全文获取类型
收费全文 | 453266篇 |
免费 | 3443篇 |
国内免费 | 1397篇 |
专业分类
化学 | 223751篇 |
晶体学 | 6630篇 |
力学 | 24024篇 |
综合类 | 16篇 |
数学 | 74114篇 |
物理学 | 129571篇 |
出版年
2020年 | 3497篇 |
2019年 | 4179篇 |
2018年 | 15852篇 |
2017年 | 15647篇 |
2016年 | 13672篇 |
2015年 | 5017篇 |
2014年 | 7451篇 |
2013年 | 16483篇 |
2012年 | 15911篇 |
2011年 | 24751篇 |
2010年 | 16530篇 |
2009年 | 16961篇 |
2008年 | 20478篇 |
2007年 | 22383篇 |
2006年 | 13036篇 |
2005年 | 12784篇 |
2004年 | 12067篇 |
2003年 | 11588篇 |
2002年 | 10507篇 |
2001年 | 10619篇 |
2000年 | 8315篇 |
1999年 | 6196篇 |
1998年 | 5381篇 |
1997年 | 5457篇 |
1996年 | 5109篇 |
1995年 | 4315篇 |
1994年 | 4472篇 |
1993年 | 4435篇 |
1992年 | 4811篇 |
1991年 | 4950篇 |
1990年 | 4732篇 |
1989年 | 4794篇 |
1988年 | 4656篇 |
1987年 | 4627篇 |
1986年 | 4431篇 |
1985年 | 5689篇 |
1984年 | 5863篇 |
1983年 | 4797篇 |
1982年 | 5062篇 |
1981年 | 4916篇 |
1980年 | 4538篇 |
1979年 | 5081篇 |
1978年 | 5171篇 |
1977年 | 5310篇 |
1976年 | 5326篇 |
1975年 | 4984篇 |
1974年 | 4896篇 |
1973年 | 5133篇 |
1972年 | 3683篇 |
1971年 | 3348篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
E. Pancheva 《Journal of Mathematical Sciences》1995,76(1):2177-2180
In this paper we give a characterization of the classMSS of all one-dimensional d.f.'s G satisfying the functional equation Gα(x)=G(L(x)), where α∈(0, 1] andL(x) is strictly monotone.
Supported by the Bulgarian Ministry of Education and Science (grant MM-17/1993).
Proceedings of the Seminar on Stability Problems for Stochastic Models, Moscow, 1993. 相似文献
994.
E. A. Bugrii 《Theoretical and Mathematical Physics》1996,109(3):1590-1607
A representation in the form of a functional integral is obtained for the partition function of the inhomogeneous 2D Ising model on a triangular lattice where the coupling parameters are arbitrary functions of coordinates. The method for transforming the partition function into an integral uses an auxiliary six-component Grassmann field in which the Grassmann fields corresponding to one of the components commute with the others. Thus, one pair of components realizes a representation of the q-deformed group SLq(2, R) with q=–1 and the other two pairs correspond to the usual Grassmann spinors (q=1). An explicit expression in terms of the modified Pfaffian is found for the Gaussian integral over these fields and its relation to the ordinary Grassmann functional integral is established.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 109, No. 3, pp. 441–463, December, 1996. 相似文献
995.
Thermoelastic stress analysis was used to document the effect of composite damage on the stress distribution in three ceramic matrix composites. Composite damage was found to significantly alter the thermoelastic response of each material, with the greatest effect noted in SiC/CAS. Thermoelastic imaging of these materials affords a more complete picture of how the various damage mechanisms affect the stress distribution. In particular, a stress concentration factor computed from thermoelastic images, serves as an indicator of stress redistribution. The stress concentration factors were computed by comparing notch root to far field temperatures, and monitored after the introduction of various amounts of damage. In each material, the stress concentration factor diminished as the damaging load approached the ultimate stress. Reduction in the stress concentration is associated with local changes in modulus, mechanistically arising from combinations of fiber, matrix and interface fracture. Stress redistribution occurs as a consequence of modulus changes, leading to lower notch sensitivity in each of the tested composites. 相似文献
996.
Alexander N Shivanyuk Dmitry M Rudkevich David N Reinhoudt 《Tetrahedron letters》1996,37(52):9341-9344
An assembly of cation receptor 1 and anion receptor 2 via the hydrogen bonding melamine-barbiturate structural motif complexes sodium thiocyanate, sodium iodide, and sodium azide in apolar solvents. 相似文献
997.
M. U. Belyi N. E. Bartnitskaya I. F. Mel'nik B. A. Okhrimenko S. M. Yablochkov 《Journal of Applied Spectroscopy》1995,62(3):564-567
T. Shevchenko Kiev University, 252022 Kiev, Pr. Akad. Glushakova, 6, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 62, No. 3, pp. 192–196, May–June, 1995. 相似文献
998.
Methods are proposed for determining the diffusion coefficients of adsorbed molecules and the adsorption isotherms from given concentrations of the solutes in the external solution. The methods are based on a comparison of experimental data with the numerical results produced by a mathematical model of internal-diffusion kinetics of adsorption from a constant bounded volume.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 66, pp. 41–46, 1988. 相似文献
999.
1000.