全文获取类型
收费全文 | 552121篇 |
免费 | 3205篇 |
国内免费 | 925篇 |
专业分类
化学 | 258090篇 |
晶体学 | 8275篇 |
力学 | 30839篇 |
综合类 | 11篇 |
数学 | 84371篇 |
物理学 | 174665篇 |
出版年
2020年 | 4671篇 |
2019年 | 5461篇 |
2018年 | 12719篇 |
2017年 | 13151篇 |
2016年 | 13047篇 |
2015年 | 5772篇 |
2014年 | 9729篇 |
2013年 | 20292篇 |
2012年 | 18556篇 |
2011年 | 26322篇 |
2010年 | 18871篇 |
2009年 | 18973篇 |
2008年 | 24289篇 |
2007年 | 26365篇 |
2006年 | 16657篇 |
2005年 | 17669篇 |
2004年 | 15343篇 |
2003年 | 14668篇 |
2002年 | 13743篇 |
2001年 | 13180篇 |
2000年 | 10608篇 |
1999年 | 7866篇 |
1998年 | 7200篇 |
1997年 | 7069篇 |
1996年 | 6704篇 |
1995年 | 6021篇 |
1994年 | 6168篇 |
1993年 | 5895篇 |
1992年 | 6294篇 |
1991年 | 6615篇 |
1990年 | 6497篇 |
1989年 | 6404篇 |
1988年 | 6279篇 |
1987年 | 6244篇 |
1986年 | 5799篇 |
1985年 | 7325篇 |
1984年 | 7756篇 |
1983年 | 6583篇 |
1982年 | 6819篇 |
1981年 | 6523篇 |
1980年 | 6318篇 |
1979年 | 6680篇 |
1978年 | 7043篇 |
1977年 | 6972篇 |
1976年 | 7194篇 |
1975年 | 6657篇 |
1974年 | 6561篇 |
1973年 | 6865篇 |
1972年 | 5279篇 |
1971年 | 4585篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
The lidar equation for the vibrational backscattering of neodymium laser radiation and its harmonics by hydrogen molecules
is solved numerically. Inclined paths in the atmosphere are investigated with the aim of selecting the transmitter wavelength
for detecting the lowest concentrations of hydrogen.
Zh. Tekh. Fiz. 68, 20–22 (January 1998) 相似文献
12.
G. Ch. Shushkevich 《Technical Physics》1998,43(7):743-748
The electrostatic problem for a thin, unclosed spherical shell and a torus is reduced to paired summation equations in the
Legendre polynomials by means of formulas relating the spherical and toroidal harmonic functions. The paired equations are
transformed to a Fredholm integral equation of the second kind. Formulas are obtained for computing the charges of the conductors
in the form of a series in a small parameter. The capacitance is computed for certain geometrical parameters of the conductors.
Zh. Tekh. Fiz. 68, 1–6 (July 1998) 相似文献
13.
14.
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.
Myagchenkov V. A. Chichkanov S. V. Proskurina V. E. Myagchenkov A. V. 《Russian Journal of Applied Chemistry》2002,75(9):1485-1488
The Thoms effect observed with water-soluble cationic copolymer of acrylamide was studied in relation to the concentration, molecular weight, and molecular weight polydispersity of the polymeric additive, with its composition and composition polydispersity being constant. 相似文献
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.