全文获取类型
收费全文 | 404篇 |
免费 | 18篇 |
国内免费 | 5篇 |
专业分类
化学 | 294篇 |
晶体学 | 2篇 |
力学 | 8篇 |
数学 | 49篇 |
物理学 | 74篇 |
出版年
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 9篇 |
2020年 | 14篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 32篇 |
2013年 | 64篇 |
2012年 | 30篇 |
2011年 | 27篇 |
2010年 | 20篇 |
2009年 | 17篇 |
2008年 | 13篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 15篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有427条查询结果,搜索用时 15 毫秒
121.
122.
Peter Munk Malek T. Abijaoude Michael E. Halbrook 《Journal of Polymer Science.Polymer Physics》1978,16(1):105-115
The intrinsic viscosity of a single sample of polystyrene was measured as a function of the composition of solvent in three mixed solvent pairs. The parameter Y introduced by Shultz and Flory was useful for prediction of trends, but severely overestimated the effect of solvent (1)–solvent (2) interaction on the expansion of polymer coils. The system polystyrene–cyclohexane–ethyl acetate was studied in detail for five samples of polystyrene. The analysis of the data provided strong experimental proof of a strict validity of the Mark–Houwink–Sakurada relation. The dependence of the Mark–Houwink–Sakurada exponent α on the composition of the solvent mixture was unexpectedly unsymmetrical. The unperturbed dimentions of the polystyrene chain are reduced by specific interaction of polystyrene with carbonyl groups in the solvent mixture. 相似文献
123.
Efficient aerobic oxidation of benzylic compounds using NHTPPI, a new NHPI analogue, as a key catalyst combined with CuCl, have been achieved under mild conditions and using as little as 1 mol% catalyst. 相似文献
124.
Tom Lada 《Applied Categorical Structures》2004,12(1):29-34
It is shown that the direct sum of an L
algebra and a module over it has a natural L
algebra structure. 相似文献
125.
126.
127.
Alexey N. Egorochkin Olga V. Kuznetsova Nadiya M. Khamaletdinova Lada G. Domratcheva‐Lvova 《Magnetic resonance in chemistry : MRC》2012,50(1):40-51
The literature data on substituent influence on the nuclear quadrupole resonance frequencies (ν), quadrupole coupling constants (e2Qq ? h? 1), and asymmetry parameters (η) for 36 series of the H‐complexes, charge–transfer complexes, transition metal complexes and other donor–acceptor complexes have been considered, using the correlation analysis. Generally the ν, e2Qq ? h? 1, and η values were first established to depend on the inductive, resonance, polarizability, and steric effects of substituents. The presence or otherwise of certain effects as well as relation between their contributions are determined by the type of series. The polarizability effect owes its existence to the appearance of an excess charge on the indicator centre as a result of the complexation. The contribution of this effect ranges up to 75%. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
128.
129.
In this study, new Fe3O4@gly@thiophen@Cu(NO3)2 magnetic nanoparticles were synthesized. The final product was used as an efficient and novel magnetic nanocatalyst for synthesizing new derivatives of thiazolo[3,2-a] chromeno[4,3-d]pyrimidine-6(7H) in a short time and with higher efficiency. In the synthesis of Fe3O4@gly@thiophen@Cu(NO3)2 magnetic nanoparticles, the use of glycine proved an inexpensive and readily available coating for Fe3O4 than previously reported materials, and the structure was confirmed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive x-ray (EDX) spectroscopy, EDX mapping, Fourier-transform infrared spectroscopy, thermogravimetric analysis/derivative thermogravimetry, and vibrating sample magnetometry. The biological properties of magnetic nanoparticles were evaluated, and they exhibited acceptable antifungal and antibacterial properties in terms of minimum inhibitory concentration, minimum fungicidal concentration, and minimum bactericidal concentration. 相似文献
130.
Issa Yavari Mohammad Bayat Malek T. Maghsoodlou Norollah Hazeri 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2599-2610
Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and strong NH-acids, such as acetanilide, 4-methylacetanilide, 2-cyanoacetanilide, 4-bromoacetanilide, 4-methoxyacetanilide, succinimide, malimide, or phthalimide. These stabilized phosphoranes exist as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. 相似文献