全文获取类型
收费全文 | 518篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
化学 | 305篇 |
晶体学 | 9篇 |
力学 | 8篇 |
数学 | 62篇 |
物理学 | 143篇 |
出版年
2021年 | 8篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 16篇 |
2012年 | 21篇 |
2011年 | 30篇 |
2010年 | 9篇 |
2009年 | 14篇 |
2008年 | 20篇 |
2007年 | 27篇 |
2006年 | 21篇 |
2005年 | 12篇 |
2004年 | 23篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 18篇 |
1993年 | 19篇 |
1992年 | 22篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 14篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1959年 | 1篇 |
1909年 | 2篇 |
排序方式: 共有527条查询结果,搜索用时 0 毫秒
101.
Kathy C. Chuang Daniel A. Scheiman Joyce Fu Marcus Crawford 《Journal of polymer science. Part A, Polymer chemistry》1999,37(14):2559-2567
Thermoplastic and thermoset polyimides derived from 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) and 4,4′-bis(4-aminophenoxy)-2,2′-dimethylbiphenyl (BAPD) were prepared and characterized. Their physical and thermal properties as well as the polyelectrolyte effect exhibited by BTDA–BAPP polyamic acids in NMP solution were discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2559–2567, 1999 相似文献
102.
The ability of microscopically organized media, in the form of surfactant micelles and α- and β-cyclodextrins, to enhance the luminescence phenomena of several licit and illicit drugs is discussed. Because physiological samples are not often amenable to direct spectrometric measurements without pretreatment, the applicability of these organized media to liquid chromatography is also considered. Fluorescence enhancements for certain hallucinogenic drugs such as N,N-dimethyltryptamine, mescaline and ibogaine are seen in cyclodextrin media compared to conventional, homogeneous solutions. Heavy-atom substituted sodium dodecyl sulfate micelles induce phosphorescence from cationic and/or hydrophobic drugs at room temperature in fluid solution; drugs such as propranolol, diflunisal, naphalozine, and selected quinoline derivatives can be determined conveniently. Sensitized phosphorescence is observed for several drugs including brethine, cocaine, didrate, estradiol, meprobarbital, methaqualone, phenobarbital, and sulfanilamide; it can be enhanced markedly when micellar solutions are used as the solvent. The energy-transfer step is facilitated by the organizing ability of the micelle; limits of detection can be decreased by over two orders of magnitude compared to homogeneous solvents. Sensitized phosphorescence can also be measured in cyclodextrin solutions, but the detectability is inferior to that in micellar media. Which form of organized medium is superior for determination of drugs is discussed. 相似文献
103.
W. Franklin Smyth Venkataraman N. Ramachandran Catherine J. Hack Clare Joyce Edmund O’Kane 《Analytica chimica acta》2006,564(2):201-210
The aim of this paper is to provide analytical chemical information on a range of naturally occurring and synthetic coumarins. This analytical chemical information on liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS), ion trap mass spectrometry (ESI-MSn), gas chromatography-flame ionisation detection (GLC-FID) and polarographic behaviour is then incorporated into a database which is of use in identifying unknown coumarins isolated from natural sources. This paper is also concerned with understanding the effect of functional groups in coumarins on their analytical chemical behaviour using the above techniques. 相似文献
104.
Yury V. Kissin Anita J. Brandolini Joyce L. Garlick 《Journal of polymer science. Part A, Polymer chemistry》2008,46(16):5315-5329
Principal kinetic data are presented for ethylene homopolymerization and ethylene/1‐hexene copolymerization reactions with two types of chromium oxide catalyst. The reaction rate of the homopolymerization reaction is first order with respect to ethylene concentration (both for gas‐phase and slurry reactions); its effective activation energy is 10.2 kcal/mol (42.8 kJ/mol). The r1 value for ethylene/1‐hexene copolymerization reactions with the catalysts is ~30, which places these catalysts in terms of efficiency of α‐olefin copolymerization with ethylene between metallocene catalysts (r1 ~ 20) and Ti‐based Ziegler‐Natta catalysts (r1 in the 80–120 range). GPC, DSC, and Crystaf data for ethylene/1‐hexene copolymers of different compositions produced with the catalysts show that the reaction products have broad molecular weight and compositional distributions. A combination of kinetic data and structural data for the copolymers provided detailed information about the frequency of chain transfer reactions for several types of active centers present in the catalysts, their copolymerization efficiency, and stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5315–5329, 2008 相似文献
105.
This paper describes a method for the numerical solution of a Riabouchinsky cavity flow. Application of a boundary element method leads to a system of non-linear equations. The mild singularity appearing at the separation point is treated with the introduction of a curved boundary element, which satisfies the exact behaviour of the free boundary in that neighbourhood. 相似文献
106.
107.
108.
109.
110.