全文获取类型
收费全文 | 44604篇 |
免费 | 395篇 |
国内免费 | 326篇 |
专业分类
化学 | 20403篇 |
晶体学 | 356篇 |
力学 | 1822篇 |
综合类 | 12篇 |
数学 | 11451篇 |
物理学 | 11281篇 |
出版年
2021年 | 146篇 |
2020年 | 166篇 |
2019年 | 181篇 |
2018年 | 1350篇 |
2017年 | 1579篇 |
2016年 | 980篇 |
2015年 | 776篇 |
2014年 | 736篇 |
2013年 | 1384篇 |
2012年 | 3622篇 |
2011年 | 2926篇 |
2010年 | 2248篇 |
2009年 | 1931篇 |
2008年 | 1149篇 |
2007年 | 1148篇 |
2006年 | 1173篇 |
2005年 | 4964篇 |
2004年 | 4409篇 |
2003年 | 2711篇 |
2002年 | 952篇 |
2001年 | 603篇 |
2000年 | 398篇 |
1999年 | 437篇 |
1998年 | 323篇 |
1997年 | 311篇 |
1996年 | 326篇 |
1995年 | 273篇 |
1994年 | 276篇 |
1993年 | 286篇 |
1992年 | 444篇 |
1991年 | 438篇 |
1990年 | 343篇 |
1989年 | 329篇 |
1988年 | 351篇 |
1987年 | 339篇 |
1986年 | 280篇 |
1985年 | 352篇 |
1984年 | 342篇 |
1983年 | 248篇 |
1982年 | 294篇 |
1981年 | 320篇 |
1980年 | 274篇 |
1979年 | 317篇 |
1978年 | 272篇 |
1977年 | 263篇 |
1976年 | 296篇 |
1975年 | 277篇 |
1974年 | 230篇 |
1973年 | 251篇 |
1972年 | 172篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
JETP Letters - Extraordinary multiparticle effects in quantizing magnetic fields that are manifested in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures have been... 相似文献
3.
4.
5.
6.
Brian R. Holder Colleen A. McNaney David Luchetti Eric Schaeffer Dieter M. Drexler 《Biomedical chromatography : BMC》2015,29(9):1375-1379
Acetyl‐l ‐carnitine (ALCAR) is a potential biomarker for the modulation of brain neurotransmitter activity, but is also present in cerebrospinal fluid (CSF). Recent studies have utilized hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC‐MS/MS) based assays to detect and quantify ALCAR within biofluids such as urine, plasma and serum, using various sample pretreatment procedures. In order to address the need to quantify ALCAR in CSF on a high‐throughput scale, a new and simple HILIC‐MS/MS assay has been successfully developed and validated. For rapid analysis, CSF sample pretreatment was performed via ‘dilute and shoot’ directly onto an advanced HILIC column prior to MS/MS detection. This newly developed HILIC‐MS/MS assay shows good recoveries of ALCAR without the need for chemical derivatization and multistep sample extraction procedures. The employment of this assay is suitable for the high‐throughput bioanalysis and quantification of ALCAR within the CSF of various animal models and human clinical studies. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
7.
8.
9.
Hendrik Van Maldeghem 《Journal of Geometry》1997,58(1-2):192-202
We characterize in a geometrical way those Suzuki-Tits ovoids which are defined over a perfect fieidK (or equivalently living inside a self polar symplectic quadrangle). We simplify our axioms in the particular cases that (1) the associated Suzuki group has exactly two orbits in the set of lines ofPG(3,K), and (2) the ovoid is finite.Senior Research Associate at the Belgian National Fund for Scientific Research 相似文献
10.
Photobleaching was studied during recording of confocal scanning laser microscopy. Studies on fluorescent gels of FITC-labeled
dextran were used to evaluate differential bleaching along thez-axis. Differential bleaching along the z-axis was observed and it was seen that this was related to the numerical aperture
of the objective in use. This points to the conclusion that photon energy flux density is an important parameter in photobleaching.
To check if photon energy flux density heterogeneity is affected by local variation in the refractive index of the sample,
photobleaching rates were calculated for different fluorescent objects (sections of seeds, animal cells stained with nuclear
stains, immunocytochemistry preparations) and a pronounced similarity was found between photobleaching rates and DIC images. 相似文献