全文获取类型
收费全文 | 19561篇 |
免费 | 3628篇 |
国内免费 | 1793篇 |
专业分类
化学 | 9664篇 |
晶体学 | 292篇 |
力学 | 3136篇 |
综合类 | 297篇 |
数学 | 2946篇 |
物理学 | 8647篇 |
出版年
2024年 | 48篇 |
2023年 | 175篇 |
2022年 | 519篇 |
2021年 | 566篇 |
2020年 | 712篇 |
2019年 | 657篇 |
2018年 | 689篇 |
2017年 | 837篇 |
2016年 | 954篇 |
2015年 | 841篇 |
2014年 | 1138篇 |
2013年 | 1841篇 |
2012年 | 1224篇 |
2011年 | 1226篇 |
2010年 | 1034篇 |
2009年 | 1110篇 |
2008年 | 1057篇 |
2007年 | 1089篇 |
2006年 | 1072篇 |
2005年 | 966篇 |
2004年 | 853篇 |
2003年 | 767篇 |
2002年 | 717篇 |
2001年 | 654篇 |
2000年 | 611篇 |
1999年 | 516篇 |
1998年 | 440篇 |
1997年 | 428篇 |
1996年 | 407篇 |
1995年 | 335篇 |
1994年 | 272篇 |
1993年 | 203篇 |
1992年 | 185篇 |
1991年 | 130篇 |
1990年 | 113篇 |
1989年 | 103篇 |
1988年 | 97篇 |
1987年 | 59篇 |
1986年 | 63篇 |
1985年 | 49篇 |
1984年 | 54篇 |
1983年 | 14篇 |
1982年 | 45篇 |
1981年 | 37篇 |
1980年 | 12篇 |
1979年 | 18篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
Introduction In the previous studies on the oxidation reaction,peroxydisulfate was widely used as an oxidizingagent.1-5 One of the advantages of this oxidant lies in itsstability in a wide range of pH values. The reaction be-tween Fe(CN)5L3- (L=N-aromatic heterocyclic li-gands) and S2O8 2- has been proved to proceed throughan outer-sphere electron transfer mechanism.5 For a re-action [(Eq. (1)] to be under an outer-sphere mechanismthe steps involved are the formation of a reactant … 相似文献
54.
In this paper, we prove convergence rates for spherical spline Hermite interpolation on the sphere Sd−1 via an error estimate given in a technical report by Luo and Levesley. The functionals in the Hermite interpolation are either point evaluations of pseudodifferential operators or rotational differential operators, the desirable feature of these operators being that they map polynomials to polynomials. Convergence rates for certain derivatives are given in terms of maximum point separation. 相似文献
55.
Based on the discrete-structural theory of thin plates and shells, a calculation model for thin-walled elements consisting
of a number of rigid anisotropic layers is put forward. It is assumed that the transverse shear and compression stresses are
equal on the interfaces. Elastic slippage is allowed over the interfaces between adjacent layers. The solution to the problem
is obtained in a geometrically nonlinear statement with account of the influence of transverse shear and compression strains.
The stress-strain state of circular two-layer transversely isotropic plates, both without defects and with a local area of
adhesion failure at their center, is investigated numerically and experimentally. It is found that the kinematic and static
contact conditions on the interfaces of layered thin-walled structural members greatly affect the magnitude of stresses and
strains. With the use of three variants of calculation models, in the cases of perfect and weakened contact conditions between
layers, the calculation results for circular plates are compared. It is revealed that the variant suggested in this paper
adequately reflects the behavior of layered thin-walled structural elements under large deformations.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 761–772, November–December, 2005. 相似文献
56.
DEEB MARJI KHAMIS ABBAS 《Journal of inclusion phenomena and macrocyclic chemistry》1997,27(4):269-277
The effect of 18-crown-6 and kryptofix (2,2,1) on the oxidation of triethylamine byaqueous ferricyanide ion has been studied at pH 4, 7, and 9.The macrocycle retarded the normal oxidation process at all pH values,the effect depending on the macrocyclic ligand concentration Kryptofix (2,2,1) had a greater effect than 18-crown-6 at all pHvalues in this study. For 18-crown-6, retardation decreases in the order pH 9 > 4 > 7 while forkryptofix it follows the order pH 9 > 7 > 4. 相似文献
57.
Two Convergence Problems for Monotone Sequences 总被引:1,自引:0,他引:1
Eight measures of rate of convergence of monotone sequences of real numbers have been proposed and discussed in a paper by Beyer, Ebanks, and Qualls (Acta Appl. Math. 20 (1990), 267–284). These rates arose in discussions of dynamical systems. In the comparisons of these rates, two problems remained. A complete answer is given to one of the problems and a partial answer is given to the other problem. 相似文献
58.
We establish the optimal asymptotic decay rate of per-session queue length tail distributions for a two-queue system where
a single constant rate server serves the two queues using the Generalized Processor Sharing (GPS) scheduling discipline. The
result is obtained using the sample-path large deviation principle and has implications in call admission control for high-speed
communication networks.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
59.
60.