全文获取类型
收费全文 | 622808篇 |
免费 | 6366篇 |
国内免费 | 1739篇 |
专业分类
化学 | 332000篇 |
晶体学 | 9291篇 |
力学 | 28109篇 |
综合类 | 20篇 |
数学 | 74833篇 |
物理学 | 186660篇 |
出版年
2021年 | 4857篇 |
2020年 | 5534篇 |
2019年 | 6008篇 |
2018年 | 7876篇 |
2017年 | 7737篇 |
2016年 | 11826篇 |
2015年 | 7404篇 |
2014年 | 11380篇 |
2013年 | 27722篇 |
2012年 | 21064篇 |
2011年 | 25778篇 |
2010年 | 18242篇 |
2009年 | 17899篇 |
2008年 | 23847篇 |
2007年 | 23862篇 |
2006年 | 22131篇 |
2005年 | 19919篇 |
2004年 | 18415篇 |
2003年 | 16419篇 |
2002年 | 16243篇 |
2001年 | 17945篇 |
2000年 | 13810篇 |
1999年 | 10848篇 |
1998年 | 9167篇 |
1997年 | 8947篇 |
1996年 | 8605篇 |
1995年 | 7812篇 |
1994年 | 7809篇 |
1993年 | 7442篇 |
1992年 | 8443篇 |
1991年 | 8460篇 |
1990年 | 8158篇 |
1989年 | 7825篇 |
1988年 | 8005篇 |
1987年 | 7779篇 |
1986年 | 7388篇 |
1985年 | 9621篇 |
1984年 | 9941篇 |
1983年 | 8137篇 |
1982年 | 8275篇 |
1981年 | 8185篇 |
1980年 | 7827篇 |
1979年 | 8165篇 |
1978年 | 8550篇 |
1977年 | 8377篇 |
1976年 | 8406篇 |
1975年 | 7701篇 |
1974年 | 7820篇 |
1973年 | 7960篇 |
1972年 | 5626篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
G. L. Booth 《Acta Mathematica Hungarica》1989,54(3-4):201-208
32.
33.
34.
M. Mirvaliev 《Journal of Mathematical Sciences》1987,38(6):2357-2363
One obtains a formula for the transformation of a vector with a given covariance matrix. The sum of the squares of the components of the transformed vector is equal to a chi-square type quadratic form, constructed with the aid of the initial vector. Taking into account this property, one finds the components of the Pearson statistic, Pearson-Fisher statistic, etc.Translated from Veroyatnostnye Raspredeleniya i Matematicheskaya Statistika, pp. 337–350, 1986. 相似文献
35.
Transport as a consequence of state-dependent diffusion 总被引:1,自引:0,他引:1
M. Büttiker 《Zeitschrift für Physik B Condensed Matter》1987,68(2-3):161-167
Overdamped particles subject to a drift in a force field with sinusoidal space dependence and also a sinusoidally modulated space-dependent diffusion, with the same period as the drift, experience a net driving force. The resulting current depends on the amplitude of the modulation of the diffusion and is a periodic function of the phase difference between the sinusoidal drift and the sinusoidal modulation of the diffusion. For small modulation amplitudes a particle subject to state-dependent noise behaves the same way as a particle subject to thermal noise but with a drift which, in addition to the sinusoidal term, contains a net force term.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday 相似文献
36.
37.
38.
Rajiv Manohar G. Tripathi A.K. Srivastava A.K. Prajapati 《Journal of Physics and Chemistry of Solids》2006,67(11):2300-2304
Dielectric properties of polymer-liquid crystal mixture, having constituent polymer, poly-butyl methacrylate (PBMA) and liquid crystal, cholesteryl nonanoate, are reported as a function of frequency and temperature. The measurement has been done in a temperature range of 300-375 K and frequency range of 100 Hz-10 MHz. The dielectric permittivity and dielectric loss shows significant changes with the addition of polymer molecules in liquid crystal. The significant feature of composite formation is that the pure liquid crystal and polymer do not show dielectric relaxation in the frequency range covered, while the composite shows relaxation peak at a particular frequency. The optical transmittance of pure liquid crystal and composite has also been measured and compared. 相似文献
39.
J. Maul I. Strachnov S. Karpuk P. Bernhard A. Oelsner G. Schönhense G. Huber 《Applied Physics A: Materials Science & Processing》2006,82(1):43-47
We report morphologic changes of metallic surfaces at the onset of ablation, starting from gentle ablation to the emergence of ablation craters. The evolution of both observed melting zones and of ablation craters therein are investigated in dependence of the ablation laser fluence for nanosecond ultraviolet laser pulses. Further, consequences of crater formation for cluster synthesis within the released atomic vapor are pointed out. PACS 52.38.Mf; 79.20.Ds; 65.40.De 相似文献
40.
Space-time directional Lyapunov exponents are introduced. They describe the maximal velocity of propagation to the right or to the left of fronts of perturbations in a frame moving with a given velocity. The continuity of these exponents as function of the velocity and an inequality relating them to the directional entropy is proved. 相似文献