全文获取类型
收费全文 | 277071篇 |
免费 | 4264篇 |
国内免费 | 2156篇 |
专业分类
化学 | 149661篇 |
晶体学 | 4301篇 |
力学 | 12541篇 |
综合类 | 103篇 |
数学 | 30799篇 |
物理学 | 86086篇 |
出版年
2020年 | 2429篇 |
2019年 | 2718篇 |
2018年 | 3464篇 |
2017年 | 3420篇 |
2016年 | 4997篇 |
2015年 | 3245篇 |
2014年 | 4876篇 |
2013年 | 11423篇 |
2012年 | 8944篇 |
2011年 | 10775篇 |
2010年 | 7792篇 |
2009年 | 7545篇 |
2008年 | 10016篇 |
2007年 | 10081篇 |
2006年 | 9384篇 |
2005年 | 8550篇 |
2004年 | 7857篇 |
2003年 | 7127篇 |
2002年 | 7156篇 |
2001年 | 7736篇 |
2000年 | 5919篇 |
1999年 | 4579篇 |
1998年 | 4042篇 |
1997年 | 3974篇 |
1996年 | 3694篇 |
1995年 | 3435篇 |
1994年 | 3572篇 |
1993年 | 3254篇 |
1992年 | 3718篇 |
1991年 | 3722篇 |
1990年 | 3635篇 |
1989年 | 3484篇 |
1988年 | 3588篇 |
1987年 | 3479篇 |
1986年 | 3294篇 |
1985年 | 4368篇 |
1984年 | 4645篇 |
1983年 | 3883篇 |
1982年 | 4009篇 |
1981年 | 3943篇 |
1980年 | 3914篇 |
1979年 | 3883篇 |
1978年 | 4193篇 |
1977年 | 4108篇 |
1976年 | 4175篇 |
1975年 | 3851篇 |
1974年 | 3898篇 |
1973年 | 4052篇 |
1972年 | 2851篇 |
1971年 | 2380篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
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
132.
P. Seelig A. Dax S. Faber M. Gerlach G. Huber T. Kühl D. Marx P. Merz W. Quint F. Schmitt H. Winter M. Würtz 《Hyperfine Interactions》1998,114(1-4):135-139
The investigation of the 1s HFS provides a good possibility for testing QED effects in a combination of a strong electric
and magnetic field. Here, we report about the laserspectroscopic measurements of the ground state hyperfine splitting in 207Pb81+. To handle this M1-transition in the infrared optical regime with its long lifetime, we developed a new detection technique
using a bunched ion beam. For the observation of fluorescence light, a new mirror system is adapted to the emission characteristics
from an ion beam at relativistic velocities.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
133.
The dependence of distribution functions of quarks, antiquarks, diquarks and their fragmentation into hadrons on the transverse momentumk t is discussed in the frame of the quark-gluon string model. We then discuss the division ofk t between 2n-quark-antiquark chains, orn-pomeron showers. Hadron and hadron-nuclear processesp?p,p?A,K +?p,K +?A are analysed. A strong dependence of the observed values on the numbern is derived by this method, which is of special importance for the analysis of hadron-nucleus collisions. Our method is compared with the regulark t division method. 相似文献
134.
A. Negr n-Mendoza G. Albarran S. Ramos-Bernal 《Radiation Physics and Chemistry》1993,42(4-6):1003-1006
The effect of clay on the radiolysis of malonic acid solutions was studied. The results showed an enhanced of decarboxylation rather than condensation reactions. 相似文献
135.
G. I. Bizhanova 《Journal of Mathematical Sciences》1997,84(1):823-844
Multidimensional two-phase Stefan (k=1) and nonstationary filtration Florin (k=0) problems for second order parabolic equations in the case when the free boundary is a graph of a functionx n =Ψ k (x′t),x′∈ n?1 ,n≥2,t∈(0,T) are studied. A unique solvability theorem in weighted Hölder spaces of functions with time power weight is proved, coercive estimates for solutions are obtained. Bibliography: 30 titles. 相似文献
136.
137.
138.
HIRFL–CSR加速器中束流与真空中剩余气体的碰撞损失 总被引:1,自引:1,他引:0
研究了重离子加速器中束流与真空中剩余气体的碰撞损失过程和碰撞截面,在依据大量实验数据的基础上,提出了一组计算离子一原子的电荷交换截面的经验公式.以兰州重离子加速器HDRFL及冷却储存环CSR为例,给出了依据碰撞截面的公式计算束流在加速器真空中的传输效率的方法,并计算了在不同真空度下HIRFL的ECR源轴向注入束运线、注入器SFC、前束运线、主加速器SSC和后束运线等不同加速阶段及CSR的传输效率,并提出合理的真空度要求.HIRFL的真空分布测量和束流的损失测量证明了该计算方法的可靠性. 相似文献
139.
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
140.