全文获取类型
收费全文 | 357224篇 |
免费 | 6688篇 |
国内免费 | 4937篇 |
专业分类
化学 | 172938篇 |
晶体学 | 5303篇 |
力学 | 20789篇 |
综合类 | 325篇 |
数学 | 50810篇 |
物理学 | 118684篇 |
出版年
2021年 | 4675篇 |
2020年 | 5140篇 |
2019年 | 5920篇 |
2018年 | 7910篇 |
2017年 | 7950篇 |
2016年 | 10040篇 |
2015年 | 5377篇 |
2014年 | 9264篇 |
2013年 | 15455篇 |
2012年 | 13756篇 |
2011年 | 15496篇 |
2010年 | 12760篇 |
2009年 | 12867篇 |
2008年 | 14344篇 |
2007年 | 13871篇 |
2006年 | 12519篇 |
2005年 | 10808篇 |
2004年 | 10263篇 |
2003年 | 9415篇 |
2002年 | 9740篇 |
2001年 | 9215篇 |
2000年 | 7292篇 |
1999年 | 5599篇 |
1998年 | 5281篇 |
1997年 | 4962篇 |
1996年 | 4568篇 |
1995年 | 4004篇 |
1994年 | 4099篇 |
1993年 | 4081篇 |
1992年 | 4002篇 |
1991年 | 4403篇 |
1990年 | 4386篇 |
1989年 | 4314篇 |
1988年 | 4031篇 |
1987年 | 4082篇 |
1986年 | 3747篇 |
1985年 | 4309篇 |
1984年 | 4515篇 |
1983年 | 3892篇 |
1982年 | 4058篇 |
1981年 | 3699篇 |
1980年 | 3456篇 |
1979年 | 3997篇 |
1978年 | 4075篇 |
1977年 | 4203篇 |
1976年 | 4362篇 |
1975年 | 4059篇 |
1974年 | 3963篇 |
1973年 | 4085篇 |
1972年 | 3544篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Yu. A. Sharin 《Russian Physics Journal》1998,41(5):447-450
Ideas previously enunciated by the author about the physical interpretation of curvilinear space with torsion are developed.
With the new equations describing the eigenstates of such a space, the static centrosymmetric solution for gravitational and
electric fields can be made consistent with the Newton and Coulomb laws. The asymptotic behavior of the axisymmetric solution
at infinity is studied. The gyromagnetic ratio obtained is characteristic of the electron.
Ural State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, p. 56–60, May, 1998. 相似文献
12.
13.
14.
在氢化丁苯共聚物13C-NMR谱脂肪碳部分谱带归属的基础上,根据各谱带的主要来源,推导出六个二单元浓度的计算公式。计算出二单元、一单元的相对含量,各结构单元的数均序列长度、嵌段含量和其它结构参数。加氢前后的1H-和13C-NMR谱的组成计算结果基本一致。初步探讨了作为粘度指数改进剂的氢化丁苯共聚物微观结构与性能的关系,为合成提供了依据。 相似文献
15.
Open circuit voltage (OCV) measurements in H2O/air concentration cells at T<580 K using Yb-doped SrCeO3 electrolyte indicate that under these conditions, protons are transported through the electrolyte as -ve ions, possibly as
hydroxyl (OH−) ions. The H+ ionic transport, which is generally reported, becomes the dominant mode for H2O/air concentration cells at temperatures greater than 750 K or when H2O/air electrodes are replaced by H2/Ar, and the anomalous OCV sign disappears. The combination of low temperature and the presence of hydrogen and oxygen as
provided by the H2O/air system appears to be necessary for the postulated hydroxyl ion electrode reactions to take place.
In addition to OCV measurements, results from impedance spectroscopy are used to provide evidence in support of the suggested
hydroxyl ion mode of protonic transport under the specified conditions. These findings are directly relevant in the development
of novel humidity sensors in the temperature range 450–580K and is reported in a separate paper in this conference.
Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996 相似文献
16.
17.
We prove a character formula for any finite-dimensional irreducible representationV of the “queer” Lie superalgebra g=q(n). It expresses chV in terms of the multiplicities of the irreducible g-subquotients of the cohomology groups of certain dominant g-bundles on
the Π-symmetric projective spaces (i.e., on the homogeneous superspacesG/P whose reduced space is a projective space, whereG=Q(n)). We also establish recurrent relations for the above multiplicities, and this enables us to compute explicitly chV for any givenV. This provides a complete solution to the Kac character problem for the Lie superalgebraq(n). Finally, we consider the particular cases ofq(2), q(3), andq(4) in which we compare the new character formula with the generic character formula of [12].
Translated from Itogi Nauki i Tekhniki, Seriya Sovremennaya Matematika i Ee Prilozheniya. Tematicheskie Obzory. Vol. 41, Algebraic
Geometry-7, 1997. 相似文献
18.
19.
We report on the first observation and studies of a weak delocalizing logarithmic temperature dependence of the conductivity,
which causes the conductivity of the 2D metal to increase as T decreases down to 16 mK. The prefactor of the logarithmic dependence is found to decrease gradually with density, to vanish
at a critical density n
c
, 2∼2×1012 cm−2, and then to have the opposite sign at n>n
c
,2. The second critical density sets the upper limit on the existence region of the 2D metal, whereas the conductivity at the
critical point, G
c
,2∼120e
2/h, sets an upper (low-temperature) limit on its conductivity.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 6, 497–501 (25 September 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
20.
N. Yu. Netsvetaev 《Journal of Mathematical Sciences》1998,91(6):3460-3468
Some corollaries of the Hirzebruch-Thom signature theorem are discussed. The multiplicativity of the signature and the naturalness
of the Pontryagin classes for coverings in the case of ℚ-homology manifolds is proved. A geometric proof of Hirzebruch’s well-known
“functional equation” for the virtual signature is outlined. Bibliography: 25 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 231, 1995, pp. 197–209.
Translated by N. Yu. Netsvetaev. 相似文献