全文获取类型
收费全文 | 392篇 |
免费 | 4篇 |
专业分类
化学 | 320篇 |
晶体学 | 11篇 |
力学 | 7篇 |
数学 | 22篇 |
物理学 | 36篇 |
出版年
2023年 | 1篇 |
2022年 | 22篇 |
2021年 | 30篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 10篇 |
2013年 | 25篇 |
2012年 | 18篇 |
2011年 | 22篇 |
2010年 | 18篇 |
2009年 | 18篇 |
2008年 | 25篇 |
2007年 | 23篇 |
2006年 | 24篇 |
2005年 | 22篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 17篇 |
2001年 | 16篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有396条查询结果,搜索用时 31 毫秒
391.
Monika Szymaska-Chargot Jolanta Ciela Patrycja Pkala Piotr M. Pieczywek Wiesaw Oleszek Marcin ya Zbigniew Szkopek Artur Zdunek 《Molecules (Basel, Switzerland)》2022,27(9)
The goal of this work is to evaluate the hop stems, a byproduct of hop cones production, as a potential source of cellulose. Hop stems contain up to 29% of cellulose. The cellulose isolation was conducted through the thermochemical treatment. After high-speed blending, the cellulose was characterized by 67% of crystallinity degree obtained from X-ray diffraction and median diameter of 6.7 nm obtained from atomic force microscopy imaging. The high-intensity ultrasonication (HIUS) was applied to reach further disintegration of cellulose fibers. The longer HIUS treatment resulted in decrease in crystallinity degree even up to 60% and decrease in the fiber diameter up to 4 nm. The Fourier transform infrared spectroscopy (FTIR) spectra showed that HIUS treatment led to changes in intermolecular hydrogen bonds. The stability of cellulose dispersions versus length of HIUS treatment was monitored over 14 days with back dynamic light scattering and laser Doppler electrophoresis methods. Obtained results are evidence that the hop stems are a potential source of cellulose and that it is possible to obtain stable dispersions after HIUS treatment. This was the first time that the properties of hop cellulose have been described so extensively and in detail after the use of HIUS treatment. 相似文献
392.
393.
Jolanta Baran Andrzej Duda Adam Kowalski Ryszard Szymanski Stanislaw Penczek 《Macromolecular rapid communications》1997,18(4):325-333
A general kinetic treatment of the system with intermolecular chain transfer followed by fast reinitiation is given. It leads to the broadening of the molecular weight distribution (MWD), the number of growing chains being invariable. Thus, this system can be considered as a special case of living polymerization. A general method has been elaborated allowing the determination of the ratio of the rate constant of propagation (kp) to the rate constant of the bimolecular transfer (k(2)tr) from the dependence of the MWD on monomer conversion. Numerical values of kp/k(2)tr equal to ≈ 102 and 25 were thus determined for the polymerization of L , L -lactide (L , L -dilactide) initiated with aluminium tris(isopropoxide) trimer ({Al(OiPr)3}3) and tributyltin ethoxide (nBu3SnOEt), respectively. 相似文献
394.
Jolanta Prywer 《Crystal Research and Technology》1994,29(2):K17-K20
Influence of growth velocities of first and second neighbours on the presence and size of the face in the crystal habit has been studied. It was established and confirmed that the consecutive neighbour affects the face size only after the disappearance of the previous neighbour. The formula for critical growth velocity governing disappearance of faces has been discussed. 相似文献
395.
The polycondensation of methyl α-D-mannopyranoside ( 1 ) with 1,n-bis(formylphenoxy)alkanes ( 2 ), using acidic catalysts, leads to the formation of linear polymers and macrocyclic compounds. The structure of the polymer and macrocycles was determined by 1H, 13C NMR spectroscopy and ESI-MS analysis. 相似文献
396.