全文获取类型
收费全文 | 5069篇 |
免费 | 993篇 |
国内免费 | 512篇 |
专业分类
化学 | 3462篇 |
晶体学 | 49篇 |
力学 | 201篇 |
综合类 | 70篇 |
数学 | 433篇 |
物理学 | 2359篇 |
出版年
2024年 | 19篇 |
2023年 | 109篇 |
2022年 | 167篇 |
2021年 | 178篇 |
2020年 | 174篇 |
2019年 | 178篇 |
2018年 | 179篇 |
2017年 | 136篇 |
2016年 | 247篇 |
2015年 | 251篇 |
2014年 | 254篇 |
2013年 | 339篇 |
2012年 | 484篇 |
2011年 | 543篇 |
2010年 | 322篇 |
2009年 | 324篇 |
2008年 | 345篇 |
2007年 | 291篇 |
2006年 | 263篇 |
2005年 | 208篇 |
2004年 | 181篇 |
2003年 | 122篇 |
2002年 | 146篇 |
2001年 | 111篇 |
2000年 | 118篇 |
1999年 | 108篇 |
1998年 | 93篇 |
1997年 | 107篇 |
1996年 | 86篇 |
1995年 | 79篇 |
1994年 | 63篇 |
1993年 | 72篇 |
1992年 | 42篇 |
1991年 | 63篇 |
1990年 | 42篇 |
1989年 | 35篇 |
1988年 | 15篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有6574条查询结果,搜索用时 0 毫秒
131.
132.
S. G. Li Q. Gong C. F. Cao X. Z. Wang J. Y. Yan Y. Wang H. L. Wang 《Optical and Quantum Electronics》2014,46(5):623-640
Since the external cavity quantum dot laser was first demonstrated, the performances have been improved in terms of operation temperature, output power, pulse generator and tuneability based on the naturally size fluctuation of quantum dot. Nowadays, the external cavity quantum dot sources have been successfully used in different absorption spectroscope techniques, in industry, biomedical and research. In this paper we reviewed the recent developments of quantum dot lasers operated in a grating-coupled external cavity system where a single frequency and wide tunable wavelength range were easily obtained by adjusting the grating angle. In all cases, we mainly stressed the significant progresses in understanding of basic optical and electronic properties to enable the importance steps forward. The prospects for further progress directed towards stability, mode-hoping-free tuning range, miniaturization and integration of the external cavity quantum dot lasers also reviewed. 相似文献
133.
A novel spectrofluorimetric method to determine abiraterone acetate and its active metabolite, abiraterone was developed, based on the fact that fluorescence intensity of abiraterone acetate and abiraterone could be enhanced in β-cyclodextrin (β-CD) due to the formation of the inclusion complex. The inclusion interaction of β-CD and abiraterone acetate and the β-cyclodextrin sensitized spectrofluorimetry was examined. The various factors influencing fluorescence were discussed in details. The results showed that under the optimized conditions, the linear range of calibration curve for the determination of biraterone acetate and abiraterone was 0.20?~?6.0 μg/mL, and the detection limit (LOD) was 6.8 (r?=?0.997) or 6.6 ng/mL (r?=?0.996), respectively. No interference was observed from common co-existing substances or pharmaceutical excipient. The method was successfully applied to the analysis of abiraterone acetate in pharmaceutical formulation and abiraterone in human serum/urine. 相似文献
134.
Application of a sensitive and specific LC‐MS/MS method for determination of eriodictyol‐8‐C‐β‐d‐glucopyranoside in rat plasma for a bioavailability study 下载免费PDF全文
This study is the first to detail the development and validation of a rapid, sensitive and specific LC‐ESI‐MS/MS method for the determination of eriodictyol‐8‐C‐β‐d ‐glucopyranoside (EG) in rat plasma. A simple protein precipitation method was used for plasma sample preparation. Chromatographic separation was successfully achieved on an Agilent Zorbax XDB C18 column (2.1 × 50 mm, 3.5 µm) using a step gradient program with the mobile phase of 0.1% formic acid aqueous solution and acetonitrile with 0.1% formic acid. EG and the internal standard (IS) were detected using an electrospray negative ionization mass spectrometry in the multiple reaction monitoring mode. This method demonstrated good linearity and did not show any endogenous interference with the active compound and IS peaks. The lower limit of quantification of EG was 0.20 ng/mL in 50 μL rat plasma. The average recoveries of EG and IS from rat plasma were both above 80%. The inter‐day precisions (relative standard deviation) of EG determined over 5 days were all within 15%. The present method was successfully applied to a quantification and bioavailability study of EG in rats after intravenous and oral administration. The oral absolute bioavailability of EG in rats was estimated to be 7.71 ± 1.52%. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
135.
136.
Inside Back Cover: Ultrathin WS2 Nanoflakes as a High‐Performance Electrocatalyst for the Hydrogen Evolution Reaction (Angew. Chem. Int. Ed. 30/2014) 下载免费PDF全文
137.
The European Physical Journal C - Hadron decay chains constitute one of the main sources of information on the QCD spectrum. We discuss the differences between several partial wave analysis... 相似文献
138.
139.
A novel fiber-optic sensor structure fabricated by cascading two optical microfiber knot resonators (MKRs) is proposed and demonstrated in this paper. A theoretical model for describing the principle of the sensing structure is given and its temperature responses are characterized experimentally. Experimental results show that high-precision and simultaneous multi-point temperature sensing in micro-scale can be achieved. Such a sensing structure also has the potential for achieving dual-parameter measurement to eliminate the cross-talk between two parameters in micro-scale. 相似文献
140.