全文获取类型
收费全文 | 142篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 71篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 13篇 |
物理学 | 55篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有143条查询结果,搜索用时 328 毫秒
71.
A reversible ‘turn-on’ sensor has been designed for ‘naked-eye’ detection of oxalate at nanomolar concentration (~12.5?nM) at pH 7.4. The sensory system shows a highly specific response towards oxalate among a wide range of antinutrients and biologically relevant anionic species. Mechanistic investigations indicate that oxalate can turn the pink-colored solution colorless by dissociating the preformed metal complex. Additionally, high specificity and good accuracy with recovery values ranging from 93.3 to 105.0% were obtained during oxalate estimation in spiked water and human urine samples, confirming the suitability of the present method in estimating trace-level of oxalate in complex matrices. With these results, quantitative estimations of endogenous oxalate were achieved in more than twenty-five different agricultural crops. Finally, low-cost, portable paper strips were developed for on-site detection of oxalate. 相似文献
72.
73.
S. D. Bhagat 《Fresenius' Journal of Analytical Chemistry》1993,347(8-9):365-367
Summary A simple gas-chromatographic technique is described to estimate the vapour pressure of compounds having low volatility. The method is fast, accurate and needs the sample in microquantities only. The methodology involves first to estimate the heat of vaporization by gas-liquid chromatography, which in turn is employed to determine the vapour pressure of the substance using the Clapeyron equation. The vapour pressure data of some aryl and alkyl phosphate esters have been obtained and are compared with the data resulting from the group contribution method.Abbreviations A
integration constant
- c
constant
- H
heat of vaporization (kJ/mol)
- m
slope
- P°
vapour pressure (mmHg)
- R
gas constant
- T
temperature (°K)
- Vv
vapour value
- x
variable
- Zv
vapour compressibility factor
- Tr
T/Tc
- Tc
critical temperature (°C) 相似文献
74.
A method to determine low levels of iodine species namely I− and IO3− in aqueous samples was developed and applied to milk and milk powder samples. It is based on selective preconcentration of I− in polymer inclusion sorbent (PIS) and neutron activation analysis (NAA) of I− sorbed in PIS. The PIS was found to be highly selective for I− in presence of IO3− and other anions commonly present in the milk samples. In order to preconcentrate total I− + IO3− content in the PIS, IO3− was reduced to I− using a mixture of acetic acid and ascorbic acid. It was found that total iodine content in milk could be determined with epithermal neutron activation analysis (ENAA). A scheme was developed to determine I−, IO3− and total iodine. The developed method was applied to milk reference materials (NIST SRM-1549 and IAEA-RM-153 milk powder) and a commercially available milk powder. The scheme for estimation of iodine in different forms was validated by using reference material NIST SRM-1549. 相似文献
75.
Continuous particle separation in spiral microchannels using Dean flows and differential migration 总被引:1,自引:0,他引:1
Microparticle separation and concentration based on size has become indispensable in many biomedical and environmental applications. In this paper we describe a passive microfluidic device with spiral microchannel geometry for complete separation of particles. The design takes advantage of the inertial lift and viscous drag forces acting on particles of various sizes to achieve differential migration, and hence separation, of microparticles. The dominant inertial forces and the Dean rotation force due to the spiral microchannel geometry cause the larger particles to occupy a single equilibrium position near the inner microchannel wall. The smaller particles migrate to the outer half of the channel under the influence of Dean forces resulting in the formation of two distinct particle streams which are collected in two separate outputs. This is the first demonstration that takes advantage of the dual role of Dean forces for focusing larger particles in a single equilibrium position and transposing the smaller particles from the inner half to the outer half of the microchannel cross-section. The 5-loop spiral microchannel 100 microm wide and 50 microm high was used to successfully demonstrate a complete separation of 7.32 microm and 1.9 microm particles at Dean number De = 0.47. Analytical analysis supporting the experiments and models is also presented. The simple planar structure of the separator offers simple fabrication and makes it ideal for integration with on-chip microfluidic systems, such as micro total analysis systems (muTAS) or lab-on-a-chip (LOC) for continuous filtration and separation applications. 相似文献
76.
We have studied the temperature dependence of the magnetic response of amorphous (FexNil-x)75P16B6A3 ribbons to a small low frequency applied field. For x ? 0.16 we identify a paramagnet-spin glass transition. With 0.17 ? x ? 0.4 a paramagnet-ferromagnet transition is observed which is followed at lower T by a spin freezing phenomenon. A magnetic phase diagram is proposed and discussed in terms of recent theories. 相似文献
77.
Vibha Gautam Veera Babu KagitaSudhir Nambiar Gutala PhaneendraSulur G. Manjunatha Sridharan RamasubramanianM. Suresh Babu Jaikumar KeshwanSagar Bhagat Ravindran PrakashRamachandra Puranik 《Tetrahedron letters》2014
A simple synthetic approach has been developed towards one pot synthesis of 2-imidazolines under mild acidic conditions from N-acetyl glucosamine via reductive amination followed by dehydrative cyclization. Synthetic studies were explored in detail with different amines and sugar derivatives. While the conversion was good, the corresponding substituted imidazolines were obtained in moderate yields. 相似文献
78.
Sunita Bhagat Manish Jain Mukesh K. Pandey Pragati Anjali Saxena Subhash C. Jain 《Heteroatom Chemistry》2006,17(4):272-276
A new bridgehead nitrogen hetero‐ cycle viz. 11‐carboethoxy‐9‐oxo‐pyrimido[3′2′:3,4]‐1,2,4‐triazino[5,6‐b]indole 3 has been synthesized from 3‐azido‐5H‐1,2,4‐triazino[5,6‐b]indole 2 by its reaction with diethyl fumerate. The intermediate 2 was obtained by treating 3‐hydrazino‐5H‐1,2,4‐triazino[5,6‐b]indole with NaNO2 in presence of polyphosphoric acid. A plausible mechanism for the formation of 3 has been formulated and discussed. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:272–276, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20199 相似文献
79.
Bhagat Singh Bhakuni Shah Jaimin Balkrishna Amit Kumar Sangit Kumar 《Tetrahedron letters》2012,53(11):1354-1357
A copper mediated sulfur–nitrogen coupling reaction for the synthesis of benzo[d]isothiazol-3(2H)-ones and related sulfur–nitrogen heterocycles has been presented, which requires 2-halo-arylamides, sulfur powder, 25–50 mol % of copper iodide/1,10-phenanthroline, and potassium carbonate as base. 相似文献
80.