoke particles. Limiting relations for various radiative regimes are derived and the physical significance of the resistances are discussed. An illustrative example is presented for thermal radiation from a smoke layer. Extension to two-phase dispersed systems is also demonstrated. 相似文献