全文获取类型
收费全文 | 404065篇 |
免费 | 3662篇 |
国内免费 | 1306篇 |
专业分类
化学 | 187871篇 |
晶体学 | 6099篇 |
力学 | 21999篇 |
综合类 | 7篇 |
数学 | 69080篇 |
物理学 | 123977篇 |
出版年
2021年 | 3152篇 |
2020年 | 3366篇 |
2019年 | 3794篇 |
2018年 | 15131篇 |
2017年 | 15162篇 |
2016年 | 13182篇 |
2015年 | 4970篇 |
2014年 | 7338篇 |
2013年 | 16243篇 |
2012年 | 15956篇 |
2011年 | 24706篇 |
2010年 | 16339篇 |
2009年 | 16688篇 |
2008年 | 19484篇 |
2007年 | 21474篇 |
2006年 | 12370篇 |
2005年 | 11774篇 |
2004年 | 11297篇 |
2003年 | 10539篇 |
2002年 | 9625篇 |
2001年 | 10614篇 |
2000年 | 7910篇 |
1999年 | 6097篇 |
1998年 | 5137篇 |
1997年 | 4937篇 |
1996年 | 4685篇 |
1995年 | 3994篇 |
1994年 | 3911篇 |
1993年 | 3807篇 |
1992年 | 4156篇 |
1991年 | 4376篇 |
1990年 | 4147篇 |
1989年 | 4076篇 |
1988年 | 3848篇 |
1987年 | 3977篇 |
1986年 | 3746篇 |
1985年 | 4693篇 |
1984年 | 4732篇 |
1983年 | 3927篇 |
1982年 | 4031篇 |
1981年 | 3750篇 |
1980年 | 3697篇 |
1979年 | 3960篇 |
1978年 | 3940篇 |
1977年 | 3928篇 |
1976年 | 3896篇 |
1975年 | 3694篇 |
1974年 | 3634篇 |
1973年 | 3678篇 |
1972年 | 2620篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Søren Riis 《Archive for Mathematical Logic》1997,36(3):157-188
For each there exists a model of which satisfies the Count() principle. Furthermore, if contains all prime factors of there exist and a bijective map mapping onto . A corollary is a complete classification of the Count() versus Count() problem. Another corollary shows that the pigeon-hole principle for injective maps does not follow from any of the Count() principles. This solves an open question [Ajtai 94].
Received August 16, 1994 / Revised version received April 29, 1996 相似文献
992.
S. P. Sosnyts'kyi 《Ukrainian Mathematical Journal》1997,49(10):1598-1606
Theorems on equilibrium instability of conservative systems with gyroscopic forces are proved. The theorems obtained are nonlinear
analogs of the Kelvin theorem. The equilibrium instability of the Chaplygin nonholonomic systems is considered.
Institute of Mathematics, Ukrainian Academy of Sciences, Kiev. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 49,
No. 10, pp. 1422–1428, October, 1997. 相似文献
993.
994.
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, p. 2899, December, 1991. 相似文献
995.
996.
997.
998.
It is shown how, with the help of approximate integral manifolds, to solve the reduction problem in stability theory in the nonsingular critical case. A generalization of the first fundamental Lyapunov-Malkin theorem in critical cases is obtained.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 10, pp. 1324–1329, October, 1991. 相似文献
999.
H. Tsertos E. Berdermann F. Bosch M. Clemente S. Huchler P. Kienle W. Koenig C. Kozhuharov 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(1):79-94
We present the results obtained from systematic studies of positron creation for a series of heavy-collision systems, with united chargeZ u =Z 1 +Z 2 ranging fromZ u =164 (Pb + Pb) toZ u =184 (U+U) at bombarding energies close to the Coulomb barrier, using the Orangeβ-spectrometer at GSI. For each collision system studied, the dominating continuous distributions due to quasiatomic and nuclear positron emission are determined accurately. This is essential in obtaining the characteristics of the still unexplained monoenergetic positron lines which appear in the energy range between 200 keV and 400 keV. Our results are compared with coupled-channels calculations for quasi-atomic positron creation. The latter describe quite well the global features of the measured spectra, but overestimate systematically their absolute values. From the comparison, a common normalization factor of about 0.75 can be established for the calculated spectra. In particular, the dependence onZ u of the measured emission probabilities was found to follow a power law (∝Z u 195±1), in fair agreement with the theoretical prediction. 相似文献
1000.
J. Kircher M. Cardona M. Alouani S. Gopalan O. Jepsen O. K. Andersen
E. Kaldis
J. Karpinski S. Rusieki 《Physica C: Superconductivity and its Applications》1992,200(3-4):413-417We report results of ellipsometric measurements of the dielectric tensor of YBa2Cu4O8 as well as calculations employing density functional theory in the local density approximation (LDA). For the computation of the one-electron eigenvalues and states the linear-muffin-tin-orbital method (LMTO) was used. Measured and calculated results show good agreement. In particular, the calculation predicts different band structures for YBa2Cu3O7 and YBa2Cu4O8 in the vicinity of the Fermi energy which lead to significant differences in the optical spectra. One such difference is a region of small ε2 in the near infrared which is a fingerprint of the high (relative to the top of the highest fully occupied band) Fermi energy as compared to the situation in YBa2Cu3O7. Our experimental results confirm the theoretical findings. 相似文献