全文获取类型
收费全文 | 1223篇 |
免费 | 20篇 |
国内免费 | 16篇 |
专业分类
化学 | 631篇 |
晶体学 | 5篇 |
力学 | 58篇 |
数学 | 302篇 |
物理学 | 263篇 |
出版年
2019年 | 16篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 19篇 |
2014年 | 15篇 |
2013年 | 39篇 |
2012年 | 48篇 |
2011年 | 45篇 |
2010年 | 42篇 |
2009年 | 22篇 |
2008年 | 40篇 |
2007年 | 55篇 |
2006年 | 40篇 |
2005年 | 35篇 |
2004年 | 17篇 |
2003年 | 22篇 |
2002年 | 22篇 |
2001年 | 28篇 |
2000年 | 32篇 |
1999年 | 24篇 |
1998年 | 11篇 |
1997年 | 11篇 |
1996年 | 28篇 |
1995年 | 22篇 |
1994年 | 22篇 |
1993年 | 18篇 |
1992年 | 25篇 |
1991年 | 16篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 23篇 |
1986年 | 14篇 |
1985年 | 21篇 |
1984年 | 12篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1979年 | 20篇 |
1978年 | 24篇 |
1977年 | 17篇 |
1976年 | 15篇 |
1975年 | 13篇 |
1974年 | 25篇 |
1973年 | 24篇 |
1971年 | 12篇 |
1970年 | 15篇 |
1969年 | 10篇 |
1968年 | 8篇 |
排序方式: 共有1259条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
The change in the light-scattering patterns upon deforming two-dimensional disordered spherulites is shown to arise from four effects occurring upon stretching: (1) the change in shape of the spherulite, (2) the change in average orientation of the optic axes of the scattering volume elements, (3) the change in deviation of the optic axis orientation angle from its average value, and (4) the change in the distance over which this deviation is correlated. The effects of these contributions upon the experimental scattering patterns are analyzed. 相似文献
65.
W. A. Stein 《Heat and Mass Transfer》1969,2(4):210-221
Zusammenfassung Methoden zum Aufstellen von Gleichungen für die dynamische Viskosität und die Wärmeleitfähigkeit reiner fluider Stoffe werden angegeben und ihre Brauchbarkeit wird bei H2O nachgewiesen. Es ergibt sich nur jeweils eine Gleichung für die Berechnung der Transportgrößen, die allerdings die Variablen Temperatur und Dichte anstelle von Temperatur und Druck enthält, dafür aber das ganze Gas- und Flüssigkeitsgebiet erfaßt. Es werden neue Erkenntnisse über die prinzipielle Abhängigkeit der Transportgrößen von Temperatur und Dichte gewonnen.
Über dieses Thema wurde am 6. 10. 1969 auf dem Thermodynamik-Kolloquium des VDI in Zürich berichtet. 相似文献
Equations for the dynamic viscosity and the thermal conductivity of pure fluid water substance
Methods for formulating equations for the dynamic viscosity and the thermal conductivity of pure fluid substances are given; their applicability is proved for H2O. It is found that only one equation is needed to calculate the transport properties, which has the variables temperature and density instead of temperature and pressure, but covers the whole gaseous and liquid region. New knowledge of the principal dependence of the transport properties on temperature and density is attained.
Über dieses Thema wurde am 6. 10. 1969 auf dem Thermodynamik-Kolloquium des VDI in Zürich berichtet. 相似文献
66.
W.B. Atwood E.D. Bloom R.L.A. Cottrell H. DeStaebler M. Mestayer C.Y. Prescott L.S. Rochester S. Stein R.E. Taylor D. Trines 《Physics letters. [Part B]》1976,64(4):479-482
Inelastic electron scattering cross sections have been measured for four-momentum transfers between 4.1 GeV2 and 30.5 GeV2. At the large scattering angles of this experiment, the dominant contribution to the cross section comes from the W1 structure function. In the conventional scaling variables, x and x′, this structure function does not exhibit scaling behavior, and at fixed x or x′ it is found to decrease with increasing four-momentum transfer. 相似文献
67.
S.K Stein 《Journal of Combinatorial Theory, Series A》1974,16(3):391-397
A theorem in convex bodies (in fact, measure theory) and a theorem about translates of sets of integers are generalized to coverings by subsets of a finite set. These theorems are then related to quasigroups and (0, 1)-matrices. 相似文献
68.
Robert E. Prud'homme Richard S. Stein 《Journal of Polymer Science.Polymer Physics》1973,11(7):1357-1374
A general equation describing the small-angle Hv light-scattering intensity for a system of N undeformed spherulites located at random within the sample and taking into account the truncation and interference effects is given. Scattering contour plots or radial scans are reported for various arrangements of the N spherulites. The results show that the interference effect may explain the speckled appearance of the experimental patterns. Moreover, the interference and truncation effects (for the special cases where truncation is considered here) do not seem to shift the position of the maximum scattering angle of the cloverleaf pattern as calculated from the single spherulite theory. Finally, the calculations show that the truncation effect increases the relative intensity of the pattern at large and low scattering angles and at azimuthal angles 0 and 90°C, as compared with the intensity at the position of maximum scattering angle. 相似文献
69.
The electron localization is studied for Anderson's tight-binding model with diagonal and off-diagonal disorder for a very large square lattice (10,000 sites) and diamond lattice (27,000 sites). The numerical investigations are based on the Lanczos recursion method. The convergence of the recursion coefficientsa
n
,b
n
is discussed with regard to the electron localization.From Anderson's criterion and an exact real space renormalization method the energy of the localization edge is found as a function of the degree of disorder. Also the dependence of the spatial decay rate of localized wave functions on the energy and the degree of disorder is evaluated. Near the Anderson transition, where all states become localized, we get two critical exponentsv
E
andv
W
, which lead us to the tentative suggestion of multicritical scaling laws for this transition. 相似文献
70.
The electron localization is studied for Anderson's tight-binding model of a disordered two-dimensional square lattice. For a large system of 104 sites the averaged squared modulus of the Green's function is evaluated by a continued-fraction method. From this quantity, following Anderson's criterion, the energy of the mobility edge is found as a function of the degree of disorder. Also the Anderson transition is recognized. 相似文献