全文获取类型
收费全文 | 3081篇 |
免费 | 127篇 |
国内免费 | 780篇 |
专业分类
化学 | 3693篇 |
晶体学 | 10篇 |
力学 | 11篇 |
综合类 | 26篇 |
数学 | 8篇 |
物理学 | 240篇 |
出版年
2024年 | 5篇 |
2023年 | 39篇 |
2022年 | 99篇 |
2021年 | 98篇 |
2020年 | 100篇 |
2019年 | 96篇 |
2018年 | 71篇 |
2017年 | 103篇 |
2016年 | 99篇 |
2015年 | 98篇 |
2014年 | 144篇 |
2013年 | 263篇 |
2012年 | 253篇 |
2011年 | 167篇 |
2010年 | 158篇 |
2009年 | 184篇 |
2008年 | 203篇 |
2007年 | 209篇 |
2006年 | 184篇 |
2005年 | 163篇 |
2004年 | 167篇 |
2003年 | 147篇 |
2002年 | 127篇 |
2001年 | 86篇 |
2000年 | 86篇 |
1999年 | 91篇 |
1998年 | 64篇 |
1997年 | 71篇 |
1996年 | 70篇 |
1995年 | 50篇 |
1994年 | 52篇 |
1993年 | 55篇 |
1992年 | 38篇 |
1991年 | 33篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 14篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有3988条查询结果,搜索用时 15 毫秒
991.
Amani Kaabi 《合成通讯》2013,43(11):1587-1593
The synthesis of a series of amino ethers was carried out in a two-step method involving phosphorylation of the corresponding amino alcohols and subsequent double displacement via an aziridinium intermediate. The new products were obtained in good yields with excellent regioselectivity. 相似文献
992.
993.
Meihua Xie Gaofeng Lin Jinhua Zhang Ming Li Chengyou Feng 《Journal of organometallic chemistry》2010,695(6):882-9965
(Z)-Tetrasubstituted allylic alcohols bearing sulfonyl group were synthesized regio- and stereoselectively by alkylzincation of acetylenic sulfone followed by addition to aldehyde. 相似文献
994.
A novel nanostructured platform for pyruvate oxidase biosensors comprises poly(neutral red) (PNR) prepared by electropolymerization of NR in ethaline deep eutectic solvent (DES) with acid dopant, on a multiwalled carbon nanotubes (MWCNT) modified glassy carbon electrode (GCE). Characterization was by cyclic voltammetry and electrochemical impedance spectroscopy and morphology was examined by scanning electron microscopy. Ascorbate and H2O2 gave a better response at PNRDES/GCE than at PNRaq/GCE. Biosensors for pyruvate and phosphate, immobilizing pyruvate oxidase onto PNRDES/MWCNT/GCE enabled selective determination of pyruvate and phosphate, with micromolar limits of detection. Pyruvate was determined in onion samples and phosphate in water samples. 相似文献
995.
《Journal of Saudi Chemical Society》2022,26(6):101538
Photocatalytic degradation method is an emerging technique for complete removal of pollutants. Several semiconductor photocatalysts are reported as photocatalysts for industrial wastewater treatment in environmental applications. In this study Magnetite/TS-1 composite materials was used for photocatalytic degradation of phenol. Magnetite nanoparticles (MNP) (10 wt%) were dispersed with nanocrystalline Titanium Silicate-1 zeolite (TS-1). The Magnetite/TS-1 composite materials were characterized with various techniques. The structural analysis reveals the presence of MNP and zeolite-MFI phases in Magnetite/TS-1 composite materials. The average particles size of the magnetite nanoparticles is less than 5 nm and that of the composite nanoparticles are in the range of about 90 nm with micropore volume 0.110 cm3/g and the external surface area 120 m2/g. The photocatalytic experiments were carried out in a thin film flow photoreactor under UV radiation. The results showed that Magnetite/TS-1 composite materials exhibited improved activity for the degradation of phenol compared to TS-1. Preliminary studies proves that aeration is necessary for the photocatalytic reaction. The reaction parameters such as flow rate, pH and phenol concentration are optimized as 8 ml/min, pH 7.0 and 75 mg/L respectively. To understand the active species involved in the degradation of phenol radical scavengers such as NaI, benzoquinone and isopropyl alcohol are used to trap hole (h+), superoxide anion radical and hydroxyl radical (OH), respectively. From the obtained results it is envisaged that hydroxyl radicals are predominantly involved in complete oxidation of phenol. The extent of degradation of phenol was determined by measuring the amount of CO2 formed in the reaction. The results confirms that 99.6 % carbon in phenol is converted to CO2. 相似文献
996.
Hsiao‐Fan Tseng Ming‐Hsiang Cheng Kai‐Sheng Jeng Jia‐Wei Li Jiun‐Tai Chen 《Macromolecular rapid communications》2016,37(22):1825-1831
Anisotropic polymer particles such as Janus particles have attracted significant attention in recent years because of their unique properties and unusual self‐assembly behavior. Most anisotropic polymer particles synthesized so far, however, only have different chemical regions compartmentalized on the particles. It remains a great challenge to fabricate anisotropic polymer particles with different shapes within a single particle. A novel approach is developed to prepare anisotropic polymer particles that contain two hemispheres with different curvatures by annealing polystyrene microspheres on poly(vinyl alcohol) films. During the annealing process, the polymer microspheres gradually sink into the polymer films and transform to asymmetric polymer particles, driven by the surface and interfacial tensions of the polymers. Selective removal techniques are also used to confirm the morphologies of the asymmetric particles.
997.
基于多壁碳纳米管的三电极血乙醇生物传感器的研究 总被引:1,自引:0,他引:1
采用丝网印刷技术在PVC基板上印制三电极,将多壁碳纳米管、麦尔多拉蓝、乙醇脱氢酶(ADH)以及氧化型辅酶Ⅰ(NAD+)依次修饰在工作电极表面,然后在该三电极表面贴一层亲水膜,形成一个5μL反应池,制成血乙醇检测新型生物传感器检测条。结果表明,此生物传感器具有良好的准确性和稳定性;检测线性范围为0.5~20mmol/L,r=0.99493;检出限为0.22mmol/L;电流达到95%稳态时间小于15s。考察了pH值、温度及干扰物对生物传感器的影响。用此生物传感器和顶空气相色谱法对10份全血标本乙醇浓度平行测试,两者相关性良好r=0.97583。利用虹吸现象吸取微量全血直接定量测定乙醇浓度是此生物传感器的特点。 相似文献
998.
999.
1000.
Fausto N. Comba María D. Rubianes Lourdes Cabrera Silvia Gutiérrez Pilar Herrasti Gustavo A. Rivas 《Electroanalysis》2010,22(14):1566-1572
This work reports the advantages of carbon paste electrodes modified with electrogenerated magnetite nanoparticles. The nanoparticles present catalytic activity towards hydrogen peroxide reduction. The incorporation of glucose oxidase (GOx) and magnetite in a carbon paste matrix have made possible the development of an efficient glucose biosensor. The effect of the amount of GOx and magnetite present in the composite on the response of the biosensor was critically evaluated. The biosensors demonstrated to be highly selective, with negligible interference of ascorbic acid and uric acid. The proposed biosensor was challenged with human blood serum demonstrating an excellent correlation with the spectrophotometric method. 相似文献