全文获取类型
收费全文 | 14084篇 |
免费 | 517篇 |
国内免费 | 607篇 |
专业分类
化学 | 4834篇 |
晶体学 | 140篇 |
力学 | 225篇 |
综合类 | 51篇 |
数学 | 6317篇 |
物理学 | 1954篇 |
综合类 | 1687篇 |
出版年
2023年 | 54篇 |
2022年 | 135篇 |
2021年 | 103篇 |
2020年 | 166篇 |
2019年 | 292篇 |
2018年 | 286篇 |
2017年 | 250篇 |
2016年 | 229篇 |
2015年 | 234篇 |
2014年 | 390篇 |
2013年 | 653篇 |
2012年 | 476篇 |
2011年 | 720篇 |
2010年 | 612篇 |
2009年 | 937篇 |
2008年 | 841篇 |
2007年 | 837篇 |
2006年 | 708篇 |
2005年 | 624篇 |
2004年 | 745篇 |
2003年 | 658篇 |
2002年 | 612篇 |
2001年 | 498篇 |
2000年 | 447篇 |
1999年 | 397篇 |
1998年 | 315篇 |
1997年 | 282篇 |
1996年 | 328篇 |
1995年 | 283篇 |
1994年 | 332篇 |
1993年 | 244篇 |
1992年 | 212篇 |
1991年 | 138篇 |
1990年 | 106篇 |
1989年 | 114篇 |
1988年 | 93篇 |
1987年 | 101篇 |
1986年 | 75篇 |
1985年 | 69篇 |
1984年 | 70篇 |
1983年 | 21篇 |
1982年 | 58篇 |
1981年 | 74篇 |
1980年 | 68篇 |
1979年 | 82篇 |
1978年 | 61篇 |
1977年 | 59篇 |
1976年 | 44篇 |
1974年 | 22篇 |
1973年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Mohamed Krir 《manuscripta mathematica》1998,96(1):9-16
Let R be a complete discrete valuation ring with mixed characteristic. Denote by K its field of fractions and by k its residue field. Let 0 →A
K
→B
K
→C
K
→ 0 be an exact sequence of abelian varieties over K and consider the corresponding complex of Nérons models 0 →A→B→C→ 0, over R. We assume that the identity component B
k
0 of the special fibre B
k
of B is a torus and we study the defect of exactmess at B in this last sequence.
Re?u: 4 décembre 1997/ Version revisée: 15 décembre 1997 相似文献
103.
谢成根 《淮北煤炭师范学院学报(自然科学版)》2002,23(2):29-31
在Na2CO3-NaHCO3介质中,酪氨酸对Luminol-K3Fe(CN)6化学发光体系有很强的增敏作用.据此建立了流动注射化学发光增强法测定酪氨酸的方法.发光信号的增强值(ΔI)与酪氨酸的浓度在5.0×10-5~4.0×10-7mol/L的范围内呈良好的线性关系,检出限为1×10-7mol/L(S/N=3),对于1.0×10-6mol/L的酪氨酸测定相对标准偏差为2.4%(N=11).该法用于测定医用氨基酸注射液中的酪氨酸,结果令人满意. 相似文献
104.
We study a degenerate nonlinear variational inequality which can be reduced to a multivalued inclusion by an appropriate change
of the unknown function. We establish existence, uniqueness and regularity results. An application arising in the theory of
water diffusion in porous media is discussed as an example.
相似文献
105.
The results of the electronic structures and conduction properties of four novel donor-acceptor polymers based on polysilole, obtained on the basis of ab initio Hartree-Fock crystal orbital method using their optimized geometries, are reported. The repeat unit of these polymers consists of bicyclopentadisilole unit bridged by an electron-accepting group Y(Y=CCH2 in PSICH, CO in PSICF, CCF2 and CC(CN)2 in PSICN). All the polymers on the basis of their geometries and π-bond order values are found to have benzenoid-type electronic structures. Comparison of the important electronic properties such as ionization potential, electron affinity and band-gap of these polymers indicates PSICN to be the best candidate for intrinsic conductivity and reductive (n-) doping while PSICH is predicted to be the best candidate for oxidative (p-) doping. All these polymers are estimated to have band-gap values ranging between 1 and 2 eV. The low band-gap values of these polymers are rationalised on the basis of the patterns of their frontier orbitals. 相似文献
106.
XIE Fu-Ding Xiao-Shan LIU Feng 《理论物理通讯》2004,42(11)
Based on the rank analysis method, algorithmization idea, and symbolic computation, in this paper we have presented a method to construct the conservation laws for nonlinear evolution equations. The polynomial conservation laws for K (n 2, n) equations and mnK(m, n) equations are found by using of this approach and some new results have been obtained. 相似文献
107.
Li Taihua An Zhu Luo Zhengming Center for Radiation Physics Institute of Nuclear Science Technology Sichuan Union University Chengdu 《原子与分子物理学报》1997,(1)
MEASUREMENTSOFFeANDCuK-ShelIONIZATIONCROSSSECTIONSBYSLOWELECTRONIMPACTLiTaihuaAnZhuLuoZhengmingCenterforRadiationPhysics,Ins... 相似文献
108.
金淦 《Annals of Differential Equations》1998,(4)
1IntroductionStabilityintermsoftwomeasures,thisconceptenableustounifyava-rietyofstabilityconceptsandtoofferageneralandunifiedframeworkforinvestigationofstabilitytheory.AndtheoriginalLiapunovtheoremshavebeenextended,generalizedandweakenedinvariousaspects[3… 相似文献
109.
C. Ruyer-Quil P. Manneville 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(2):277-292
A new model of film flow down an inclined plane is derived by a method combining results of the classical long wavelength
expansion to a weighted-residuals technique. It can be expressed as a set of three coupled evolution equations for three slowly
varying fields, the thickness h, the flow-rate q, and a new variable that measures the departure of the wall shear from the shear predicted by a parabolic velocity profile. Results of a preliminary
study are in good agreement with theoretical asymptotic properties close to the instability threshold, laboratory experiments
beyond threshold and numerical simulations of the full Navier-Stokes equations.
Received: 16 April 1998 / Revised: 29 June 1998 / Accepted: 2 July 1998 相似文献
110.
Let (X,0) be the germ of a normal space of dimension n+1 and let f be the germ at 0 of a holomorphic function on X. Assume both X and f have an isolated singularity at 0. Denote by J the image of the restriction map , where F is the Milnor fibre of f at 0. We prove that the canonical Hermitian form on , given by poles of order at in the meromorphic extension of , passes to the quotient by J and is non-degenerate on . We show that any non-zero element in J produces a “mass concentration” at the singularity which is related to a simple pole concentrated at for (in a non-na?ve sense). We conclude with an application to the asymptotic expansion of oscillatory integrals , for , when .
Received: 28 May 2001 / Published online: 26 April 2002 相似文献