全文获取类型
收费全文 | 4383篇 |
免费 | 244篇 |
国内免费 | 497篇 |
专业分类
化学 | 323篇 |
力学 | 83篇 |
综合类 | 49篇 |
数学 | 4188篇 |
物理学 | 481篇 |
出版年
2023年 | 59篇 |
2022年 | 30篇 |
2021年 | 47篇 |
2020年 | 81篇 |
2019年 | 118篇 |
2018年 | 123篇 |
2017年 | 109篇 |
2016年 | 123篇 |
2015年 | 102篇 |
2014年 | 204篇 |
2013年 | 397篇 |
2012年 | 140篇 |
2011年 | 237篇 |
2010年 | 179篇 |
2009年 | 315篇 |
2008年 | 361篇 |
2007年 | 306篇 |
2006年 | 258篇 |
2005年 | 263篇 |
2004年 | 198篇 |
2003年 | 200篇 |
2002年 | 194篇 |
2001年 | 141篇 |
2000年 | 128篇 |
1999年 | 137篇 |
1998年 | 125篇 |
1997年 | 132篇 |
1996年 | 68篇 |
1995年 | 46篇 |
1994年 | 43篇 |
1993年 | 27篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 5篇 |
1982年 | 21篇 |
1981年 | 19篇 |
1980年 | 15篇 |
1979年 | 19篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1976年 | 5篇 |
1973年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有5124条查询结果,搜索用时 15 毫秒
81.
Considering a system ofN identical interacting particles, which obey Fermi-Dirac or Bose-Einstein statistics, we derive new formulas for correlation functions of the type
(whereB
j is diagonal in the free-particle states) in the thermodynamic limit. Thereby we apply and extend a superoperator formalism, recently developed for the derivation of long-time tails in semiclassical systems. As an illustrative application, the Boltzmann equation value of the time-integrated correlation functionC(t) is derived in a straightforward manner. Due to exchange effects, the obtained t-matrix and the resulting scattering cross section, which occurs in the Boltzmann collision operator, are now functionals of the Fermi-Dirac or Bose-Einstein distribution. 相似文献
82.
Valentin Herbez 《Tetrahedron letters》2005,46(40):6797-6799
Polyethylene glycol tert-octylphenyl ether and polyoxyethylenesorbitan trioleate are polydisperse macromolecular detergent molecules, containing a single hydroxyl function, which was transformed by 1,1-carbonyldiimidazole into imidazole-detergent conjugates with a carbamate linkage. 相似文献
83.
G. A. Mezincescu 《Journal of statistical physics》1987,49(5-6):1181-1190
UsingX-bounding (lower bounds by Laplacians with mixed boundary conditions and discrete analogs), we obtain the Lifschitz exponent at the bottom of the spectrum for random operators of typeH
=T+V
, withT a (periodic) generator of a positivity-preserving semigroup, extending results by Kirsch and Simon. 相似文献
84.
We describe the first example of a catalytic enantioselective intermolecular reductive aldol reaction. Three types of reactions were studied: (1) reactions between acetophenone and methyl acrylate; (2) reactions between symmetric ketones and β-substituted α,β-unsaturated esters; and (3) reactions between acetophenone derivatives and an allenic ester. Although only moderate enantioselectivity was obtained in the first reaction type, high to excellent enantioselectivity was realized in the enantio-induction at the α-position in the second reaction type and at the δ-position in the third reaction type. Specifically, the third reaction type afforded the corresponding tertiary alcohols with up to 99% ee. Pre-activation of the nucleophile by silyl enolate formation is not necessary in these one-pot catalytic enantioselective reductive aldol reactions. 相似文献
85.
Yoann Coquerel 《Journal of organometallic chemistry》2007,692(22):4805-4808
The palladium hydride-iminium complex generated from Pd/C and triethylamine catalyses the isomerisation of allylic alcohols into carbonyl compounds, and Pd/C catalyses the conjugate reduction of activated double bonds using triethylamine as the source of the two newly incorporated hydrogen atoms via the same complex. 相似文献
86.
Some Estimates for $θ$-Type Calderόn–Zygmund Operators and Linear Commutators on Certain Weighted Amalgam Spaces
下载免费PDF全文
![点击此处可从《分析论及其应用》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, we first introduce some new kinds of weighted amalgam
spaces. Then we discuss the strong type and weak type estimates for a class of
Calderόn–Zygmund type operators $T_θ$ in these new weighted spaces. Furthermore,
the strong type estimate and endpoint estimate of linear commutators $[b, T_θ]$ formed
by $b$ and $T_θ$ are established. Also we study related problems about two-weight, weak
type inequalities for $T_θ$ and $[b, T_θ]$ in the weighted amalgam spaces and give some
results. 相似文献
87.
Jean Saint Raymond 《Rendiconti del Circolo Matematico di Palermo》1995,44(1):162-168
Let (T, ℐ, μ) be a σ-finite atomless measure space,p∈[1,∞),E a real Banach space andf a measurable function:E xT→ℝ. We denote byF the functionalF:
and byDom(F) its domain, it is the set {uεL
p(T,E):ū(t)=f(u),t)εL
1(T)}, and we prove that the sublevelsS(λ)={u:F(u)≤λ} are all connected in the subspaceDom(F) of the Banach spaceL
p(T, E). 相似文献
88.
Ronghui Ji 《K-Theory》1995,9(1):59-76
For certain classes of discrete groups we verify the idempotent conjectures for various group algebras by the method of cyclic cohomology. In particular, the Banach 1 (G) of a torsion free word hyperbolic groupG of Gromov contains no nontrivial idempotents. Moreover, the range of any tracial state onK
0(1(G)) is .Sponsored in part by a grant from the National Science Foundation. 相似文献
89.
给出 Banach空间列{Xi}i=1∞的 lp乘积B-凸的特征刻划, 证明B-凸空间上的每个黎斯算子可West分解,即分解成一个紧算子和一个拟幂 零算子的和. 相似文献
90.
Alain Joye 《Journal of statistical physics》1994,75(5-6):929-952
The spectrum of the Floquet operator associated with time-periodic perturbations of discrete Hamiltonians is considered. If the gap between successive eigenvalues
j
of the unperturbed Hamiltonian grows as
j
-
j-1
j
and the multiplicity of
j
grows asj
with >0 asj tends to infinity, then the corresponding Floquet operator possesses no absolutely continuous spectrum provided the perturbation is smooth enough. 相似文献