全文获取类型
收费全文 | 211篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 141篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 13篇 |
物理学 | 52篇 |
出版年
2020年 | 2篇 |
2019年 | 2篇 |
2016年 | 7篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 9篇 |
2011年 | 17篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 16篇 |
2007年 | 8篇 |
2006年 | 11篇 |
2005年 | 14篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 5篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 3篇 |
1965年 | 2篇 |
1961年 | 1篇 |
1960年 | 3篇 |
1959年 | 3篇 |
1948年 | 2篇 |
1902年 | 1篇 |
排序方式: 共有213条查询结果,搜索用时 93 毫秒
91.
R. P. Bahuguna Y. C. Joshi M. P. Dobhal R. K. Pande B. C. Joshi 《Journal of heterocyclic chemistry》1982,19(4):957-960
Synthesis and spectral studies (ir, 1H nmr, ms) of 1- and 3-substituted arylthiobenzo[f]quinolines (IIIa-IIIc, IVa-IVc) obtained through nucleophilic displacement of the corresponding halobenzo[f]quinoline by various thiols (a-c) were done. 相似文献
92.
93.
Alkaline aqueous solutions of β-naphthylamine show the edge effect; a decrease in the relative intensity or emission from the anion (RNH?) and the neutral molecule (RNH2) on red-edge excitation (REE) is observed. The nature of quenching of the neutral molecule by OH? ions also changes on REE. It is suggested that on REE, participation of some non-promoting out-of-plane modes slows down the proton-transfer rate in the excited state. 相似文献
94.
In previous work, we described a Markovian state model (MSM) for analyzing molecular-dynamics trajectories, which involved grouping conformations into states and estimating the transition probabilities between states. In this paper, we analyze the errors in this model caused by finite sampling. We give different methods with various approximations to determine the precision of the reported mean first passage times. These approximations are validated on an 87 state toy Markovian system. In addition, we propose an efficient and practical sampling algorithm that uses these error calculations to build a MSM that has the same precision in mean first passage time values but requires an order of magnitude fewer samples. We also show how these methods can be scaled to large systems using sparse matrix methods. 相似文献
95.
Recent work has demonstrated the Bennett acceptance ratio method is the best asymptotically unbiased method for determining the equilibrium free energy between two end states given work distributions collected from either equilibrium and nonequilibrium data. However, it is still not clear what the practical advantage of this acceptance ratio method is over other common methods in atomistic simulations. In this study, we first review theoretical estimates of the bias and variance of exponential averaging (EXP), thermodynamic integration (TI), and the Bennett acceptance ratio (BAR). In the process, we present a new simple scheme for computing the variance and bias of many estimators, and demonstrate the connections between BAR and the weighted histogram analysis method. Next, a series of analytically solvable toy problems is examined to shed more light on the relative performance in terms of the bias and efficiency of these three methods. Interestingly, it is impossible to conclusively identify a "best" method for calculating the free energy, as each of the three methods performs more efficiently than the others in at least one situation examined in these toy problems. Finally, sample problems of the insertion/deletion of both a Lennard-Jones particle and a much larger molecule in TIP3P water are examined by these three methods. In all tests of atomistic systems, free energies obtained with BAR have significantly lower bias and smaller variance than when using EXP or TI, especially when the overlap in phase space between end states is small. For example, BAR can extract as much information from multiple fast, far-from-equilibrium simulations as from fewer simulations near equilibrium, which EXP cannot. Although TI and sometimes even EXP can be somewhat more efficient in idealized toy problems, in the realistic atomistic situations tested in this paper, BAR is significantly more efficient than all other methods. 相似文献
96.
Summary A direct complexometric titration of iron(III) with EDTA using o- and p-cresotic acids indicators is given. The colour change at the end point is from blue-violet to light yellow or colourless [at low concentrations of iron(III)]. The optimum range of pH and temperature for carrying out the titrations is 1.99 to 4.2 and 35° to 55°C and 1.42 to 4.4 and 30° to 60° C, respectively. Iron(III) may easily and accurately be estimated in macro- and micro-gram quantities with the help of these metal indicators. Be, Mg, Ca, Sr, Ba, Cd, UO2 and Mn are without any interference in the estimation. Back titration procedures for determination of zirconium and thorium with iron(III) and o- and p-cresotic acids are carried out.Part V: See Z. analyt. Chem. 173, 196 (1960). 相似文献
97.
98.
Superparamagnetic monodispersed spherical beta-MnO 2 nanoparticles of approximately 10 nm size with a band gap of 2.52 eV have been synthesized in toluene and support the oxidative phenol coupling reaction as a photocatalyst. 相似文献
99.
100.
Asha Chaubey Krishan K. Pande Manoj K. Pandey Vijai S. Singh 《Applied biochemistry and biotechnology》2001,96(1-3):239-248
The bienzyme electrodes were fabricated by coimmobilization of lactate oxidase (LOD) and lactate dehydrogenase (LDH) onto
electrochemically prepared polyaniline (PANI) films. These PANI/LOD/LDH bienzyme electrodes were shown to provide signal amplification
by substrate recycling, making it possible to detect l-lactate at lower concentrations (0.1-1 mM). The PANI/LOD/LDH bienzyme electrodes were found to be stable for about 21 d at
4–10°C. 相似文献