全文获取类型
收费全文 | 254篇 |
免费 | 13篇 |
国内免费 | 2篇 |
专业分类
化学 | 230篇 |
力学 | 3篇 |
数学 | 8篇 |
物理学 | 28篇 |
出版年
2023年 | 1篇 |
2022年 | 13篇 |
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 19篇 |
2013年 | 16篇 |
2012年 | 14篇 |
2011年 | 15篇 |
2010年 | 22篇 |
2009年 | 13篇 |
2008年 | 17篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1937年 | 1篇 |
1934年 | 1篇 |
1931年 | 2篇 |
排序方式: 共有269条查询结果,搜索用时 31 毫秒
51.
52.
Bogusław Buszewski Michał Szumski Ewa Kłodzińska Reda Jarmalavičienė Audrius Maruška 《Journal of chromatography. A》2009,1216(33):6146-6150
The separation of bacteria by electromigration techniques was a subject of several of our previous papers. This contribution presents the results of investigation of the porosity of the monolithic bed and migration of Staphylococcus aureus cells through it. The gigaporous monolith was thermally synthesized using glycidyl methacrylate, triethylene glycol dimethacrylate and trimethylolpropane trimethacrylate as the monomers in the presence of porogen solvent containing 1-decanol, polyethylene glycol and 2-methoxyethanol. The porous properties were evaluated by inverse size-exclusion chromatography (ISEC) using a wide range of polystyrene standards of different molecular weights. The results have shown, that large pores (ca. 300 nm) dominate in the monolithic bed structure, however much larger flow-through pores must also be present as ca. 1 μm sized S. aureus bacteria were able to migrate through the bed. 相似文献
53.
54.
Joachim Stasiek Rafał Malinowski Tomasz Ligor Bogusław Buszewski 《Chemical Papers》2010,64(5):579-583
Results of the investigation of volatile organic compounds emission during polyethylene extrusion are presented. Two polymers
of different processing properties were tested, namely linear low density polyethylene (ExxonMobil) and high density polyethylene
(Liten FB 29). Blowing film extrusion in experimental technological line using a single screw extruder as the imported element
was done. VOCs were collected on sorbent tubes containing Tenax. Gas chromatography coupled with mass spectrometry (GC/MS)
was applied for the identification of volatile degradation products. PE LLD material emits a significantly larger amount of
hydrocarbons than PE-HD. Its emission contains mainly C18 and C20 hydrocarbons (alkanes, 1-alkenes, and α,ω-alkadienes). In case of the PE-HD polymer, lower degradation was observed and C18 and C23 hydrocarbons were emitted. 相似文献
55.
Synthesis and properties are described of multilayered stationary phases containing quaternary amine functional groups used for the analysis of inorganic anions by ion chromatography. The bonded phases were characterized by elemental analysis, solid state (13)C NMR spectroscopy and chromatographic methods. The surface of polyhydroxyethyl methacrylate (solid support) was coated with polymeric layers formed by condensation polymerization of primary amine with diepoxide. Each layer of the anion exchange stationary phase consisted of methylamine and 1,4-butanedioldiglycidyl ether copolymer. A series of stationary phases with different number of polymerized layers were tested. Separation of inorganic anions, such as F(-), Cl(-), NO(2) (-), Br(-), NO(3) (-), were performed. Aqueous hydroxide, carbonate and bicarbonate solutions were used as mobile phases. 相似文献
56.
Boguslaw Buszewski Jacek Nowaczyk Tomasz Ligor Pawel Olszowy Magdalena Ligor Bartlomiej Wasiniak Wolfram Miekisch Jochen K. Schubert Anton Amann 《Journal of separation science》2009,32(14):2448-2454
The aim of this study was the preparation of polypyrrole (PPy) fibers for solid phase microextraction (SPME). PPy coatings were obtained during the electrochemical polymerization process. The utility of various metal wires (Fe, Cu, Ag, Cu/Ag, kanthal and medical stainless steel) as a support for polymers was compared. Various experimental conditions of the synthesis process such as scan rate, voltage limits and number of scans and deposition time were applied. The average polymer thickness was in the range of 7–125 μm and its weight was in the scope of 0.65–5.6 mg. Different techniques, mainly elemental analysis, Fourier transform infrared spectroscopy, microscopy, and chromatography were performed for the characterization of obtained fibers with microporous structure. The extraction efficiency of cardiovascular drugs (metoprolol, propranolol, oxprenolol, propafenone and mexiletine) by means of fibers was tested. The concentration of mentioned compounds in standard solution was in the span of 10–150 ng/mL. LC‐MS was employed for determination of drugs in desorption solution. LODs varied from 0.013 to 1.51 ng/mL for metoprolol and mexiletine respectively. The repeatability of extraction was obtained with the RSD values lower than 10%. 相似文献
57.
Buszewski B Welerowicz T Tegowska E Krzemiński TF 《Analytical and bioanalytical chemistry》2009,393(1):263-272
A new method is presented for the determination of five selected β-receptor antagonists by HPLC, which emphasizes sample preparation
via retention on a new type of silica gel sorbent used for solid-phase extraction (SPE). Sorbents of this type were obtained
by the chemical modification of silica gels of various porosities by cholesterol ligands. The cholesterol-based packing material
was investigated by spectroscopic methods and elemental analysis. The recoveries obtained with the extraction procedure were
optimum over a relatively broad sample pH range (3.08–7.50). Analytical factors such as the sample loading, the washing step
and elution conditions, the concentration of β-receptor antagonists to be extracted, and the type of sorbent were found to
play significant roles in the sample preparation procedure and would therefore need to be controlled to achieve optimum recoveries
of the analytes. Under optimum conditions, the recoveries of nadolol, acebutolol, esmolol, oxprenolol and propranolol from
spiked buffers, blood and urine were reproducible and dependent on the polarity or hydrophilicity of the compounds. The above
analytes were determined by reverse-phase high-performance liquid chromatography (HPLC) with UV and ESI-ion trap mass spectrometry
(MS) detection. The described method was found to be suitable for the routine measurement of compounds that are both polar
and basic, and can be applied for the analysis of biological samples such as urine and blood in clinical, toxicological or
forensic laboratories. The recovery measurements were performed on spiked human urine and serum, and on real samples of mouse
blood serum. 相似文献
58.
The chemical character, geometry, and architecture of chemically formed surface layers determine interactions between stationary phase, analyte, and mobile phase, and therefore the retention mechanisms (partitioning, adsorption, ion exchange, steric exclusion) of separated analytes. These interactions also depend on the structure and chemical character of the solutes and the composition of the mobile phase. High-molecular-weight fullerenes (C60 and C70) and water-soluble selenium-containing peptides (833 and 2607 Da) were used for the evaluation of laboratory-prepared octadecyl stationary phases with high and low coverage density before and after end-capping. The aim of this work was to study differences in surface coverage density and homogeneity and conformational changes of chemically bonded moieties and the influence of these parameters on the separation of mixtures of selenopeptides and fullerenes with significantly different molecular masses. A topographical model of the chemically modified stationary surface is presented. 相似文献
59.
Chromatographic behavior of synthetic block (co)oligomer samples (EO)n(PO)m(EO)n and (PO)n(EO)m(PO)n with different distribution of propylene oxide (PO) and ethylene oxide (EO) monomer units was investigated on three types of stationary phases on zirconium dioxide support: Zr-PS (polystyrene), Zr-carbon, and Zr-carbon C18. The effects of the distribution and sequence of the oxyethylene and oxypropylene monomer units on the chromatographic retention depend on the type of the stationary phase, but are strongly affected by the organic modifier (methanol or ACN) in aqueous-organic mobile phase. Special attention was focused on the influence of the mobile-phase composition on the separation according to the EO and PO distribution. Zirconia-based columns are stable at elevated temperatures and can be used in high-temperature LC (HTLC); hence, we investigated the temperature effects on the chromatographic behavior up to 90 degrees C. The applications of solvent and temperature gradients were compared on the zirconia stationary phases in the RP mode. 相似文献
60.
Boguslaw Buszewski Pawel Olszowy Tomasz Ligor Malgorzata Szultka Jacek Nowaczyk Maciej Jaworski Marek Jackowski 《Analytical and bioanalytical chemistry》2010,397(1):173-179
Five adrenolytic drugs have been analyzed by liquid chromatography–mass spectrometry (LC–MS). Samples were prepared by solid-phase
microextraction (SPME) using polypyrrole fibers coated on stainless steel support as an adsorbent for the drugs. Adsorption
efficiencies were 95% and were close for all the drugs investigated. Relative standard deviations (RSD), calculated for samples
prepared in standard solutions, were in the range 2.5–13%, however RSD values for the drugs in human plasma were 2.5–4.5%.
Using LC–MS the limit of detection (LOD) and the limit of quantification (LOQ) were in the ranges 0.11–0.18 and 0.39–0.54 ng mL−1, respectively, for the five drugs. 相似文献