全文获取类型
收费全文 | 309143篇 |
免费 | 4780篇 |
国内免费 | 1247篇 |
专业分类
化学 | 154803篇 |
晶体学 | 3564篇 |
力学 | 15206篇 |
综合类 | 12篇 |
数学 | 59939篇 |
物理学 | 81646篇 |
出版年
2022年 | 1430篇 |
2021年 | 1888篇 |
2020年 | 2109篇 |
2019年 | 2160篇 |
2018年 | 12129篇 |
2017年 | 11886篇 |
2016年 | 10252篇 |
2015年 | 4558篇 |
2014年 | 4698篇 |
2013年 | 12142篇 |
2012年 | 13766篇 |
2011年 | 21580篇 |
2010年 | 12665篇 |
2009年 | 12900篇 |
2008年 | 16935篇 |
2007年 | 18752篇 |
2006年 | 10364篇 |
2005年 | 10665篇 |
2004年 | 9766篇 |
2003年 | 8945篇 |
2002年 | 7660篇 |
2001年 | 7490篇 |
2000年 | 6050篇 |
1999年 | 4513篇 |
1998年 | 3505篇 |
1997年 | 3410篇 |
1996年 | 3612篇 |
1995年 | 2997篇 |
1994年 | 2944篇 |
1993年 | 2819篇 |
1992年 | 3081篇 |
1991年 | 2898篇 |
1990年 | 2645篇 |
1989年 | 2558篇 |
1988年 | 2555篇 |
1987年 | 2473篇 |
1986年 | 2362篇 |
1985年 | 3363篇 |
1984年 | 3337篇 |
1983年 | 2680篇 |
1982年 | 2857篇 |
1981年 | 2733篇 |
1980年 | 2659篇 |
1979年 | 2583篇 |
1978年 | 2618篇 |
1977年 | 2549篇 |
1976年 | 2489篇 |
1975年 | 2424篇 |
1974年 | 2336篇 |
1973年 | 2458篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Design and development of a two‐dimensional system based on hydrophilic and reversed‐phase liquid chromatography with on‐line sample treatment for the simultaneous separation of excreted xenobiotics and endogenous metabolites in urine
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Diego García‐Gómez Encarnación Rodríguez‐Gonzalo Rita Carabias‐Martínez 《Biomedical chromatography : BMC》2015,29(8):1190-1196
In the present work we describe a two‐dimensional liquid chromatographic system (2D‐LC) with detection by mass spectrometry (MS) for the simultaneous separation of endogenous metabolites of clinical interest and excreted xenobiotics deriving from exposure to toxic compounds. The 2D‐LC system involves two orthogonal chromatographic modes, hydrophilic interaction liquid chromatography (HILIC) to separate polar endogenous metabolites and reversed‐phase (RP) chromatography to separate excreted xenobiotics of low and intermediate polarity. Additionally, the present proposal has the novelty of incorporating an on‐line sample treatment based on the use of restricted access materials (RAMs), which permits the direct injection of urine samples into the system. The work is focused on the instrumental coupling, studying all possible options and attempting to circumvent the problems of solvent incompatibility between the RAM device and the two chromatographic columns, HILIC and RP. The instrumental configuration developed, RAM‐HILIC‐RPLC‐MS/MS, allows the simultaneous assessment of urinary metabolites of clinical interest and excreted compounds derived from exposure to toxic agents with minimal sample manipulation. Thus, it may be of interest in areas such as occupational and environmental toxicology in order to explore the possible relationship between the two types of compounds. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
103.
104.
Natalia L. Calvo Sebastian O. SimonettiRubén M. Maggio Teodoro S. Kaufman 《Analytica chimica acta》2015
Exposure of cimetidine (CIM) to dry heat (160–180 °C) afforded, upon cooling, a glassy solid containing new and hitherto unknown products. The kinetics of this process was studied by a second order chemometrics-assisted multi-spectroscopic approach. Proton and carbon-13 nuclear magnetic resonance (NMR), as well as ultraviolet and infrared spectroscopic data were jointly used, whereas multivariate curve resolution with alternating least squares (MCR-ALS) was employed as the chemometrics method to extract process information. It was established that drug degradation follows a first order kinetics. 相似文献
105.
106.
107.
108.
109.
Experimental Mechanics - There have been relatively few studies on mechanical properties of nanomaterials under high strain rates, mainly due to the lack of capable nanomechanical testing devices.... 相似文献
110.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献