全文获取类型
收费全文 | 592篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
化学 | 475篇 |
晶体学 | 13篇 |
力学 | 8篇 |
数学 | 20篇 |
物理学 | 104篇 |
出版年
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 18篇 |
2015年 | 17篇 |
2014年 | 16篇 |
2013年 | 17篇 |
2012年 | 21篇 |
2011年 | 18篇 |
2010年 | 19篇 |
2009年 | 20篇 |
2008年 | 37篇 |
2007年 | 38篇 |
2006年 | 29篇 |
2005年 | 24篇 |
2004年 | 25篇 |
2003年 | 21篇 |
2002年 | 26篇 |
2001年 | 12篇 |
2000年 | 18篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 13篇 |
1979年 | 15篇 |
1978年 | 13篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1969年 | 4篇 |
1923年 | 3篇 |
排序方式: 共有620条查询结果,搜索用时 31 毫秒
601.
602.
The Raman Scattering from amorphous SeGe is studied in the whole range of germanium content up to 80%. The result suggests an appearance of three-fold coordinated bond between Se and Ge above the germanium con- content of 40%. 相似文献
603.
The propagation of light rays in a slab-waveguide whose dielectric constant varies radially with a quadratic law but has fourth and sixth order terms in it is described. Exact solutions consisting of Jacobi elliptic functions are shown. The exact ray trajectory and delay time of an optical pulse, therefore, can be obtained. The results show that the optimum fourth-order and sixth-order coefficients are near 2/3 and 17/45, respectively. 相似文献
604.
605.
606.
Y. Taniguchi A. Irizawa K. Iizuka K. Shimai T. Nanba T. Matsumura 《Infrared Physics & Technology》2008,51(5):438-439
We performed a spectromicroscopic measurement on TmTe single crystal with fractured surface in THz to visible regions (25 meV to 2.5 eV) at 300 K and at pressures up to 6 GPa by using a diamond anvil cell (DAC) at the spectromicroscopy station (BL43IR) of SPring-8 in the THz region and also at Kobe University in the IR–visible regions. At pressures above around 1 GPa, a prominent Drude-like structure due to the appearance of the conduction electrons was resolved in the reflection spectra. From the analysis of the spectra by a simple Drude model, we found that the pressure-induced metallic state behaves as a heavy electron system. 相似文献
607.
Matsumura S Sakamoto S Ueno A Mihara H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(10):1781-1788
In order to apply de novo peptide design to molecular sensing, we designed and synthesized a-helical peptides with beta-cyclodextrin (beta-CDx) as a binding site and a dansyl unit (Dns) as a fluorescence sensing site. The conformational and molecular sensing properties of the peptides with beta-CDx and Dns in various positions were investigated. Circular dichroism and fluorescence measurements revealed that beta-CDx and Dns form intramolecular complexes which depend on their positions in the peptides. In the 17 residual peptides named EK3 and EK3R, in which beta-CDx and Dns were introduced at the fourth and the eighth positions (EK3) or at the eighth and the fourth positions (EK3R), Dns was deeply included in the CDx cavity and formed a more stable self-inclusion complex with CDx than in the peptides EK6 and EK6R, in which these moieties were at the eighth and the fifteenth positions or at the fifteenth and the eighth positions, respectively. The stability of the self-inclusion complex between beta-CDx and Dns controlled the a-helix structure as well as the binding and sensing abilities for the exogenous guests. These results demonstrate the usefulness of peptide tertiary structure for arranging CDx and other functional units, and suggest that this approach is important in the development of a new type of CDx-based sensory system. 相似文献
608.
The first total synthesis of dragmacidin A has been accomplished using condensation of two indolylglycines followed by cyclization and reduction. The general and practical method for synthesis of indolylglycines via Wittig reaction, azide addition, and reduction from indolin-3-ones is also described. 相似文献
609.
Effect of wood properties on within-tree variation in ultrasonic wave velocity in softwood 总被引:2,自引:0,他引:2
The radial variations in the velocity of longitudinal waves propagating through Japanese cedar and Japanese cypress were experimentally investigated. In addition, the tracheid length (TL), microfibril angle (MFA), air-dried density (AD), and moisture content (MC) were measured in order to determine the effect of wood properties on velocity variations within the wood trunk. For both species, the longitudinal wave velocities measured in the longitudinal direction (VL) exhibited minimum values near the pith. For Japanese cedar, VL increased from 3600 m/s toward the bark and soon attained a constant value (=4500 m/s). On the other hand, for Japanese cypress, VL kept increasing from 4000 m/s near the pith to 4800 m/s at the bark. These radial variations in VL coincided with those in the tracheid length. VL exhibited strong correlations with TL and MFA with a significant level of (p < 0.01). These findings suggest that the TL and MFA greatly affect the radial variation in the ultrasonic wave velocity in softwood. 相似文献
610.
Yamaguchi K Okamoto N Tokuoka K Sugiyama S Uchiyama N Matsumura H Inaka K Urade Y Inoue T 《Journal of synchrotron radiation》2011,18(1):66-69
Old yellow enzyme (OYE) is an NADPH oxidoreductase which contains flavin mononucleotide as prosthetic group. The X-ray structures of OYE from Trypanosoma cruzi (TcOYE) which produces prostaglandin (PG) F(2α) from PGH(2) have been determined in the presence or absence of menadione. The binding motif of menadione, known as one of the inhibitors for TcOYE, should accelerate the structure-based development of novel anti-chagasic drugs that inhibit PGF(2α) production specifically. 相似文献