全文获取类型
收费全文 | 330323篇 |
免费 | 19277篇 |
国内免费 | 10044篇 |
专业分类
化学 | 190459篇 |
晶体学 | 4551篇 |
力学 | 15554篇 |
综合类 | 514篇 |
数学 | 37031篇 |
物理学 | 111535篇 |
出版年
2022年 | 4447篇 |
2021年 | 4994篇 |
2020年 | 5649篇 |
2019年 | 5509篇 |
2018年 | 5647篇 |
2017年 | 5241篇 |
2016年 | 8344篇 |
2015年 | 6897篇 |
2014年 | 9153篇 |
2013年 | 17820篇 |
2012年 | 16135篇 |
2011年 | 18217篇 |
2010年 | 12011篇 |
2009年 | 11745篇 |
2008年 | 14622篇 |
2007年 | 14042篇 |
2006年 | 12995篇 |
2005年 | 11505篇 |
2004年 | 9802篇 |
2003年 | 8425篇 |
2002年 | 8170篇 |
2001年 | 8908篇 |
2000年 | 6896篇 |
1999年 | 6010篇 |
1998年 | 5094篇 |
1997年 | 5111篇 |
1996年 | 4811篇 |
1995年 | 4420篇 |
1994年 | 4075篇 |
1993年 | 3967篇 |
1992年 | 4110篇 |
1991年 | 4089篇 |
1990年 | 3774篇 |
1989年 | 3588篇 |
1988年 | 3521篇 |
1987年 | 3329篇 |
1986年 | 3244篇 |
1985年 | 4245篇 |
1984年 | 4294篇 |
1983年 | 3516篇 |
1982年 | 3845篇 |
1981年 | 3696篇 |
1980年 | 3559篇 |
1979年 | 3566篇 |
1978年 | 3778篇 |
1977年 | 3606篇 |
1976年 | 3815篇 |
1975年 | 3387篇 |
1974年 | 3516篇 |
1973年 | 3819篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In this article, we construct and analyze a residual-based a posteriori error estimator for a quadratic finite volume method (FVM) for solving nonlinear elliptic partial differential equations with homogeneous Dirichlet boundary conditions. We shall prove that the a posteriori error estimator yields the global upper and local lower bounds for the norm error of the FVM. So that the a posteriori error estimator is equivalent to the true error in a certain sense. Numerical experiments are performed to illustrate the theoretical results. 相似文献
2.
3.
Paired single residue‐transposed Lys‐N and Lys‐C digestions for label‐free identification of N‐terminal and C‐terminal MS/MS peptide product ions: ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry for peptide de novo sequencing 下载免费PDF全文
4.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
5.
Nano palladium supported on high‐surface‐area metal–organic framework MIL‐101: an efficient catalyst for Sonogashira coupling of aryl and heteroaryl bromides with alkynes 下载免费PDF全文
Manne Annapurna T. Parsharamulu P. Vishnuvardhan Reddy M. Suresh Pravin R. Likhar Mannepalli Lakshmi Kantam 《应用有机金属化学》2015,29(4):234-239
Palladium nanoparticle‐incorporated metal–organic framework MIL‐101 (Pd/MIL‐101) was successfully synthesized and characterized using X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron, UV–visible and infrared spectroscopies, and transmission electron microscopy. The characterization techniques confirmed high porosity and high surface area of MIL‐101 and high stability of nano‐size palladium particles. Pd/MIL‐101 nanocomposite was investigated for the Sonogashira cross‐coupling reaction of aryl and heteroaryl bromides with various alkynes under copper‐free conditions. The reusability of the catalyst was tested for up to four cycles without any significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Jing Zhihong Ling Baoping Yu Yang Qi Wei Zhang Shufang 《Journal of Sol-Gel Science and Technology》2015,73(1):112-117
Journal of Sol-Gel Science and Technology - A novel gas sensing material, La–Y co-doped TiO2 nanoparticles, was synthesized by sol–gel method and applied to detect organic pollutants... 相似文献
7.
8.
9.
10.
Antonio R. Montoro Bustos Marta Garcia-Cortes Hector González-Iglesias Jorge Ruiz Encinar José M. Costa-Fernández Miguel Coca-Prados Alfredo Sanz-Medel 《Analytica chimica acta》2015
A generic strategy based on the use of CdSe/ZnS Quantum Dots (QDs) as elemental labels for protein quantification, using immunoassays with elemental mass spectrometry (ICP-MS), detection is presented. In this strategy, streptavidin modified QDs (QDs-SA) are bioconjugated to a biotinylated secondary antibody (b-Ab2). After a multi-technique characterization of the synthesized generic platform (QDs-SA-b-Ab2) it was applied to the sequential quantification of five proteins (transferrin, complement C3, apolipoprotein A1, transthyretin and apolipoprotein A4) at different concentration levels in human serum samples. It is shown how this generic strategy does only require the appropriate unlabeled primary antibody for each protein to be detected. Therefore, it introduces a way out to the need for the cumbersome and specific bioconjugation of the QDs to the corresponding specific recognition antibody for every target analyte (protein). Results obtained were validated with those obtained using UV–vis spectrophotometry and commercial ELISA Kits. 相似文献