全文获取类型
收费全文 | 2453篇 |
免费 | 314篇 |
国内免费 | 238篇 |
专业分类
化学 | 1048篇 |
晶体学 | 12篇 |
力学 | 438篇 |
综合类 | 40篇 |
数学 | 641篇 |
物理学 | 826篇 |
出版年
2024年 | 2篇 |
2023年 | 20篇 |
2022年 | 28篇 |
2021年 | 63篇 |
2020年 | 60篇 |
2019年 | 59篇 |
2018年 | 64篇 |
2017年 | 72篇 |
2016年 | 67篇 |
2015年 | 70篇 |
2014年 | 117篇 |
2013年 | 142篇 |
2012年 | 141篇 |
2011年 | 143篇 |
2010年 | 127篇 |
2009年 | 142篇 |
2008年 | 152篇 |
2007年 | 157篇 |
2006年 | 156篇 |
2005年 | 122篇 |
2004年 | 117篇 |
2003年 | 120篇 |
2002年 | 113篇 |
2001年 | 70篇 |
2000年 | 94篇 |
1999年 | 86篇 |
1998年 | 72篇 |
1997年 | 60篇 |
1996年 | 53篇 |
1995年 | 51篇 |
1994年 | 52篇 |
1993年 | 54篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 10篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 17篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有3005条查询结果,搜索用时 46 毫秒
1.
Enantiomeric Cyclic Peptides with Different Caco‐2 Permeability Suggest Carrier‐Mediated Transport 下载免费PDF全文
B. Sc. Eduard Puig Prof. Dr. Beat Ernst Prof. Dr. Horst Kessler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8023-8027
Recently, oral absorption of cyclic hexapeptides was improved by N‐methylation of their backbone amides. However, the number and position of N‐methylations or of solvent exposed NHs did not correlate to intestinal permeability, measured in a Caco‐2 model. In this study, we investigate enantiomeric pairs of three polar and two lipophilic peptides to demonstrate the participation of carrier‐mediated transporters. As expected, all the enantiomeric peptides exhibited identical lipophilicity (logD7.4) and passive transcellular permeability determined by the parallel artificial membrane permeability assay (PAMPA). However, the enantiomeric polar peptides exhibited different Caco‐2 permeability (Papp) in both directions a–b and b–a. The same trend was observed for one of the lipophilic peptide, whereas the second lipophilic enantiomer pair showed identical Caco‐2 permeability (within the errors). These findings provide the first evidence for the involvement of carrier‐mediated transport for peptides, especially for those of polar nature. 相似文献
2.
3.
通过建立具有平面近横向各向异性场的非晶态合金薄带及膜的磁畴结构模型,利用线性化Maxwell方程组及Landau-Lifshitz方程,推出了在高频交变磁场及外加面内轴向直流磁场Hex作用下的铁磁材料的与取向相关的磁导率表达式,得到了对方位角平均的相对磁导率及阻抗的计算式,导出了磁导率与张量磁化率分量间的关系,对材料磁导率的实部及虚部随Hex的变化进行了计算,并给出了对应的磁谱图.建立的磁导率与外磁场的理论关系可将Panina及Kraus给出的理论结果统一起来.
关键词:
非晶态合金薄带及膜
取向相关磁导率
GMI效应理论与计算
近横向各向异性场 相似文献
4.
5.
6.
R. J. Saykally K. M. Evenson D. A. Jennings L. R. Zink A. Scalabrin 《International Journal of Infrared and Millimeter Waves》1987,8(6):653-662
Twenty new cw FIR laser lines in CD3OH, optically pumped by a CO2 laser, are reported. The frequencies of 39 of the stronger laser lines were measured relative to stabilized CO2 lasers with a fractional uncertainty, as determined by the reproducibility of the FIR frequency itself, of 2 parts in 107.Contribution of the U.S. Government, not subject to copyright. 相似文献
7.
A one-dimensional bulk reaction model for the oxidation of nickeltitanium is formulated, with preferential oxidation of titaniumbeing included. The modelling is directed at the better understandingof the dominant mechanisms involved in the oxidation processand their significance for the biocompatibility of the alloy.Two different regimes for the relative diffusivities of oxygenand the metals are investigated. By assuming fast bulk reactions,different asymptotic structures emerge in different parameterregimes and the resulting models take the form of moving boundaryproblems. Different profiles of nickel concentration are obtained:in particular a nickel-rich layer (observed in practice) ispresent below the oxide/metal interface for the case when oxygenand the metals diffuse at comparable rates. 相似文献
8.
We investigate the effects of adding uniformity requirements to concepts in computable structure theory such as computable categoricity (of a structure) and intrinsic computability (of a relation on a computable structure). We consider and compare two different notions of uniformity, previously studied by Kudinov and by Ventsov. We discuss some of their results and establish new ones, while also exploring the connections with the relative computable structure theory of Ash, Knight, Manasse, and Slaman and Chisholm and with previous work of Ash, Knight, and Slaman on uniformity in a general computable structure-theoretical setting. 相似文献
9.
10.
We investigate a new interpretation for the Navier-Stokes corrections to the hydrodynamic equation of asymmetric interacting particle systems. We consider a system that starts from a measure associated with a profile that is constant along the drift direction. We show that under diffusive scaling the macroscopic behavior of the process is described by a nonlinear parabolic equation whose diffusion coefficient coincides with the diffusion coefficient of the hydrodynamic equation of the symmetric version of the process. 相似文献