全文获取类型
收费全文 | 76篇 |
免费 | 17篇 |
国内免费 | 14篇 |
专业分类
化学 | 31篇 |
力学 | 3篇 |
数学 | 3篇 |
物理学 | 70篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有107条查询结果,搜索用时 15 毫秒
1.
Fluorescence decay and quenching of pyrene labels on copolymers of 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N,N-dimethylacrylamide were observed in dilute salt-free aqueous solutions as a function of the mole fraction FAMPS of AMPS from 0 to 0.896. Monoexponential decay was found for the samples of FAMPS<0.35 and biexponential decay for the samples of FAMPS>0.35. The fast decay component is 80%, and the averaged lifetime 〈τ〉 and lifetime τ1 of the fast decay is decreased with increasing FAMPS. Quenching efficiency of Cu2+, I−, CH3NO2, and dinitrobenzene to the pyrene label was investigated in the framework of Stern-Volmer plot. With increasing FAMPS the quenching efficiency of Cu2+ is increased while that of I− decreased. For the neutral quenchers, the quenching rate constant kq increases when FAMPS<0.449 then decreases, showing a decline of accessibility to the pyrene label. These results were interpreted consistently with the counterion condensation concept, where condensed counterions caused the polyelectrolyte chains to aggregate. The existence of less-polar “temporal aggregated domain” in highly charged polyelectrolytes appears to lead to the slower decay and lower accessibility of the pyrene labels. 相似文献
2.
Dr. Roberta Pievo Brigitta Angerstein Dr. Alistair J. Fielding Dr. Christian Koch Prof. Dr. Ivo Feussner Prof. Dr. Marina Bennati 《Chemphyschem》2013,14(18):4094-4101
Electron paramagnetic resonance (EPR) spectroscopy in combination with the rapid freeze‐quench (RFQ) technique is a well‐established method to trap and characterize intermediates in chemical or enzymatic reactions at the millisecond or even shorter time scales. The method is particularly powerful for mechanistic studies of enzymatic reactions when combined with high‐frequency EPR (ν≥90 GHz), which permits the identification of substrate or protein radical intermediates by their electronic g values. In this work, we describe a new custom‐designed micro‐mix rapid freeze‐quench apparatus, for which reagent volumes for biological samples as small as 20 μL are required. The apparatus was implemented with homemade sample collectors appropriate for 9, 34, and 94 GHz EPR capillaries (4, 2, and 0.87 mm outer diameter, respectively) and the performance was evaluated. We demonstrate the application potential of the RFQ apparatus by following the enzymatic reaction of PpoA, a fungal dioxygenase producing hydro(pero)xylated fatty acids. The larger spectral resolution at 94 GHz allows the discernment of structural changes in the EPR spectra, which are not detectable in the same samples at the standard 9 GHz frequency. 相似文献
3.
Quench is important and dangerous to superconducting RF cavities. This paper illustrates the mechanism of quench and how a quench detector works, and analyzes the quench events happening during beam operations and cavity conditioning. We find that the quench protection is mostly triggered by some reasons such as fluctuation of cavity voltage, multipacting or arc, rather than a real cavity thermal breakdown. The results will be beneficial to optimize the operation parameters of superconducting cavities, to discover the real reasons for beam trip by quench interlock, and to improve the operation stability of superconducting RF systems. 相似文献
4.
5.
6.
The effects of adding A–B diblock copolymer to a polymer blend (A/B) on phase‐separation kinetics and morphology have been investigated in a fixed shallow‐quench condition (ΔT = 1.5 °C) by in situ time‐resolved light scattering and phase‐contrast optical microscopy. A shear‐quench technique was used in this study instead of a conventional temperature‐quench method. Mixtures of nearly monodisperse low relative‐molecular masses of polybutadiene (Mw = 2.8 kg/mol), polystyrene (Mw = 2.6 kg/mol), and a near‐symmetric butadiene–styrene diblock copolymer (Mw = 6.3 kg/mol) as an interfacial modifier were studied. We observed that the addition of the diblock copolymer could either retard or accelerate the phase‐separation kinetics depending on the concentration of the diblock copolymer in the homopolymer blends. In contrast to the conventional temperature quench, we observed complex phase‐separation kinetics in the intermediate and late stages of phase separation by the shear‐quench technique. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 819–830, 2001 相似文献
7.
国际反质子与离子研究装置(FAIR)项目中的Super-FRS超导二极磁铁是一个大型温铁结构的超导磁体,由中国负责设计、研制和测试。为了研究超导线圈的性能和其设计的可靠性,前期研制了一个测试线圈。建立了一个基于ANSYS和OPERA 3D的三维失超模型,不仅将模拟结果和实验数据进行对比,更可以获得失超过程的更多细节。模型将环氧浸渍的超导线圈简化为各项异性连续介质。将ANSYS求解器用于瞬态传热过程的分析,OPERA 3D用于磁场计算,并采用ANSYS脚本语言(APDL)进行焦耳热的计算和保护电路方程的求解。模拟得到了温度、电压、电流随时间的变化曲线和失超传播过程。最后将模拟结果和测试线圈的测试结果进行了比较。 相似文献
8.
In a previous paper we discussed co-crystallization in a LDPE/HDPE blend using TREF and DSC. As part of that study it was observed that pure HDPE showed an unexpected fractionation behavior when quench crystallized in TREF. The overall peak broadened and two peaks appeared instead of the previously observed single peak for slow cooled HDPE.The development of two peaks was observed for all commercial HDPEs investigated, independent of their melting indices and densities. TREF and GPC were used in an attempt to evaluate the origin of the two HDPE components.The authors appreciate support from CAPES-BRAZIL (C.A.F.). Additional thanks go to Dr. G. W. Knight in Dow Chemical Company for kindly providing the polymer samples and performing the GPC analysis. 相似文献
9.
荧光猝灭法研究苯乙烯氧化物与DNA的相互作用 总被引:1,自引:0,他引:1
荧光猝灭法是一种可以研究苯化合物与DNA相互作用的动态过程的方法。研究结果表明,苯乙烯氧化物与DNA的相互作用与苯乙烯氧化物浓度的关系服从动力学一级方程。 相似文献
10.