全文获取类型
收费全文 | 86篇 |
免费 | 25篇 |
国内免费 | 18篇 |
专业分类
化学 | 59篇 |
力学 | 5篇 |
数学 | 4篇 |
物理学 | 61篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 12篇 |
2013年 | 4篇 |
2012年 | 15篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有129条查询结果,搜索用时 265 毫秒
91.
《Electroanalysis》2006,18(24):2405-2412
A method based on the combined use of multivariate curve resolution by alternating least squares (MCR‐ALS) with phase sensitive alternating current polarography (ACP) is proposed to evaluate the phase angle where capacitive current is minimized in a much more accurate way than the visual inspection of ACP signals. The method allows, through the analysis of series of AC polarograms measured at different phase angles out the potential, to distinguish between faradaic and capacitive contributions. Then the angle at which the capacitive current is negligible can be shown and, in some cases, the influence of adsorption on measured currents minimized. 相似文献
92.
Noureldin M. Ibrahim Ismail H. A. Fattah Mahmoud H. Ahmed 《Fiber and Integrated Optics》1994,13(4):373-379
A design for a 3-dB single-mode Y-junction has been developed and investigated by the beam propagation method with a purpose of decreasing radiation loss in the case of power dividers. The design has two aspects. The first introduces a general design of the boundaries of the 3-dB Y-junction. The second aspect is the replacement of a strip of the guiding material with a lower refractive index near the branching vertex. The design is optimized for low radiation loss, so the output power is increased by 42% over a conventional design. 相似文献
93.
Mahmoud Labib Martin Hedstr?m Magdy Amin Bo Mattiasson 《Analytical and bioanalytical chemistry》2009,393(5):1539-1544
A sensitive method for the detection of staphylococcal enterotoxin B (SEB) using a flow-injection capacitive biosensor is
presented. SEB was purified from a crude culture filtrate of Staphylococcus aureus through three chromatographic steps. The first two steps were based on ion-exchange chromatography, and the last step was
carried out on a gel filtration column. The SEB recovery values after the purification stages were 88%, 74%, and 12%, respectively.
A horseradish peroxidase labeled antistaphylococcal enterotoxin B was prepared by the periodate method and was further employed
in a sandwich-enzyme-linked immunosorbent assay (ELISA) for the determination of SEB concentrations in different samples obtained
during the processing of the crude filtrate. The capacitive biosensor could detect SEB concentrations as low as 0.3 pg ml−1 with a linearity ranging from 2.8 pg ml−1 to 2.8 ng ml−1 under optimized conditions. The response time was about 10 min. A good agreement was achieved between the developed capacitive
biosensor system and ELISA as a reference method for detection of SEB levels in different purification samples. The newly
developed sensor has the benefits of simplicity, high sensitivity, and multiple use capability. 相似文献
94.
95.
为提高宽带高功率微波辐射天线的总体功率容量和增益,研究了2×2宽带高功率贴片天线阵列的阵元互耦特性、馈电功分器设计及对宽带电磁脉冲的辐射特性。阵元采用宽带高功率双层贴片天线,分析了阵元反射和互耦系数随阵元间距的变化关系,结合增益变化曲线,选取阵元间距为30 cm。优化设计了1分4的同轴功分器,采用阻抗渐变方法,提高了功分器的带宽,使其在224~415 MHz时的反射系数小于0.1。模拟了带功分器的完整天线阵,结果表明天线阵带宽达到了57.4%,280~390 MHz频带范围内的增益大于12 dB,在360 MHz时达到最大增益14.23 dB,对中心频率320 MHz,带宽10%的宽带电磁脉冲辐射效率为868%,峰值功率增益大于11 dB。 相似文献
96.
97.
Haochen Qi Meiqi Zhao Huaguo Liang Jayne Wu Zhengfeng Huang Anming Hu Jian Wang Yingchun Lu Jian Zhang 《Electrophoresis》2019,40(20):2699-2705
Copper is an indispensable trace element for human health. Too much or too little intake of copper ion (Cu2+) can lead to its own adverse health conditions. Therefore, detection of Cu2+ is always of vital importance. In this work, a simple sensor was developed for rapid detection of trace Cu2+ in water, in which L‐cysteine (Cys) as a molecular probe was self‐assembled on a gold interdigital electrode to form a monolayer for specific capture of Cu2+. The interfacial capacitance of interdigital electrode was detected to indicate the target adsorption level under an AC signal working as the excitation to induce directed movement and enrichment of Cu2+ to the electrode surface. This sensor reached a limit of detection of 4.14 fM and a satisfactory selectivity against eight other ions (Zn2+, Hg2+, Pb2+, Cd2+, Mg2+, Fe2+, As3+, and As5+). Testing of spiked tap water was also performed, demonstrating the sensor's usability. This sensor as well as the detection method shows a great application potential in fields such as environmental monitoring and medical diagnosis. 相似文献
98.
A novel 35GHz 3dB power divider using coupled transmission line is presented. Unlike conventional Wilkinson divider circuit, only the 50 transmission lines are used in the design. The impedance matching can be achieved by coupled transmission line even mode characteristic impedance. The predicated and measured performances agree well. 相似文献
99.
Capacitive chemical sensor for fenvalerate assay based on electropolymerized molecularly imprinted polymer as the sensitive layer 总被引:2,自引:0,他引:2
Gong JL Gong FC Kuang Y Zeng GM Shen GL Yu RQ 《Analytical and bioanalytical chemistry》2004,379(2):302-307
A capacitive chemical sensor for fenvalerate is reported. By using ac impedance measurements the sensor has been based on the decrease in capacitance caused by the analyte used as the template in the formulation of an electropolymerized molecularly imprinted polymer as receptor layer. Improvement of the insulating properties of the sensor was investigated in detail. The capacitive sensor was prepared by a deposition of a self-assembled monolayer of 2-mercaptobenzimidazole (2-MBI) before electropolymerization of 2-MBI and subsequent treatment with n-dodecanethiol to eliminate pinholes and defects in the polymerized 2-MBI film. From the calibration curve concentrations of fenvalerate up to 9 g mL–1 could be detected with a linear determination range up to 5 g mL–1 and a detection limit of 0.36 g mL–1. No significant interference was observed from common pyrethroid insecticides. 相似文献
100.
The considerable growth of the world population, concomitant with an increase in environmental pollution, aggravates the antinomy between supply and demand for drinking water. Various desalination technologies have been developed to address this issue, allowing for abundant saltwater as a source for drinking water. Electrochemical desalination attracts more and more attention due to its high energy efficiency, facile operation, and low cost. Especially within the last decade, tremendous scientific progress on electrochemical desalination technologies has been made. This article reviews the development of electrochemical desalination technologies and introduces a facile classification into three generations based on the different working principles. The cell architecture, metrics, advantages, and disadvantages of other electrochemical desalination technologies are introduced and compared. 相似文献