全文获取类型
收费全文 | 419028篇 |
免费 | 7208篇 |
国内免费 | 4949篇 |
专业分类
化学 | 191148篇 |
晶体学 | 5992篇 |
力学 | 26200篇 |
综合类 | 325篇 |
数学 | 69470篇 |
物理学 | 138050篇 |
出版年
2021年 | 4607篇 |
2020年 | 5140篇 |
2019年 | 5922篇 |
2018年 | 13228篇 |
2017年 | 13474篇 |
2016年 | 12616篇 |
2015年 | 5789篇 |
2014年 | 9319篇 |
2013年 | 15510篇 |
2012年 | 16636篇 |
2011年 | 23669篇 |
2010年 | 17166篇 |
2009年 | 17482篇 |
2008年 | 21318篇 |
2007年 | 23330篇 |
2006年 | 12638篇 |
2005年 | 14240篇 |
2004年 | 11981篇 |
2003年 | 11669篇 |
2002年 | 10802篇 |
2001年 | 9317篇 |
2000年 | 7574篇 |
1999年 | 5635篇 |
1998年 | 5308篇 |
1997年 | 4975篇 |
1996年 | 4738篇 |
1995年 | 4111篇 |
1994年 | 4193篇 |
1993年 | 4162篇 |
1992年 | 4072篇 |
1991年 | 4480篇 |
1990年 | 4464篇 |
1989年 | 4401篇 |
1988年 | 4126篇 |
1987年 | 4173篇 |
1986年 | 3831篇 |
1985年 | 4403篇 |
1984年 | 4627篇 |
1983年 | 3992篇 |
1982年 | 4154篇 |
1981年 | 3795篇 |
1980年 | 3549篇 |
1979年 | 4109篇 |
1978年 | 4196篇 |
1977年 | 4237篇 |
1976年 | 4433篇 |
1975年 | 4113篇 |
1974年 | 4014篇 |
1973年 | 4177篇 |
1972年 | 3584篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Nishio Yu Komori Kohei Izawa Seiichiro Fukunishi Yu 《Theoretical and Computational Fluid Dynamics》2020,34(1):105-117
Theoretical and Computational Fluid Dynamics - The present study aims to simulate a collision of two droplets containing immiscible liquids by employing a three- dimensional incompressible smoothed... 相似文献
72.
Synthesis,spectral investigation and development of tetrahedral copper(II) complexes as artificial metallonucleases and antimalarial agents
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Seven new copper(II) complexes of type [Cu(A)(L)]?H2O (A = sparfloxacin, ciprofloxacin, levofloxacin, gatifloxacin, pefloxacin, ofloxacin, norfloxacin; L = 5‐[(3‐chlorophenyl)diazenyl]‐4‐hydroxy‐1,3‐thiazole‐2(3H)‐thione) were synthesized and characterized using elemental and thermogravimetric analyses, and electronic, electron paramagnetic resonance (EPR), Fourier transform infrared and liquid chromatography–mass spectroscopies. Tetrahedral geometry around copper is assigned in all complexes using EPR and electronic spectral analyses. All complexes were investigated for their interaction with herring sperm DNA utilizing absorption titration (Kb = 1.27–3.13 × 105 M?1) and hydrodynamic volume measurement studies. The studies suggest the classical intercalative mode of DNA binding. The cleavage reaction on pUC19 DNA was monitored by agarose gel electrophoresis. The results indicate that the Cu(II) complexes can more effectively promote the cleavage of plasmid DNA. The superoxide dismutase mimic activity of the complexes was evaluated by nitroblue tetrazolium assay, and the complexes catalysed the dismutation of superoxide at pH = 7.8 with IC50 values in the range 0.597–0.900 μM. The complexes were screened for their in vitro antibacterial activity against five pathogenic bacteria. All the complexes are good cytotoxic agents and show LC50 values ranging from 5.559 to 11.912 µg ml?1. All newly synthesized Cu(II) complexes were also evaluated for their in vitro antimalarial activity against Plasmodium falciparum strain (IC50 = 0.62–2.0 µg ml?1). Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
73.
74.
75.
K.V. Stepurska О.О. Soldatkin I.S. Kucherenko V.M. Arkhypova S.V. Dzyadevych A.P. Soldatkin 《Analytica chimica acta》2015
This study was aimed at the development of a conductometric biosensor based on acetylcholinesterase considering the feasibility of its application for the inhibitory analysis of various toxicants. In this paper, the optimum conditions for enzyme immobilization on the transducer surface are selected as well as the optimum concentration of substrate for inhibitory analysis. Sensitivity of the developed biosensor to different classes of toxic compounds (organophosphorus pesticides, heavy metal ions, surfactants, aflatoxin, glycoalkaloids) was tested. It is shown that the developed biosensor can be successfully used for the analysis of pesticides and mycotoxins, as well as for determination of total toxicity of the samples. A new method of biosensor analysis of toxic substances of different classes in complex multicomponent aqueous samples is proposed. 相似文献
76.
77.
78.
79.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献
80.
Gurenkova Yu. S. Kornyakov I. V. Ostrovsky V. A. Skrylnikova M. A. Khramchikhin A. V. 《Russian Journal of General Chemistry》2020,90(7):1202-1206
Russian Journal of General Chemistry - 8-Phenyltetrazolo[5,1-b][1,3,4]thiadiazepine was obtained as a result of intermolecular cyclization of 1-amino-1H-tetrazole-5-thiol and 3-phenyl-2-propynal.... 相似文献