全文获取类型
收费全文 | 34508篇 |
免费 | 4074篇 |
国内免费 | 2689篇 |
专业分类
化学 | 23462篇 |
晶体学 | 338篇 |
力学 | 1648篇 |
综合类 | 230篇 |
数学 | 4026篇 |
物理学 | 11567篇 |
出版年
2023年 | 552篇 |
2022年 | 517篇 |
2021年 | 819篇 |
2020年 | 1039篇 |
2019年 | 1016篇 |
2018年 | 856篇 |
2017年 | 800篇 |
2016年 | 1319篇 |
2015年 | 1272篇 |
2014年 | 1487篇 |
2013年 | 2212篇 |
2012年 | 2523篇 |
2011年 | 2682篇 |
2010年 | 1819篇 |
2009年 | 1641篇 |
2008年 | 2003篇 |
2007年 | 2022篇 |
2006年 | 1717篇 |
2005年 | 1597篇 |
2004年 | 1305篇 |
2003年 | 1189篇 |
2002年 | 1093篇 |
2001年 | 834篇 |
2000年 | 746篇 |
1999年 | 735篇 |
1998年 | 539篇 |
1997年 | 534篇 |
1996年 | 474篇 |
1995年 | 516篇 |
1994年 | 510篇 |
1993年 | 413篇 |
1992年 | 358篇 |
1991年 | 369篇 |
1990年 | 360篇 |
1989年 | 261篇 |
1988年 | 217篇 |
1987年 | 223篇 |
1986年 | 179篇 |
1985年 | 258篇 |
1984年 | 270篇 |
1983年 | 182篇 |
1982年 | 200篇 |
1981年 | 162篇 |
1980年 | 164篇 |
1979年 | 136篇 |
1978年 | 114篇 |
1977年 | 162篇 |
1976年 | 142篇 |
1975年 | 119篇 |
1973年 | 114篇 |
排序方式: 共有10000条查询结果,搜索用时 255 毫秒
91.
Target cell extraction coupled with LC‐MS/MS analysis for screening potential bioactive components in Ginkgo biloba extract with preventive effect against diabetic nephropathy 下载免费PDF全文
Jing‐ying Qiu Xu Chen Xiao‐xiao Zheng Xiang‐lan Jiang Dong‐zhi Yang Yan‐yan Yu Qian Du Dao‐quan Tang Xiao‐xing Yin 《Biomedical chromatography : BMC》2015,29(2):226-232
A rapid and useful approach for screening potential bioactive components in Ginkgo biloba extract (GBE) with preventive effect against diabetic nephropathy (DN) was developed using mesangial cells extraction coupled with high‐performance liquid chromatography tandem mass spectrometry (LC‐MS/MS) analysis. Mesangial cells were first divided into two groups according to their treatments with high glucose or high glucose plus GBE. After incubation for 4, 8, 12, 16, 24 and 48 h, the cells were harvested and extracted with 40% acetic acid in water before LC‐MS/MS analysis. Then, 19 compounds and five metabolites were found to selectively combine with mesangial cells. Notably, compounds including quercetin and rutin were identified or tentatively characterized according to the results of retention time and MS spectra, which is highly consistent with our previous reports that quercetin and rutin are potent protective agents against glomerulosclerosis in DN. Therefore, all these results indicate that target cell extraction coupled with LC‐MS/MS analysis can be successfully applied for predicting the bioactive components in GBE with preventive effect against DN. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
92.
This minireview describes the strategies for synthesis of fiuorinated surfactants potentially nonbioaccumulable.Various strategies have been focused on(Ⅰ) reducing the length of the perfluorocarbon chain,(Ⅱ) introducing hetero atoms into the fluorocarbon chain,(Ⅲ) introducing branch(herein and after branch means the fluoro-carbon chain section is not straight).In most cases,the surface tensions versus the surfactant concentrations have been assessed.These above strategies led to various highly fiuorinated(perfluorinated or not perfluorinated) surfactants whose chemical changes enabled to obtain novel alternatives to perfluorooctanoic acid(PFOA) and perfluorooctane sulphonate(PFOS). 相似文献
93.
94.
Functional Binding Surface of a β‐Hairpin VEGF Receptor Targeting Peptide Determined by NMR Spectroscopy in Living Cells 下载免费PDF全文
Dr. Donatella Diana Anna Russomanno Dr. Lucia De Rosa Dr. Rossella Di Stasi Dr. Domenica Capasso Dr. Sonia Di Gaetano Dr. Alessandra Romanelli Dr. Luigi Russo Dr. Luca D. D'Andrea Prof. Roberto Fattorusso 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):91-95
In this study, the functional interaction of HPLW peptide with VEGFR2 (Vascular Endothelial Growth Factor Receptor 2) was determined by using fast 15N‐edited NMR spectroscopic experiments. To this aim, 15N uniformly labelled HPLW has been added to Porcine Aortic Endothelial Cells. The acquisition of isotope‐edited NMR spectroscopic experiments, including 15N relaxation measurements, allowed a precise characterization of the in‐cell HPLW epitope recognized by VEGFR2. 相似文献
95.
From single‐chain folding to polymer nanoparticles via intramolecular quadruple hydrogen‐bonding interaction 下载免费PDF全文
Fei Wang Hongting Pu Ming Jin Haiyan Pan Zhihong Chang Decheng Wan Jiang Du 《Journal of polymer science. Part A, Polymer chemistry》2015,53(15):1832-1840
Single‐chain folding via intramolecular noncovalent interaction is regarded as a facile mimicry of biomacromolecules. Single‐chain folding and intramolecular crosslinking is also an effective method to prepare polymer nanoparticles. In this study, poly(methyl methacrylate‐co?2‐ureido‐5‐deazapterines functionalized ethylene methacrylate) (P(MMA‐co‐EMA‐DeAP)) is synthesized via free radical polymerization. The single‐chain folding of P(MMA‐co‐EMA‐DeAP) and the formation of the nanoparticles in diluted solution (concentration <0.005 mg/mL) are achieved via supramolecular interaction and intramolecular collapsing during the disruption‐reformation process of the hydrogen bonding triggered by water. The size and the morphology of the nanoparticles are characterized by dynamic light scattering, transmission electron microscope, and atomic force microscope. The results show that the size of the nanoparticles depends on the molecular weight of the polymer and the loading of 2‐ureido‐5‐deazapterines functionalized ethylene methacrylate (EMA‐DeAP) on the polymer backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1832–1840 相似文献
96.
97.
98.
JPC – Journal of Planar Chromatography – Modern TLC - A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of... 相似文献
99.
100.