全文获取类型
收费全文 | 107篇 |
免费 | 2篇 |
专业分类
化学 | 72篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 6篇 |
物理学 | 29篇 |
出版年
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 10篇 |
2011年 | 12篇 |
2010年 | 11篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1988年 | 2篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1941年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 15 毫秒
81.
82.
Hydroxyzine hydrochloride forms two 1:1 inclusion complexes with β‐cyclodextrin in aqueous solution as confirmed by the 1H NMR titration and ROESY studies. One complex is formed by the deep penetration of the chlorophenyl ring from the wider rim side, while the mode of entry of the phenyl ring into the β‐CD cavity is not clear. The stoichiometry and overall association constant of the complexes have been determined by the treatment of 1H NMR shift data. Some chiral discrimination by the host between the two enantiomers of hydroxyzine hydrochloride is also indicated. 相似文献
83.
A method based on symmetrized splitting of the propagation operator in the finite difference scheme for non-paraxial beam propagation is presented. The formulation allows the solution of the second order scalar wave equation without having to make the slowly varying envelope and one-way propagation approximations. The method is highly accurate and numerically efficient. Unlike most Padé approximant based methods, it is non-iterative in nature and requires less computation. The method can be used for bi-directional propagation as well. 相似文献
84.
The yrast spectra, intrinsic quadrupole moments and root mean square radii for each angular momentum state, calculated for108–112Ru isotopes by carrying out Cranked-Hartree-Fock-Bogoliubov (CHFB) calculations. These calculations have been performed by employing pairing-plus-quadrupole-quadrupole effective interaction operating in a reasonably large valence space outside76Sr core. The experimentally available spectra upto 10+ is reasonably well reproduced. Our results indicate that there is a possibility for observing backbending phenomenon in108,110,112Ru at spins 12+, 20+ and 14+, respectively, which remains yet to be confirmed experimentally. 相似文献
85.
Recent studies in single-molecule enzyme kinetics reveal that the turnover statistics of a single enzyme is governed by the waiting time distribution that decays as mono-exponential at low substrate concentration and multi-exponential at high substrate concentration. The multi-exponentiality arises due to protein conformational fluctuations, which act on the time scale longer than or comparable to the catalytic reaction step, thereby inducing temporal fluctuations in the catalytic rate resulting in dynamic disorder. In this work, we study the turnover statistics of a single enzyme in the presence of inhibitors to show that the multi-exponentiality in the waiting time distribution can arise even when protein conformational fluctuations do not influence the catalytic rate. From the Michaelis-Menten mechanism of inhibited enzymes, we derive exact expressions for the waiting time distribution for competitive, uncompetitive, and mixed inhibitions to quantitatively show that the presence of inhibitors can induce dynamic disorder in all three modes of inhibitions resulting in temporal fluctuations in the reaction rate. In the presence of inhibitors, dynamic disorder arises due to transitions between active and inhibited states of enzymes, which occur on time scale longer than or comparable to the catalytic step. In this limit, the randomness parameter (dimensionless variance) is greater than unity indicating the presence of dynamic disorder in all three modes of inhibitions. In the opposite limit, when the time scale of the catalytic step is longer than the time scale of transitions between active and inhibited enzymatic states, the randomness parameter is unity, implying no dynamic disorder in the reaction pathway. 相似文献
86.
87.
Satendra S. Chauhan Arti Varshney Bhavana Verma Michael W. Pennington 《Tetrahedron letters》2007,48(23):4051-4054
l-Phosphonophenylalanine (Ppa) derivatives were synthesized from l-4-iodophenylalanine and suitably protected phosphites using Michaelis-Arbuzov reaction conditions in the presence of Pd(0) and triethylamine at 70 ± 2 °C. 相似文献
88.
89.
P.D. Townsend R. Brooks D.E. Hole Z. Wu A. Turkler N. Can A. Suarez-Garcia J. Gonzalo 《Applied physics. B, Lasers and optics》2001,73(4):345-353
The presence of copper nanoparticles in alumina and silica modifies their luminescence, and the changes in spectra are influenced
by variations in the nanoparticle size distributions. Luminescence signals are sensitive to the total defect population. Thus
the luminescence not only reflects changes caused by thermal annealing, which can modify both intrinsic defects and the copper
nanoparticles, but also responds to the method of preparation of thin film layers. Copper nanoparticle influence on luminescence
is reported both for ion-implanted bulk silica and for copper in pulsed laser deposition within alumina. Luminescence thus
potentially offers a non-destructive monitor of the layer quality, reproducibility and growth conditions, as well as the state
and size of the copper nanoparticles.
Received: 29 June 2001 / Published online: 10 October 2001 相似文献
90.
The heat and mass transfer characteristics of natural convection about a vertical surface embedded in a doubly stratified saturated porous medium subjected to a magnetic field is studied, taking into account the Dufour and Soret effects. It is found that the similarity solution exists for the case of uniform surface heat and mass flux conditions when the thermal and solutal stratification of the medium are assumed to have power function form x1/3. The resulting set of ordinary coupled nonlinear differential equations is solved numerically using shooting technique. Nusselt and Sherwood numbers are tabulated for various values of the involved parameters. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献