全文获取类型
收费全文 | 287537篇 |
免费 | 3173篇 |
国内免费 | 671篇 |
专业分类
化学 | 154916篇 |
晶体学 | 4292篇 |
力学 | 12364篇 |
综合类 | 10篇 |
数学 | 33505篇 |
物理学 | 86294篇 |
出版年
2020年 | 2365篇 |
2019年 | 2619篇 |
2018年 | 3597篇 |
2017年 | 3525篇 |
2016年 | 5261篇 |
2015年 | 3289篇 |
2014年 | 4938篇 |
2013年 | 12093篇 |
2012年 | 9451篇 |
2011年 | 11268篇 |
2010年 | 7909篇 |
2009年 | 7624篇 |
2008年 | 10470篇 |
2007年 | 10692篇 |
2006年 | 9856篇 |
2005年 | 9035篇 |
2004年 | 8280篇 |
2003年 | 7408篇 |
2002年 | 7228篇 |
2001年 | 7692篇 |
2000年 | 6015篇 |
1999年 | 4635篇 |
1998年 | 4051篇 |
1997年 | 4024篇 |
1996年 | 3844篇 |
1995年 | 3514篇 |
1994年 | 3693篇 |
1993年 | 3362篇 |
1992年 | 3822篇 |
1991年 | 3819篇 |
1990年 | 3749篇 |
1989年 | 3587篇 |
1988年 | 3674篇 |
1987年 | 3575篇 |
1986年 | 3402篇 |
1985年 | 4521篇 |
1984年 | 4783篇 |
1983年 | 3982篇 |
1982年 | 4113篇 |
1981年 | 4051篇 |
1980年 | 4038篇 |
1979年 | 3961篇 |
1978年 | 4280篇 |
1977年 | 4189篇 |
1976年 | 4244篇 |
1975年 | 3923篇 |
1974年 | 3936篇 |
1973年 | 4112篇 |
1972年 | 2881篇 |
1971年 | 2410篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
151.
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
152.
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
153.
Matt Visser Carlos Barceló Stefano Liberati 《General Relativity and Gravitation》2002,34(10):1719-1734
Condensed matter systems, such as acoustics in flowing fluids, light in moving dielectrics, or quasiparticles in a moving superfluid, can be used to mimic aspects of general relativity. More precisely these systems (and others) provide experimentally accessible models of curved-space quantum field theory. As such they mimic kinematic aspects of general relativity, though typically they do not mimic the dynamics. Although these analogue models are thereby limited in their ability to duplicate all the effects of Einstein gravity they nevertheless are extremely important—they provide black hole analogues (some of which have already been seen experimentally) and lead to tests of basic principles of curved-space quantum field theory. Currently these tests are still in the realm of gedanken-experiments, but there are plausible candidate models that should lead to laboratory experiments in the not too distant future. 相似文献
154.
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
155.
156.
157.
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
158.
159.
160.