全文获取类型
收费全文 | 314篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
化学 | 219篇 |
力学 | 1篇 |
数学 | 36篇 |
物理学 | 72篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 15篇 |
2012年 | 14篇 |
2011年 | 13篇 |
2010年 | 13篇 |
2009年 | 19篇 |
2008年 | 20篇 |
2007年 | 15篇 |
2006年 | 16篇 |
2005年 | 17篇 |
2004年 | 19篇 |
2003年 | 14篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1967年 | 1篇 |
1958年 | 3篇 |
排序方式: 共有328条查询结果,搜索用时 15 毫秒
51.
We redox-regulated alpha-helicity of short peptides intramolecularly cross-linked with a ferrocenyl linker between amino acid side chains. The helical content of the cross-linked peptide was estimated to be 56% in the neutral state of the ferrocene core at 25 degrees C. The addition of an oxidant to the solution of the cross-linked peptide enhanced the helicity up to 75%. The increased helical content returned to the same level as that in the previous ferrocene state by further addition of a reductant. 相似文献
52.
53.
Simon Burk Markus Albrecht Kazuhisa Hiratani 《Journal of inclusion phenomena and macrocyclic chemistry》2008,61(3-4):353-359
A novel tripodand-type ligand (L1) having three 2,3-dihydroxynaphthalene end groups and a C3 symmetric 1,3,5-tryimethylbenzene based backbone was prepared by the reaction of 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene with 3-(2-(hydroxymethyl)allyloxy)naphthalene-2-ol followed by triple Claisen rearrangement. A 1:1 titanium complex which acts as a metallo-cryptand is obtained by the reaction of ligand (L1) with Ti(IV)(=O)(acac)2 in the presence of base. The formation of the metallo-cryptand strongly depends on templating effects by counter cations and it shows a high selectively for the encapsulation of cesium cations in its cavity. 相似文献
54.
An Inverse Problem for Maxwell’s Equations in Anisotropic Media 总被引:3,自引:0,他引:3
The authors consider Maxwell's equations for an isomagnctic anisotropic and inhomogeneous medium in two dimensions, and discuss an inverse problem of determining the permittivity tensor (ε1ε2ε2ε3) and the permeabilityμin the constitutive relations from a finite number of lateral boundary measurements. Applying a Carlcman estimate, the authors prove an estimate of the Lipschitz type for stability, provided thatε1,ε2,ε3,μsatisfy some a priori conditions. 相似文献
55.
Shimizu H Fujimoto K Furusyo M Maeda H Nanai Y Mizuno K Inouye M 《The Journal of organic chemistry》2007,72(4):1530-1533
We newly prepared para- and meta-linked alkynylpyrene oligomers and examined their photophysical properties. Oligomerization of monomeric building blocks was performed by CuI-promoted oxidative coupling reaction. The resulting oligomers mainly consist of 2-mer to 6-mer that were assigned on the basis of MALDI-TOF mass spectra, and the 2-mer, 3-mer, and 4-mer were isolated and fully characterized. From their absorption and fluorescence spectra, the para-linked oligomers were found to be somewhat pi-conjugated compared with meta-linked ones, and the fluorescence quantum yields decreased with increasing oligomer length (Phif = 0.79-0.55). 相似文献
56.
Takashi Nakamura Keiji Yashiro Kazuhisa Sato Junichiro Mizusaki 《Journal of solid state chemistry》2009,182(5):1121-299
In order to elucidate the relation between thermodynamic quantities, the defect structure, and the defect equilibrium in La2−xSrxNiO4+δ, statistical thermodynamic calculation is carried out and calculated results are compared to those obtained from experimental data. Partial molar enthalpy of oxygen and partial molar entropy of oxygen are obtained from δ-P(O2)-T relation by using Gibbs-Helmholtz equation. Statistical thermodynamic model is derived from defect equilibrium models proposed before by authors, localized electron model and delocalized electron model which could well explain the variation of oxygen content of La2−xSrxNiO4+δ. Although assumed defect species and their equilibrium are different, the results of thermodynamic calculation by localized electron model and delocalized electron model show minor difference. Calculated results by the both models agree with the thermodynamic quantities obtained from oxygen nonstoichiometry of La2−xSrxNiO4+δ. 相似文献
57.
The authors prove a new Carleman estimate for general linear second order parabolic equation with nonhomogeneous boundary conditions. On the basis of this estimate, improved Carleman estimates for the Stokes system and for a system of parabolic equations with a penalty term are obtained. This system can be viewed as an approximation of the Stokes system. 相似文献
58.
Kazuo YAMAMOTO 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2014,90(2):67-82
Glycoprotein quality control is categorized into three kinds of reactions; the folding of nascent glycoproteins, ER-associated degradation of misfolded or unassembled glycoproteins, and transport and sorting of correctly folded glycoproteins. In all three processes, N-glycans on the glycoproteins are used as tags that are recognized by intracellular lectins. We analyzed the functions of these intracellular lectins and their sugar-binding specificities. The results clearly showed that the A, B, and C-arms of high mannose-type glycans participate in the folding, transport and sorting, and degradation, respectively, of newly synthesized peptides. After correctly folded glycoproteins are transported to the Golgi apparatus, N-glycans are trimmed into Man3GlcNAc2 and then rebuilt into various complex-type glycans in the Golgi, resulting in the addition of diverse sugar structures that allow glycoproteins to play various roles outside of the cells. 相似文献
59.
Dr. Kazuhisa Fujimoto Dr. Masaoki Kajino Ikumi Sakaguchi Prof. Dr. Masahiko Inouye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(32):9834-9840
Diarylethene‐bridged peptides were developed to photoregulate biomolecular interactions. The peptides are made up of diarylethene‐bridged and DNA‐binding regions at their N‐ and C termini, respectively. The two regions could be independently designed and combined as desired. The α‐helicities of the peptides were photoregulated in on/off or off/on manners, and the manner depended on the positions of two ornithine (Orn) residues for cross‐linking reaction at the diarylethene‐bridged region. In the case of the on/off manner, when the diarylethene structure adopted the open form on the peptides, the peptides folded into stable α‐helices. Upon UV irradiation, the diarylethene moiety isomerized to its closed form to destabilize the helical structures. Quartz crystal microbalance (QCM) analysis showed that the open isomer strongly associated with a target DNA, as compared with the closed one. When the closed‐form peptide existing in the DNA complex was irradiated with a fluorescent lamp in the middle of the QCM monitoring, the frequency change (ΔF) was enhanced by the diarylethene photoisomerization. 相似文献
60.
Kazuhisa Makino Yushi Uno Toshihide Ibaraki 《Journal of Algorithms in Cognition, Informatics and Logic》2001,38(2):411
In this paper, we introduce the problem of computing a minimum edge ranking spanning tree (MERST); i.e., find a spanning tree of a given graph G whose edge ranking is minimum. Although the minimum edge ranking of a given tree can be computed in polynomial time, we show that problem MERST is NP-hard. Furthermore, we present an approximation algorithm for MERST, which realizes its worst case performance ratio
where n is the number of vertices in G and Δ* is the maximum degree of a spanning tree whose maximum degree is minimum. Although the approximation algorithm is a combination of two existing algorithms for the restricted spanning tree problem and for the minimum edge ranking problem of trees, the analysis is based on novel properties of the edge ranking of trees. 相似文献