全文获取类型
收费全文 | 253篇 |
免费 | 10篇 |
专业分类
化学 | 182篇 |
晶体学 | 1篇 |
力学 | 14篇 |
数学 | 29篇 |
物理学 | 37篇 |
出版年
2024年 | 2篇 |
2022年 | 8篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 11篇 |
2010年 | 13篇 |
2009年 | 9篇 |
2008年 | 13篇 |
2007年 | 19篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 10篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有263条查询结果,搜索用时 31 毫秒
21.
22.
V. P. Chizhkov V. N. Boitsov A. V. Demin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(2):306-310
The pressure of combined fractions and total entropy changes at pyramidal cascade nodes were estimated for the general case
of processing of a binary mixture with an arbitrary composition. The difference between the work of separation determined
using the Dirac-Peierls potential and the thermodynamically estimated work of mixing of products obtained was shown to be
a consequence of an increase in entropy caused by combining fractions at cascade nodes. 相似文献
23.
Stepan Oryshchyn Volodymyr Babizhetskyy Olga Zhak Jean-Yves Pivan Arndt Simon 《Journal of solid state chemistry》2010,183(11):2534-2543
The new ternary pnictides Er12Ni30P21 and Er13Ni25As19 have been synthesized from the elements. They crystallize with hexagonal structures determined from single-crystal X-ray data for Er12Ni30P21 (space group P63/m, a=1.63900(3) nm, c=0.37573(1) nm, Z=1, RF=0.062 for 1574 F-values and 74 variable parameters), and for Er13Ni25As19 (Tm13Ni25As19-type structure, space group P6?, a=1.6208(1) nm, c=0.38847(2) nm, Z=1, RF=0.026 for 1549 F-values and 116 variable parameters). These compounds belong to a large family of hexagonal structures with a metal-metalloid ratio of 2:1. HRTEM investigations were conducted to probe for local ordering of the disordered structure at the nanoscale. The magnetic properties of the phosphide Er12Ni30P21 have been studied in the temperature of range 2<T<300 K and with applied fields up to 5 T. The magnetic susceptibility follows the Curie-Weiss law from 4 to 300 K. The measured value of μeff=9.59 μB corresponds to the theoretical value of Er3+. 相似文献
24.
25.
Chizhkov V. P. Boitsov V. N. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(11):2315-2319
Russian Journal of Physical Chemistry A - The relationship between the separation capacity and a change in the Gibbs energy of an extraction system with a phase transition of one mixture component... 相似文献
26.
Alexander V. Stepakov Ekatherine A. Popova Liubov V. Stepakova Vitaly M. Boitsov Galina L. Starova Elena V. Grinenko 《Tetrahedron》2010,66(27-28):5262-5269
Imides of arylmaleic acids in the presence of 3,5-dimethyl-1H-pyrazole underwent (4+2) dimerization under heating in chlorobenzene within 24 h to afford 1,2,3,3a,3b,4,5,6,6a,10b-decahydrobenzo[e]pyrrolo[3,4-g]isoindole-1,3,4,6-tetraones in good yields. It was established that during the heating of imides of arylmaleic acid in 2,6-lutidine at 100 °C the (4+2) dimerization products containing a lutidine fragment are obtained. 相似文献
27.
28.
The paper concerns the possibilities for mathematical modelling of safety related systems (equipment oriented on safety). Some mathematical models have been required by the present European Standards for the railway transport. We are interested in the possibility of using Markov's models to meet these Standards. In the text an example of using that method in the interlocking equipment life cycle is given. An efficient aggregation/disaggregation method for computing some characteristics of Markov chains is presented. 相似文献
29.
Structure of Framework Aluminum Lewis Sites and Perturbed Aluminum Atoms in Zeolites as Determined by 27Al{1H} REDOR (3Q) MAS NMR Spectroscopy and DFT/Molecular Mechanics
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Jiří Brus Libor Kobera Dr. Wolfgang Schoefberger Dr. Martina Urbanová Petr Klein Dr. Petr Sazama Dr. Edyta Tabor Dr. Stepan Sklenak Dr. Anna V. Fishchuk Dr. Jiří Dědeček 《Angewandte Chemie (International ed. in English)》2015,54(2):541-545
Zeolites are highly important heterogeneous catalysts. Besides Brønsted SiOHAl acid sites, also framework AlFR Lewis acid sites are often found in their H‐forms. The formation of AlFR Lewis sites in zeolites is a key issue regarding their selectivity in acid‐catalyzed reactions. The local structures of AlFR Lewis sites in dehydrated zeolites and their precursors—“perturbed” AlFR atoms in hydrated zeolites—were studied by high‐resolution MAS NMR and FTIR spectroscopy and DFT/MM calculations. Perturbed framework Al atoms correspond to (SiO)3AlOH groups and are characterized by a broad 27Al NMR resonance (δi=59–62 ppm, CQ=5 MHz, and η=0.3–0.4) with a shoulder at 40 ppm in the 27Al MAS NMR spectrum. Dehydroxylation of (SiO)3AlOH occurs at mild temperatures and leads to the formation of AlFR Lewis sites tricoordinated to the zeolite framework. Al atoms of these (SiO)3Al Lewis sites exhibit an extremely broad 27Al NMR resonance (δi≈67 ppm, CQ≈20 MHz, and η≈0.1). 相似文献
30.
V. P. Chizhkov V. N. Boitsov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(1):138-142
An interpretation of the thermodynamic work performed in fractionation distribution systems upon the separation of a multicomponent mixture is offered. 相似文献