全文获取类型
收费全文 | 440585篇 |
免费 | 20780篇 |
国内免费 | 12869篇 |
专业分类
化学 | 256980篇 |
晶体学 | 5443篇 |
力学 | 20206篇 |
综合类 | 683篇 |
数学 | 47900篇 |
物理学 | 143022篇 |
出版年
2022年 | 3454篇 |
2021年 | 5606篇 |
2020年 | 6704篇 |
2019年 | 6727篇 |
2018年 | 6757篇 |
2017年 | 6523篇 |
2016年 | 10282篇 |
2015年 | 8465篇 |
2014年 | 11382篇 |
2013年 | 23125篇 |
2012年 | 20668篇 |
2011年 | 23866篇 |
2010年 | 16221篇 |
2009年 | 16155篇 |
2008年 | 19811篇 |
2007年 | 19021篇 |
2006年 | 17968篇 |
2005年 | 16002篇 |
2004年 | 13991篇 |
2003年 | 12121篇 |
2002年 | 11562篇 |
2001年 | 13054篇 |
2000年 | 10213篇 |
1999年 | 8372篇 |
1998年 | 6632篇 |
1997年 | 6324篇 |
1996年 | 5800篇 |
1995年 | 5545篇 |
1994年 | 5261篇 |
1993年 | 4765篇 |
1992年 | 5542篇 |
1991年 | 5313篇 |
1990年 | 4912篇 |
1989年 | 4731篇 |
1988年 | 4677篇 |
1987年 | 4589篇 |
1986年 | 4361篇 |
1985年 | 5868篇 |
1984年 | 5786篇 |
1983年 | 4559篇 |
1982年 | 4778篇 |
1981年 | 4712篇 |
1980年 | 4454篇 |
1979年 | 4683篇 |
1978年 | 4793篇 |
1977年 | 4848篇 |
1976年 | 4661篇 |
1975年 | 4394篇 |
1974年 | 4266篇 |
1973年 | 4288篇 |
排序方式: 共有10000条查询结果,搜索用时 474 毫秒
11.
High Energy Chemistry - Modification of Polyvinylidene fluoride (PVDF) by radiation grafting is a research hotspot in recent years. In this study, the monomer 2-Hydroxyethyl methacrylate (HEMA) was... 相似文献
12.
In the pursuit to enlarge the library of polyimide materials for energy applications, new polyimide/MWCNTs composite films have been developed by MWCNTs-assisted polycondensation reaction of a hydroxyl and triphenylmethane-containing diamine with benzophenone tetracarboxylic dianhydride targeting to highlight their electrical storage capability as flexible electrodes in micro-supercapacitors (mSCs). The Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, UV–vis, fluorescence, and Raman spectroscopies were used to demonstrate the evolution of interfacial interactions between MWCNTs and the precursors (diamine monomer and intermediate polyamidic acid) and polyimide matrix that proved to be the origin of MWCNTs homogeneous dispersion. Thus, composite films incorporating 1, 3, 5, and 10 w.t.% MWCNTs were obtained and thoroughly investigated with regard to their morphology, mechanical behavior, thermal stability, and electrical conductivity. The electrochemical performance of these composites was first analyzed in a classical three-electrode cell by cyclic voltammetry and galvanostatic charge-discharge in both aqueous and organic electrolyte systems. By far, the best electrical storage capacity was obtained with the composite polyimide film containing 10% MWCNTs that was further used as both active material and current collector in a flexible symmetric mSC realized by a straightforward and low-cost procedure. In the attempt to better exploit the advantages of this composite film, it was layered with a graphite-containing paint and tested as an electrode in a flexible mSC, which provided satisfactory results. To our knowledge, this is the first report on the electrical charge storage capability of a polyimide/MWCNTs free-standing film as a flexible electrode in mSCs, which do not require time- and resource-consuming processing steps. 相似文献
13.
14.
15.
16.
Roopa K. P. Keshavamurthy K. Mahesh B. Veena K. P. Shankara B. S. Basavaiah K. 《Journal of Applied Spectroscopy》2022,89(4):809-818
Journal of Applied Spectroscopy - Three simple, sensitive, precise, and rapid spectrophotometric methods are developed and optimized for the assay of vardenafil in pharmaceutical formulations. The... 相似文献
17.
Moroz Ya. A. Lozinskyy N. S. Lopanov A. N. Chebyshev K. A. 《Russian Journal of General Chemistry》2022,92(1):101-107
Russian Journal of General Chemistry - Tungstophosphatozincates with the Keggin anion structure Kt5[PW11O39Zn(H2O)]?nH2O, Kt = Rb+, Cs+, (CH3)4N+; (C2H5)4N+ were synthesized. Their... 相似文献
18.
Filatova S. M. Guseva M. K. Bodrova T. G. Parshina D. V. Budanova U. A. Sebyakin Yu. L. 《Russian Journal of General Chemistry》2022,91(1):S13-S23
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial... 相似文献
19.
20.
Russian Journal of Organic Chemistry - A highly efficient green protocol has been proposed for the synthesis of symmetrical S-aryl arenesulfonothioates by irradiation of N-hydroxy arenesulfonamides... 相似文献